4 TGSI, Tungsten Graphics Shader Infrastructure, is an intermediate language
5 for describing shaders. Since Gallium is inherently shaderful, shaders are
6 an important part of the API. TGSI is the only intermediate representation
12 All TGSI instructions, known as *opcodes*, operate on arbitrary-precision
13 floating-point four-component vectors. An opcode may have up to one
14 destination register, known as *dst*, and between zero and three source
15 registers, called *src0* through *src2*, or simply *src* if there is only
18 Some instructions, like :opcode:`I2F`, permit re-interpretation of vector
19 components as integers. Other instructions permit using registers as
20 two-component vectors with double precision; see :ref:`doubleopcodes`.
22 When an instruction has a scalar result, the result is usually copied into
23 each of the components of *dst*. When this happens, the result is said to be
24 *replicated* to *dst*. :opcode:`RCP` is one such instruction.
29 TGSI supports modifiers on inputs (as well as saturate modifier on instructions).
31 For inputs which have a floating point type, both absolute value and negation
32 modifiers are supported (with absolute value being applied first).
33 TGSI_OPCODE_MOV is considered to have float input type for applying modifiers.
35 For inputs which have signed or unsigned type only the negate modifier is
42 ^^^^^^^^^^^^^^^^^^^^^^^^^
44 These opcodes are guaranteed to be available regardless of the driver being
47 .. opcode:: ARL - Address Register Load
51 dst.x = (int) \lfloor src.x\rfloor
53 dst.y = (int) \lfloor src.y\rfloor
55 dst.z = (int) \lfloor src.z\rfloor
57 dst.w = (int) \lfloor src.w\rfloor
60 .. opcode:: MOV - Move
73 .. opcode:: LIT - Light Coefficients
78 dst.y &= max(src.x, 0) \\
79 dst.z &= (src.x > 0) ? max(src.y, 0)^{clamp(src.w, -128, 128))} : 0 \\
83 .. opcode:: RCP - Reciprocal
85 This instruction replicates its result.
92 .. opcode:: RSQ - Reciprocal Square Root
94 This instruction replicates its result. The results are undefined for src <= 0.
98 dst = \frac{1}{\sqrt{src.x}}
101 .. opcode:: SQRT - Square Root
103 This instruction replicates its result. The results are undefined for src < 0.
110 .. opcode:: EXP - Approximate Exponential Base 2
114 dst.x &= 2^{\lfloor src.x\rfloor} \\
115 dst.y &= src.x - \lfloor src.x\rfloor \\
116 dst.z &= 2^{src.x} \\
120 .. opcode:: LOG - Approximate Logarithm Base 2
124 dst.x &= \lfloor\log_2{|src.x|}\rfloor \\
125 dst.y &= \frac{|src.x|}{2^{\lfloor\log_2{|src.x|}\rfloor}} \\
126 dst.z &= \log_2{|src.x|} \\
130 .. opcode:: MUL - Multiply
134 dst.x = src0.x \times src1.x
136 dst.y = src0.y \times src1.y
138 dst.z = src0.z \times src1.z
140 dst.w = src0.w \times src1.w
143 .. opcode:: ADD - Add
147 dst.x = src0.x + src1.x
149 dst.y = src0.y + src1.y
151 dst.z = src0.z + src1.z
153 dst.w = src0.w + src1.w
156 .. opcode:: DP3 - 3-component Dot Product
158 This instruction replicates its result.
162 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
165 .. opcode:: DP4 - 4-component Dot Product
167 This instruction replicates its result.
171 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
174 .. opcode:: DST - Distance Vector
179 dst.y &= src0.y \times src1.y\\
184 .. opcode:: MIN - Minimum
188 dst.x = min(src0.x, src1.x)
190 dst.y = min(src0.y, src1.y)
192 dst.z = min(src0.z, src1.z)
194 dst.w = min(src0.w, src1.w)
197 .. opcode:: MAX - Maximum
201 dst.x = max(src0.x, src1.x)
203 dst.y = max(src0.y, src1.y)
205 dst.z = max(src0.z, src1.z)
207 dst.w = max(src0.w, src1.w)
210 .. opcode:: SLT - Set On Less Than
214 dst.x = (src0.x < src1.x) ? 1.0F : 0.0F
216 dst.y = (src0.y < src1.y) ? 1.0F : 0.0F
218 dst.z = (src0.z < src1.z) ? 1.0F : 0.0F
220 dst.w = (src0.w < src1.w) ? 1.0F : 0.0F
223 .. opcode:: SGE - Set On Greater Equal Than
227 dst.x = (src0.x >= src1.x) ? 1.0F : 0.0F
229 dst.y = (src0.y >= src1.y) ? 1.0F : 0.0F
231 dst.z = (src0.z >= src1.z) ? 1.0F : 0.0F
233 dst.w = (src0.w >= src1.w) ? 1.0F : 0.0F
236 .. opcode:: MAD - Multiply And Add
240 dst.x = src0.x \times src1.x + src2.x
242 dst.y = src0.y \times src1.y + src2.y
244 dst.z = src0.z \times src1.z + src2.z
246 dst.w = src0.w \times src1.w + src2.w
249 .. opcode:: SUB - Subtract
253 dst.x = src0.x - src1.x
255 dst.y = src0.y - src1.y
257 dst.z = src0.z - src1.z
259 dst.w = src0.w - src1.w
262 .. opcode:: LRP - Linear Interpolate
266 dst.x = src0.x \times src1.x + (1 - src0.x) \times src2.x
268 dst.y = src0.y \times src1.y + (1 - src0.y) \times src2.y
270 dst.z = src0.z \times src1.z + (1 - src0.z) \times src2.z
272 dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w
275 .. opcode:: FMA - Fused Multiply-Add
277 Perform a * b + c with no intermediate rounding step.
281 dst.x = src0.x \times src1.x + src2.x
283 dst.y = src0.y \times src1.y + src2.y
285 dst.z = src0.z \times src1.z + src2.z
287 dst.w = src0.w \times src1.w + src2.w
290 .. opcode:: DP2A - 2-component Dot Product And Add
294 dst.x = src0.x \times src1.x + src0.y \times src1.y + src2.x
296 dst.y = src0.x \times src1.x + src0.y \times src1.y + src2.x
298 dst.z = src0.x \times src1.x + src0.y \times src1.y + src2.x
300 dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x
303 .. opcode:: FRC - Fraction
307 dst.x = src.x - \lfloor src.x\rfloor
309 dst.y = src.y - \lfloor src.y\rfloor
311 dst.z = src.z - \lfloor src.z\rfloor
313 dst.w = src.w - \lfloor src.w\rfloor
316 .. opcode:: CLAMP - Clamp
320 dst.x = clamp(src0.x, src1.x, src2.x)
322 dst.y = clamp(src0.y, src1.y, src2.y)
324 dst.z = clamp(src0.z, src1.z, src2.z)
326 dst.w = clamp(src0.w, src1.w, src2.w)
329 .. opcode:: FLR - Floor
333 dst.x = \lfloor src.x\rfloor
335 dst.y = \lfloor src.y\rfloor
337 dst.z = \lfloor src.z\rfloor
339 dst.w = \lfloor src.w\rfloor
342 .. opcode:: ROUND - Round
355 .. opcode:: EX2 - Exponential Base 2
357 This instruction replicates its result.
364 .. opcode:: LG2 - Logarithm Base 2
366 This instruction replicates its result.
373 .. opcode:: POW - Power
375 This instruction replicates its result.
379 dst = src0.x^{src1.x}
381 .. opcode:: XPD - Cross Product
385 dst.x = src0.y \times src1.z - src1.y \times src0.z
387 dst.y = src0.z \times src1.x - src1.z \times src0.x
389 dst.z = src0.x \times src1.y - src1.x \times src0.y
394 .. opcode:: ABS - Absolute
407 .. opcode:: DPH - Homogeneous Dot Product
409 This instruction replicates its result.
413 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
416 .. opcode:: COS - Cosine
418 This instruction replicates its result.
425 .. opcode:: DDX, DDX_FINE - Derivative Relative To X
427 The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
428 advertised. When it is, the fine version guarantees one derivative per row
429 while DDX is allowed to be the same for the entire 2x2 quad.
433 dst.x = partialx(src.x)
435 dst.y = partialx(src.y)
437 dst.z = partialx(src.z)
439 dst.w = partialx(src.w)
442 .. opcode:: DDY, DDY_FINE - Derivative Relative To Y
444 The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
445 advertised. When it is, the fine version guarantees one derivative per column
446 while DDY is allowed to be the same for the entire 2x2 quad.
450 dst.x = partialy(src.x)
452 dst.y = partialy(src.y)
454 dst.z = partialy(src.z)
456 dst.w = partialy(src.w)
459 .. opcode:: PK2H - Pack Two 16-bit Floats
461 This instruction replicates its result.
465 dst = f32\_to\_f16(src.x) | f32\_to\_f16(src.y) << 16
468 .. opcode:: PK2US - Pack Two Unsigned 16-bit Scalars
473 .. opcode:: PK4B - Pack Four Signed 8-bit Scalars
478 .. opcode:: PK4UB - Pack Four Unsigned 8-bit Scalars
483 .. opcode:: SEQ - Set On Equal
487 dst.x = (src0.x == src1.x) ? 1.0F : 0.0F
489 dst.y = (src0.y == src1.y) ? 1.0F : 0.0F
491 dst.z = (src0.z == src1.z) ? 1.0F : 0.0F
493 dst.w = (src0.w == src1.w) ? 1.0F : 0.0F
496 .. opcode:: SGT - Set On Greater Than
500 dst.x = (src0.x > src1.x) ? 1.0F : 0.0F
502 dst.y = (src0.y > src1.y) ? 1.0F : 0.0F
504 dst.z = (src0.z > src1.z) ? 1.0F : 0.0F
506 dst.w = (src0.w > src1.w) ? 1.0F : 0.0F
509 .. opcode:: SIN - Sine
511 This instruction replicates its result.
518 .. opcode:: SLE - Set On Less Equal Than
522 dst.x = (src0.x <= src1.x) ? 1.0F : 0.0F
524 dst.y = (src0.y <= src1.y) ? 1.0F : 0.0F
526 dst.z = (src0.z <= src1.z) ? 1.0F : 0.0F
528 dst.w = (src0.w <= src1.w) ? 1.0F : 0.0F
531 .. opcode:: SNE - Set On Not Equal
535 dst.x = (src0.x != src1.x) ? 1.0F : 0.0F
537 dst.y = (src0.y != src1.y) ? 1.0F : 0.0F
539 dst.z = (src0.z != src1.z) ? 1.0F : 0.0F
541 dst.w = (src0.w != src1.w) ? 1.0F : 0.0F
544 .. opcode:: TEX - Texture Lookup
546 for array textures src0.y contains the slice for 1D,
547 and src0.z contain the slice for 2D.
