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:`Double Opcodes`.
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 = \lfloor src.x\rfloor
53 dst.y = \lfloor src.y\rfloor
55 dst.z = \lfloor src.z\rfloor
57 dst.w = \lfloor src.w\rfloor
60 .. opcode:: MOV - Move
73 .. opcode:: LIT - Light Coefficients
81 dst.z = (src.x > 0) ? max(src.y, 0)^{clamp(src.w, -128, 128))} : 0
86 .. opcode:: RCP - Reciprocal
88 This instruction replicates its result.
95 .. opcode:: RSQ - Reciprocal Square Root
97 This instruction replicates its result. The results are undefined for src <= 0.
101 dst = \frac{1}{\sqrt{src.x}}
104 .. opcode:: SQRT - Square Root
106 This instruction replicates its result. The results are undefined for src < 0.
113 .. opcode:: EXP - Approximate Exponential Base 2
117 dst.x = 2^{\lfloor src.x\rfloor}
119 dst.y = src.x - \lfloor src.x\rfloor
126 .. opcode:: LOG - Approximate Logarithm Base 2
130 dst.x = \lfloor\log_2{|src.x|}\rfloor
132 dst.y = \frac{|src.x|}{2^{\lfloor\log_2{|src.x|}\rfloor}}
134 dst.z = \log_2{|src.x|}
139 .. opcode:: MUL - Multiply
143 dst.x = src0.x \times src1.x
145 dst.y = src0.y \times src1.y
147 dst.z = src0.z \times src1.z
149 dst.w = src0.w \times src1.w
152 .. opcode:: ADD - Add
156 dst.x = src0.x + src1.x
158 dst.y = src0.y + src1.y
160 dst.z = src0.z + src1.z
162 dst.w = src0.w + src1.w
165 .. opcode:: DP3 - 3-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
174 .. opcode:: DP4 - 4-component Dot Product
176 This instruction replicates its result.
180 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
183 .. opcode:: DST - Distance Vector
189 dst.y = src0.y \times src1.y
196 .. opcode:: MIN - Minimum
200 dst.x = min(src0.x, src1.x)
202 dst.y = min(src0.y, src1.y)
204 dst.z = min(src0.z, src1.z)
206 dst.w = min(src0.w, src1.w)
209 .. opcode:: MAX - Maximum
213 dst.x = max(src0.x, src1.x)
215 dst.y = max(src0.y, src1.y)
217 dst.z = max(src0.z, src1.z)
219 dst.w = max(src0.w, src1.w)
222 .. opcode:: SLT - Set On Less Than
226 dst.x = (src0.x < src1.x) ? 1 : 0
228 dst.y = (src0.y < src1.y) ? 1 : 0
230 dst.z = (src0.z < src1.z) ? 1 : 0
232 dst.w = (src0.w < src1.w) ? 1 : 0
235 .. opcode:: SGE - Set On Greater Equal Than
239 dst.x = (src0.x >= src1.x) ? 1 : 0
241 dst.y = (src0.y >= src1.y) ? 1 : 0
243 dst.z = (src0.z >= src1.z) ? 1 : 0
245 dst.w = (src0.w >= src1.w) ? 1 : 0
248 .. opcode:: MAD - Multiply And Add
252 dst.x = src0.x \times src1.x + src2.x
254 dst.y = src0.y \times src1.y + src2.y
256 dst.z = src0.z \times src1.z + src2.z
258 dst.w = src0.w \times src1.w + src2.w
261 .. opcode:: SUB - Subtract
265 dst.x = src0.x - src1.x
267 dst.y = src0.y - src1.y
269 dst.z = src0.z - src1.z
271 dst.w = src0.w - src1.w
274 .. opcode:: LRP - Linear Interpolate
278 dst.x = src0.x \times src1.x + (1 - src0.x) \times src2.x
280 dst.y = src0.y \times src1.y + (1 - src0.y) \times src2.y
282 dst.z = src0.z \times src1.z + (1 - src0.z) \times src2.z
284 dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w
287 .. opcode:: CND - Condition
291 dst.x = (src2.x > 0.5) ? src0.x : src1.x
293 dst.y = (src2.y > 0.5) ? src0.y : src1.y
295 dst.z = (src2.z > 0.5) ? src0.z : src1.z
297 dst.w = (src2.w > 0.5) ? src0.w : src1.w
300 .. opcode:: DP2A - 2-component Dot Product And Add
304 dst.x = src0.x \times src1.x + src0.y \times src1.y + src2.x
306 dst.y = src0.x \times src1.x + src0.y \times src1.y + src2.x
308 dst.z = src0.x \times src1.x + src0.y \times src1.y + src2.x
310 dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x
313 .. opcode:: FRC - Fraction
317 dst.x = src.x - \lfloor src.x\rfloor
319 dst.y = src.y - \lfloor src.y\rfloor
321 dst.z = src.z - \lfloor src.z\rfloor
323 dst.w = src.w - \lfloor src.w\rfloor
326 .. opcode:: CLAMP - Clamp
330 dst.x = clamp(src0.x, src1.x, src2.x)
332 dst.y = clamp(src0.y, src1.y, src2.y)
334 dst.z = clamp(src0.z, src1.z, src2.z)
336 dst.w = clamp(src0.w, src1.w, src2.w)
339 .. opcode:: FLR - Floor
341 This is identical to :opcode:`ARL`.
345 dst.x = \lfloor src.x\rfloor
347 dst.y = \lfloor src.y\rfloor
349 dst.z = \lfloor src.z\rfloor
351 dst.w = \lfloor src.w\rfloor
354 .. opcode:: ROUND - Round
367 .. opcode:: EX2 - Exponential Base 2
369 This instruction replicates its result.
376 .. opcode:: LG2 - Logarithm Base 2
378 This instruction replicates its result.
385 .. opcode:: POW - Power
387 This instruction replicates its result.
391 dst = src0.x^{src1.x}
393 .. opcode:: XPD - Cross Product
397 dst.x = src0.y \times src1.z - src1.y \times src0.z
399 dst.y = src0.z \times src1.x - src1.z \times src0.x
401 dst.z = src0.x \times src1.y - src1.x \times src0.y
406 .. opcode:: ABS - Absolute
419 .. opcode:: RCC - Reciprocal Clamped
421 This instruction replicates its result.
423 XXX cleanup on aisle three
427 dst = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
430 .. opcode:: DPH - Homogeneous Dot Product
432 This instruction replicates its result.
436 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
439 .. opcode:: COS - Cosine
441 This instruction replicates its result.
448 .. opcode:: DDX - Derivative Relative To X
452 dst.x = partialx(src.x)
454 dst.y = partialx(src.y)
456 dst.z = partialx(src.z)
458 dst.w = partialx(src.w)
461 .. opcode:: DDY - Derivative Relative To Y
465 dst.x = partialy(src.x)
467 dst.y = partialy(src.y)
469 dst.z = partialy(src.z)
471 dst.w = partialy(src.w)
474 .. opcode:: PK2H - Pack Two 16-bit Floats
479 .. opcode:: PK2US - Pack Two Unsigned 16-bit Scalars
484 .. opcode:: PK4B - Pack Four Signed 8-bit Scalars
489 .. opcode:: PK4UB - Pack Four Unsigned 8-bit Scalars
494 .. opcode:: RFL - Reflection Vector
498 dst.x = 2 \times (src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z) / (src0.x \times src0.x + src0.y \times src0.y + src0.z \times src0.z) \times src0.x - src1.x
500 dst.y = 2 \times (src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z) / (src0.x \times src0.x + src0.y \times src0.y + src0.z \times src0.z) \times src0.y - src1.y
502 dst.z = 2 \times (src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z) / (src0.x \times src0.x + src0.y \times src0.y + src0.z \times src0.z) \times src0.z - src1.z
