From bc600ecc3bdf0f189861dfb840f70c2339a7a853 Mon Sep 17 00:00:00 2001 From: Kimplul Date: Fri, 24 May 2024 13:24:27 +0300 Subject: rename common to src + I keep starting to type src and wondering why autocomplete won't work, I guess src is just uncounciously a better name --- src/bits.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 src/bits.c (limited to 'src/bits.c') diff --git a/src/bits.c b/src/bits.c new file mode 100644 index 0000000..6462d21 --- /dev/null +++ b/src/bits.c @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: copyleft-next-0.3.1 */ +/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */ + +/** + * @file bits.c + * Bit manipulation helper implementations, currently just byte swaps. + */ + +#include +#include +#include +#include + +#undef __bswap16 +__weak uint16_t __bswap16(const uint16_t u) +{ + return (u & 0xff00) >> 8 | (u & 0x00ff) << 8; +} + +#undef __bswap32 +__weak uint32_t __bswap32(const uint32_t u) +{ + return (u & 0xff000000) >> 24 | (u & 0x00ff0000) >> 8 | + (u & 0x0000ff00) << 8 | (u & 0x000000ff) << 24; +} + +#undef __bswap64 +__weak uint64_t __bswap64(const uint64_t u) +{ + return (u & 0xff00000000000000ULL) >> 56 | + (u & 0x00ff000000000000ULL) >> 40 | + (u & 0x0000ff0000000000ULL) >> 24 | + (u & 0x000000ff00000000ULL) >> 8 | + (u & 0x00000000ff000000ULL) << 8 | + (u & 0x0000000000ff0000ULL) << 24 | + (u & 0x000000000000ff00ULL) << 40 | + (u & 0x00000000000000ffULL) << 56; +} + +#undef ffs +__weak int ffs(int v) +{ + /* http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightParallel */ + if (v == 0) + return 0; + + /* silence ubsan warning */ + if (v == INT_MIN) + return 32; + + int c = 32; + v &= -v; + + if (v) c--; + if (v & 0x0000FFFF) c -= 16; + if (v & 0x00FF00FF) c -= 8; + if (v & 0x0F0F0F0F) c -= 4; + if (v & 0x33333333) c -= 2; + if (v & 0x55555555) c -= 1; + + return c + 1; +} -- cgit v1.3