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.
101 dst = \frac{1}{\sqrt{|src.x|}}
104 .. opcode:: SQRT - Square Root
106 This instruction replicates its result.
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
1259 dst.x = src0.x << src1.x
1261 dst.y = src0.y << src1.x
1263 dst.z = src0.z << src1.x
1265 dst.w = src0.w << src1.x
1268 .. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)
1272 dst.x = src0.x >> src1.x
1274 dst.y = src0.y >> src1.x
1276 dst.z = src0.z >> src1.x
1278 dst.w = src0.w >> src1.x
1281 .. opcode:: USHR - Logical Shift Right
1285 dst.x = src0.x >> (unsigned) src1.x
1287 dst.y = src0.y >> (unsigned) src1.x
1289 dst.z = src0.z >> (unsigned) src1.x
1291 dst.w = src0.w >> (unsigned) src1.x
1294 .. opcode:: UCMP - Integer Conditional Move
1298 dst.x = src0.x ? src1.x : src2.x
1300 dst.y = src0.y ? src1.y : src2.y
1302 dst.z = src0.z ? src1.z : src2.z
1304 dst.w = src0.w ? src1.w : src2.w
1308 .. opcode:: ISSG - Integer Set Sign
1312 dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0
1314 dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0
1316 dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0
1318 dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0
1322 .. opcode:: ISLT - Signed Integer Set On Less Than
1326 dst.x = (src0.x < src1.x) ? ~0 : 0
1328 dst.y = (src0.y < src1.y) ? ~0 : 0
1330 dst.z = (src0.z < src1.z) ? ~0 : 0
1332 dst.w = (src0.w < src1.w) ? ~0 : 0
1335 .. opcode:: USLT - Unsigned Integer Set On Less Than
1339 dst.x = (src0.x < src1.x) ? ~0 : 0
1341 dst.y = (src0.y < src1.y) ? ~0 : 0
1343 dst.z = (src0.z < src1.z) ? ~0 : 0
1345 dst.w = (src0.w < src1.w) ? ~0 : 0
1348 .. opcode:: ISGE - Signed Integer Set On Greater Equal Than
1352 dst.x = (src0.x >= src1.x) ? ~0 : 0
1354 dst.y = (src0.y >= src1.y) ? ~0 : 0
1356 dst.z = (src0.z >= src1.z) ? ~0 : 0
1358 dst.w = (src0.w >= src1.w) ? ~0 : 0
1361 .. opcode:: USGE - Unsigned Integer Set On Greater Equal Than
1365 dst.x = (src0.x >= src1.x) ? ~0 : 0
1367 dst.y = (src0.y >= src1.y) ? ~0 : 0
1369 dst.z = (src0.z >= src1.z) ? ~0 : 0
1371 dst.w = (src0.w >= src1.w) ? ~0 : 0
1374 .. opcode:: USEQ - Integer Set On Equal
1378 dst.x = (src0.x == src1.x) ? ~0 : 0
1380 dst.y = (src0.y == src1.y) ? ~0 : 0
1382 dst.z = (src0.z == src1.z) ? ~0 : 0
1384 dst.w = (src0.w == src1.w) ? ~0 : 0
1387 .. opcode:: USNE - Integer Set On Not Equal
1391 dst.x = (src0.x != src1.x) ? ~0 : 0
1393 dst.y = (src0.y != src1.y) ? ~0 : 0
1395 dst.z = (src0.z != src1.z) ? ~0 : 0
1397 dst.w = (src0.w != src1.w) ? ~0 : 0
1400 .. opcode:: INEG - Integer Negate
1415 .. opcode:: IABS - Integer Absolute Value
1429 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1431 These opcodes are only supported in geometry shaders; they have no meaning
1432 in any other type of shader.
1434 .. opcode:: EMIT - Emit
1436 Generate a new vertex for the current primitive using the values in the
1440 .. opcode:: ENDPRIM - End Primitive
1442 Complete the current primitive (consisting of the emitted vertices),
1443 and start a new one.
1449 These opcodes are part of :term:`GLSL`'s opcode set. Support for these
1450 opcodes is determined by a special capability bit, ``GLSL``.
1451 Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
1453 .. opcode:: CAL - Subroutine Call
1459 .. opcode:: RET - Subroutine Call Return
1464 .. opcode:: CONT - Continue
1466 Unconditionally moves the point of execution to the instruction after the
1467 last bgnloop. The instruction must appear within a bgnloop/endloop.
