cosmopolitan/libc/tinymath/truncf.S
2021-03-02 13:57:23 -08:00

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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
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"
// Rounds to integer, toward zero.
//
// @param 𝑥 is float scalar in low quarter of %xmm0
// @return float scalar in low quarter of %xmm0
// @define trunc(𝑥+copysign(.5,𝑥))
// @see round(),rint(),nearbyint()
// @see roundss $_MM_FROUND_TO_ZERO|_MM_FROUND_NO_EXC,%xmm0,%xmm0
truncf: .leafprologue
.profilable
movss 3f(%rip),%xmm2
movss 2f(%rip),%xmm4
movaps %xmm0,%xmm3
movaps %xmm0,%xmm1
andps %xmm2,%xmm3
ucomiss %xmm3,%xmm4
jbe 1f
cvttss2sil %xmm0,%eax
pxor %xmm0,%xmm0
andnps %xmm1,%xmm2
cvtsi2ssl %eax,%xmm0
orps %xmm2,%xmm0
1: .leafepilogue
.endfn truncf,globl
.rodata.cst4
2: .long 0x4b000000
.rodata.cst16
3: .long 0x7fffffff,0,0,0