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https://github.com/jart/cosmopolitan.git
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edd9297eba
Your Actually Portable Executables now contains a simple virtual memory that works similarly to the Linux Kernel in the sense that it maps your physical memory to negative addresses. This is needed to support mmap() and malloc(). This functionality has zero code size impact. For example the MODE=tiny LIFE.COM executable is still only 12KB in size. The APE bootloader code has also been simplified to improve readibility and further elevate the elegance by which we're able to support so many platforms thereby enhancing verifiability so that we may engender trust in this bootloading process.
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 "libc/runtime/pc.internal.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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