1471 Support for CONT is determined by a special capability bit,
1472 ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
1475 .. opcode:: BGNLOOP - Begin a Loop
1477 Start a loop. Must have a matching endloop.
1480 .. opcode:: BGNSUB - Begin Subroutine
1482 Starts definition of a subroutine. Must have a matching endsub.
1485 .. opcode:: ENDLOOP - End a Loop
1487 End a loop started with bgnloop.
1490 .. opcode:: ENDSUB - End Subroutine
1492 Ends definition of a subroutine.
1495 .. opcode:: NOP - No Operation
1500 .. opcode:: BRK - Break
1502 Unconditionally moves the point of execution to the instruction after the
1503 next endloop or endswitch. The instruction must appear within a loop/endloop
1504 or switch/endswitch.
1507 .. opcode:: BREAKC - Break Conditional
1509 Conditionally moves the point of execution to the instruction after the
1510 next endloop or endswitch. The instruction must appear within a loop/endloop
1511 or switch/endswitch.
1512 Condition evaluates to true if src0.x != 0 where src0.x is interpreted
1513 as an integer register.
1517 Considered for removal as it's quite inconsistent wrt other opcodes
1518 (could emulate with UIF/BRK/ENDIF).
1521 .. opcode:: IF - Float If
1523 Start an IF ... ELSE .. ENDIF block. Condition evaluates to true if
1527 where src0.x is interpreted as a floating point register.
1530 .. opcode:: UIF - Bitwise If
1532 Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if
1536 where src0.x is interpreted as an integer register.
1539 .. opcode:: ELSE - Else
1541 Starts an else block, after an IF or UIF statement.
1544 .. opcode:: ENDIF - End If
1546 Ends an IF or UIF block.
1549 .. opcode:: SWITCH - Switch
1551 Starts a C-style switch expression. The switch consists of one or multiple
1552 CASE statements, and at most one DEFAULT statement. Execution of a statement
1553 ends when a BRK is hit, but just like in C falling through to other cases
1554 without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
1555 just as last statement, and fallthrough is allowed into/from it.
1556 CASE src arguments are evaluated at bit level against the SWITCH src argument.
1561 (some instructions here)
1564 (some instructions here)
1567 (some instructions here)
1572 .. opcode:: CASE - Switch case
1574 This represents a switch case label. The src arg must be an integer immediate.
1577 .. opcode:: DEFAULT - Switch default
1579 This represents the default case in the switch, which is taken if no other
1583 .. opcode:: ENDSWITCH - End of switch
1585 Ends a switch expression.
1588 .. opcode:: NRM4 - 4-component Vector Normalise
1590 This instruction replicates its result.
1594 dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
1602 The double-precision opcodes reinterpret four-component vectors into
1603 two-component vectors with doubled precision in each component.
1605 Support for these opcodes is XXX undecided. :T
1607 .. opcode:: DADD - Add
1611 dst.xy = src0.xy + src1.xy
1613 dst.zw = src0.zw + src1.zw
1616 .. opcode:: DDIV - Divide
1620 dst.xy = src0.xy / src1.xy
1622 dst.zw = src0.zw / src1.zw
1624 .. opcode:: DSEQ - Set on Equal
1628 dst.xy = src0.xy == src1.xy ? 1.0F : 0.0F
1630 dst.zw = src0.zw == src1.zw ? 1.0F : 0.0F
1632 .. opcode:: DSLT - Set on Less than
1636 dst.xy = src0.xy < src1.xy ? 1.0F : 0.0F
1638 dst.zw = src0.zw < src1.zw ? 1.0F : 0.0F
1640 .. opcode:: DFRAC - Fraction
1644 dst.xy = src.xy - \lfloor src.xy\rfloor
1646 dst.zw = src.zw - \lfloor src.zw\rfloor
1649 .. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components
1651 Like the ``frexp()`` routine in many math libraries, this opcode stores the
1652 exponent of its source to ``dst0``, and the significand to ``dst1``, such that
1653 :math:`dst1 \times 2^{dst0} = src` .
1657 dst0.xy = exp(src.xy)
1659 dst1.xy = frac(src.xy)
1661 dst0.zw = exp(src.zw)
1663 dst1.zw = frac(src.zw)
1665 .. opcode:: DLDEXP - Multiply Number by Integral Power of 2
1667 This opcode is the inverse of :opcode:`DFRACEXP`.
1671 dst.xy = src0.xy \times 2^{src1.xy}
1673 dst.zw = src0.zw \times 2^{src1.zw}
1675 .. opcode:: DMIN - Minimum
1679 dst.xy = min(src0.xy, src1.xy)
1681 dst.zw = min(src0.zw, src1.zw)
1683 .. opcode:: DMAX - Maximum
1687 dst.xy = max(src0.xy, src1.xy)
1689 dst.zw = max(src0.zw, src1.zw)
1691 .. opcode:: DMUL - Multiply
1695 dst.xy = src0.xy \times src1.xy
1697 dst.zw = src0.zw \times src1.zw
1700 .. opcode:: DMAD - Multiply And Add
1704 dst.xy = src0.xy \times src1.xy + src2.xy
1706 dst.zw = src0.zw \times src1.zw + src2.zw
1709 .. opcode:: DRCP - Reciprocal
1713 dst.xy = \frac{1}{src.xy}
1715 dst.zw = \frac{1}{src.zw}
1717 .. opcode:: DSQRT - Square Root
1721 dst.xy = \sqrt{src.xy}
1723 dst.zw = \sqrt{src.zw}
1726 .. _samplingopcodes:
1728 Resource Sampling Opcodes
1729 ^^^^^^^^^^^^^^^^^^^^^^^^^
1731 Those opcodes follow very closely semantics of the respective Direct3D
1732 instructions. If in doubt double check Direct3D documentation.