508 Considered for removal.
511 .. opcode:: SEQ - Set On Equal
515 dst.x = (src0.x == src1.x) ? 1 : 0
517 dst.y = (src0.y == src1.y) ? 1 : 0
519 dst.z = (src0.z == src1.z) ? 1 : 0
521 dst.w = (src0.w == src1.w) ? 1 : 0
524 .. opcode:: SFL - Set On False
526 This instruction replicates its result.
534 Considered for removal.
537 .. opcode:: SGT - Set On Greater Than
541 dst.x = (src0.x > src1.x) ? 1 : 0
543 dst.y = (src0.y > src1.y) ? 1 : 0
545 dst.z = (src0.z > src1.z) ? 1 : 0
547 dst.w = (src0.w > src1.w) ? 1 : 0
550 .. opcode:: SIN - Sine
552 This instruction replicates its result.
559 .. opcode:: SLE - Set On Less Equal Than
563 dst.x = (src0.x <= src1.x) ? 1 : 0
565 dst.y = (src0.y <= src1.y) ? 1 : 0
567 dst.z = (src0.z <= src1.z) ? 1 : 0
569 dst.w = (src0.w <= src1.w) ? 1 : 0
572 .. opcode:: SNE - Set On Not Equal
576 dst.x = (src0.x != src1.x) ? 1 : 0
578 dst.y = (src0.y != src1.y) ? 1 : 0
580 dst.z = (src0.z != src1.z) ? 1 : 0
582 dst.w = (src0.w != src1.w) ? 1 : 0
585 .. opcode:: STR - Set On True
587 This instruction replicates its result.
594 .. opcode:: TEX - Texture Lookup
602 dst = texture_sample(unit, coord, bias)
604 for array textures src0.y contains the slice for 1D,
605 and src0.z contain the slice for 2D.
606 for shadow textures with no arrays, src0.z contains
608 for shadow textures with arrays, src0.z contains
609 the reference value for 1D arrays, and src0.w contains
610 the reference value for 2D arrays.
611 There is no way to pass a bias in the .w value for
612 shadow arrays, and GLSL doesn't allow this.
613 GLSL does allow cube shadows maps to take a bias value,
614 and we have to determine how this will look in TGSI.
616 .. opcode:: TXD - Texture Lookup with Derivatives
628 dst = texture_sample_deriv(unit, coord, bias, ddx, ddy)
631 .. opcode:: TXP - Projective Texture Lookup
635 coord.x = src0.x / src.w
637 coord.y = src0.y / src.w
639 coord.z = src0.z / src.w
645 dst = texture_sample(unit, coord, bias)
648 .. opcode:: UP2H - Unpack Two 16-Bit Floats
654 Considered for removal.
656 .. opcode:: UP2US - Unpack Two Unsigned 16-Bit Scalars
662 Considered for removal.
664 .. opcode:: UP4B - Unpack Four Signed 8-Bit Values
670 Considered for removal.
672 .. opcode:: UP4UB - Unpack Four Unsigned 8-Bit Scalars
678 Considered for removal.
680 .. opcode:: X2D - 2D Coordinate Transformation
684 dst.x = src0.x + src1.x \times src2.x + src1.y \times src2.y
686 dst.y = src0.y + src1.x \times src2.z + src1.y \times src2.w
688 dst.z = src0.x + src1.x \times src2.x + src1.y \times src2.y
690 dst.w = src0.y + src1.x \times src2.z + src1.y \times src2.w
694 Considered for removal.
697 .. opcode:: ARA - Address Register Add
703 Considered for removal.
705 .. opcode:: ARR - Address Register Load With Round
718 .. opcode:: SSG - Set Sign
722 dst.x = (src.x > 0) ? 1 : (src.x < 0) ? -1 : 0
724 dst.y = (src.y > 0) ? 1 : (src.y < 0) ? -1 : 0
726 dst.z = (src.z > 0) ? 1 : (src.z < 0) ? -1 : 0
728 dst.w = (src.w > 0) ? 1 : (src.w < 0) ? -1 : 0
731 .. opcode:: CMP - Compare
735 dst.x = (src0.x < 0) ? src1.x : src2.x
737 dst.y = (src0.y < 0) ? src1.y : src2.y
739 dst.z = (src0.z < 0) ? src1.z : src2.z
741 dst.w = (src0.w < 0) ? src1.w : src2.w
744 .. opcode:: KILL_IF - Conditional Discard
746 Conditional discard. Allowed in fragment shaders only.
750 if (src.x < 0 || src.y < 0 || src.z < 0 || src.w < 0)
755 .. opcode:: KILL - Discard
757 Unconditional discard. Allowed in fragment shaders only.
760 .. opcode:: SCS - Sine Cosine
773 .. opcode:: TXB - Texture Lookup With Bias
787 dst = texture_sample(unit, coord, bias)
790 .. opcode:: NRM - 3-component Vector Normalise
794 dst.x = src.x / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
796 dst.y = src.y / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
798 dst.z = src.z / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
803 .. opcode:: DIV - Divide
807 dst.x = \frac{src0.x}{src1.x}
809 dst.y = \frac{src0.y}{src1.y}
811 dst.z = \frac{src0.z}{src1.z}
813 dst.w = \frac{src0.w}{src1.w}
816 .. opcode:: DP2 - 2-component Dot Product
818 This instruction replicates its result.
822 dst = src0.x \times src1.x + src0.y \times src1.y
825 .. opcode:: TXL - Texture Lookup With explicit LOD
839 dst = texture_sample(unit, coord, lod)
842 .. opcode:: PUSHA - Push Address Register On Stack
851 Considered for cleanup.
855 Considered for removal.
857 .. opcode:: POPA - Pop Address Register From Stack
866 Considered for cleanup.
870 Considered for removal.
873 .. opcode:: BRA - Branch
879 Considered for removal.
882 .. opcode:: CALLNZ - Subroutine Call If Not Zero
888 Considered for cleanup.
892 Considered for removal.
896 ^^^^^^^^^^^^^^^^^^^^^^^^
898 These opcodes are primarily provided for special-use computational shaders.
899 Support for these opcodes indicated by a special pipe capability bit (TBD).
901 XXX doesn't look like most of the opcodes really belong here.
903 .. opcode:: CEIL - Ceiling
907 dst.x = \lceil src.x\rceil
909 dst.y = \lceil src.y\rceil
911 dst.z = \lceil src.z\rceil
913 dst.w = \lceil src.w\rceil
916 .. opcode:: TRUNC - Truncate
929 .. opcode:: MOD - Modulus
933 dst.x = src0.x \bmod src1.x
935 dst.y = src0.y \bmod src1.y
937 dst.z = src0.z \bmod src1.z
939 dst.w = src0.w \bmod src1.w
942 .. opcode:: UARL - Integer Address Register Load
944 Moves the contents of the source register, assumed to be an integer, into the
945 destination register, which is assumed to be an address (ADDR) register.
