cosmopolitan/libc/tinymath/roundf.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"
#include "libc/bits/smmintrin.internal.h"
#include "libc/nexgen32e/x86feature.h"
.source __FILE__
/ Rounds to nearest integer, away from zero.
/
/ @param 𝑥 is float scalar in low quarter of %xmm0
/ @return float scalar in low quarter of %xmm0
tinymath_roundf:
#if !X86_NEED(SSE4_2)
testb X86_HAVE(SSE4_2)+kCpuids(%rip)
jz tinymath_roundf$k8
.text.antiquity
tinymath_roundf$k8:
.leafprologue
.profilable
movaps %xmm0,%xmm1
movss D(%rip),%xmm2
movss C(%rip),%xmm3
andps %xmm2,%xmm1
ucomiss %xmm1,%xmm3
jbe 2f
addss A(%rip),%xmm1
cvttss2sil %xmm1,%eax
pxor %xmm1,%xmm1
cvtsi2ssl %eax,%xmm1
andnps %xmm0,%xmm2
movaps %xmm2,%xmm0
orps %xmm1,%xmm0
2: .leafepilogue
.endfn tinymath_roundf$k8,globl,hidden
.previous
.rodata.cst16
C: .long 0x4b000000,0,0,0
D: .long 0x7fffffff,0,0,0
.previous
#endif
movaps %xmm0,%xmm1
andps B(%rip),%xmm0
orps A(%rip),%xmm0
addss %xmm1,%xmm0
roundss $_MM_FROUND_TO_ZERO,%xmm0,%xmm0
ret
.endfn tinymath_roundf,globl
.alias tinymath_roundf,roundf
.rodata.cst16
A: .long 0x3effffff,0,0,0
B: .long 0x80000000,0,0,0