cosmopolitan/libc/tinymath/round.S
Justine Tunney 416fd86676 Make improvements
- Emulator can now test the αcτµαlly pδrταblε εxεcµταblε bootloader

- Whipped up a webserver named redbean. It services 150k requests per
  second on a single core. Bundling assets inside zip enables extremely
  fast serving for two reasons. The first is that zip central directory
  lookups go faster than stat() system calls. The second is that both
  zip and gzip content-encoding use DEFLATE, therefore, compressed
  responses can be served via the sendfile() system call which does an
  in-kernel copy directly from the zip executable structure. Also note
  that red bean zip executables can be deployed easily to all platforms,
  since these native executables work on Linux, Mac, BSD, and Windows.

- Address sanitizer now works very well
2020-09-14 00:02:34 -07:00

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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
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.h"
#include "libc/nexgen32e/x86feature.h"
.source __FILE__
/ Rounds to nearest integer, away from zero.
/
/ @param 𝑥 is double scalar in low half of %xmm0
/ @return double scalar in low half of %xmm0
/ @define round(𝑥) = copysign(trunc(fabs(𝑥)+.5),𝑥)
/ round(𝑥) = trunc(𝑥+copysign(.5,𝑥))
tinymath_round:
#if !X86_NEED(SSE4_2)
testb X86_HAVE(SSE4_2)+kCpuids(%rip)
jz tinymath_round$k8
.text.antiquity
tinymath_round$k8:
.leafprologue
.profilable
movapd %xmm0,%xmm1
movsd D(%rip),%xmm2
movsd C(%rip),%xmm3
andpd %xmm2,%xmm1
ucomisd %xmm1,%xmm3
jbe 2f
addsd A(%rip),%xmm1
andnpd %xmm0,%xmm2
movapd %xmm2,%xmm0
cvttsd2siq %xmm1,%rax
pxor %xmm1,%xmm1
cvtsi2sdq %rax,%xmm1
orpd %xmm1,%xmm0
2: .leafepilogue
.endfn tinymath_round$k8,globl,hidden
.previous
.rodata.cst16
C: .quad 0x4330000000000000,0
D: .quad 0x7fffffffffffffff,0
.previous
#endif
movapd %xmm0,%xmm1
andpd B(%rip),%xmm0
orpd A(%rip),%xmm0
addsd %xmm1,%xmm0
roundsd $_MM_FROUND_TO_ZERO,%xmm0,%xmm0
ret
.endfn tinymath_round,globl
.alias tinymath_round,round
.rodata.cst16
A: .quad 0x3fdfffffffffffff,0
B: .quad 0x8000000000000000,0