948 .. opcode:: SAD - Sum Of Absolute Differences
952 dst.x = |src0.x - src1.x| + src2.x
954 dst.y = |src0.y - src1.y| + src2.y
956 dst.z = |src0.z - src1.z| + src2.z
958 dst.w = |src0.w - src1.w| + src2.w
961 .. opcode:: TXF - Texel Fetch (as per NV_gpu_shader4), extract a single texel
962 from a specified texture image. The source sampler may
963 not be a CUBE or SHADOW.
964 src 0 is a four-component signed integer vector used to
965 identify the single texel accessed. 3 components + level.
966 src 1 is a 3 component constant signed integer vector,
967 with each component only have a range of
968 -8..+8 (hw only seems to deal with this range, interface
969 allows for up to unsigned int).
970 TXF(uint_vec coord, int_vec offset).
973 .. opcode:: TXQ - Texture Size Query (as per NV_gpu_program4)
974 retrieve the dimensions of the texture
975 depending on the target. For 1D (width), 2D/RECT/CUBE
976 (width, height), 3D (width, height, depth),
977 1D array (width, layers), 2D array (width, height, layers)
983 dst.x = texture_width(unit, lod)
985 dst.y = texture_height(unit, lod)
987 dst.z = texture_depth(unit, lod)
991 ^^^^^^^^^^^^^^^^^^^^^^^^
992 These opcodes are used for integer operations.
993 Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?)
996 .. opcode:: I2F - Signed Integer To Float
998 Rounding is unspecified (round to nearest even suggested).
1002 dst.x = (float) src.x
1004 dst.y = (float) src.y
1006 dst.z = (float) src.z
1008 dst.w = (float) src.w
1011 .. opcode:: U2F - Unsigned Integer To Float
1013 Rounding is unspecified (round to nearest even suggested).
1017 dst.x = (float) src.x
1019 dst.y = (float) src.y
1021 dst.z = (float) src.z
1023 dst.w = (float) src.w
1026 .. opcode:: F2I - Float to Signed Integer
1028 Rounding is towards zero (truncate).
1029 Values outside signed range (including NaNs) produce undefined results.
1042 .. opcode:: F2U - Float to Unsigned Integer
1044 Rounding is towards zero (truncate).
1045 Values outside unsigned range (including NaNs) produce undefined results.
1049 dst.x = (unsigned) src.x
1051 dst.y = (unsigned) src.y
1053 dst.z = (unsigned) src.z
1055 dst.w = (unsigned) src.w
1058 .. opcode:: UADD - Integer Add
1060 This instruction works the same for signed and unsigned integers.
1061 The low 32bit of the result is returned.
1065 dst.x = src0.x + src1.x
1067 dst.y = src0.y + src1.y
1069 dst.z = src0.z + src1.z
1071 dst.w = src0.w + src1.w
1074 .. opcode:: UMAD - Integer Multiply And Add
1076 This instruction works the same for signed and unsigned integers.
1077 The multiplication returns the low 32bit (as does the result itself).
1081 dst.x = src0.x \times src1.x + src2.x
1083 dst.y = src0.y \times src1.y + src2.y
1085 dst.z = src0.z \times src1.z + src2.z
1087 dst.w = src0.w \times src1.w + src2.w
1090 .. opcode:: UMUL - Integer Multiply
1092 This instruction works the same for signed and unsigned integers.
1093 The low 32bit of the result is returned.
1097 dst.x = src0.x \times src1.x
1099 dst.y = src0.y \times src1.y
1101 dst.z = src0.z \times src1.z
1103 dst.w = src0.w \times src1.w
1106 .. opcode:: IDIV - Signed Integer Division
1108 TBD: behavior for division by zero.
1112 dst.x = src0.x \ src1.x
1114 dst.y = src0.y \ src1.y
1116 dst.z = src0.z \ src1.z
1118 dst.w = src0.w \ src1.w
1121 .. opcode:: UDIV - Unsigned Integer Division
1123 For division by zero, 0xffffffff is returned.
1127 dst.x = src0.x \ src1.x
1129 dst.y = src0.y \ src1.y
1131 dst.z = src0.z \ src1.z
1133 dst.w = src0.w \ src1.w
1136 .. opcode:: UMOD - Unsigned Integer Remainder
1138 If second arg is zero, 0xffffffff is returned.
1142 dst.x = src0.x \ src1.x
1144 dst.y = src0.y \ src1.y
1146 dst.z = src0.z \ src1.z
1148 dst.w = src0.w \ src1.w
1151 .. opcode:: NOT - Bitwise Not
1164 .. opcode:: AND - Bitwise And
1168 dst.x = src0.x & src1.x
1170 dst.y = src0.y & src1.y
1172 dst.z = src0.z & src1.z
1174 dst.w = src0.w & src1.w
1177 .. opcode:: OR - Bitwise Or
1181 dst.x = src0.x | src1.x
1183 dst.y = src0.y | src1.y
1185 dst.z = src0.z | src1.z
1187 dst.w = src0.w | src1.w
1190 .. opcode:: XOR - Bitwise Xor
1194 dst.x = src0.x \oplus src1.x
1196 dst.y = src0.y \oplus src1.y
1198 dst.z = src0.z \oplus src1.z
1200 dst.w = src0.w \oplus src1.w
1203 .. opcode:: IMAX - Maximum of Signed Integers
1207 dst.x = max(src0.x, src1.x)
1209 dst.y = max(src0.y, src1.y)
1211 dst.z = max(src0.z, src1.z)
1213 dst.w = max(src0.w, src1.w)
1216 .. opcode:: UMAX - Maximum of Unsigned Integers
1220 dst.x = max(src0.x, src1.x)
1222 dst.y = max(src0.y, src1.y)
1224 dst.z = max(src0.z, src1.z)
1226 dst.w = max(src0.w, src1.w)
1229 .. opcode:: IMIN - Minimum of Signed Integers
1233 dst.x = min(src0.x, src1.x)
1235 dst.y = min(src0.y, src1.y)
1237 dst.z = min(src0.z, src1.z)
1239 dst.w = min(src0.w, src1.w)
1242 .. opcode:: UMIN - Minimum of Unsigned Integers
1246 dst.x = min(src0.x, src1.x)
1248 dst.y = min(src0.y, src1.y)
1250 dst.z = min(src0.z, src1.z)
1252 dst.w = min(src0.w, src1.w)
1255 .. opcode:: SHL - Shift Left
1257 The shift count is masked with 0x1f before the shift is applied.
1261 dst.x = src0.x << (0x1f & src1.x)
1263 dst.y = src0.y << (0x1f & src1.y)
1265 dst.z = src0.z << (0x1f & src1.z)
1267 dst.w = src0.w << (0x1f & src1.w)
1270 .. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)
1272 The shift count is masked with 0x1f before the shift is applied.
1276 dst.x = src0.x >> (0x1f & src1.x)
1278 dst.y = src0.y >> (0x1f & src1.y)
1280 dst.z = src0.z >> (0x1f & src1.z)
1282 dst.w = src0.w >> (0x1f & src1.w)
1285 .. opcode:: USHR - Logical Shift Right
1287 The shift count is masked with 0x1f before the shift is applied.
1291 dst.x = src0.x >> (unsigned) (0x1f & src1.x)
1293 dst.y = src0.y >> (unsigned) (0x1f & src1.y)
1295 dst.z = src0.z >> (unsigned) (0x1f & src1.z)
1297 dst.w = src0.w >> (unsigned) (0x1f & src1.w)
1300 .. opcode:: UCMP - Integer Conditional Move
1304 dst.x = src0.x ? src1.x : src2.x
1306 dst.y = src0.y ? src1.y : src2.y
1308 dst.z = src0.z ? src1.z : src2.z
1310 dst.w = src0.w ? src1.w : src2.w
1314 .. opcode:: ISSG - Integer Set Sign
1318 dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0
1320 dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0
1322 dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0
1324 dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0
1328 .. opcode:: ISLT - Signed Integer Set On Less Than
1332 dst.x = (src0.x < src1.x) ? ~0 : 0
1334 dst.y = (src0.y < src1.y) ? ~0 : 0
1336 dst.z = (src0.z < src1.z) ? ~0 : 0
1338 dst.w = (src0.w < src1.w) ? ~0 : 0
1341 .. opcode:: USLT - Unsigned Integer Set On Less Than
1345 dst.x = (src0.x < src1.x) ? ~0 : 0
1347 dst.y = (src0.y < src1.y) ? ~0 : 0
1349 dst.z = (src0.z < src1.z) ? ~0 : 0
1351 dst.w = (src0.w < src1.w) ? ~0 : 0
1354 .. opcode:: ISGE - Signed Integer Set On Greater Equal Than
1358 dst.x = (src0.x >= src1.x) ? ~0 : 0
1360 dst.y = (src0.y >= src1.y) ? ~0 : 0
1362 dst.z = (src0.z >= src1.z) ? ~0 : 0
1364 dst.w = (src0.w >= src1.w) ? ~0 : 0
1367 .. opcode:: USGE - Unsigned Integer Set On Greater Equal Than
1371 dst.x = (src0.x >= src1.x) ? ~0 : 0
1373 dst.y = (src0.y >= src1.y) ? ~0 : 0
1375 dst.z = (src0.z >= src1.z) ? ~0 : 0
1377 dst.w = (src0.w >= src1.w) ? ~0 : 0
1380 .. opcode:: USEQ - Integer Set On Equal
1384 dst.x = (src0.x == src1.x) ? ~0 : 0
1386 dst.y = (src0.y == src1.y) ? ~0 : 0
1388 dst.z = (src0.z == src1.z) ? ~0 : 0
1390 dst.w = (src0.w == src1.w) ? ~0 : 0
1393 .. opcode:: USNE - Integer Set On Not Equal
1397 dst.x = (src0.x != src1.x) ? ~0 : 0
1399 dst.y = (src0.y != src1.y) ? ~0 : 0
1401 dst.z = (src0.z != src1.z) ? ~0 : 0
1403 dst.w = (src0.w != src1.w) ? ~0 : 0
1406 .. opcode:: INEG - Integer Negate
1421 .. opcode:: IABS - Integer Absolute Value
1435 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1437 These opcodes are only supported in geometry shaders; they have no meaning
1438 in any other type of shader.
1440 .. opcode:: EMIT - Emit
1442 Generate a new vertex for the current primitive using the values in the
1446 .. opcode:: ENDPRIM - End Primitive
1448 Complete the current primitive (consisting of the emitted vertices),
1449 and start a new one.
1455 These opcodes are part of :term:`GLSL`'s opcode set. Support for these
1456 opcodes is determined by a special capability bit, ``GLSL``.
1457 Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
1459 .. opcode:: CAL - Subroutine Call
1465 .. opcode:: RET - Subroutine Call Return
1470 .. opcode:: CONT - Continue
1472 Unconditionally moves the point of execution to the instruction after the
1473 last bgnloop. The instruction must appear within a bgnloop/endloop.
1477 Support for CONT is determined by a special capability bit,
1478 ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
1481 .. opcode:: BGNLOOP - Begin a Loop
1483 Start a loop. Must have a matching endloop.
1486 .. opcode:: BGNSUB - Begin Subroutine
1488 Starts definition of a subroutine. Must have a matching endsub.
1491 .. opcode:: ENDLOOP - End a Loop
1493 End a loop started with bgnloop.
1496 .. opcode:: ENDSUB - End Subroutine
1498 Ends definition of a subroutine.
1501 .. opcode:: NOP - No Operation
1506 .. opcode:: BRK - Break
1508 Unconditionally moves the point of execution to the instruction after the
1509 next endloop or endswitch. The instruction must appear within a loop/endloop
1510 or switch/endswitch.
1513 .. opcode:: BREAKC - Break Conditional
1515 Conditionally moves the point of execution to the instruction after the
1516 next endloop or endswitch. The instruction must appear within a loop/endloop
1517 or switch/endswitch.
1518 Condition evaluates to true if src0.x != 0 where src0.x is interpreted
1519 as an integer register.
1523 Considered for removal as it's quite inconsistent wrt other opcodes
1524 (could emulate with UIF/BRK/ENDIF).
1527 .. opcode:: IF - Float If
1529 Start an IF ... ELSE .. ENDIF block. Condition evaluates to true if
1533 where src0.x is interpreted as a floating point register.
1536 .. opcode:: UIF - Bitwise If
1538 Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if
1542 where src0.x is interpreted as an integer register.
1545 .. opcode:: ELSE - Else
1547 Starts an else block, after an IF or UIF statement.
1550 .. opcode:: ENDIF - End If
1552 Ends an IF or UIF block.
1555 .. opcode:: SWITCH - Switch
1557 Starts a C-style switch expression. The switch consists of one or multiple
1558 CASE statements, and at most one DEFAULT statement. Execution of a statement
1559 ends when a BRK is hit, but just like in C falling through to other cases
1560 without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
1561 just as last statement, and fallthrough is allowed into/from it.
1562 CASE src arguments are evaluated at bit level against the SWITCH src argument.
1567 (some instructions here)
1570 (some instructions here)
1573 (some instructions here)
1578 .. opcode:: CASE - Switch case
1580 This represents a switch case label. The src arg must be an integer immediate.
1583 .. opcode:: DEFAULT - Switch default
1585 This represents the default case in the switch, which is taken if no other
1589 .. opcode:: ENDSWITCH - End of switch
1591 Ends a switch expression.
1594 .. opcode:: NRM4 - 4-component Vector Normalise
1596 This instruction replicates its result.
1600 dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
1608 The double-precision opcodes reinterpret four-component vectors into
1609 two-component vectors with doubled precision in each component.
1611 Support for these opcodes is XXX undecided. :T
1613 .. opcode:: DADD - Add
1617 dst.xy = src0.xy + src1.xy
1619 dst.zw = src0.zw + src1.zw
1622 .. opcode:: DDIV - Divide
1626 dst.xy = src0.xy / src1.xy
1628 dst.zw = src0.zw / src1.zw
1630 .. opcode:: DSEQ - Set on Equal
1634 dst.xy = src0.xy == src1.xy ? 1.0F : 0.0F
1636 dst.zw = src0.zw == src1.zw ? 1.0F : 0.0F
1638 .. opcode:: DSLT - Set on Less than
1642 dst.xy = src0.xy < src1.xy ? 1.0F : 0.0F
1644 dst.zw = src0.zw < src1.zw ? 1.0F : 0.0F
1646 .. opcode:: DFRAC - Fraction
1650 dst.xy = src.xy - \lfloor src.xy\rfloor
1652 dst.zw = src.zw - \lfloor src.zw\rfloor
1655 .. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components
1657 Like the ``frexp()`` routine in many math libraries, this opcode stores the
1658 exponent of its source to ``dst0``, and the significand to ``dst1``, such that
1659 :math:`dst1 \times 2^{dst0} = src` .
