diff options
author | Ilia Mirkin <[email protected]> | 2014-04-25 01:43:05 -0400 |
---|---|---|
committer | Ilia Mirkin <[email protected]> | 2014-04-28 19:04:46 -0400 |
commit | a52eaba78737fd6473490ee8fe6a8415cd52ef98 (patch) | |
tree | 2184708689b714ad0650d993c2e68a8ecb5d3e8e /src/gallium/docs/source/tgsi.rst | |
parent | b125c92aa9837c80d1b7e26554d0b66b4db3f2e1 (diff) |
gallium: add new opcodes for ARB_gs5 bit manipulation support
Signed-off-by: Ilia Mirkin <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>
Diffstat (limited to 'src/gallium/docs/source/tgsi.rst')
-rw-r--r-- | src/gallium/docs/source/tgsi.rst | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index 0ea0759aa1c..9500b9d615e 100644 --- a/src/gallium/docs/source/tgsi.rst +++ b/src/gallium/docs/source/tgsi.rst @@ -1558,6 +1558,81 @@ Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?) dst.w = |src.w| +Bitwise ISA +^^^^^^^^^^^ +These opcodes are used for bit-level manipulation of integers. + +.. opcode:: IBFE - Signed Bitfield Extract + + See SM5 instruction of the same name. Extracts a set of bits from the input, + and sign-extends them if the high bit of the extracted window is set. + + Pseudocode:: + + def ibfe(value, offset, bits): + offset = offset & 0x1f + bits = bits & 0x1f + if bits == 0: return 0 + # Note: >> sign-extends + if width + offset < 32: + return (value << (32 - offset - bits)) >> (32 - bits) + else: + return value >> offset + +.. opcode:: UBFE - Unsigned Bitfield Extract + + See SM5 instruction of the same name. Extracts a set of bits from the input, + without any sign-extension. + + Pseudocode:: + + def ubfe(value, offset, bits): + offset = offset & 0x1f + bits = bits & 0x1f + if bits == 0: return 0 + # Note: >> does not sign-extend + if width + offset < 32: + return (value << (32 - offset - bits)) >> (32 - bits) + else: + return value >> offset + +.. opcode:: BFI - Bitfield Insert + + See SM5 instruction of the same name. Replaces a bit region of 'base' with + the low bits of 'insert'. + + Pseudocode:: + + def bfi(base, insert, offset, bits): + offset = offset & 0x1f + bits = bits & 0x1f + mask = ((1 << bits) - 1) << offset + return ((insert << offset) & mask) | (base & ~mask) + +.. opcode:: BREV - Bitfield Reverse + + See SM5 instruction BFREV. Reverses the bits of the argument. + +.. opcode:: POPC - Population Count + + See SM5 instruction COUNTBITS. Counts the number of set bits in the argument. + +.. opcode:: LSB - Index of lowest set bit + + See SM5 instruction FIRSTBIT_LO. Computes the 0-based index of the first set + bit of the argument. Returns -1 if none are set. + +.. opcode:: IMSB - Index of highest non-sign bit + + See SM5 instruction FIRSTBIT_SHI. Computes the 0-based index of the highest + non-sign bit of the argument (i.e. highest 0 bit for negative numbers, + highest 1 bit for positive numbers). Returns -1 if all bits are the same + (i.e. for inputs 0 and -1). + +.. opcode:: UMSB - Index of highest set bit + + See SM5 instruction FIRSTBIT_HI. Computes the 0-based index of the highest + set bit of the argument. Returns -1 if none are set. Geometry ISA ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |