mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
868af3f950
You can now use the hardest fastest and most dangerous language there is with Cosmopolitan. So far about 75% of LLVM libcxx has been added. A few breaking changes needed to be made to help this go smoothly. - Rename nothrow to dontthrow - Rename nodiscard to dontdiscard - Add some libm functions, e.g. lgamma, nan, etc. - Change intmax_t from int128 to int64 like everything else - Introduce %jjd formatting directive for int128_t - Introduce strtoi128(), strtou128(), etc. - Rename bsrmax() to bsr128() Some of the templates that should be working currently are std::vector, std::string, std::map, std::set, std::deque, etc.
44 lines
2.7 KiB
ArmAsm
44 lines
2.7 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
|
||
│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
|
||
╞══════════════════════════════════════════════════════════════════════════════╡
|
||
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
||
│ │
|
||
│ Permission to use, copy, modify, and/or distribute this software for │
|
||
│ any purpose with or without fee is hereby granted, provided that the │
|
||
│ above copyright notice and this permission notice appear in all copies. │
|
||
│ │
|
||
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
||
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
||
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
||
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
||
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
||
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
||
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
||
│ PERFORMANCE OF THIS SOFTWARE. │
|
||
╚─────────────────────────────────────────────────────────────────────────────*/
|
||
#include "libc/macros.internal.h"
|
||
|
||
// Returns binary logarithm of integer 𝑥.
|
||
//
|
||
// uint32 𝑥 bsf(𝑥) tzcnt(𝑥) ffs(𝑥) bsr(𝑥) lzcnt(𝑥)
|
||
// 0x00000000 wut 32 0 wut 32
|
||
// 0x00000001 0 0 1 0 31
|
||
// 0x80000001 0 0 1 31 0
|
||
// 0x80000000 31 31 32 31 0
|
||
// 0x00000010 4 4 5 4 27
|
||
// 0x08000010 4 4 5 27 4
|
||
// 0x08000000 27 27 28 27 4
|
||
// 0xffffffff 0 0 1 31 0
|
||
//
|
||
// @param rsi:rdi is 128-bit unsigned 𝑥 value
|
||
// @return eax number in range [0,128) or undef if 𝑥 is 0
|
||
// @see also treasure trove of nearly identical functions
|
||
bsr128: .leafprologue
|
||
.profilable
|
||
bsr %rsi,%rax
|
||
jnz 2f
|
||
bsr %rdi,%rax
|
||
1: .leafepilogue
|
||
2: add $64,%eax
|
||
jmp 1b
|
||
.endfn bsr128,globl
|