1663 dst0.xy = exp(src.xy)
1665 dst1.xy = frac(src.xy)
1667 dst0.zw = exp(src.zw)
1669 dst1.zw = frac(src.zw)
1671 .. opcode:: DLDEXP - Multiply Number by Integral Power of 2
1673 This opcode is the inverse of :opcode:`DFRACEXP`.
1677 dst.xy = src0.xy \times 2^{src1.xy}
1679 dst.zw = src0.zw \times 2^{src1.zw}
1681 .. opcode:: DMIN - Minimum
1685 dst.xy = min(src0.xy, src1.xy)
1687 dst.zw = min(src0.zw, src1.zw)
1689 .. opcode:: DMAX - Maximum
1693 dst.xy = max(src0.xy, src1.xy)
1695 dst.zw = max(src0.zw, src1.zw)
1697 .. opcode:: DMUL - Multiply
1701 dst.xy = src0.xy \times src1.xy
1703 dst.zw = src0.zw \times src1.zw
1706 .. opcode:: DMAD - Multiply And Add
1710 dst.xy = src0.xy \times src1.xy + src2.xy
1712 dst.zw = src0.zw \times src1.zw + src2.zw
1715 .. opcode:: DRCP - Reciprocal
1719 dst.xy = \frac{1}{src.xy}
1721 dst.zw = \frac{1}{src.zw}
1723 .. opcode:: DSQRT - Square Root
1727 dst.xy = \sqrt{src.xy}
1729 dst.zw = \sqrt{src.zw}
1732 .. _samplingopcodes:
1734 Resource Sampling Opcodes
1735 ^^^^^^^^^^^^^^^^^^^^^^^^^
1737 Those opcodes follow very closely semantics of the respective Direct3D
1738 instructions. If in doubt double check Direct3D documentation.
1739 Note that the swizzle on SVIEW (src1) determines texel swizzling
1742 .. opcode:: SAMPLE - Using provided address, sample data from the
1743 specified texture using the filtering mode identified
1744 by the gven sampler. The source data may come from
1745 any resource type other than buffers.
1746 SAMPLE dst, address, sampler_view, sampler
1748 SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
1750 .. opcode:: SAMPLE_I - Simplified alternative to the SAMPLE instruction.
1751 Using the provided integer address, SAMPLE_I fetches data
1752 from the specified sampler view without any filtering.
1753 The source data may come from any resource type other
1755 SAMPLE_I dst, address, sampler_view
1757 SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]
1758 The 'address' is specified as unsigned integers. If the
1759 'address' is out of range [0...(# texels - 1)] the
1760 result of the fetch is always 0 in all components.
1761 As such the instruction doesn't honor address wrap
1762 modes, in cases where that behavior is desirable
1763 'SAMPLE' instruction should be used.
1764 address.w always provides an unsigned integer mipmap
1765 level. If the value is out of the range then the
1766 instruction always returns 0 in all components.
1767 address.yz are ignored for buffers and 1d textures.
1768 address.z is ignored for 1d texture arrays and 2d
1770 For 1D texture arrays address.y provides the array
1771 index (also as unsigned integer). If the value is
1772 out of the range of available array indices
1773 [0... (array size - 1)] then the opcode always returns
1774 0 in all components.
1775 For 2D texture arrays address.z provides the array
1776 index, otherwise it exhibits the same behavior as in
1777 the case for 1D texture arrays.
1778 The exact semantics of the source address are presented
1780 resource type X Y Z W
1781 ------------- ------------------------
1782 PIPE_BUFFER x ignored
1783 PIPE_TEXTURE_1D x mpl
1784 PIPE_TEXTURE_2D x y mpl
1785 PIPE_TEXTURE_3D x y z mpl
1786 PIPE_TEXTURE_RECT x y mpl
1787 PIPE_TEXTURE_CUBE not allowed as source
1788 PIPE_TEXTURE_1D_ARRAY x idx mpl
1789 PIPE_TEXTURE_2D_ARRAY x y idx mpl
1791 Where 'mpl' is a mipmap level and 'idx' is the
1794 .. opcode:: SAMPLE_I_MS - Just like SAMPLE_I but allows fetch data from
1795 multi-sampled surfaces.
1796 SAMPLE_I_MS dst, address, sampler_view, sample
1798 .. opcode:: SAMPLE_B - Just like the SAMPLE instruction with the
1799 exception that an additional bias is applied to the
1800 level of detail computed as part of the instruction
1802 SAMPLE_B dst, address, sampler_view, sampler, lod_bias
1804 SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
1806 .. opcode:: SAMPLE_C - Similar to the SAMPLE instruction but it
1807 performs a comparison filter. The operands to SAMPLE_C
1808 are identical to SAMPLE, except that there is an additional
1809 float32 operand, reference value, which must be a register
1810 with single-component, or a scalar literal.
1811 SAMPLE_C makes the hardware use the current samplers
1812 compare_func (in pipe_sampler_state) to compare
1813 reference value against the red component value for the
1814 surce resource at each texel that the currently configured
1815 texture filter covers based on the provided coordinates.
1816 SAMPLE_C dst, address, sampler_view.r, sampler, ref_value
1818 SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
1820 .. opcode:: SAMPLE_C_LZ - Same as SAMPLE_C, but LOD is 0 and derivatives
1821 are ignored. The LZ stands for level-zero.
1822 SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value
1824 SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
1827 .. opcode:: SAMPLE_D - SAMPLE_D is identical to the SAMPLE opcode except
1828 that the derivatives for the source address in the x
1829 direction and the y direction are provided by extra
1831 SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y
1833 SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]
1835 .. opcode:: SAMPLE_L - SAMPLE_L is identical to the SAMPLE opcode except
1836 that the LOD is provided directly as a scalar value,
1837 representing no anisotropy.
1838 SAMPLE_L dst, address, sampler_view, sampler, explicit_lod
1840 SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
1842 .. opcode:: GATHER4 - Gathers the four texels to be used in a bi-linear
1843 filtering operation and packs them into a single register.
1844 Only works with 2D, 2D array, cubemaps, and cubemaps arrays.
1845 For 2D textures, only the addressing modes of the sampler and
1846 the top level of any mip pyramid are used. Set W to zero.
1847 It behaves like the SAMPLE instruction, but a filtered
1848 sample is not generated. The four samples that contribute
1849 to filtering are placed into xyzw in counter-clockwise order,
1850 starting with the (u,v) texture coordinate delta at the
1851 following locations (-, +), (+, +), (+, -), (-, -), where
1852 the magnitude of the deltas are half a texel.
1855 .. opcode:: SVIEWINFO - query the dimensions of a given sampler view.
1856 dst receives width, height, depth or array size and
1857 number of mipmap levels as int4. The dst can have a writemask
1858 which will specify what info is the caller interested
1860 SVIEWINFO dst, src_mip_level, sampler_view
1862 SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]
1863 src_mip_level is an unsigned integer scalar. If it's
1864 out of range then returns 0 for width, height and
1865 depth/array size but the total number of mipmap is
1866 still returned correctly for the given sampler view.
1867 The returned width, height and depth values are for
1868 the mipmap level selected by the src_mip_level and
1869 are in the number of texels.
1870 For 1d texture array width is in dst.x, array size
1871 is in dst.y and dst.zw are always 0.
1873 .. opcode:: SAMPLE_POS - query the position of a given sample.