549 for shadow textures with no arrays (and not cube map),
550 src0.z contains the reference value.
552 for shadow textures with arrays, src0.z contains
553 the reference value for 1D arrays, and src0.w contains
554 the reference value for 2D arrays and cube maps.
556 for cube map array shadow textures, the reference value
557 cannot be passed in src0.w, and TEX2 must be used instead.
563 shadow_ref = src0.z or src0.w (optional)
567 dst = texture\_sample(unit, coord, shadow_ref)
570 .. opcode:: TEX2 - Texture Lookup (for shadow cube map arrays only)
572 this is the same as TEX, but uses another reg to encode the
583 dst = texture\_sample(unit, coord, shadow_ref)
588 .. opcode:: TXD - Texture Lookup with Derivatives
600 dst = texture\_sample\_deriv(unit, coord, ddx, ddy)
603 .. opcode:: TXP - Projective Texture Lookup
607 coord.x = src0.x / src0.w
609 coord.y = src0.y / src0.w
611 coord.z = src0.z / src0.w
617 dst = texture\_sample(unit, coord)
620 .. opcode:: UP2H - Unpack Two 16-Bit Floats
624 dst.x = f16\_to\_f32(src0.x \& 0xffff)
626 dst.y = f16\_to\_f32(src0.x >> 16)
628 dst.z = f16\_to\_f32(src0.x \& 0xffff)
630 dst.w = f16\_to\_f32(src0.x >> 16)
634 Considered for removal.
636 .. opcode:: UP2US - Unpack Two Unsigned 16-Bit Scalars
642 Considered for removal.
644 .. opcode:: UP4B - Unpack Four Signed 8-Bit Values
650 Considered for removal.
652 .. opcode:: UP4UB - Unpack Four Unsigned 8-Bit Scalars
658 Considered for removal.
661 .. opcode:: ARR - Address Register Load With Round
665 dst.x = (int) round(src.x)
667 dst.y = (int) round(src.y)
669 dst.z = (int) round(src.z)
671 dst.w = (int) round(src.w)
674 .. opcode:: SSG - Set Sign
678 dst.x = (src.x > 0) ? 1 : (src.x < 0) ? -1 : 0
680 dst.y = (src.y > 0) ? 1 : (src.y < 0) ? -1 : 0
682 dst.z = (src.z > 0) ? 1 : (src.z < 0) ? -1 : 0
684 dst.w = (src.w > 0) ? 1 : (src.w < 0) ? -1 : 0
687 .. opcode:: CMP - Compare
691 dst.x = (src0.x < 0) ? src1.x : src2.x
693 dst.y = (src0.y < 0) ? src1.y : src2.y
695 dst.z = (src0.z < 0) ? src1.z : src2.z
697 dst.w = (src0.w < 0) ? src1.w : src2.w
700 .. opcode:: KILL_IF - Conditional Discard
702 Conditional discard. Allowed in fragment shaders only.
706 if (src.x < 0 || src.y < 0 || src.z < 0 || src.w < 0)
711 .. opcode:: KILL - Discard
713 Unconditional discard. Allowed in fragment shaders only.
716 .. opcode:: SCS - Sine Cosine
729 .. opcode:: TXB - Texture Lookup With Bias
731 for cube map array textures and shadow cube maps, the bias value
732 cannot be passed in src0.w, and TXB2 must be used instead.
734 if the target is a shadow texture, the reference value is always
735 in src.z (this prevents shadow 3d and shadow 2d arrays from
736 using this instruction, but this is not needed).
752 dst = texture\_sample(unit, coord, bias)
755 .. opcode:: TXB2 - Texture Lookup With Bias (some cube maps only)
757 this is the same as TXB, but uses another reg to encode the
758 lod bias value for cube map arrays and shadow cube maps.
759 Presumably shadow 2d arrays and shadow 3d targets could use
760 this encoding too, but this is not legal.
762 shadow cube map arrays are neither possible nor required.
772 dst = texture\_sample(unit, coord, bias)
775 .. opcode:: DIV - Divide
779 dst.x = \frac{src0.x}{src1.x}
781 dst.y = \frac{src0.y}{src1.y}
783 dst.z = \frac{src0.z}{src1.z}
785 dst.w = \frac{src0.w}{src1.w}
788 .. opcode:: DP2 - 2-component Dot Product
790 This instruction replicates its result.
794 dst = src0.x \times src1.x + src0.y \times src1.y
797 .. opcode:: TXL - Texture Lookup With explicit LOD
799 for cube map array textures, the explicit lod value
800 cannot be passed in src0.w, and TXL2 must be used instead.
802 if the target is a shadow texture, the reference value is always
803 in src.z (this prevents shadow 3d / 2d array / cube targets from
804 using this instruction, but this is not needed).
820 dst = texture\_sample(unit, coord, lod)
823 .. opcode:: TXL2 - Texture Lookup With explicit LOD (for cube map arrays only)
825 this is the same as TXL, but uses another reg to encode the
827 Presumably shadow 3d / 2d array / cube targets could use
828 this encoding too, but this is not legal.
830 shadow cube map arrays are neither possible nor required.
840 dst = texture\_sample(unit, coord, lod)
843 .. opcode:: PUSHA - Push Address Register On Stack
852 Considered for cleanup.
856 Considered for removal.
858 .. opcode:: POPA - Pop Address Register From Stack
867 Considered for cleanup.
871 Considered for removal.
874 .. opcode:: CALLNZ - Subroutine Call If Not Zero
880 Considered for cleanup.
884 Considered for removal.
888 ^^^^^^^^^^^^^^^^^^^^^^^^
890 These opcodes are primarily provided for special-use computational shaders.
891 Support for these opcodes indicated by a special pipe capability bit (TBD).
893 XXX doesn't look like most of the opcodes really belong here.
895 .. opcode:: CEIL - Ceiling
899 dst.x = \lceil src.x\rceil
901 dst.y = \lceil src.y\rceil
903 dst.z = \lceil src.z\rceil
905 dst.w = \lceil src.w\rceil
908 .. opcode:: TRUNC - Truncate
921 .. opcode:: MOD - Modulus
925 dst.x = src0.x \bmod src1.x
927 dst.y = src0.y \bmod src1.y
929 dst.z = src0.z \bmod src1.z
931 dst.w = src0.w \bmod src1.w
934 .. opcode:: UARL - Integer Address Register Load
936 Moves the contents of the source register, assumed to be an integer, into the
937 destination register, which is assumed to be an address (ADDR) register.
940 .. opcode:: SAD - Sum Of Absolute Differences
944 dst.x = |src0.x - src1.x| + src2.x
946 dst.y = |src0.y - src1.y| + src2.y
948 dst.z = |src0.z - src1.z| + src2.z
950 dst.w = |src0.w - src1.w| + src2.w
953 .. opcode:: TXF - Texel Fetch
955 As per NV_gpu_shader4, extract a single texel from a specified texture
956 image. The source sampler may not be a CUBE or SHADOW. src 0 is a
957 four-component signed integer vector used to identify the single texel
958 accessed. 3 components + level. Just like texture instructions, an optional
959 offset vector is provided, which is subject to various driver restrictions
960 (regarding range, source of offsets).
961 TXF(uint_vec coord, int_vec offset).
964 .. opcode:: TXQ - Texture Size Query
966 As per NV_gpu_program4, retrieve the dimensions of the texture depending on
967 the target. For 1D (width), 2D/RECT/CUBE (width, height), 3D (width, height,
968 depth), 1D array (width, layers), 2D array (width, height, layers).
969 Also return the number of accessible levels (last_level - first_level + 1)
972 For components which don't return a resource dimension, their value
979 dst.x = texture\_width(unit, lod)
981 dst.y = texture\_height(unit, lod)
983 dst.z = texture\_depth(unit, lod)
985 dst.w = texture\_levels(unit)
988 .. opcode:: TXQS - Texture Samples Query
990 This retrieves the number of samples in the texture, and stores it
991 into the x component. The other components are undefined.
995 dst.x = texture\_samples(unit)
998 .. opcode:: TG4 - Texture Gather
1000 As per ARB_texture_gather, gathers the four texels to be used in a bi-linear
1001 filtering operation and packs them into a single register. Only works with
1002 2D, 2D array, cubemaps, and cubemaps arrays. For 2D textures, only the
1003 addressing modes of the sampler and the top level of any mip pyramid are
1004 used. Set W to zero. It behaves like the TEX instruction, but a filtered
1005 sample is not generated. The four samples that contribute to filtering are
1006 placed into xyzw in clockwise order, starting with the (u,v) texture
1007 coordinate delta at the following locations (-, +), (+, +), (+, -), (-, -),
1008 where the magnitude of the deltas are half a texel.
1010 PIPE_CAP_TEXTURE_SM5 enhances this instruction to support shadow per-sample
1011 depth compares, single component selection, and a non-constant offset. It
1012 doesn't allow support for the GL independent offset to get i0,j0. This would
1013 require another CAP is hw can do it natively. For now we lower that before
1022 dst = texture\_gather4 (unit, coord, component)
1024 (with SM5 - cube array shadow)
1032 dst = texture\_gather (uint, coord, compare)
1034 .. opcode:: LODQ - level of detail query
1036 Compute the LOD information that the texture pipe would use to access the
1037 texture. The Y component contains the computed LOD lambda_prime. The X
1038 component contains the LOD that will be accessed, based on min/max lod's
1045 dst.xy = lodq(uint, coord);
1048 ^^^^^^^^^^^^^^^^^^^^^^^^
1049 These opcodes are used for integer operations.
1050 Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?)
