cosmopolitan/libc/tinymath/roundl.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 "ape/lib/pc.h"
#include "libc/macros.h"
/ Rounds to nearest integer, away from zero.
/
/ @param 𝑥 is an 80-bit long double passed on stack in 16-bytes
/ @return result of exponentiation on FPU stack in %st
tinymath_roundl:
push %rbp
mov %rsp,%rbp
.profilable
push %rax
fldt 16(%rbp)
fnstcw -6(%rbp)
fnstcw -8(%rbp)
orb $0b00001100,-7(%rbp) # RC = 0
fxam # C1 is set to sign bit
fnstsw
fabs
test $FPU_C1>>8,%ah
fadds .Lhalf(%rip)
fldcw -8(%rbp)
frndint
fldcw -6(%rbp)
je 1f
fchs
1: leave
ret
.endfn tinymath_roundl,globl
.alias tinymath_roundl,roundl
.source __FILE__
.rodata.cst4
.Lhalf: .float .5