mirror of
https://github.com/logos-storage/constantine.git
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1f4bb174a3
* Add PoC of JIT exec on Nvidia GPUs [skip ci] * Split GPU bindings into low-level (ABI) and high-level [skip ci] * small typedef reorg [skip ci] * refine LLVM IR/Nvidia GPU hello worlds * [Nvidia GPU] PoC implementation of field addition [skip ci] * prod-ready field addition + tests on Nvidia GPUs via LLVM codegen
87 lines
3.8 KiB
Nim
87 lines
3.8 KiB
Nim
# Constantine
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# Copyright (c) 2018-2019 Status Research & Development GmbH
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# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import ../constant_time/ct_types
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when GCC_Compatible:
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func builtin_clz(n: uint32): cint {.importc: "__builtin_clz", nodecl.}
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## Count the number of leading zeros
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## undefined if n is zero
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func builtin_clzll(n: uint64): cint {.importc: "__builtin_clzll", nodecl.}
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## Count the number of leading zeros
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## undefined if n is zero
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func log2_c_compiler_vartime*(n: uint8|uint16|uint32): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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cast[int](31 - cast[cuint](builtin_clz(n.uint32)))
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func log2_c_compiler_vartime*(n: uint64): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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cast[int](63 - cast[cuint](builtin_clzll(n)))
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elif defined(icc):
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func bitScanReverse(r: var uint32, n: uint32): uint8 {.importc: "_BitScanReverse", header: "<immintrin.h>".}
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## Returns 0 if n is zero and non-zero otherwise
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## Returns the position of the first set bit in `r`
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func bitScanReverse64(r: var uint32, n: uint64): uint8 {.importc: "_BitScanReverse64", header: "<immintrin.h>".}
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## Returns 0 if n is zero and non-zero otherwise
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## Returns the position of the first set bit in `r`
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template bitscan(fnc: untyped; v: untyped): int {.inline.} =
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var index: uint32
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if fnc(index.addr, v) == 0:
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return 0
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return index.int
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func log2_c_compiler_vartime*(n: uint8|uint16|uint32): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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bitscan(bitScanReverse, c.uint32)
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func log2_c_compiler_vartime*(n: uint64): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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bitscan(bitScanReverse64, n)
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elif defined(vcc):
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func bitScanReverse(p: ptr uint32, b: uint32): uint8 {.importc: "_BitScanReverse", header: "<intrin.h>".}
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## Returns 0 if n s no set bit and non-zero otherwise
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## Returns the position of the first set bit in `r`
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func bitScanReverse64(p: ptr uint32, b: uint64): uint8 {.importc: "_BitScanReverse64", header: "<intrin.h>".}
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## Returns 0 if n s no set bit and non-zero otherwise
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## Returns the position of the first set bit in `r`
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template bitscan(fnc: untyped; v: untyped): int =
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var index: uint32
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if fnc(index.addr, v) == 0:
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return 0
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return index.int
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func log2_c_compiler_vartime*(n: uint8|uint16|uint32): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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bitscan(bitScanReverse, c.uint32)
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func log2_c_compiler_vartime*(n: uint64): int {.inline.} =
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## Compute the log2 of n using compiler builtin
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## ⚠ Depending on the compiler:
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## - It is undefined if n == 0
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## - It is not constant-time as a zero input is checked
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bitscan(bitScanReverse64, n)
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else:
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{. error: "Unsupported compiler".} |