1053 .. opcode:: I2F - Signed Integer To Float
1055 Rounding is unspecified (round to nearest even suggested).
1059 dst.x = (float) src.x
1061 dst.y = (float) src.y
1063 dst.z = (float) src.z
1065 dst.w = (float) src.w
1068 .. opcode:: U2F - Unsigned Integer To Float
1070 Rounding is unspecified (round to nearest even suggested).
1074 dst.x = (float) src.x
1076 dst.y = (float) src.y
1078 dst.z = (float) src.z
1080 dst.w = (float) src.w
1083 .. opcode:: F2I - Float to Signed Integer
1085 Rounding is towards zero (truncate).
1086 Values outside signed range (including NaNs) produce undefined results.
1099 .. opcode:: F2U - Float to Unsigned Integer
1101 Rounding is towards zero (truncate).
1102 Values outside unsigned range (including NaNs) produce undefined results.
1106 dst.x = (unsigned) src.x
1108 dst.y = (unsigned) src.y
1110 dst.z = (unsigned) src.z
1112 dst.w = (unsigned) src.w
1115 .. opcode:: UADD - Integer Add
1117 This instruction works the same for signed and unsigned integers.
1118 The low 32bit of the result is returned.
1122 dst.x = src0.x + src1.x
1124 dst.y = src0.y + src1.y
1126 dst.z = src0.z + src1.z
1128 dst.w = src0.w + src1.w
1131 .. opcode:: UMAD - Integer Multiply And Add
1133 This instruction works the same for signed and unsigned integers.
1134 The multiplication returns the low 32bit (as does the result itself).
1138 dst.x = src0.x \times src1.x + src2.x
1140 dst.y = src0.y \times src1.y + src2.y
1142 dst.z = src0.z \times src1.z + src2.z
1144 dst.w = src0.w \times src1.w + src2.w
1147 .. opcode:: UMUL - Integer Multiply
1149 This instruction works the same for signed and unsigned integers.
1150 The low 32bit of the result is returned.
1154 dst.x = src0.x \times src1.x
1156 dst.y = src0.y \times src1.y
1158 dst.z = src0.z \times src1.z
1160 dst.w = src0.w \times src1.w
1163 .. opcode:: IMUL_HI - Signed Integer Multiply High Bits
1165 The high 32bits of the multiplication of 2 signed integers are returned.
1169 dst.x = (src0.x \times src1.x) >> 32
1171 dst.y = (src0.y \times src1.y) >> 32
1173 dst.z = (src0.z \times src1.z) >> 32
1175 dst.w = (src0.w \times src1.w) >> 32
1178 .. opcode:: UMUL_HI - Unsigned Integer Multiply High Bits
1180 The high 32bits of the multiplication of 2 unsigned integers are returned.
1184 dst.x = (src0.x \times src1.x) >> 32
1186 dst.y = (src0.y \times src1.y) >> 32
1188 dst.z = (src0.z \times src1.z) >> 32
1190 dst.w = (src0.w \times src1.w) >> 32
1193 .. opcode:: IDIV - Signed Integer Division
1195 TBD: behavior for division by zero.
1199 dst.x = src0.x \ src1.x
1201 dst.y = src0.y \ src1.y
1203 dst.z = src0.z \ src1.z
1205 dst.w = src0.w \ src1.w
1208 .. opcode:: UDIV - Unsigned Integer Division
1210 For division by zero, 0xffffffff is returned.
1214 dst.x = src0.x \ src1.x
1216 dst.y = src0.y \ src1.y
1218 dst.z = src0.z \ src1.z
1220 dst.w = src0.w \ src1.w
1223 .. opcode:: UMOD - Unsigned Integer Remainder
1225 If second arg is zero, 0xffffffff is returned.
1229 dst.x = src0.x \ src1.x
1231 dst.y = src0.y \ src1.y
1233 dst.z = src0.z \ src1.z
1235 dst.w = src0.w \ src1.w
1238 .. opcode:: NOT - Bitwise Not
1251 .. opcode:: AND - Bitwise And
1255 dst.x = src0.x \& src1.x
1257 dst.y = src0.y \& src1.y
1259 dst.z = src0.z \& src1.z
1261 dst.w = src0.w \& src1.w
1264 .. opcode:: OR - Bitwise Or
1268 dst.x = src0.x | src1.x
1270 dst.y = src0.y | src1.y
1272 dst.z = src0.z | src1.z
1274 dst.w = src0.w | src1.w
1277 .. opcode:: XOR - Bitwise Xor
1281 dst.x = src0.x \oplus src1.x
1283 dst.y = src0.y \oplus src1.y
1285 dst.z = src0.z \oplus src1.z
1287 dst.w = src0.w \oplus src1.w
1290 .. opcode:: IMAX - Maximum of Signed Integers
1294 dst.x = max(src0.x, src1.x)
1296 dst.y = max(src0.y, src1.y)
1298 dst.z = max(src0.z, src1.z)
1300 dst.w = max(src0.w, src1.w)
1303 .. opcode:: UMAX - Maximum of Unsigned Integers
1307 dst.x = max(src0.x, src1.x)
1309 dst.y = max(src0.y, src1.y)
1311 dst.z = max(src0.z, src1.z)
1313 dst.w = max(src0.w, src1.w)
1316 .. opcode:: IMIN - Minimum of Signed Integers
1320 dst.x = min(src0.x, src1.x)
1322 dst.y = min(src0.y, src1.y)
1324 dst.z = min(src0.z, src1.z)
1326 dst.w = min(src0.w, src1.w)
1329 .. opcode:: UMIN - Minimum of Unsigned Integers
1333 dst.x = min(src0.x, src1.x)
1335 dst.y = min(src0.y, src1.y)
1337 dst.z = min(src0.z, src1.z)
1339 dst.w = min(src0.w, src1.w)
1342 .. opcode:: SHL - Shift Left
1344 The shift count is masked with 0x1f before the shift is applied.
1348 dst.x = src0.x << (0x1f \& src1.x)
1350 dst.y = src0.y << (0x1f \& src1.y)
1352 dst.z = src0.z << (0x1f \& src1.z)
1354 dst.w = src0.w << (0x1f \& src1.w)
1357 .. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)
1359 The shift count is masked with 0x1f before the shift is applied.
1363 dst.x = src0.x >> (0x1f \& src1.x)
1365 dst.y = src0.y >> (0x1f \& src1.y)
1367 dst.z = src0.z >> (0x1f \& src1.z)
1369 dst.w = src0.w >> (0x1f \& src1.w)
1372 .. opcode:: USHR - Logical Shift Right
1374 The shift count is masked with 0x1f before the shift is applied.
1378 dst.x = src0.x >> (unsigned) (0x1f \& src1.x)
1380 dst.y = src0.y >> (unsigned) (0x1f \& src1.y)
1382 dst.z = src0.z >> (unsigned) (0x1f \& src1.z)
1384 dst.w = src0.w >> (unsigned) (0x1f \& src1.w)
1387 .. opcode:: UCMP - Integer Conditional Move
1391 dst.x = src0.x ? src1.x : src2.x
1393 dst.y = src0.y ? src1.y : src2.y
1395 dst.z = src0.z ? src1.z : src2.z
1397 dst.w = src0.w ? src1.w : src2.w
1401 .. opcode:: ISSG - Integer Set Sign
1405 dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0
1407 dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0
1409 dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0
1411 dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0
1415 .. opcode:: FSLT - Float Set On Less Than (ordered)
1417 Same comparison as SLT but returns integer instead of 1.0/0.0 float
1421 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1423 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1425 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1427 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1430 .. opcode:: ISLT - Signed Integer Set On Less Than
1434 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1436 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1438 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1440 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1443 .. opcode:: USLT - Unsigned Integer Set On Less Than
1447 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1449 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1451 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1453 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1456 .. opcode:: FSGE - Float Set On Greater Equal Than (ordered)
1458 Same comparison as SGE but returns integer instead of 1.0/0.0 float
1462 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1464 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1466 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1468 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1471 .. opcode:: ISGE - Signed Integer Set On Greater Equal Than
1475 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1477 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1479 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1481 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1484 .. opcode:: USGE - Unsigned Integer Set On Greater Equal Than
1488 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1490 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1492 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1494 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1497 .. opcode:: FSEQ - Float Set On Equal (ordered)
1499 Same comparison as SEQ but returns integer instead of 1.0/0.0 float
1503 dst.x = (src0.x == src1.x) ? \sim 0 : 0
1505 dst.y = (src0.y == src1.y) ? \sim 0 : 0
1507 dst.z = (src0.z == src1.z) ? \sim 0 : 0
1509 dst.w = (src0.w == src1.w) ? \sim 0 : 0
1512 .. opcode:: USEQ - Integer Set On Equal
1516 dst.x = (src0.x == src1.x) ? \sim 0 : 0
1518 dst.y = (src0.y == src1.y) ? \sim 0 : 0
1520 dst.z = (src0.z == src1.z) ? \sim 0 : 0
1522 dst.w = (src0.w == src1.w) ? \sim 0 : 0
1525 .. opcode:: FSNE - Float Set On Not Equal (unordered)
1527 Same comparison as SNE but returns integer instead of 1.0/0.0 float
1531 dst.x = (src0.x != src1.x) ? \sim 0 : 0
1533 dst.y = (src0.y != src1.y) ? \sim 0 : 0
1535 dst.z = (src0.z != src1.z) ? \sim 0 : 0
1537 dst.w = (src0.w != src1.w) ? \sim 0 : 0
1540 .. opcode:: USNE - Integer Set On Not Equal
1544 dst.x = (src0.x != src1.x) ? \sim 0 : 0
1546 dst.y = (src0.y != src1.y) ? \sim 0 : 0
1548 dst.z = (src0.z != src1.z) ? \sim 0 : 0
1550 dst.w = (src0.w != src1.w) ? \sim 0 : 0
1553 .. opcode:: INEG - Integer Negate
1568 .. opcode:: IABS - Integer Absolute Value
1582 These opcodes are used for bit-level manipulation of integers.
1584 .. opcode:: IBFE - Signed Bitfield Extract
1586 See SM5 instruction of the same name. Extracts a set of bits from the input,
1587 and sign-extends them if the high bit of the extracted window is set.
1591 def ibfe(value, offset, bits):
1592 offset = offset & 0x1f
1594 if bits == 0: return 0
1595 # Note: >> sign-extends
1596 if width + offset < 32:
1597 return (value << (32 - offset - bits)) >> (32 - bits)
1599 return value >> offset
1601 .. opcode:: UBFE - Unsigned Bitfield Extract
1603 See SM5 instruction of the same name. Extracts a set of bits from the input,
1604 without any sign-extension.