1874 dst receives float4 (x, y, 0, 0) indicated where the
1875 sample is located. If the resource is not a multi-sample
1876 resource and not a render target, the result is 0.
1878 .. opcode:: SAMPLE_INFO - dst receives number of samples in x.
1879 If the resource is not a multi-sample resource and
1880 not a render target, the result is 0.
1883 .. _resourceopcodes:
1885 Resource Access Opcodes
1886 ^^^^^^^^^^^^^^^^^^^^^^^
1888 .. opcode:: LOAD - Fetch data from a shader resource
1890 Syntax: ``LOAD dst, resource, address``
1892 Example: ``LOAD TEMP[0], RES[0], TEMP[1]``
1894 Using the provided integer address, LOAD fetches data
1895 from the specified buffer or texture without any
1898 The 'address' is specified as a vector of unsigned
1899 integers. If the 'address' is out of range the result
1902 Only the first mipmap level of a resource can be read
1903 from using this instruction.
1905 For 1D or 2D texture arrays, the array index is
1906 provided as an unsigned integer in address.y or
1907 address.z, respectively. address.yz are ignored for
1908 buffers and 1D textures. address.z is ignored for 1D
1909 texture arrays and 2D textures. address.w is always
1912 .. opcode:: STORE - Write data to a shader resource
1914 Syntax: ``STORE resource, address, src``
1916 Example: ``STORE RES[0], TEMP[0], TEMP[1]``
1918 Using the provided integer address, STORE writes data
1919 to the specified buffer or texture.
1921 The 'address' is specified as a vector of unsigned
1922 integers. If the 'address' is out of range the result
1925 Only the first mipmap level of a resource can be
1926 written to using this instruction.
1928 For 1D or 2D texture arrays, the array index is
1929 provided as an unsigned integer in address.y or
1930 address.z, respectively. address.yz are ignored for
1931 buffers and 1D textures. address.z is ignored for 1D
1932 texture arrays and 2D textures. address.w is always
1936 .. _threadsyncopcodes:
1938 Inter-thread synchronization opcodes
1939 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1941 These opcodes are intended for communication between threads running
1942 within the same compute grid. For now they're only valid in compute
1945 .. opcode:: MFENCE - Memory fence
1947 Syntax: ``MFENCE resource``
1949 Example: ``MFENCE RES[0]``
1951 This opcode forces strong ordering between any memory access
1952 operations that affect the specified resource. This means that
1953 previous loads and stores (and only those) will be performed and
1954 visible to other threads before the program execution continues.
1957 .. opcode:: LFENCE - Load memory fence
1959 Syntax: ``LFENCE resource``
1961 Example: ``LFENCE RES[0]``
1963 Similar to MFENCE, but it only affects the ordering of memory loads.
1966 .. opcode:: SFENCE - Store memory fence
1968 Syntax: ``SFENCE resource``
1970 Example: ``SFENCE RES[0]``
1972 Similar to MFENCE, but it only affects the ordering of memory stores.
1975 .. opcode:: BARRIER - Thread group barrier
1979 This opcode suspends the execution of the current thread until all
1980 the remaining threads in the working group reach the same point of
1981 the program. Results are unspecified if any of the remaining
1982 threads terminates or never reaches an executed BARRIER instruction.
1990 These opcodes provide atomic variants of some common arithmetic and
1991 logical operations. In this context atomicity means that another
1992 concurrent memory access operation that affects the same memory
1993 location is guaranteed to be performed strictly before or after the
1994 entire execution of the atomic operation.
1996 For the moment they're only valid in compute programs.
1998 .. opcode:: ATOMUADD - Atomic integer addition
2000 Syntax: ``ATOMUADD dst, resource, offset, src``
2002 Example: ``ATOMUADD TEMP[0], RES[0], TEMP[1], TEMP[2]``
2004 The following operation is performed atomically on each component:
2008 dst_i = resource[offset]_i
2010 resource[offset]_i = dst_i + src_i
2013 .. opcode:: ATOMXCHG - Atomic exchange
2015 Syntax: ``ATOMXCHG dst, resource, offset, src``
2017 Example: ``ATOMXCHG TEMP[0], RES[0], TEMP[1], TEMP[2]``
2019 The following operation is performed atomically on each component:
2023 dst_i = resource[offset]_i
2025 resource[offset]_i = src_i
2028 .. opcode:: ATOMCAS - Atomic compare-and-exchange
2030 Syntax: ``ATOMCAS dst, resource, offset, cmp, src``
2032 Example: ``ATOMCAS TEMP[0], RES[0], TEMP[1], TEMP[2], TEMP[3]``
2034 The following operation is performed atomically on each component:
2038 dst_i = resource[offset]_i
2040 resource[offset]_i = (dst_i == cmp_i ? src_i : dst_i)
2043 .. opcode:: ATOMAND - Atomic bitwise And
2045 Syntax: ``ATOMAND dst, resource, offset, src``
2047 Example: ``ATOMAND TEMP[0], RES[0], TEMP[1], TEMP[2]``
2049 The following operation is performed atomically on each component:
2053 dst_i = resource[offset]_i
2055 resource[offset]_i = dst_i \& src_i
2058 .. opcode:: ATOMOR - Atomic bitwise Or
2060 Syntax: ``ATOMOR dst, resource, offset, src``
2062 Example: ``ATOMOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2064 The following operation is performed atomically on each component:
2068 dst_i = resource[offset]_i
2070 resource[offset]_i = dst_i | src_i
2073 .. opcode:: ATOMXOR - Atomic bitwise Xor
2075 Syntax: ``ATOMXOR dst, resource, offset, src``
2077 Example: ``ATOMXOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2079 The following operation is performed atomically on each component:
2083 dst_i = resource[offset]_i
2085 resource[offset]_i = dst_i \oplus src_i
2088 .. opcode:: ATOMUMIN - Atomic unsigned minimum
2090 Syntax: ``ATOMUMIN dst, resource, offset, src``
2092 Example: ``ATOMUMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2094 The following operation is performed atomically on each component:
2098 dst_i = resource[offset]_i
2100 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2103 .. opcode:: ATOMUMAX - Atomic unsigned maximum
2105 Syntax: ``ATOMUMAX dst, resource, offset, src``
2107 Example: ``ATOMUMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2109 The following operation is performed atomically on each component:
2113 dst_i = resource[offset]_i
2115 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2118 .. opcode:: ATOMIMIN - Atomic signed minimum
2120 Syntax: ``ATOMIMIN dst, resource, offset, src``
2122 Example: ``ATOMIMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2124 The following operation is performed atomically on each component:
2128 dst_i = resource[offset]_i
2130 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2133 .. opcode:: ATOMIMAX - Atomic signed maximum
2135 Syntax: ``ATOMIMAX dst, resource, offset, src``
2137 Example: ``ATOMIMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2139 The following operation is performed atomically on each component:
2143 dst_i = resource[offset]_i
2145 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2149 Explanation of symbols used
2150 ------------------------------
2157 :math:`|x|` Absolute value of `x`.
2159 :math:`\lceil x \rceil` Ceiling of `x`.
2161 clamp(x,y,z) Clamp x between y and z.
2162 (x < y) ? y : (x > z) ? z : x
2164 :math:`\lfloor x\rfloor` Floor of `x`.
2166 :math:`\log_2{x}` Logarithm of `x`, base 2.
2168 max(x,y) Maximum of x and y.
2171 min(x,y) Minimum of x and y.
2174 partialx(x) Derivative of x relative to fragment's X.
