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https://github.com/jart/cosmopolitan.git
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fdc3fa9148
The libm code from musl wasn't being used since most of these functions are implemented using x87 which goes faster than a library intended for risc machines.
50 lines
2.4 KiB
ArmAsm
50 lines
2.4 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "ape/lib/pc.h"
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#include "libc/macros.h"
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/ Rounds to nearest integer, away from zero.
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/
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/ @param 𝑥 is an 80-bit long double passed on stack in 16-bytes
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/ @return result of exponentiation on FPU stack in %st
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roundl: push %rbp
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mov %rsp,%rbp
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.profilable
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push %rax
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fldt 16(%rbp)
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fnstcw -6(%rbp)
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fnstcw -8(%rbp)
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orb $0b00001100,-7(%rbp) # RC = →0
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fxam # C1 is set to sign bit
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fnstsw
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fabs
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test $FPU_C1>>8,%ah
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fadds .Lhalf(%rip)
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fldcw -8(%rbp)
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frndint
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fldcw -6(%rbp)
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je 1f
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fchs
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1: leave
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ret
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.endfn roundl,globl
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.source __FILE__
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.rodata.cst4
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.Lhalf: .float .5
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