43 lines
2.4 KiB
ArmAsm
43 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/macros.h"
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/ Support code for fast integer division by Si units.
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/
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/ Division by magnums is described in Hacker's Delight and is
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/ usually generated automatically by compilers, but sadly not
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/ when we optimize for size and idiv goes at least 10x slower
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/ so we do this which saves space while avoiding build tuning
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/
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/ @param rdi is number to divide
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/ @param cl is magnum #1
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/ @param rdx is magnum #2
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/ @return quotient
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tinydivsi:
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.leafprologue
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mov %rdi,%rax
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imul %rdx
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mov %rdx,%rax
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sar %cl,%rax
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sar $63,%rdi
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sub %rdi,%rax
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.leafepilogue
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.endfn tinydivsi,globl
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.source __FILE__
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