2176 partialy(x) Derivative of x relative to fragment's Y.
2178 pop() Pop from stack.
2180 :math:`x^y` `x` to the power `y`.
2182 push(x) Push x on stack.
2186 trunc(x) Truncate x, i.e. drop the fraction bits.
2193 discard Discard fragment.
2197 target Label of target instruction.
2208 Declares a register that is will be referenced as an operand in Instruction
2211 File field contains register file that is being declared and is one
2214 UsageMask field specifies which of the register components can be accessed
2215 and is one of TGSI_WRITEMASK.
2217 The Local flag specifies that a given value isn't intended for
2218 subroutine parameter passing and, as a result, the implementation
2219 isn't required to give any guarantees of it being preserved across
2220 subroutine boundaries. As it's merely a compiler hint, the
2221 implementation is free to ignore it.
2223 If Dimension flag is set to 1, a Declaration Dimension token follows.
2225 If Semantic flag is set to 1, a Declaration Semantic token follows.
2227 If Interpolate flag is set to 1, a Declaration Interpolate token follows.
2229 If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.
2231 If Array flag is set to 1, a Declaration Array token follows.
2234 ^^^^^^^^^^^^^^^^^^^^^^^^
2236 Declarations can optional have an ArrayID attribute which can be referred by
2237 indirect addressing operands. An ArrayID of zero is reserved and treaded as
2238 if no ArrayID is specified.
2240 If an indirect addressing operand refers to a specific declaration by using
2241 an ArrayID only the registers in this declaration are guaranteed to be
2242 accessed, accessing any register outside this declaration results in undefined
2243 behavior. Note that for compatibility the effective index is zero-based and
2244 not relative to the specified declaration
2246 If no ArrayID is specified with an indirect addressing operand the whole
2247 register file might be accessed by this operand. This is strongly discouraged
2248 and will prevent packing of scalar/vec2 arrays and effective alias analysis.
2250 Declaration Semantic
2251 ^^^^^^^^^^^^^^^^^^^^^^^^
2253 Vertex and fragment shader input and output registers may be labeled
2254 with semantic information consisting of a name and index.
2256 Follows Declaration token if Semantic bit is set.
2258 Since its purpose is to link a shader with other stages of the pipeline,
2259 it is valid to follow only those Declaration tokens that declare a register
2260 either in INPUT or OUTPUT file.
2262 SemanticName field contains the semantic name of the register being declared.
2263 There is no default value.
2265 SemanticIndex is an optional subscript that can be used to distinguish
2266 different register declarations with the same semantic name. The default value
2269 The meanings of the individual semantic names are explained in the following
2272 TGSI_SEMANTIC_POSITION
2273 """"""""""""""""""""""
2275 For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
2276 output register which contains the homogeneous vertex position in the clip
2277 space coordinate system. After clipping, the X, Y and Z components of the
2278 vertex will be divided by the W value to get normalized device coordinates.
2280 For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
2281 fragment shader input contains the fragment's window position. The X
2282 component starts at zero and always increases from left to right.
2283 The Y component starts at zero and always increases but Y=0 may either
2284 indicate the top of the window or the bottom depending on the fragment
2285 coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
2286 The Z coordinate ranges from 0 to 1 to represent depth from the front
2287 to the back of the Z buffer. The W component contains the reciprocol
2288 of the interpolated vertex position W component.
2290 Fragment shaders may also declare an output register with
2291 TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows
2292 the fragment shader to change the fragment's Z position.
2299 For vertex shader outputs or fragment shader inputs/outputs, this
2300 label indicates that the resister contains an R,G,B,A color.
2302 Several shader inputs/outputs may contain colors so the semantic index
2303 is used to distinguish them. For example, color[0] may be the diffuse
2304 color while color[1] may be the specular color.
2306 This label is needed so that the flat/smooth shading can be applied
2307 to the right interpolants during rasterization.
2311 TGSI_SEMANTIC_BCOLOR
2312 """"""""""""""""""""
2314 Back-facing colors are only used for back-facing polygons, and are only valid
2315 in vertex shader outputs. After rasterization, all polygons are front-facing
2316 and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
2317 so all BCOLORs effectively become regular COLORs in the fragment shader.
2323 Vertex shader inputs and outputs and fragment shader inputs may be
2324 labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
2325 a fog coordinate in the form (F, 0, 0, 1). Typically, the fragment
2326 shader will use the fog coordinate to compute a fog blend factor which
2327 is used to blend the normal fragment color with a constant fog color.
2329 Only the first component matters when writing from the vertex shader;
2330 the driver will ensure that the coordinate is in this format when used
2331 as a fragment shader input.
2337 Vertex shader input and output registers may be labeled with
2338 TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
2339 in the form (S, 0, 0, 1). The point size controls the width or diameter
2340 of points for rasterization. This label cannot be used in fragment
2343 When using this semantic, be sure to set the appropriate state in the
2344 :ref:`rasterizer` first.
2347 TGSI_SEMANTIC_TEXCOORD
2348 """"""""""""""""""""""
2350 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2352 Vertex shader outputs and fragment shader inputs may be labeled with
2353 this semantic to make them replaceable by sprite coordinates via the
2354 sprite_coord_enable state in the :ref:`rasterizer`.
2355 The semantic index permitted with this semantic is limited to <= 7.
2357 If the driver does not support TEXCOORD, sprite coordinate replacement
2358 applies to inputs with the GENERIC semantic instead.
2360 The intended use case for this semantic is gl_TexCoord.
2363 TGSI_SEMANTIC_PCOORD
2364 """"""""""""""""""""
2366 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2368 Fragment shader inputs may be labeled with TGSI_SEMANTIC_PCOORD to indicate
2369 that the register contains sprite coordinates in the form (x, y, 0, 1), if
2370 the current primitive is a point and point sprites are enabled. Otherwise,
2371 the contents of the register are undefined.
2373 The intended use case for this semantic is gl_PointCoord.
2376 TGSI_SEMANTIC_GENERIC
2377 """""""""""""""""""""
2379 All vertex/fragment shader inputs/outputs not labeled with any other
2380 semantic label can be considered to be generic attributes. Typical
2381 uses of generic inputs/outputs are texcoords and user-defined values.
2384 TGSI_SEMANTIC_NORMAL
2385 """"""""""""""""""""
2387 Indicates that a vertex shader input is a normal vector. This is
2388 typically only used for legacy graphics APIs.
2394 This label applies to fragment shader inputs only and indicates that
2395 the register contains front/back-face information of the form (F, 0,
2396 0, 1). The first component will be positive when the fragment belongs
2397 to a front-facing polygon, and negative when the fragment belongs to a
2398 back-facing polygon.
2401 TGSI_SEMANTIC_EDGEFLAG
2402 """"""""""""""""""""""
2404 For vertex shaders, this sematic label indicates that an input or
2405 output is a boolean edge flag. The register layout is [F, x, x, x]
2406 where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader
2407 simply copies the edge flag input to the edgeflag output.
2409 Edge flags are used to control which lines or points are actually
2410 drawn when the polygon mode converts triangles/quads/polygons into
2414 TGSI_SEMANTIC_STENCIL
2415 """""""""""""""""""""
2417 For fragment shaders, this semantic label indicates that an output
2418 is a writable stencil reference value. Only the Y component is writable.
