cosmopolitan/libc/tinymath/acosl.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 sw=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"
.source __FILE__
/ Returns arc cosine of 𝑥.
/
/ @param 𝑥 is an 80-bit long double passed on stack in 16-bytes
/ @return result of computation on FPU stack in %st
/ @define atan2(abs(sqrt((1-𝑥)*(1+𝑥))),𝑥)
/ @domain -1 ≤ 𝑥 ≤ 1
/ @mode long,legacy
tinymath_acosl:
push %rbp
mov %rsp,%rbp
.profilable
fldl 16(%rbp)
fld %st
#ifdef __FAST_MATH__
fmul %st(1),%st
fsubrs .Lone(%rip)
fsqrt
#else
fld1
fsubp
fld1
fadd %st(2)
fmulp
fsqrt
fabs # needed in downward rounding mode
#endif
fxch
fpatan
pop %rbp
ret
.endfn tinymath_acosl,globl
.alias tinymath_acosl,acosl
.rodata.cst4
.Lone: .float 1.0