cosmopolitan/libc/nexgen32e/rem1000000int64.S

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/*-*- 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
This program is free software; you can redistribute it and/or modify │
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License. │
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of │
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software │
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/macros.h"
/ Returns 𝑥 % 1,000,000.
/
/ @param rdi int64 𝑥
/ @return rax has remainder
rem1000000int64:
movabs $0x431bde82d7b634db,%rdx
mov %rdi,%rax
imul %rdx
mov %rdx,%rax
sar $0x12,%rax
mov %rdi,%rdx
sar $0x3f,%rdx
sub %rdx,%rax
imul $0xf4240,%rax,%rax
sub %rax,%rdi
mov %rdi,%rax
ret
.endfn rem1000000int64,globl
.source __FILE__