2419 This allows the fragment shader to change the fragments stencilref value.
2422 TGSI_SEMANTIC_VIEWPORT_INDEX
2423 """"""""""""""""""""""""""""
2425 For geometry shaders, this semantic label indicates that an output
2426 contains the index of the viewport (and scissor) to use.
2427 Only the X value is used.
2433 For geometry shaders, this semantic label indicates that an output
2434 contains the layer value to use for the color and depth/stencil surfaces.
2435 Only the X value is used. (Also known as rendertarget array index.)
2438 TGSI_SEMANTIC_CULLDIST
2439 """"""""""""""""""""""
2441 Used as distance to plane for performing application-defined culling
2442 of individual primitives against a plane. When components of vertex
2443 elements are given this label, these values are assumed to be a
2444 float32 signed distance to a plane. Primitives will be completely
2445 discarded if the plane distance for all of the vertices in the
2446 primitive are < 0. If a vertex has a cull distance of NaN, that
2447 vertex counts as "out" (as if its < 0);
2448 The limits on both clip and cull distances are bound
2449 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2450 the maximum number of components that can be used to hold the
2451 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2452 which specifies the maximum number of registers which can be
2453 annotated with those semantics.
2456 TGSI_SEMANTIC_CLIPDIST
2457 """"""""""""""""""""""
2459 When components of vertex elements are identified this way, these
2460 values are each assumed to be a float32 signed distance to a plane.
2461 Primitive setup only invokes rasterization on pixels for which
2462 the interpolated plane distances are >= 0. Multiple clip planes
2463 can be implemented simultaneously, by annotating multiple
2464 components of one or more vertex elements with the above specified
2465 semantic. The limits on both clip and cull distances are bound
2466 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2467 the maximum number of components that can be used to hold the
2468 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2469 which specifies the maximum number of registers which can be
2470 annotated with those semantics.
2473 Declaration Interpolate
2474 ^^^^^^^^^^^^^^^^^^^^^^^
2476 This token is only valid for fragment shader INPUT declarations.
2478 The Interpolate field specifes the way input is being interpolated by
2479 the rasteriser and is one of TGSI_INTERPOLATE_*.
2481 The CylindricalWrap bitfield specifies which register components
2482 should be subject to cylindrical wrapping when interpolating by the
2483 rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
2484 should be interpolated according to cylindrical wrapping rules.
2487 Declaration Sampler View
2488 ^^^^^^^^^^^^^^^^^^^^^^^^
2490 Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.
2492 DCL SVIEW[#], resource, type(s)
2494 Declares a shader input sampler view and assigns it to a SVIEW[#]
2497 resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.
2499 type must be 1 or 4 entries (if specifying on a per-component
2500 level) out of UNORM, SNORM, SINT, UINT and FLOAT.
2503 Declaration Resource
2504 ^^^^^^^^^^^^^^^^^^^^
2506 Follows Declaration token if file is TGSI_FILE_RESOURCE.
2508 DCL RES[#], resource [, WR] [, RAW]
2510 Declares a shader input resource and assigns it to a RES[#]
2513 resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
2516 If the RAW keyword is not specified, the texture data will be
2517 subject to conversion, swizzling and scaling as required to yield
2518 the specified data type from the physical data format of the bound
2521 If the RAW keyword is specified, no channel conversion will be
2522 performed: the values read for each of the channels (X,Y,Z,W) will
2523 correspond to consecutive words in the same order and format
2524 they're found in memory. No element-to-address conversion will be
2525 performed either: the value of the provided X coordinate will be
2526 interpreted in byte units instead of texel units. The result of
2527 accessing a misaligned address is undefined.
2529 Usage of the STORE opcode is only allowed if the WR (writable) flag
2534 ^^^^^^^^^^^^^^^^^^^^^^^^
2537 Properties are general directives that apply to the whole TGSI program.
2542 Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
2543 The default value is UPPER_LEFT.
2545 If UPPER_LEFT, the position will be (0,0) at the upper left corner and
2546 increase downward and rightward.
2547 If LOWER_LEFT, the position will be (0,0) at the lower left corner and
2548 increase upward and rightward.
2550 OpenGL defaults to LOWER_LEFT, and is configurable with the
2551 GL_ARB_fragment_coord_conventions extension.
2553 DirectX 9/10 use UPPER_LEFT.
2555 FS_COORD_PIXEL_CENTER
2556 """""""""""""""""""""
2558 Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
2559 The default value is HALF_INTEGER.
2561 If HALF_INTEGER, the fractionary part of the position will be 0.5
2562 If INTEGER, the fractionary part of the position will be 0.0
2564 Note that this does not affect the set of fragments generated by
2565 rasterization, which is instead controlled by half_pixel_center in the
2568 OpenGL defaults to HALF_INTEGER, and is configurable with the
2569 GL_ARB_fragment_coord_conventions extension.
2571 DirectX 9 uses INTEGER.
2572 DirectX 10 uses HALF_INTEGER.
2574 FS_COLOR0_WRITES_ALL_CBUFS
2575 """"""""""""""""""""""""""
2576 Specifies that writes to the fragment shader color 0 are replicated to all
2577 bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
2578 fragData is directed to a single color buffer, but fragColor is broadcast.
2581 """"""""""""""""""""""""""
2582 If this property is set on the program bound to the shader stage before the
2583 fragment shader, user clip planes should have no effect (be disabled) even if
2584 that shader does not write to any clip distance outputs and the rasterizer's
2585 clip_plane_enable is non-zero.
2586 This property is only supported by drivers that also support shader clip
2588 This is useful for APIs that don't have UCPs and where clip distances written
2589 by a shader cannot be disabled.
2592 Texture Sampling and Texture Formats
2593 ------------------------------------
2595 This table shows how texture image components are returned as (x,y,z,w) tuples
2596 by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
2597 :opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
2600 +--------------------+--------------+--------------------+--------------+
2601 | Texture Components | Gallium | OpenGL | Direct3D 9 |
2602 +====================+==============+====================+==============+
2603 | R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) |
2604 +--------------------+--------------+--------------------+--------------+
2605 | RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) |
2606 +--------------------+--------------+--------------------+--------------+
2607 | RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) |
2608 +--------------------+--------------+--------------------+--------------+
2609 | RGBA | (r, g, b, a) | (r, g, b, a) | (r, g, b, a) |
2610 +--------------------+--------------+--------------------+--------------+
2611 | A | (0, 0, 0, a) | (0, 0, 0, a) | (0, 0, 0, a) |
2612 +--------------------+--------------+--------------------+--------------+
2613 | L | (l, l, l, 1) | (l, l, l, 1) | (l, l, l, 1) |
2614 +--------------------+--------------+--------------------+--------------+
2615 | LA | (l, l, l, a) | (l, l, l, a) | (l, l, l, a) |
2616 +--------------------+--------------+--------------------+--------------+
2617 | I | (i, i, i, i) | (i, i, i, i) | N/A |
2618 +--------------------+--------------+--------------------+--------------+
2619 | UV | XXX TBD | (0, 0, 0, 1) | (u, v, 1, 1) |
2620 | | | [#envmap-bumpmap]_ | |
2621 +--------------------+--------------+--------------------+--------------+
2622 | Z | XXX TBD | (z, z, z, 1) | (0, z, 0, 1) |
2623 | | | [#depth-tex-mode]_ | |
2624 +--------------------+--------------+--------------------+--------------+
2625 | S | (s, s, s, s) | unknown | unknown |
2626 +--------------------+--------------+--------------------+--------------+
2628 .. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
2629 .. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
2630 or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.