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https://github.com/jart/cosmopolitan.git
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54 lines
2.4 KiB
ArmAsm
54 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 sw=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 "libc/macros.internal.h"
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.source __FILE__
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// Returns arc cosine of 𝑥.
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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 computation on FPU stack in %st
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// @define atan2(abs(sqrt((1-𝑥)*(1+𝑥))),𝑥)
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// @domain -1 ≤ 𝑥 ≤ 1
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// @mode long,legacy
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acosl: push %rbp
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mov %rsp,%rbp
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.profilable
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fldl 16(%rbp)
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fld %st
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#ifdef __FAST_MATH__
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fmul %st(1),%st
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fsubrs .Lone(%rip)
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fsqrt
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#else
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fld1
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fsubp
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fld1
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fadd %st(2)
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fmulp
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fsqrt
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fabs # needed in downward rounding mode
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#endif
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fxch
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fpatan
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pop %rbp
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ret
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.endfn acosl,globl
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.rodata.cst4
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.Lone: .float 1.0
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