1734 .. opcode:: SAMPLE - Using provided address, sample data from the
1735 specified texture using the filtering mode identified
1736 by the gven sampler. The source data may come from
1737 any resource type other than buffers.
1738 SAMPLE dst, address, sampler_view, sampler
1740 SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
1742 .. opcode:: SAMPLE_I - Simplified alternative to the SAMPLE instruction.
1743 Using the provided integer address, SAMPLE_I fetches data
1744 from the specified sampler view without any filtering.
1745 The source data may come from any resource type other
1747 SAMPLE_I dst, address, sampler_view
1749 SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]
1750 The 'address' is specified as unsigned integers. If the
1751 'address' is out of range [0...(# texels - 1)] the
1752 result of the fetch is always 0 in all components.
1753 As such the instruction doesn't honor address wrap
1754 modes, in cases where that behavior is desirable
1755 'SAMPLE' instruction should be used.
1756 address.w always provides an unsigned integer mipmap
1757 level. If the value is out of the range then the
1758 instruction always returns 0 in all components.
1759 address.yz are ignored for buffers and 1d textures.
1760 address.z is ignored for 1d texture arrays and 2d
1762 For 1D texture arrays address.y provides the array
1763 index (also as unsigned integer). If the value is
1764 out of the range of available array indices
1765 [0... (array size - 1)] then the opcode always returns
1766 0 in all components.
1767 For 2D texture arrays address.z provides the array
1768 index, otherwise it exhibits the same behavior as in
1769 the case for 1D texture arrays.
1770 The exact semantics of the source address are presented
1772 resource type X Y Z W
1773 ------------- ------------------------
1774 PIPE_BUFFER x ignored
1775 PIPE_TEXTURE_1D x mpl
1776 PIPE_TEXTURE_2D x y mpl
1777 PIPE_TEXTURE_3D x y z mpl
1778 PIPE_TEXTURE_RECT x y mpl
1779 PIPE_TEXTURE_CUBE not allowed as source
1780 PIPE_TEXTURE_1D_ARRAY x idx mpl
1781 PIPE_TEXTURE_2D_ARRAY x y idx mpl
1783 Where 'mpl' is a mipmap level and 'idx' is the
1786 .. opcode:: SAMPLE_I_MS - Just like SAMPLE_I but allows fetch data from
1787 multi-sampled surfaces.
1788 SAMPLE_I_MS dst, address, sampler_view, sample
1790 .. opcode:: SAMPLE_B - Just like the SAMPLE instruction with the
1791 exception that an additional bias is applied to the
1792 level of detail computed as part of the instruction
1794 SAMPLE_B dst, address, sampler_view, sampler, lod_bias
1796 SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
1798 .. opcode:: SAMPLE_C - Similar to the SAMPLE instruction but it
1799 performs a comparison filter. The operands to SAMPLE_C
1800 are identical to SAMPLE, except that there is an additional
1801 float32 operand, reference value, which must be a register
1802 with single-component, or a scalar literal.
1803 SAMPLE_C makes the hardware use the current samplers
1804 compare_func (in pipe_sampler_state) to compare
1805 reference value against the red component value for the
1806 surce resource at each texel that the currently configured
1807 texture filter covers based on the provided coordinates.
1808 SAMPLE_C dst, address, sampler_view.r, sampler, ref_value
1810 SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
1812 .. opcode:: SAMPLE_C_LZ - Same as SAMPLE_C, but LOD is 0 and derivatives
1813 are ignored. The LZ stands for level-zero.
1814 SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value
1816 SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
1819 .. opcode:: SAMPLE_D - SAMPLE_D is identical to the SAMPLE opcode except
1820 that the derivatives for the source address in the x
1821 direction and the y direction are provided by extra
1823 SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y
1825 SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]
1827 .. opcode:: SAMPLE_L - SAMPLE_L is identical to the SAMPLE opcode except
1828 that the LOD is provided directly as a scalar value,
1829 representing no anisotropy.
1830 SAMPLE_L dst, address, sampler_view, sampler, explicit_lod
1832 SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
1834 .. opcode:: GATHER4 - Gathers the four texels to be used in a bi-linear
1835 filtering operation and packs them into a single register.