1608 def ubfe(value, offset, bits):
1609 offset = offset & 0x1f
1611 if bits == 0: return 0
1612 # Note: >> does not sign-extend
1613 if width + offset < 32:
1614 return (value << (32 - offset - bits)) >> (32 - bits)
1616 return value >> offset
1618 .. opcode:: BFI - Bitfield Insert
1620 See SM5 instruction of the same name. Replaces a bit region of 'base' with
1621 the low bits of 'insert'.
1625 def bfi(base, insert, offset, bits):
1626 offset = offset & 0x1f
1628 mask = ((1 << bits) - 1) << offset
1629 return ((insert << offset) & mask) | (base & ~mask)
1631 .. opcode:: BREV - Bitfield Reverse
1633 See SM5 instruction BFREV. Reverses the bits of the argument.
1635 .. opcode:: POPC - Population Count
1637 See SM5 instruction COUNTBITS. Counts the number of set bits in the argument.
1639 .. opcode:: LSB - Index of lowest set bit
1641 See SM5 instruction FIRSTBIT_LO. Computes the 0-based index of the first set
1642 bit of the argument. Returns -1 if none are set.
1644 .. opcode:: IMSB - Index of highest non-sign bit
1646 See SM5 instruction FIRSTBIT_SHI. Computes the 0-based index of the highest
1647 non-sign bit of the argument (i.e. highest 0 bit for negative numbers,
1648 highest 1 bit for positive numbers). Returns -1 if all bits are the same
1649 (i.e. for inputs 0 and -1).
1651 .. opcode:: UMSB - Index of highest set bit
1653 See SM5 instruction FIRSTBIT_HI. Computes the 0-based index of the highest
1654 set bit of the argument. Returns -1 if none are set.
1657 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1659 These opcodes are only supported in geometry shaders; they have no meaning
1660 in any other type of shader.
1662 .. opcode:: EMIT - Emit
1664 Generate a new vertex for the current primitive into the specified vertex
1665 stream using the values in the output registers.
1668 .. opcode:: ENDPRIM - End Primitive
1670 Complete the current primitive in the specified vertex stream (consisting of
1671 the emitted vertices), and start a new one.
1677 These opcodes are part of :term:`GLSL`'s opcode set. Support for these
1678 opcodes is determined by a special capability bit, ``GLSL``.
1679 Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
1681 .. opcode:: CAL - Subroutine Call
1687 .. opcode:: RET - Subroutine Call Return
1692 .. opcode:: CONT - Continue
1694 Unconditionally moves the point of execution to the instruction after the
1695 last bgnloop. The instruction must appear within a bgnloop/endloop.
1699 Support for CONT is determined by a special capability bit,
1700 ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
1703 .. opcode:: BGNLOOP - Begin a Loop
1705 Start a loop. Must have a matching endloop.
1708 .. opcode:: BGNSUB - Begin Subroutine
1710 Starts definition of a subroutine. Must have a matching endsub.
1713 .. opcode:: ENDLOOP - End a Loop
1715 End a loop started with bgnloop.
1718 .. opcode:: ENDSUB - End Subroutine
1720 Ends definition of a subroutine.
1723 .. opcode:: NOP - No Operation
1728 .. opcode:: BRK - Break
1730 Unconditionally moves the point of execution to the instruction after the
1731 next endloop or endswitch. The instruction must appear within a loop/endloop
1732 or switch/endswitch.
1735 .. opcode:: BREAKC - Break Conditional
1737 Conditionally moves the point of execution to the instruction after the
1738 next endloop or endswitch. The instruction must appear within a loop/endloop
1739 or switch/endswitch.
1740 Condition evaluates to true if src0.x != 0 where src0.x is interpreted
1741 as an integer register.
1745 Considered for removal as it's quite inconsistent wrt other opcodes
1746 (could emulate with UIF/BRK/ENDIF).
1749 .. opcode:: IF - Float If
1751 Start an IF ... ELSE .. ENDIF block. Condition evaluates to true if
1755 where src0.x is interpreted as a floating point register.
1758 .. opcode:: UIF - Bitwise If
1760 Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if
1764 where src0.x is interpreted as an integer register.
1767 .. opcode:: ELSE - Else
1769 Starts an else block, after an IF or UIF statement.
1772 .. opcode:: ENDIF - End If
1774 Ends an IF or UIF block.
1777 .. opcode:: SWITCH - Switch
1779 Starts a C-style switch expression. The switch consists of one or multiple
1780 CASE statements, and at most one DEFAULT statement. Execution of a statement
1781 ends when a BRK is hit, but just like in C falling through to other cases
1782 without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
1783 just as last statement, and fallthrough is allowed into/from it.
1784 CASE src arguments are evaluated at bit level against the SWITCH src argument.
1790 (some instructions here)
1793 (some instructions here)
1796 (some instructions here)
1801 .. opcode:: CASE - Switch case
1803 This represents a switch case label. The src arg must be an integer immediate.
1806 .. opcode:: DEFAULT - Switch default
1808 This represents the default case in the switch, which is taken if no other
1812 .. opcode:: ENDSWITCH - End of switch
1814 Ends a switch expression.
1820 The interpolation instructions allow an input to be interpolated in a
1821 different way than its declaration. This corresponds to the GLSL 4.00
1822 interpolateAt* functions. The first argument of each of these must come from
1823 ``TGSI_FILE_INPUT``.
1825 .. opcode:: INTERP_CENTROID - Interpolate at the centroid
1827 Interpolates the varying specified by src0 at the centroid
1829 .. opcode:: INTERP_SAMPLE - Interpolate at the specified sample
1831 Interpolates the varying specified by src0 at the sample id specified by
1832 src1.x (interpreted as an integer)
1834 .. opcode:: INTERP_OFFSET - Interpolate at the specified offset
1836 Interpolates the varying specified by src0 at the offset src1.xy from the
1837 pixel center (interpreted as floats)
1845 The double-precision opcodes reinterpret four-component vectors into
1846 two-component vectors with doubled precision in each component.
1848 .. opcode:: DABS - Absolute
1853 .. opcode:: DADD - Add
1857 dst.xy = src0.xy + src1.xy
1859 dst.zw = src0.zw + src1.zw
1861 .. opcode:: DSEQ - Set on Equal
1865 dst.x = src0.xy == src1.xy ? \sim 0 : 0
1867 dst.z = src0.zw == src1.zw ? \sim 0 : 0
1869 .. opcode:: DSNE - Set on Equal
1873 dst.x = src0.xy != src1.xy ? \sim 0 : 0
1875 dst.z = src0.zw != src1.zw ? \sim 0 : 0
1877 .. opcode:: DSLT - Set on Less than
1881 dst.x = src0.xy < src1.xy ? \sim 0 : 0
1883 dst.z = src0.zw < src1.zw ? \sim 0 : 0
1885 .. opcode:: DSGE - Set on Greater equal
1889 dst.x = src0.xy >= src1.xy ? \sim 0 : 0
1891 dst.z = src0.zw >= src1.zw ? \sim 0 : 0
1893 .. opcode:: DFRAC - Fraction
1897 dst.xy = src.xy - \lfloor src.xy\rfloor
1899 dst.zw = src.zw - \lfloor src.zw\rfloor
1901 .. opcode:: DTRUNC - Truncate
1905 dst.xy = trunc(src.xy)
1907 dst.zw = trunc(src.zw)
1909 .. opcode:: DCEIL - Ceiling
1913 dst.xy = \lceil src.xy\rceil
1915 dst.zw = \lceil src.zw\rceil
1917 .. opcode:: DFLR - Floor
1921 dst.xy = \lfloor src.xy\rfloor
1923 dst.zw = \lfloor src.zw\rfloor
1925 .. opcode:: DROUND - Fraction
1929 dst.xy = round(src.xy)
1931 dst.zw = round(src.zw)
1933 .. opcode:: DSSG - Set Sign
1937 dst.xy = (src.xy > 0) ? 1.0 : (src.xy < 0) ? -1.0 : 0.0
1939 dst.zw = (src.zw > 0) ? 1.0 : (src.zw < 0) ? -1.0 : 0.0
1941 .. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components
1943 Like the ``frexp()`` routine in many math libraries, this opcode stores the
1944 exponent of its source to ``dst0``, and the significand to ``dst1``, such that
1945 :math:`dst1 \times 2^{dst0} = src` .
1949 dst0.xy = exp(src.xy)
1951 dst1.xy = frac(src.xy)
1953 dst0.zw = exp(src.zw)
1955 dst1.zw = frac(src.zw)
1957 .. opcode:: DLDEXP - Multiply Number by Integral Power of 2
1959 This opcode is the inverse of :opcode:`DFRACEXP`. The second
1960 source is an integer.
1964 dst.xy = src0.xy \times 2^{src1.x}
1966 dst.zw = src0.zw \times 2^{src1.y}
1968 .. opcode:: DMIN - Minimum
1972 dst.xy = min(src0.xy, src1.xy)
1974 dst.zw = min(src0.zw, src1.zw)
1976 .. opcode:: DMAX - Maximum
1980 dst.xy = max(src0.xy, src1.xy)
1982 dst.zw = max(src0.zw, src1.zw)
1984 .. opcode:: DMUL - Multiply
1988 dst.xy = src0.xy \times src1.xy
1990 dst.zw = src0.zw \times src1.zw
1993 .. opcode:: DMAD - Multiply And Add
1997 dst.xy = src0.xy \times src1.xy + src2.xy
1999 dst.zw = src0.zw \times src1.zw + src2.zw
2002 .. opcode:: DFMA - Fused Multiply-Add
2004 Perform a * b + c with no intermediate rounding step.
2008 dst.xy = src0.xy \times src1.xy + src2.xy
2010 dst.zw = src0.zw \times src1.zw + src2.zw
2013 .. opcode:: DRCP - Reciprocal
2017 dst.xy = \frac{1}{src.xy}
2019 dst.zw = \frac{1}{src.zw}
2021 .. opcode:: DSQRT - Square Root
2025 dst.xy = \sqrt{src.xy}
2027 dst.zw = \sqrt{src.zw}
2029 .. opcode:: DRSQ - Reciprocal Square Root
2033 dst.xy = \frac{1}{\sqrt{src.xy}}
2035 dst.zw = \frac{1}{\sqrt{src.zw}}
2037 .. opcode:: F2D - Float to Double
2041 dst.xy = double(src0.x)
2043 dst.zw = double(src0.y)
2045 .. opcode:: D2F - Double to Float
2049 dst.x = float(src0.xy)
2051 dst.y = float(src0.zw)
2053 .. opcode:: I2D - Int to Double
2057 dst.xy = double(src0.x)
2059 dst.zw = double(src0.y)
2061 .. opcode:: D2I - Double to Int
2065 dst.x = int(src0.xy)
2067 dst.y = int(src0.zw)
2069 .. opcode:: U2D - Unsigned Int to Double
2073 dst.xy = double(src0.x)
2075 dst.zw = double(src0.y)
2077 .. opcode:: D2U - Double to Unsigned Int
2081 dst.x = unsigned(src0.xy)
2083 dst.y = unsigned(src0.zw)
2085 .. _samplingopcodes:
2087 Resource Sampling Opcodes
2088 ^^^^^^^^^^^^^^^^^^^^^^^^^
2090 Those opcodes follow very closely semantics of the respective Direct3D
2091 instructions. If in doubt double check Direct3D documentation.
