mpir/mpn/x86_64/divebyBm1of.as

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; X86_64 mpn_diveby (B-1)/f
; Copyright 2009 Jason Moxham
; 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.
%include "yasm_mac.inc"
; (rdi,rdx)=(rsi,rdx)/rcx where r8=(B-1)/rcx
; rax=carry out
; The two imul's are only needed if want strict compatibility with
; mpn_divexact_1 when the division is not exact
GLOBAL_FUNC mpn_divexact_byBm1of
mov r10d, 3
lea rsi, [rsi+rdx*8-24]
lea rdi, [rdi+rdx*8-24]
; r9 is our carry in
mov r9, 0
; imul %r8,%r9 this is needed if we have non-zero carry in
sub r10, rdx
jnc skiploop
align 16
lp:
mov rax, [rsi+r10*8]
mul r8
sub r9, rax
mov [rdi+r10*8], r9
sbb r9, rdx
mov rax, [rsi+r10*8+8]
mul r8
sub r9, rax
mov [rdi+r10*8+8], r9
sbb r9, rdx
mov rax, [rsi+r10*8+16]
mul r8
sub r9, rax
mov [rdi+r10*8+16], r9
sbb r9, rdx
mov rax, [rsi+r10*8+24]
mul r8
sub r9, rax
mov [rdi+r10*8+24], r9
sbb r9, rdx
add r10, 4
jnc lp
skiploop:
test r10, 2
jnz skip
mov rax, [rsi+r10*8]
mul r8
sub r9, rax
mov [rdi+r10*8], r9
sbb r9, rdx
mov rax, [rsi+r10*8+8]
mul r8
sub r9, rax
mov [rdi+r10*8+8], r9
sbb r9, rdx
add r10, 2
skip:
test r10, 1
jnz fin
mov rax, [rsi+r10*8]
mul r8
sub r9, rax
mov [rdi+r10*8], r9
sbb r9, rdx
fin:
imul r9, rcx
mov rax, r9
neg rax
ret
end