1836 Only works with 2D, 2D array, cubemaps, and cubemaps arrays.
1837 For 2D textures, only the addressing modes of the sampler and
1838 the top level of any mip pyramid are used. Set W to zero.
1839 It behaves like the SAMPLE instruction, but a filtered
1840 sample is not generated. The four samples that contribute
1841 to filtering are placed into xyzw in counter-clockwise order,
1842 starting with the (u,v) texture coordinate delta at the
1843 following locations (-, +), (+, +), (+, -), (-, -), where
1844 the magnitude of the deltas are half a texel.
1847 .. opcode:: SVIEWINFO - query the dimensions of a given sampler view.
1848 dst receives width, height, depth or array size and
1849 number of mipmap levels as int4. The dst can have a writemask
1850 which will specify what info is the caller interested
1852 SVIEWINFO dst, src_mip_level, sampler_view
1854 SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]
1855 src_mip_level is an unsigned integer scalar. If it's
1856 out of range then returns 0 for width, height and
1857 depth/array size but the total number of mipmap is
1858 still returned correctly for the given sampler view.
1859 The returned width, height and depth values are for
1860 the mipmap level selected by the src_mip_level and
1861 are in the number of texels.
1862 For 1d texture array width is in dst.x, array size
1863 is in dst.y and dst.zw are always 0.
1865 .. opcode:: SAMPLE_POS - query the position of a given sample.
1866 dst receives float4 (x, y, 0, 0) indicated where the
1867 sample is located. If the resource is not a multi-sample
1868 resource and not a render target, the result is 0.
1870 .. opcode:: SAMPLE_INFO - dst receives number of samples in x.
1871 If the resource is not a multi-sample resource and
1872 not a render target, the result is 0.
1875 .. _resourceopcodes:
1877 Resource Access Opcodes
1878 ^^^^^^^^^^^^^^^^^^^^^^^
1880 .. opcode:: LOAD - Fetch data from a shader resource
1882 Syntax: ``LOAD dst, resource, address``
1884 Example: ``LOAD TEMP[0], RES[0], TEMP[1]``
1886 Using the provided integer address, LOAD fetches data
1887 from the specified buffer or texture without any
1890 The 'address' is specified as a vector of unsigned
1891 integers. If the 'address' is out of range the result
1894 Only the first mipmap level of a resource can be read
1895 from using this instruction.
1897 For 1D or 2D texture arrays, the array index is
1898 provided as an unsigned integer in address.y or
1899 address.z, respectively. address.yz are ignored for
1900 buffers and 1D textures. address.z is ignored for 1D
1901 texture arrays and 2D textures. address.w is always
1904 .. opcode:: STORE - Write data to a shader resource
1906 Syntax: ``STORE resource, address, src``
1908 Example: ``STORE RES[0], TEMP[0], TEMP[1]``
1910 Using the provided integer address, STORE writes data
1911 to the specified buffer or texture.
1913 The 'address' is specified as a vector of unsigned
1914 integers. If the 'address' is out of range the result
1917 Only the first mipmap level of a resource can be
1918 written to using this instruction.
1920 For 1D or 2D texture arrays, the array index is
1921 provided as an unsigned integer in address.y or
1922 address.z, respectively. address.yz are ignored for
1923 buffers and 1D textures. address.z is ignored for 1D
1924 texture arrays and 2D textures. address.w is always
1928 .. _threadsyncopcodes:
1930 Inter-thread synchronization opcodes
1931 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1933 These opcodes are intended for communication between threads running
1934 within the same compute grid. For now they're only valid in compute
1937 .. opcode:: MFENCE - Memory fence
1939 Syntax: ``MFENCE resource``
1941 Example: ``MFENCE RES[0]``
1943 This opcode forces strong ordering between any memory access
1944 operations that affect the specified resource. This means that
1945 previous loads and stores (and only those) will be performed and
1946 visible to other threads before the program execution continues.
1949 .. opcode:: LFENCE - Load memory fence
1951 Syntax: ``LFENCE resource``
1953 Example: ``LFENCE RES[0]``
1955 Similar to MFENCE, but it only affects the ordering of memory loads.
1958 .. opcode:: SFENCE - Store memory fence
1960 Syntax: ``SFENCE resource``
1962 Example: ``SFENCE RES[0]``
1964 Similar to MFENCE, but it only affects the ordering of memory stores.
1967 .. opcode:: BARRIER - Thread group barrier
1971 This opcode suspends the execution of the current thread until all
1972 the remaining threads in the working group reach the same point of
1973 the program. Results are unspecified if any of the remaining
1974 threads terminates or never reaches an executed BARRIER instruction.
1982 These opcodes provide atomic variants of some common arithmetic and
1983 logical operations. In this context atomicity means that another
1984 concurrent memory access operation that affects the same memory
1985 location is guaranteed to be performed strictly before or after the
1986 entire execution of the atomic operation.