2092 Note that the swizzle on SVIEW (src1) determines texel swizzling
2097 Using provided address, sample data from the specified texture using the
2098 filtering mode identified by the given sampler. The source data may come from
2099 any resource type other than buffers.
2101 Syntax: ``SAMPLE dst, address, sampler_view, sampler``
2103 Example: ``SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]``
2105 .. opcode:: SAMPLE_I
2107 Simplified alternative to the SAMPLE instruction. Using the provided
2108 integer address, SAMPLE_I fetches data from the specified sampler view
2109 without any filtering. The source data may come from any resource type
2112 Syntax: ``SAMPLE_I dst, address, sampler_view``
2114 Example: ``SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]``
2116 The 'address' is specified as unsigned integers. If the 'address' is out of
2117 range [0...(# texels - 1)] the result of the fetch is always 0 in all
2118 components. As such the instruction doesn't honor address wrap modes, in
2119 cases where that behavior is desirable 'SAMPLE' instruction should be used.
2120 address.w always provides an unsigned integer mipmap level. If the value is
2121 out of the range then the instruction always returns 0 in all components.
2122 address.yz are ignored for buffers and 1d textures. address.z is ignored
2123 for 1d texture arrays and 2d textures.
2125 For 1D texture arrays address.y provides the array index (also as unsigned
2126 integer). If the value is out of the range of available array indices
2127 [0... (array size - 1)] then the opcode always returns 0 in all components.
2128 For 2D texture arrays address.z provides the array index, otherwise it
2129 exhibits the same behavior as in the case for 1D texture arrays. The exact
2130 semantics of the source address are presented in the table below:
2132 +---------------------------+----+-----+-----+---------+
2133 | resource type | X | Y | Z | W |
2134 +===========================+====+=====+=====+=========+
2135 | ``PIPE_BUFFER`` | x | | | ignored |
2136 +---------------------------+----+-----+-----+---------+
2137 | ``PIPE_TEXTURE_1D`` | x | | | mpl |
2138 +---------------------------+----+-----+-----+---------+
2139 | ``PIPE_TEXTURE_2D`` | x | y | | mpl |
2140 +---------------------------+----+-----+-----+---------+
2141 | ``PIPE_TEXTURE_3D`` | x | y | z | mpl |
2142 +---------------------------+----+-----+-----+---------+
2143 | ``PIPE_TEXTURE_RECT`` | x | y | | mpl |
2144 +---------------------------+----+-----+-----+---------+
2145 | ``PIPE_TEXTURE_CUBE`` | not allowed as source |
2146 +---------------------------+----+-----+-----+---------+
2147 | ``PIPE_TEXTURE_1D_ARRAY`` | x | idx | | mpl |
2148 +---------------------------+----+-----+-----+---------+
2149 | ``PIPE_TEXTURE_2D_ARRAY`` | x | y | idx | mpl |
2150 +---------------------------+----+-----+-----+---------+
2152 Where 'mpl' is a mipmap level and 'idx' is the array index.
2154 .. opcode:: SAMPLE_I_MS
2156 Just like SAMPLE_I but allows fetch data from multi-sampled surfaces.
2158 Syntax: ``SAMPLE_I_MS dst, address, sampler_view, sample``
2160 .. opcode:: SAMPLE_B
2162 Just like the SAMPLE instruction with the exception that an additional bias
2163 is applied to the level of detail computed as part of the instruction
2166 Syntax: ``SAMPLE_B dst, address, sampler_view, sampler, lod_bias``
2168 Example: ``SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``
2170 .. opcode:: SAMPLE_C
2172 Similar to the SAMPLE instruction but it performs a comparison filter. The
2173 operands to SAMPLE_C are identical to SAMPLE, except that there is an
2174 additional float32 operand, reference value, which must be a register with
2175 single-component, or a scalar literal. SAMPLE_C makes the hardware use the
2176 current samplers compare_func (in pipe_sampler_state) to compare reference
2177 value against the red component value for the surce resource at each texel
2178 that the currently configured texture filter covers based on the provided
2181 Syntax: ``SAMPLE_C dst, address, sampler_view.r, sampler, ref_value``
2183 Example: ``SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``
2185 .. opcode:: SAMPLE_C_LZ
2187 Same as SAMPLE_C, but LOD is 0 and derivatives are ignored. The LZ stands
2190 Syntax: ``SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value``
2192 Example: ``SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``
2195 .. opcode:: SAMPLE_D
2197 SAMPLE_D is identical to the SAMPLE opcode except that the derivatives for
2198 the source address in the x direction and the y direction are provided by
2201 Syntax: ``SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y``
2203 Example: ``SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]``
2205 .. opcode:: SAMPLE_L
2207 SAMPLE_L is identical to the SAMPLE opcode except that the LOD is provided
2208 directly as a scalar value, representing no anisotropy.
2210 Syntax: ``SAMPLE_L dst, address, sampler_view, sampler, explicit_lod``
2212 Example: ``SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``
2216 Gathers the four texels to be used in a bi-linear filtering operation and
2217 packs them into a single register. Only works with 2D, 2D array, cubemaps,
2218 and cubemaps arrays. For 2D textures, only the addressing modes of the
2219 sampler and the top level of any mip pyramid are used. Set W to zero. It
2220 behaves like the SAMPLE instruction, but a filtered sample is not
2221 generated. The four samples that contribute to filtering are placed into
2222 xyzw in counter-clockwise order, starting with the (u,v) texture coordinate
2223 delta at the following locations (-, +), (+, +), (+, -), (-, -), where the
2224 magnitude of the deltas are half a texel.
2227 .. opcode:: SVIEWINFO
2229 Query the dimensions of a given sampler view. dst receives width, height,
2230 depth or array size and number of mipmap levels as int4. The dst can have a
2231 writemask which will specify what info is the caller interested in.
2233 Syntax: ``SVIEWINFO dst, src_mip_level, sampler_view``
2235 Example: ``SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]``
2237 src_mip_level is an unsigned integer scalar. If it's out of range then
2238 returns 0 for width, height and depth/array size but the total number of
2239 mipmap is still returned correctly for the given sampler view. The returned
2240 width, height and depth values are for the mipmap level selected by the
2241 src_mip_level and are in the number of texels. For 1d texture array width
2242 is in dst.x, array size is in dst.y and dst.z is 0. The number of mipmaps is
2243 still in dst.w. In contrast to d3d10 resinfo, there's no way in the tgsi
2244 instruction encoding to specify the return type (float/rcpfloat/uint), hence
2245 always using uint. Also, unlike the SAMPLE instructions, the swizzle on src1
2246 resinfo allowing swizzling dst values is ignored (due to the interaction
2247 with rcpfloat modifier which requires some swizzle handling in the state
2250 .. opcode:: SAMPLE_POS
2252 Query the position of a given sample. dst receives float4 (x, y, 0, 0)
2253 indicated where the sample is located. If the resource is not a multi-sample
2254 resource and not a render target, the result is 0.
2256 .. opcode:: SAMPLE_INFO
2258 dst receives number of samples in x. If the resource is not a multi-sample
2259 resource and not a render target, the result is 0.
2262 .. _resourceopcodes:
2264 Resource Access Opcodes
2265 ^^^^^^^^^^^^^^^^^^^^^^^
2267 .. opcode:: LOAD - Fetch data from a shader buffer or image
2269 Syntax: ``LOAD dst, resource, address``
2271 Example: ``LOAD TEMP[0], BUFFER[0], TEMP[1]``
2273 Using the provided integer address, LOAD fetches data
2274 from the specified buffer or texture without any
2277 The 'address' is specified as a vector of unsigned
2278 integers. If the 'address' is out of range the result
2281 Only the first mipmap level of a resource can be read
2282 from using this instruction.
2284 For 1D or 2D texture arrays, the array index is
2285 provided as an unsigned integer in address.y or
2286 address.z, respectively. address.yz are ignored for
2287 buffers and 1D textures. address.z is ignored for 1D
2288 texture arrays and 2D textures. address.w is always
2291 A swizzle suffix may be added to the resource argument
2292 this will cause the resource data to be swizzled accordingly.
2294 .. opcode:: STORE - Write data to a shader resource
2296 Syntax: ``STORE resource, address, src``
2298 Example: ``STORE BUFFER[0], TEMP[0], TEMP[1]``
2300 Using the provided integer address, STORE writes data
2301 to the specified buffer or texture.
2303 The 'address' is specified as a vector of unsigned
2304 integers. If the 'address' is out of range the result
2307 Only the first mipmap level of a resource can be
2308 written to using this instruction.
