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include system/countbits_impl

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ringabout
2025-12-17 21:07:18 +08:00
parent d9cc42a4ed
commit 6038535db1
5 changed files with 15 additions and 12 deletions
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13
lib/system/countbits_impl.nim
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@@ -11,13 +11,7 @@
include std/private/bitops_utils
const useBuiltins* = not defined(noIntrinsicsBitOpts)
const noUndefined* = defined(noUndefinedBitOpts)
const useGCC_builtins* = (defined(gcc) or defined(llvm_gcc) or
defined(clang)) and useBuiltins
const useICC_builtins* = defined(icc) and useBuiltins
const useVCC_builtins* = defined(vcc) and useBuiltins
const arch64* = sizeof(int) == 8
const arch64 = sizeof(int) == 8
template countBitsImpl(n: uint32): int =
# generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
@@ -60,7 +54,7 @@ elif useICC_builtins:
importc: "_popcnt64", header: "<immintrin.h>".}
func countSetBitsImpl*(x: SomeInteger): int {.inline.} =
func countSetBitsImpl(x: SomeInteger): int {.inline.} =
## Counts the set bits in an integer (also called `Hamming weight`:idx:).
# TODO: figure out if ICC support _popcnt32/_popcnt64 on platform without POPCNT.
# like GCC and MSVC
@@ -85,3 +79,6 @@ func countSetBitsImpl*(x: SomeInteger): int {.inline.} =
else:
when sizeof(x) <= 4: result = countBitsImpl(x.uint32)
else: result = countBitsImpl(x.uint64)
func countSetBitsSysimpl*(x: SomeInteger): int {.inline.} =
result = countSetBitsImpl(x)