1988 For the moment they're only valid in compute programs.
1990 .. opcode:: ATOMUADD - Atomic integer addition
1992 Syntax: ``ATOMUADD dst, resource, offset, src``
1994 Example: ``ATOMUADD TEMP[0], RES[0], TEMP[1], TEMP[2]``
1996 The following operation is performed atomically on each component:
2000 dst_i = resource[offset]_i
2002 resource[offset]_i = dst_i + src_i
2005 .. opcode:: ATOMXCHG - Atomic exchange
2007 Syntax: ``ATOMXCHG dst, resource, offset, src``
2009 Example: ``ATOMXCHG TEMP[0], RES[0], TEMP[1], TEMP[2]``
2011 The following operation is performed atomically on each component:
2015 dst_i = resource[offset]_i
2017 resource[offset]_i = src_i
2020 .. opcode:: ATOMCAS - Atomic compare-and-exchange
2022 Syntax: ``ATOMCAS dst, resource, offset, cmp, src``
2024 Example: ``ATOMCAS TEMP[0], RES[0], TEMP[1], TEMP[2], TEMP[3]``
2026 The following operation is performed atomically on each component:
2030 dst_i = resource[offset]_i
2032 resource[offset]_i = (dst_i == cmp_i ? src_i : dst_i)
2035 .. opcode:: ATOMAND - Atomic bitwise And
2037 Syntax: ``ATOMAND dst, resource, offset, src``
2039 Example: ``ATOMAND TEMP[0], RES[0], TEMP[1], TEMP[2]``
2041 The following operation is performed atomically on each component:
2045 dst_i = resource[offset]_i
2047 resource[offset]_i = dst_i \& src_i
2050 .. opcode:: ATOMOR - Atomic bitwise Or
2052 Syntax: ``ATOMOR dst, resource, offset, src``
2054 Example: ``ATOMOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2056 The following operation is performed atomically on each component:
2060 dst_i = resource[offset]_i
2062 resource[offset]_i = dst_i | src_i
2065 .. opcode:: ATOMXOR - Atomic bitwise Xor
2067 Syntax: ``ATOMXOR dst, resource, offset, src``
2069 Example: ``ATOMXOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2071 The following operation is performed atomically on each component:
2075 dst_i = resource[offset]_i
2077 resource[offset]_i = dst_i \oplus src_i
2080 .. opcode:: ATOMUMIN - Atomic unsigned minimum
2082 Syntax: ``ATOMUMIN dst, resource, offset, src``
2084 Example: ``ATOMUMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2086 The following operation is performed atomically on each component:
2090 dst_i = resource[offset]_i
2092 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2095 .. opcode:: ATOMUMAX - Atomic unsigned maximum
2097 Syntax: ``ATOMUMAX dst, resource, offset, src``
2099 Example: ``ATOMUMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2101 The following operation is performed atomically on each component:
2105 dst_i = resource[offset]_i
2107 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2110 .. opcode:: ATOMIMIN - Atomic signed minimum
2112 Syntax: ``ATOMIMIN dst, resource, offset, src``
2114 Example: ``ATOMIMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2116 The following operation is performed atomically on each component:
2120 dst_i = resource[offset]_i
2122 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2125 .. opcode:: ATOMIMAX - Atomic signed maximum
2127 Syntax: ``ATOMIMAX dst, resource, offset, src``
2129 Example: ``ATOMIMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2131 The following operation is performed atomically on each component:
2135 dst_i = resource[offset]_i
2137 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2141 Explanation of symbols used
2142 ------------------------------
2149 :math:`|x|` Absolute value of `x`.
2151 :math:`\lceil x \rceil` Ceiling of `x`.
2153 clamp(x,y,z) Clamp x between y and z.
2154 (x < y) ? y : (x > z) ? z : x
2156 :math:`\lfloor x\rfloor` Floor of `x`.
2158 :math:`\log_2{x}` Logarithm of `x`, base 2.
2160 max(x,y) Maximum of x and y.
2163 min(x,y) Minimum of x and y.
2166 partialx(x) Derivative of x relative to fragment's X.
2168 partialy(x) Derivative of x relative to fragment's Y.
2170 pop() Pop from stack.
2172 :math:`x^y` `x` to the power `y`.
2174 push(x) Push x on stack.
2178 trunc(x) Truncate x, i.e. drop the fraction bits.
2185 discard Discard fragment.
2189 target Label of target instruction.
2200 Declares a register that is will be referenced as an operand in Instruction
2203 File field contains register file that is being declared and is one
2206 UsageMask field specifies which of the register components can be accessed
2207 and is one of TGSI_WRITEMASK.