2310 For 1D or 2D texture arrays, the array index is
2311 provided as an unsigned integer in address.y or
2312 address.z, respectively. address.yz are ignored for
2313 buffers and 1D textures. address.z is ignored for 1D
2314 texture arrays and 2D textures. address.w is always
2317 .. opcode:: RESQ - Query information about a resource
2319 Syntax: ``RESQ dst, resource``
2321 Example: ``RESQ TEMP[0], BUFFER[0]``
2323 Returns information about the buffer or image resource. For buffer
2324 resources, the size (in bytes) is returned in the x component. For
2325 image resources, .xyz will contain the width/height/layers of the
2326 image, while .w will contain the number of samples for multi-sampled
2330 .. _threadsyncopcodes:
2332 Inter-thread synchronization opcodes
2333 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2335 These opcodes are intended for communication between threads running
2336 within the same compute grid. For now they're only valid in compute
2339 .. opcode:: MFENCE - Memory fence
2341 Syntax: ``MFENCE resource``
2343 Example: ``MFENCE RES[0]``
2345 This opcode forces strong ordering between any memory access
2346 operations that affect the specified resource. This means that
2347 previous loads and stores (and only those) will be performed and
2348 visible to other threads before the program execution continues.
2351 .. opcode:: LFENCE - Load memory fence
2353 Syntax: ``LFENCE resource``
2355 Example: ``LFENCE RES[0]``
2357 Similar to MFENCE, but it only affects the ordering of memory loads.
2360 .. opcode:: SFENCE - Store memory fence
2362 Syntax: ``SFENCE resource``
2364 Example: ``SFENCE RES[0]``
2366 Similar to MFENCE, but it only affects the ordering of memory stores.
2369 .. opcode:: BARRIER - Thread group barrier
2373 This opcode suspends the execution of the current thread until all
2374 the remaining threads in the working group reach the same point of
2375 the program. Results are unspecified if any of the remaining
2376 threads terminates or never reaches an executed BARRIER instruction.
2378 .. opcode:: MEMBAR - Memory barrier
2382 This opcode waits for the completion of all memory accesses based on
2383 the type passed in. The type is an immediate bitfield with the following
2386 Bit 0: Shader storage buffers
2387 Bit 1: Atomic buffers
2389 Bit 3: Shared memory
2392 These may be passed in in any combination. An implementation is free to not
2393 distinguish between these as it sees fit. However these map to all the
2394 possibilities made available by GLSL.
2401 These opcodes provide atomic variants of some common arithmetic and
2402 logical operations. In this context atomicity means that another
2403 concurrent memory access operation that affects the same memory
2404 location is guaranteed to be performed strictly before or after the
2405 entire execution of the atomic operation. The resource may be a buffer
2406 or an image. In the case of an image, the offset works the same as for
2407 ``LOAD`` and ``STORE``, specified above. These atomic operations may
2408 only be used with 32-bit integer image formats.
2410 .. opcode:: ATOMUADD - Atomic integer addition
2412 Syntax: ``ATOMUADD dst, resource, offset, src``
2414 Example: ``ATOMUADD TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2416 The following operation is performed atomically:
2420 dst_x = resource[offset]
2422 resource[offset] = dst_x + src_x
2425 .. opcode:: ATOMXCHG - Atomic exchange
2427 Syntax: ``ATOMXCHG dst, resource, offset, src``
2429 Example: ``ATOMXCHG TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2431 The following operation is performed atomically:
2435 dst_x = resource[offset]
2437 resource[offset] = src_x
2440 .. opcode:: ATOMCAS - Atomic compare-and-exchange
2442 Syntax: ``ATOMCAS dst, resource, offset, cmp, src``
2444 Example: ``ATOMCAS TEMP[0], BUFFER[0], TEMP[1], TEMP[2], TEMP[3]``
2446 The following operation is performed atomically:
2450 dst_x = resource[offset]
2452 resource[offset] = (dst_x == cmp_x ? src_x : dst_x)
2455 .. opcode:: ATOMAND - Atomic bitwise And
2457 Syntax: ``ATOMAND dst, resource, offset, src``
2459 Example: ``ATOMAND TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2461 The following operation is performed atomically:
2465 dst_x = resource[offset]
2467 resource[offset] = dst_x \& src_x
2470 .. opcode:: ATOMOR - Atomic bitwise Or
2472 Syntax: ``ATOMOR dst, resource, offset, src``
2474 Example: ``ATOMOR TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2476 The following operation is performed atomically:
2480 dst_x = resource[offset]
2482 resource[offset] = dst_x | src_x
2485 .. opcode:: ATOMXOR - Atomic bitwise Xor
2487 Syntax: ``ATOMXOR dst, resource, offset, src``
2489 Example: ``ATOMXOR TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2491 The following operation is performed atomically:
2495 dst_x = resource[offset]
2497 resource[offset] = dst_x \oplus src_x
2500 .. opcode:: ATOMUMIN - Atomic unsigned minimum
2502 Syntax: ``ATOMUMIN dst, resource, offset, src``
2504 Example: ``ATOMUMIN TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2506 The following operation is performed atomically:
2510 dst_x = resource[offset]
2512 resource[offset] = (dst_x < src_x ? dst_x : src_x)
2515 .. opcode:: ATOMUMAX - Atomic unsigned maximum
2517 Syntax: ``ATOMUMAX dst, resource, offset, src``
2519 Example: ``ATOMUMAX TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2521 The following operation is performed atomically:
2525 dst_x = resource[offset]
2527 resource[offset] = (dst_x > src_x ? dst_x : src_x)
2530 .. opcode:: ATOMIMIN - Atomic signed minimum
2532 Syntax: ``ATOMIMIN dst, resource, offset, src``
2534 Example: ``ATOMIMIN TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2536 The following operation is performed atomically:
2540 dst_x = resource[offset]
2542 resource[offset] = (dst_x < src_x ? dst_x : src_x)
2545 .. opcode:: ATOMIMAX - Atomic signed maximum
2547 Syntax: ``ATOMIMAX dst, resource, offset, src``
2549 Example: ``ATOMIMAX TEMP[0], BUFFER[0], TEMP[1], TEMP[2]``
2551 The following operation is performed atomically:
2555 dst_x = resource[offset]
2557 resource[offset] = (dst_x > src_x ? dst_x : src_x)
2565 These opcodes compare the given value across the shader invocations
2566 running in the current SIMD group. The details of exactly which
2567 invocations get compared are implementation-defined, and it would be a
2568 correct implementation to only ever consider the current thread's
2569 value. (i.e. SIMD group of 1). The argument is treated as a boolean.
2571 .. opcode:: VOTE_ANY - Value is set in any of the current invocations
2573 .. opcode:: VOTE_ALL - Value is set in all of the current invocations
2575 .. opcode:: VOTE_EQ - Value is the same in all of the current invocations
2578 Explanation of symbols used
2579 ------------------------------
2586 :math:`|x|` Absolute value of `x`.
2588 :math:`\lceil x \rceil` Ceiling of `x`.
2590 clamp(x,y,z) Clamp x between y and z.
2591 (x < y) ? y : (x > z) ? z : x
2593 :math:`\lfloor x\rfloor` Floor of `x`.
2595 :math:`\log_2{x}` Logarithm of `x`, base 2.
2597 max(x,y) Maximum of x and y.
2600 min(x,y) Minimum of x and y.
2603 partialx(x) Derivative of x relative to fragment's X.
2605 partialy(x) Derivative of x relative to fragment's Y.
2607 pop() Pop from stack.
2609 :math:`x^y` `x` to the power `y`.
2611 push(x) Push x on stack.
2615 trunc(x) Truncate x, i.e. drop the fraction bits.
2622 discard Discard fragment.
2626 target Label of target instruction.
2637 Declares a register that is will be referenced as an operand in Instruction
2640 File field contains register file that is being declared and is one
2643 UsageMask field specifies which of the register components can be accessed
2644 and is one of TGSI_WRITEMASK.
2646 The Local flag specifies that a given value isn't intended for
2647 subroutine parameter passing and, as a result, the implementation
2648 isn't required to give any guarantees of it being preserved across
2649 subroutine boundaries. As it's merely a compiler hint, the
2650 implementation is free to ignore it.
2652 If Dimension flag is set to 1, a Declaration Dimension token follows.
2654 If Semantic flag is set to 1, a Declaration Semantic token follows.
2656 If Interpolate flag is set to 1, a Declaration Interpolate token follows.
2658 If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.
2660 If Array flag is set to 1, a Declaration Array token follows.
2663 ^^^^^^^^^^^^^^^^^^^^^^^^
2665 Declarations can optional have an ArrayID attribute which can be referred by
2666 indirect addressing operands. An ArrayID of zero is reserved and treated as
2667 if no ArrayID is specified.
2669 If an indirect addressing operand refers to a specific declaration by using
2670 an ArrayID only the registers in this declaration are guaranteed to be
2671 accessed, accessing any register outside this declaration results in undefined
2672 behavior. Note that for compatibility the effective index is zero-based and
2673 not relative to the specified declaration
2675 If no ArrayID is specified with an indirect addressing operand the whole
2676 register file might be accessed by this operand. This is strongly discouraged
2677 and will prevent packing of scalar/vec2 arrays and effective alias analysis.
2678 This is only legal for TEMP and CONST register files.
2680 Declaration Semantic
2681 ^^^^^^^^^^^^^^^^^^^^^^^^
2683 Vertex and fragment shader input and output registers may be labeled
2684 with semantic information consisting of a name and index.
2686 Follows Declaration token if Semantic bit is set.
2688 Since its purpose is to link a shader with other stages of the pipeline,
2689 it is valid to follow only those Declaration tokens that declare a register
2690 either in INPUT or OUTPUT file.
2692 SemanticName field contains the semantic name of the register being declared.
2693 There is no default value.
2695 SemanticIndex is an optional subscript that can be used to distinguish
2696 different register declarations with the same semantic name. The default value
2699 The meanings of the individual semantic names are explained in the following
2702 TGSI_SEMANTIC_POSITION
2703 """"""""""""""""""""""
2705 For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
2706 output register which contains the homogeneous vertex position in the clip
2707 space coordinate system. After clipping, the X, Y and Z components of the
2708 vertex will be divided by the W value to get normalized device coordinates.
2710 For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
2711 fragment shader input (or system value, depending on which one is
2712 supported by the driver) contains the fragment's window position. The X
2713 component starts at zero and always increases from left to right.
2714 The Y component starts at zero and always increases but Y=0 may either
2715 indicate the top of the window or the bottom depending on the fragment
2716 coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
2717 The Z coordinate ranges from 0 to 1 to represent depth from the front
2718 to the back of the Z buffer. The W component contains the interpolated
2719 reciprocal of the vertex position W component (corresponding to gl_Fragcoord,
2720 but unlike d3d10 which interpolates the same 1/w but then gives back
2721 the reciprocal of the interpolated value).
