69 lines
1.9 KiB
NASM
69 lines
1.9 KiB
NASM
; PROLOGUE(mpn_half)
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; Copyright 2009 Jason Moxham
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;
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; Windows Conversion Copyright 2008 Brian Gladman
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;
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; This file is part of the MPIR Library.
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; The MPIR Library is free software; you can redistribute it and/or modify
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; it under the terms of the GNU Lesser General Public License as published
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; by the Free Software Foundation; either version 2.1 of the License, or (at
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; your option) any later version.
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; The MPIR Library is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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; License for more details.
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; You should have received a copy of the GNU Lesser General Public License
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; along with the MPIR Library; see the file COPYING.LIB. If not, write
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; to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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; Boston, MA 02110-1301, USA.
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;
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; mp_limb_t mpn_half(mp_ptr, mp_size_t)
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; rdi rsi
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; rcx rdx
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%include "yasm_mac.inc"
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CPU Athlon64
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BITS 64
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LEAF_PROC mpn_half
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mov rax, rdx
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lea rcx, [rcx+rdx*8-8]
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shr rdx, 2
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and eax, 3
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jz .1
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shr qword [rcx], 1
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lea rcx, [rcx-8]
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dec rax
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jz .1
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rcr qword [rcx], 1
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lea rcx, [rcx-8]
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dec rax
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jz .1
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rcr qword [rcx], 1
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lea rcx, [rcx-8]
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dec rax
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.1: sbb r8, r8
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cmp rdx, 0
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jz .3
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add r8, r8
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xalign 16
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.2: rcr qword [rcx], 1
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nop
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rcr qword [rcx-8], 1
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rcr qword [rcx-16], 1
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rcr qword [rcx-24], 1
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nop
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dec rdx
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lea rcx, [rcx-32]
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jnz .2
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sbb r8, r8
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.3: sub rax, r8
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shl rax, 63
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ret
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end
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