2209 The Local flag specifies that a given value isn't intended for
2210 subroutine parameter passing and, as a result, the implementation
2211 isn't required to give any guarantees of it being preserved across
2212 subroutine boundaries. As it's merely a compiler hint, the
2213 implementation is free to ignore it.
2215 If Dimension flag is set to 1, a Declaration Dimension token follows.
2217 If Semantic flag is set to 1, a Declaration Semantic token follows.
2219 If Interpolate flag is set to 1, a Declaration Interpolate token follows.
2221 If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.
2223 If Array flag is set to 1, a Declaration Array token follows.
2226 ^^^^^^^^^^^^^^^^^^^^^^^^
2228 Declarations can optional have an ArrayID attribute which can be referred by
2229 indirect addressing operands. An ArrayID of zero is reserved and treaded as
2230 if no ArrayID is specified.
2232 If an indirect addressing operand refers to a specific declaration by using
2233 an ArrayID only the registers in this declaration are guaranteed to be
2234 accessed, accessing any register outside this declaration results in undefined
2235 behavior. Note that for compatibility the effective index is zero-based and
2236 not relative to the specified declaration
2238 If no ArrayID is specified with an indirect addressing operand the whole
2239 register file might be accessed by this operand. This is strongly discouraged
2240 and will prevent packing of scalar/vec2 arrays and effective alias analysis.
2242 Declaration Semantic
2243 ^^^^^^^^^^^^^^^^^^^^^^^^
2245 Vertex and fragment shader input and output registers may be labeled
2246 with semantic information consisting of a name and index.
2248 Follows Declaration token if Semantic bit is set.
2250 Since its purpose is to link a shader with other stages of the pipeline,
2251 it is valid to follow only those Declaration tokens that declare a register
2252 either in INPUT or OUTPUT file.
2254 SemanticName field contains the semantic name of the register being declared.
2255 There is no default value.
2257 SemanticIndex is an optional subscript that can be used to distinguish
2258 different register declarations with the same semantic name. The default value
2261 The meanings of the individual semantic names are explained in the following
2264 TGSI_SEMANTIC_POSITION
2265 """"""""""""""""""""""
2267 For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
2268 output register which contains the homogeneous vertex position in the clip
2269 space coordinate system. After clipping, the X, Y and Z components of the
2270 vertex will be divided by the W value to get normalized device coordinates.
2272 For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
2273 fragment shader input contains the fragment's window position. The X
2274 component starts at zero and always increases from left to right.
2275 The Y component starts at zero and always increases but Y=0 may either
2276 indicate the top of the window or the bottom depending on the fragment
2277 coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
2278 The Z coordinate ranges from 0 to 1 to represent depth from the front
2279 to the back of the Z buffer. The W component contains the reciprocol
2280 of the interpolated vertex position W component.
2282 Fragment shaders may also declare an output register with
2283 TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows
2284 the fragment shader to change the fragment's Z position.
2291 For vertex shader outputs or fragment shader inputs/outputs, this
2292 label indicates that the resister contains an R,G,B,A color.
2294 Several shader inputs/outputs may contain colors so the semantic index
2295 is used to distinguish them. For example, color[0] may be the diffuse
2296 color while color[1] may be the specular color.
2298 This label is needed so that the flat/smooth shading can be applied
2299 to the right interpolants during rasterization.
2303 TGSI_SEMANTIC_BCOLOR
2304 """"""""""""""""""""
2306 Back-facing colors are only used for back-facing polygons, and are only valid
2307 in vertex shader outputs. After rasterization, all polygons are front-facing
2308 and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
2309 so all BCOLORs effectively become regular COLORs in the fragment shader.
2315 Vertex shader inputs and outputs and fragment shader inputs may be
2316 labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
2317 a fog coordinate in the form (F, 0, 0, 1). Typically, the fragment
2318 shader will use the fog coordinate to compute a fog blend factor which
2319 is used to blend the normal fragment color with a constant fog color.
2321 Only the first component matters when writing from the vertex shader;
2322 the driver will ensure that the coordinate is in this format when used
2323 as a fragment shader input.
2329 Vertex shader input and output registers may be labeled with
2330 TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
2331 in the form (S, 0, 0, 1). The point size controls the width or diameter
2332 of points for rasterization. This label cannot be used in fragment
2335 When using this semantic, be sure to set the appropriate state in the
2336 :ref:`rasterizer` first.
2339 TGSI_SEMANTIC_TEXCOORD
2340 """"""""""""""""""""""
2342 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2344 Vertex shader outputs and fragment shader inputs may be labeled with
2345 this semantic to make them replaceable by sprite coordinates via the
2346 sprite_coord_enable state in the :ref:`rasterizer`.
2347 The semantic index permitted with this semantic is limited to <= 7.
2349 If the driver does not support TEXCOORD, sprite coordinate replacement
2350 applies to inputs with the GENERIC semantic instead.
2352 The intended use case for this semantic is gl_TexCoord.
2355 TGSI_SEMANTIC_PCOORD
2356 """"""""""""""""""""
2358 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2360 Fragment shader inputs may be labeled with TGSI_SEMANTIC_PCOORD to indicate
2361 that the register contains sprite coordinates in the form (x, y, 0, 1), if
2362 the current primitive is a point and point sprites are enabled. Otherwise,
2363 the contents of the register are undefined.
2365 The intended use case for this semantic is gl_PointCoord.
2368 TGSI_SEMANTIC_GENERIC
2369 """""""""""""""""""""
2371 All vertex/fragment shader inputs/outputs not labeled with any other
2372 semantic label can be considered to be generic attributes. Typical
2373 uses of generic inputs/outputs are texcoords and user-defined values.
2376 TGSI_SEMANTIC_NORMAL
2377 """"""""""""""""""""
2379 Indicates that a vertex shader input is a normal vector. This is
2380 typically only used for legacy graphics APIs.
2386 This label applies to fragment shader inputs only and indicates that
2387 the register contains front/back-face information of the form (F, 0,
2388 0, 1). The first component will be positive when the fragment belongs
2389 to a front-facing polygon, and negative when the fragment belongs to a
2390 back-facing polygon.
2393 TGSI_SEMANTIC_EDGEFLAG
2394 """"""""""""""""""""""
2396 For vertex shaders, this sematic label indicates that an input or
2397 output is a boolean edge flag. The register layout is [F, x, x, x]
2398 where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader
2399 simply copies the edge flag input to the edgeflag output.
2401 Edge flags are used to control which lines or points are actually
2402 drawn when the polygon mode converts triangles/quads/polygons into
2406 TGSI_SEMANTIC_STENCIL
2407 """""""""""""""""""""
2409 For fragment shaders, this semantic label indicates that an output
2410 is a writable stencil reference value. Only the Y component is writable.
2411 This allows the fragment shader to change the fragments stencilref value.
2414 TGSI_SEMANTIC_VIEWPORT_INDEX
2415 """"""""""""""""""""""""""""
2417 For geometry shaders, this semantic label indicates that an output
2418 contains the index of the viewport (and scissor) to use.
2419 Only the X value is used.
2425 For geometry shaders, this semantic label indicates that an output
2426 contains the layer value to use for the color and depth/stencil surfaces.
2427 Only the X value is used. (Also known as rendertarget array index.)
2430 TGSI_SEMANTIC_CULLDIST
2431 """"""""""""""""""""""
2433 Used as distance to plane for performing application-defined culling
2434 of individual primitives against a plane. When components of vertex
2435 elements are given this label, these values are assumed to be a
2436 float32 signed distance to a plane. Primitives will be completely
2437 discarded if the plane distance for all of the vertices in the
2438 primitive are < 0. If a vertex has a cull distance of NaN, that
2439 vertex counts as "out" (as if its < 0);
2440 The limits on both clip and cull distances are bound
2441 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2442 the maximum number of components that can be used to hold the
2443 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2444 which specifies the maximum number of registers which can be
2445 annotated with those semantics.
2448 TGSI_SEMANTIC_CLIPDIST
2449 """"""""""""""""""""""
2451 When components of vertex elements are identified this way, these
2452 values are each assumed to be a float32 signed distance to a plane.
2453 Primitive setup only invokes rasterization on pixels for which
2454 the interpolated plane distances are >= 0. Multiple clip planes
2455 can be implemented simultaneously, by annotating multiple
2456 components of one or more vertex elements with the above specified
2457 semantic. The limits on both clip and cull distances are bound
2458 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2459 the maximum number of components that can be used to hold the
2460 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2461 which specifies the maximum number of registers which can be
2462 annotated with those semantics.
2465 Declaration Interpolate
2466 ^^^^^^^^^^^^^^^^^^^^^^^
2468 This token is only valid for fragment shader INPUT declarations.
2470 The Interpolate field specifes the way input is being interpolated by
2471 the rasteriser and is one of TGSI_INTERPOLATE_*.
2473 The CylindricalWrap bitfield specifies which register components
2474 should be subject to cylindrical wrapping when interpolating by the
2475 rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
2476 should be interpolated according to cylindrical wrapping rules.
2479 Declaration Sampler View
2480 ^^^^^^^^^^^^^^^^^^^^^^^^
2482 Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.
2484 DCL SVIEW[#], resource, type(s)
2486 Declares a shader input sampler view and assigns it to a SVIEW[#]
2489 resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.
2491 type must be 1 or 4 entries (if specifying on a per-component
2492 level) out of UNORM, SNORM, SINT, UINT and FLOAT.