2723 Fragment shaders may also declare an output register with
2724 TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows
2725 the fragment shader to change the fragment's Z position.
2732 For vertex shader outputs or fragment shader inputs/outputs, this
2733 label indicates that the register contains an R,G,B,A color.
2735 Several shader inputs/outputs may contain colors so the semantic index
2736 is used to distinguish them. For example, color[0] may be the diffuse
2737 color while color[1] may be the specular color.
2739 This label is needed so that the flat/smooth shading can be applied
2740 to the right interpolants during rasterization.
2744 TGSI_SEMANTIC_BCOLOR
2745 """"""""""""""""""""
2747 Back-facing colors are only used for back-facing polygons, and are only valid
2748 in vertex shader outputs. After rasterization, all polygons are front-facing
2749 and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
2750 so all BCOLORs effectively become regular COLORs in the fragment shader.
2756 Vertex shader inputs and outputs and fragment shader inputs may be
2757 labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
2758 a fog coordinate. Typically, the fragment shader will use the fog coordinate
2759 to compute a fog blend factor which is used to blend the normal fragment color
2760 with a constant fog color. But fog coord really is just an ordinary vec4
2761 register like regular semantics.
2767 Vertex shader input and output registers may be labeled with
2768 TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
2769 in the form (S, 0, 0, 1). The point size controls the width or diameter
2770 of points for rasterization. This label cannot be used in fragment
2773 When using this semantic, be sure to set the appropriate state in the
2774 :ref:`rasterizer` first.
2777 TGSI_SEMANTIC_TEXCOORD
2778 """"""""""""""""""""""
2780 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2782 Vertex shader outputs and fragment shader inputs may be labeled with
2783 this semantic to make them replaceable by sprite coordinates via the
2784 sprite_coord_enable state in the :ref:`rasterizer`.
2785 The semantic index permitted with this semantic is limited to <= 7.
2787 If the driver does not support TEXCOORD, sprite coordinate replacement
2788 applies to inputs with the GENERIC semantic instead.
2790 The intended use case for this semantic is gl_TexCoord.
2793 TGSI_SEMANTIC_PCOORD
2794 """"""""""""""""""""
2796 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2798 Fragment shader inputs may be labeled with TGSI_SEMANTIC_PCOORD to indicate
2799 that the register contains sprite coordinates in the form (x, y, 0, 1), if
2800 the current primitive is a point and point sprites are enabled. Otherwise,
2801 the contents of the register are undefined.
2803 The intended use case for this semantic is gl_PointCoord.
2806 TGSI_SEMANTIC_GENERIC
2807 """""""""""""""""""""
2809 All vertex/fragment shader inputs/outputs not labeled with any other
2810 semantic label can be considered to be generic attributes. Typical
2811 uses of generic inputs/outputs are texcoords and user-defined values.
2814 TGSI_SEMANTIC_NORMAL
2815 """"""""""""""""""""
2817 Indicates that a vertex shader input is a normal vector. This is
2818 typically only used for legacy graphics APIs.
2824 This label applies to fragment shader inputs (or system values,
2825 depending on which one is supported by the driver) and indicates that
2826 the register contains front/back-face information.
2828 If it is an input, it will be a floating-point vector in the form (F, 0, 0, 1),
2829 where F will be positive when the fragment belongs to a front-facing polygon,
2830 and negative when the fragment belongs to a back-facing polygon.
2832 If it is a system value, it will be an integer vector in the form (F, 0, 0, 1),
2833 where F is 0xffffffff when the fragment belongs to a front-facing polygon and
2834 0 when the fragment belongs to a back-facing polygon.
2837 TGSI_SEMANTIC_EDGEFLAG
2838 """"""""""""""""""""""
2840 For vertex shaders, this sematic label indicates that an input or
2841 output is a boolean edge flag. The register layout is [F, x, x, x]
2842 where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader
2843 simply copies the edge flag input to the edgeflag output.
2845 Edge flags are used to control which lines or points are actually
2846 drawn when the polygon mode converts triangles/quads/polygons into
2850 TGSI_SEMANTIC_STENCIL
2851 """""""""""""""""""""
2853 For fragment shaders, this semantic label indicates that an output
2854 is a writable stencil reference value. Only the Y component is writable.
2855 This allows the fragment shader to change the fragments stencilref value.
2858 TGSI_SEMANTIC_VIEWPORT_INDEX
2859 """"""""""""""""""""""""""""
2861 For geometry shaders, this semantic label indicates that an output
2862 contains the index of the viewport (and scissor) to use.
2863 This is an integer value, and only the X component is used.
2869 For geometry shaders, this semantic label indicates that an output
2870 contains the layer value to use for the color and depth/stencil surfaces.
2871 This is an integer value, and only the X component is used.
2872 (Also known as rendertarget array index.)
2875 TGSI_SEMANTIC_CULLDIST
2876 """"""""""""""""""""""
2878 Used as distance to plane for performing application-defined culling
2879 of individual primitives against a plane. When components of vertex
2880 elements are given this label, these values are assumed to be a
2881 float32 signed distance to a plane. Primitives will be completely
2882 discarded if the plane distance for all of the vertices in the
2883 primitive are < 0. If a vertex has a cull distance of NaN, that
2884 vertex counts as "out" (as if its < 0);
2885 The limits on both clip and cull distances are bound
2886 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2887 the maximum number of components that can be used to hold the
2888 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2889 which specifies the maximum number of registers which can be
2890 annotated with those semantics.
2893 TGSI_SEMANTIC_CLIPDIST
2894 """"""""""""""""""""""
2896 Note this covers clipping and culling distances.
2898 When components of vertex elements are identified this way, these
2899 values are each assumed to be a float32 signed distance to a plane.
2902 Primitive setup only invokes rasterization on pixels for which
2903 the interpolated plane distances are >= 0.
2906 Primitives will be completely discarded if the plane distance
2907 for all of the vertices in the primitive are < 0.
2908 If a vertex has a cull distance of NaN, that vertex counts as "out"
2911 Multiple clip/cull planes can be implemented simultaneously, by
2912 annotating multiple components of one or more vertex elements with
2913 the above specified semantic.
2914 The limits on both clip and cull distances are bound
2915 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2916 the maximum number of components that can be used to hold the
2917 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2918 which specifies the maximum number of registers which can be
2919 annotated with those semantics.
2920 The properties NUM_CLIPDIST_ENABLED and NUM_CULLDIST_ENABLED
2921 are used to divide up the 2 x vec4 space between clipping and culling.
2923 TGSI_SEMANTIC_SAMPLEID
2924 """"""""""""""""""""""
2926 For fragment shaders, this semantic label indicates that a system value
2927 contains the current sample id (i.e. gl_SampleID).
2928 This is an integer value, and only the X component is used.
2930 TGSI_SEMANTIC_SAMPLEPOS
2931 """""""""""""""""""""""
2933 For fragment shaders, this semantic label indicates that a system value
2934 contains the current sample's position (i.e. gl_SamplePosition). Only the X
2935 and Y values are used.
2937 TGSI_SEMANTIC_SAMPLEMASK
2938 """"""""""""""""""""""""
2940 For fragment shaders, this semantic label indicates that an output contains
2941 the sample mask used to disable further sample processing
2942 (i.e. gl_SampleMask). Only the X value is used, up to 32x MS.
2944 TGSI_SEMANTIC_INVOCATIONID
2945 """"""""""""""""""""""""""
2947 For geometry shaders, this semantic label indicates that a system value
2948 contains the current invocation id (i.e. gl_InvocationID).
2949 This is an integer value, and only the X component is used.
2951 TGSI_SEMANTIC_INSTANCEID
2952 """"""""""""""""""""""""
2954 For vertex shaders, this semantic label indicates that a system value contains
2955 the current instance id (i.e. gl_InstanceID). It does not include the base
2956 instance. This is an integer value, and only the X component is used.
2958 TGSI_SEMANTIC_VERTEXID
2959 """"""""""""""""""""""
2961 For vertex shaders, this semantic label indicates that a system value contains
2962 the current vertex id (i.e. gl_VertexID). It does (unlike in d3d10) include the
2963 base vertex. This is an integer value, and only the X component is used.
2965 TGSI_SEMANTIC_VERTEXID_NOBASE
2966 """""""""""""""""""""""""""""""
2968 For vertex shaders, this semantic label indicates that a system value contains
2969 the current vertex id without including the base vertex (this corresponds to
2970 d3d10 vertex id, so TGSI_SEMANTIC_VERTEXID_NOBASE + TGSI_SEMANTIC_BASEVERTEX
2971 == TGSI_SEMANTIC_VERTEXID). This is an integer value, and only the X component
2974 TGSI_SEMANTIC_BASEVERTEX
2975 """"""""""""""""""""""""
2977 For vertex shaders, this semantic label indicates that a system value contains
2978 the base vertex (i.e. gl_BaseVertex). Note that for non-indexed draw calls,
2979 this contains the first (or start) value instead.
2980 This is an integer value, and only the X component is used.
2982 TGSI_SEMANTIC_PRIMID
2983 """"""""""""""""""""
2985 For geometry and fragment shaders, this semantic label indicates the value
2986 contains the primitive id (i.e. gl_PrimitiveID). This is an integer value,
2987 and only the X component is used.
2988 FIXME: This right now can be either a ordinary input or a system value...
2994 For tessellation evaluation/control shaders, this semantic label indicates a
2995 generic per-patch attribute. Such semantics will not implicitly be per-vertex
2998 TGSI_SEMANTIC_TESSCOORD
2999 """""""""""""""""""""""
3001 For tessellation evaluation shaders, this semantic label indicates the
3002 coordinates of the vertex being processed. This is available in XYZ; W is
3005 TGSI_SEMANTIC_TESSOUTER
3006 """""""""""""""""""""""
3008 For tessellation evaluation/control shaders, this semantic label indicates the
3009 outer tessellation levels of the patch. Isoline tessellation will only have XY
3010 defined, triangle will have XYZ and quads will have XYZW defined. This
3011 corresponds to gl_TessLevelOuter.
3013 TGSI_SEMANTIC_TESSINNER
3014 """""""""""""""""""""""
3016 For tessellation evaluation/control shaders, this semantic label indicates the
3017 inner tessellation levels of the patch. The X value is only defined for
3018 triangle tessellation, while quads will have XY defined. This is entirely
3019 undefined for isoline tessellation.
