mpir/mpn/x86_64w/core2/diveby3.asm

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; Core2 mpn_divexact_by3c -- divide exact by 3
; Version 1.0.4.
;
; Copyright 2008 Jason Moxham and Brian Gladman
;
; This file is part of the MPIR Library.
; The MPIR Library is free software; you can redistribute it and/or modify
; it under the terms of the GNU Lesser General Public License as published
; by the Free Software Foundation; either version 2.1 of the License, or (at
; your option) any later version.
; The MPIR Library is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
; License for more details.
; You should have received a copy of the GNU Lesser General Public License
; along with the MPIR Library; see the file COPYING.LIB. If not, write
; to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
; Boston, MA 02110-1301, USA.
;
; Calling interface:
;
; mp_limb_t mpn_divexact_by3c (
; mp_ptr rp, rcx
; mp_srcptr up, rdx
; mp_size_t un, r8
; mp_limb_t c r9
; )
;
; This is an SEH leaf function
%include "..\yasm_mac.inc"
BITS 64
%define MLT1 0x5555555555555555
%macro mul_sub1 1
mov rax, [r10+r8*8+8*%1]
mul r11
sub r9, rax
mov [rcx+r8*8+8*%1], r9
sbb r9, rdx
%endmacro
%define MLT2 0xaaaaaaaaaaaaaaab
%macro mul_sub2 1
mov rax, [r10+r8*8+8*%1]
sub rax, r9
mov r9, 0
adc r9, r9
mul r11
mov [rcx+r8*8+8*%1], rax
mov rdx, r11
dec rdx
cmp rdx, rax
adc r9, 0
shr rdx, 1
cmp rdx, rax
adc r9, 0
%endmacro
; div_by_3 name, algorithm, carry_input (if present use carry)
%macro div_by_3 2-3
LEAF_PROC %1
movsxd rax, r8d
mov r8d, 3
lea r10, [rdx+rax*8-24]
lea rcx, [rcx+rax*8-24]
mov r11, MLT%2
%if %0 == 2
xor r9, r9
%else
imul r9, r11
%endif
sub r8, rax
jnc %%2
alignb 16, nop
%%1:mul_sub%2 0
mul_sub%2 1
mul_sub%2 2
mul_sub%2 3
add r8, 4
jnc %%1
; so have 3-r8 limbs left to do
%%2:test r8, 2
jnz %%3
mul_sub%2 0
mul_sub%2 1
add r8, 2
%%3:test r8, 1
jnz %%4
mul_sub%2 0
%%4:lea rax, [r9+r9*2]
neg rax
ret
%endmacro
div_by_3 mpn_divexact_by3, 1
div_by_3 mpn_divexact_by3c, 1, 1
end