2495 Declaration Resource
2496 ^^^^^^^^^^^^^^^^^^^^
2498 Follows Declaration token if file is TGSI_FILE_RESOURCE.
2500 DCL RES[#], resource [, WR] [, RAW]
2502 Declares a shader input resource and assigns it to a RES[#]
2505 resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
2508 If the RAW keyword is not specified, the texture data will be
2509 subject to conversion, swizzling and scaling as required to yield
2510 the specified data type from the physical data format of the bound
2513 If the RAW keyword is specified, no channel conversion will be
2514 performed: the values read for each of the channels (X,Y,Z,W) will
2515 correspond to consecutive words in the same order and format
2516 they're found in memory. No element-to-address conversion will be
2517 performed either: the value of the provided X coordinate will be
2518 interpreted in byte units instead of texel units. The result of
2519 accessing a misaligned address is undefined.
2521 Usage of the STORE opcode is only allowed if the WR (writable) flag
2526 ^^^^^^^^^^^^^^^^^^^^^^^^
2529 Properties are general directives that apply to the whole TGSI program.
2534 Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
2535 The default value is UPPER_LEFT.
2537 If UPPER_LEFT, the position will be (0,0) at the upper left corner and
2538 increase downward and rightward.
2539 If LOWER_LEFT, the position will be (0,0) at the lower left corner and
2540 increase upward and rightward.
2542 OpenGL defaults to LOWER_LEFT, and is configurable with the
2543 GL_ARB_fragment_coord_conventions extension.
2545 DirectX 9/10 use UPPER_LEFT.
2547 FS_COORD_PIXEL_CENTER
2548 """""""""""""""""""""
2550 Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
2551 The default value is HALF_INTEGER.
2553 If HALF_INTEGER, the fractionary part of the position will be 0.5
2554 If INTEGER, the fractionary part of the position will be 0.0
2556 Note that this does not affect the set of fragments generated by
2557 rasterization, which is instead controlled by half_pixel_center in the
2560 OpenGL defaults to HALF_INTEGER, and is configurable with the
2561 GL_ARB_fragment_coord_conventions extension.
2563 DirectX 9 uses INTEGER.
2564 DirectX 10 uses HALF_INTEGER.
2566 FS_COLOR0_WRITES_ALL_CBUFS
2567 """"""""""""""""""""""""""
2568 Specifies that writes to the fragment shader color 0 are replicated to all
2569 bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
2570 fragData is directed to a single color buffer, but fragColor is broadcast.
2573 """"""""""""""""""""""""""
2574 If this property is set on the program bound to the shader stage before the
2575 fragment shader, user clip planes should have no effect (be disabled) even if
2576 that shader does not write to any clip distance outputs and the rasterizer's
2577 clip_plane_enable is non-zero.
2578 This property is only supported by drivers that also support shader clip
2580 This is useful for APIs that don't have UCPs and where clip distances written
2581 by a shader cannot be disabled.
2584 Texture Sampling and Texture Formats
2585 ------------------------------------
2587 This table shows how texture image components are returned as (x,y,z,w) tuples
2588 by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
2589 :opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
2592 +--------------------+--------------+--------------------+--------------+
2593 | Texture Components | Gallium | OpenGL | Direct3D 9 |
2594 +====================+==============+====================+==============+
2595 | R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) |
2596 +--------------------+--------------+--------------------+--------------+
2597 | RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) |
2598 +--------------------+--------------+--------------------+--------------+
2599 | RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) |
2600 +--------------------+--------------+--------------------+--------------+
2601 | RGBA | (r, g, b, a) | (r, g, b, a) | (r, g, b, a) |
2602 +--------------------+--------------+--------------------+--------------+
2603 | A | (0, 0, 0, a) | (0, 0, 0, a) | (0, 0, 0, a) |
2604 +--------------------+--------------+--------------------+--------------+
2605 | L | (l, l, l, 1) | (l, l, l, 1) | (l, l, l, 1) |
2606 +--------------------+--------------+--------------------+--------------+
2607 | LA | (l, l, l, a) | (l, l, l, a) | (l, l, l, a) |
2608 +--------------------+--------------+--------------------+--------------+
2609 | I | (i, i, i, i) | (i, i, i, i) | N/A |
2610 +--------------------+--------------+--------------------+--------------+
2611 | UV | XXX TBD | (0, 0, 0, 1) | (u, v, 1, 1) |
2612 | | | [#envmap-bumpmap]_ | |
2613 +--------------------+--------------+--------------------+--------------+
2614 | Z | XXX TBD | (z, z, z, 1) | (0, z, 0, 1) |
2615 | | | [#depth-tex-mode]_ | |
2616 +--------------------+--------------+--------------------+--------------+
2617 | S | (s, s, s, s) | unknown | unknown |
2618 +--------------------+--------------+--------------------+--------------+
2620 .. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
2621 .. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
2622 or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.