3021 TGSI_SEMANTIC_VERTICESIN
3022 """"""""""""""""""""""""
3024 For tessellation evaluation/control shaders, this semantic label indicates the
3025 number of vertices provided in the input patch. Only the X value is defined.
3027 TGSI_SEMANTIC_HELPER_INVOCATION
3028 """""""""""""""""""""""""""""""
3030 For fragment shaders, this semantic indicates whether the current
3031 invocation is covered or not. Helper invocations are created in order
3032 to properly compute derivatives, however it may be desirable to skip
3033 some of the logic in those cases. See ``gl_HelperInvocation`` documentation.
3035 TGSI_SEMANTIC_BASEINSTANCE
3036 """"""""""""""""""""""""""
3038 For vertex shaders, the base instance argument supplied for this
3039 draw. This is an integer value, and only the X component is used.
3041 TGSI_SEMANTIC_DRAWID
3042 """"""""""""""""""""
3044 For vertex shaders, the zero-based index of the current draw in a
3045 ``glMultiDraw*`` invocation. This is an integer value, and only the X
3049 TGSI_SEMANTIC_WORK_DIM
3050 """"""""""""""""""""""
3052 For compute shaders started via opencl this retrieves the work_dim
3053 parameter to the clEnqueueNDRangeKernel call with which the shader
3057 Declaration Interpolate
3058 ^^^^^^^^^^^^^^^^^^^^^^^
3060 This token is only valid for fragment shader INPUT declarations.
3062 The Interpolate field specifes the way input is being interpolated by
3063 the rasteriser and is one of TGSI_INTERPOLATE_*.
3065 The Location field specifies the location inside the pixel that the
3066 interpolation should be done at, one of ``TGSI_INTERPOLATE_LOC_*``. Note that
3067 when per-sample shading is enabled, the implementation may choose to
3068 interpolate at the sample irrespective of the Location field.
3070 The CylindricalWrap bitfield specifies which register components
3071 should be subject to cylindrical wrapping when interpolating by the
3072 rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
3073 should be interpolated according to cylindrical wrapping rules.
3076 Declaration Sampler View
3077 ^^^^^^^^^^^^^^^^^^^^^^^^
3079 Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.
3081 DCL SVIEW[#], resource, type(s)
3083 Declares a shader input sampler view and assigns it to a SVIEW[#]
3086 resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.
3088 type must be 1 or 4 entries (if specifying on a per-component
3089 level) out of UNORM, SNORM, SINT, UINT and FLOAT.
3091 For TEX\* style texture sample opcodes (as opposed to SAMPLE\* opcodes
3092 which take an explicit SVIEW[#] source register), there may be optionally
3093 SVIEW[#] declarations. In this case, the SVIEW index is implied by the
3094 SAMP index, and there must be a corresponding SVIEW[#] declaration for
3095 each SAMP[#] declaration. Drivers are free to ignore this if they wish.
3096 But note in particular that some drivers need to know the sampler type
3097 (float/int/unsigned) in order to generate the correct code, so cases
3098 where integer textures are sampled, SVIEW[#] declarations should be
3101 NOTE: It is NOT legal to mix SAMPLE\* style opcodes and TEX\* opcodes
3104 Declaration Resource
3105 ^^^^^^^^^^^^^^^^^^^^
3107 Follows Declaration token if file is TGSI_FILE_RESOURCE.
3109 DCL RES[#], resource [, WR] [, RAW]
3111 Declares a shader input resource and assigns it to a RES[#]
3114 resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
3117 If the RAW keyword is not specified, the texture data will be
3118 subject to conversion, swizzling and scaling as required to yield
3119 the specified data type from the physical data format of the bound
3122 If the RAW keyword is specified, no channel conversion will be
3123 performed: the values read for each of the channels (X,Y,Z,W) will
3124 correspond to consecutive words in the same order and format
3125 they're found in memory. No element-to-address conversion will be
3126 performed either: the value of the provided X coordinate will be
3127 interpreted in byte units instead of texel units. The result of
3128 accessing a misaligned address is undefined.
3130 Usage of the STORE opcode is only allowed if the WR (writable) flag
3135 ^^^^^^^^^^^^^^^^^^^^^^^^
3137 Properties are general directives that apply to the whole TGSI program.
3142 Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
3143 The default value is UPPER_LEFT.
3145 If UPPER_LEFT, the position will be (0,0) at the upper left corner and
3146 increase downward and rightward.
3147 If LOWER_LEFT, the position will be (0,0) at the lower left corner and
3148 increase upward and rightward.
3150 OpenGL defaults to LOWER_LEFT, and is configurable with the
3151 GL_ARB_fragment_coord_conventions extension.
3153 DirectX 9/10 use UPPER_LEFT.
3155 FS_COORD_PIXEL_CENTER
3156 """""""""""""""""""""
3158 Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
3159 The default value is HALF_INTEGER.
3161 If HALF_INTEGER, the fractionary part of the position will be 0.5
3162 If INTEGER, the fractionary part of the position will be 0.0
3164 Note that this does not affect the set of fragments generated by
3165 rasterization, which is instead controlled by half_pixel_center in the
3168 OpenGL defaults to HALF_INTEGER, and is configurable with the
3169 GL_ARB_fragment_coord_conventions extension.
3171 DirectX 9 uses INTEGER.
3172 DirectX 10 uses HALF_INTEGER.
3174 FS_COLOR0_WRITES_ALL_CBUFS
3175 """"""""""""""""""""""""""
3176 Specifies that writes to the fragment shader color 0 are replicated to all
3177 bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
3178 fragData is directed to a single color buffer, but fragColor is broadcast.
3181 """"""""""""""""""""""""""
3182 If this property is set on the program bound to the shader stage before the
3183 fragment shader, user clip planes should have no effect (be disabled) even if
3184 that shader does not write to any clip distance outputs and the rasterizer's
3185 clip_plane_enable is non-zero.
3186 This property is only supported by drivers that also support shader clip
3188 This is useful for APIs that don't have UCPs and where clip distances written
3189 by a shader cannot be disabled.
3194 Specifies the number of times a geometry shader should be executed for each
3195 input primitive. Each invocation will have a different
3196 TGSI_SEMANTIC_INVOCATIONID system value set. If not specified, assumed to
3199 VS_WINDOW_SPACE_POSITION
3200 """"""""""""""""""""""""""
3201 If this property is set on the vertex shader, the TGSI_SEMANTIC_POSITION output
3202 is assumed to contain window space coordinates.
3203 Division of X,Y,Z by W and the viewport transformation are disabled, and 1/W is
3204 directly taken from the 4-th component of the shader output.
3205 Naturally, clipping is not performed on window coordinates either.
3206 The effect of this property is undefined if a geometry or tessellation shader
3212 The number of vertices written by the tessellation control shader. This
3213 effectively defines the patch input size of the tessellation evaluation shader
3219 This sets the tessellation primitive mode, one of ``PIPE_PRIM_TRIANGLES``,
3220 ``PIPE_PRIM_QUADS``, or ``PIPE_PRIM_LINES``. (Unlike in GL, there is no
3221 separate isolines settings, the regular lines is assumed to mean isolines.)
3226 This sets the spacing mode of the tessellation generator, one of
3227 ``PIPE_TESS_SPACING_*``.
3232 This sets the vertex order to be clockwise if the value is 1, or
3233 counter-clockwise if set to 0.
3238 If set to a non-zero value, this turns on point mode for the tessellator,
3239 which means that points will be generated instead of primitives.
3241 NUM_CLIPDIST_ENABLED
3244 How many clip distance scalar outputs are enabled.
3246 NUM_CULLDIST_ENABLED
3249 How many cull distance scalar outputs are enabled.
3251 FS_EARLY_DEPTH_STENCIL
3252 """"""""""""""""""""""
3254 Whether depth test, stencil test, and occlusion query should run before
3255 the fragment shader (regardless of fragment shader side effects). Corresponds
3256 to GLSL early_fragment_tests.
3261 Which shader stage will MOST LIKELY follow after this shader when the shader
3262 is bound. This is only a hint to the driver and doesn't have to be precise.
3263 Only set for VS and TES.
3265 TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH / HEIGHT / DEPTH
3266 """""""""""""""""""""""""""""""""""""""""""""""""""
3268 Threads per block in each dimension, if known at compile time. If the block size
3269 is known all three should be at least 1. If it is unknown they should all be set
3272 Texture Sampling and Texture Formats
3273 ------------------------------------
3275 This table shows how texture image components are returned as (x,y,z,w) tuples
3276 by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
3277 :opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
3280 +--------------------+--------------+--------------------+--------------+
3281 | Texture Components | Gallium | OpenGL | Direct3D 9 |
3282 +====================+==============+====================+==============+
3283 | R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) |
3284 +--------------------+--------------+--------------------+--------------+
3285 | RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) |
3286 +--------------------+--------------+--------------------+--------------+
3287 | RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) |
3288 +--------------------+--------------+--------------------+--------------+
3289 | RGBA | (r, g, b, a) | (r, g, b, a) | (r, g, b, a) |
3290 +--------------------+--------------+--------------------+--------------+
3291 | A | (0, 0, 0, a) | (0, 0, 0, a) | (0, 0, 0, a) |
3292 +--------------------+--------------+--------------------+--------------+
3293 | L | (l, l, l, 1) | (l, l, l, 1) | (l, l, l, 1) |
3294 +--------------------+--------------+--------------------+--------------+
3295 | LA | (l, l, l, a) | (l, l, l, a) | (l, l, l, a) |
3296 +--------------------+--------------+--------------------+--------------+
3297 | I | (i, i, i, i) | (i, i, i, i) | N/A |
3298 +--------------------+--------------+--------------------+--------------+
3299 | UV | XXX TBD | (0, 0, 0, 1) | (u, v, 1, 1) |
3300 | | | [#envmap-bumpmap]_ | |
3301 +--------------------+--------------+--------------------+--------------+
3302 | Z | XXX TBD | (z, z, z, 1) | (0, z, 0, 1) |
3303 | | | [#depth-tex-mode]_ | |
3304 +--------------------+--------------+--------------------+--------------+
3305 | S | (s, s, s, s) | unknown | unknown |
3306 +--------------------+--------------+--------------------+--------------+
3308 .. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
3309 .. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
3310 or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.