dnl  AMD64 mpn_divexact_1 -- mpn by limb exact division.

dnl  Copyright 2001, 2002, 2004-2006, 2011, 2012 Free Software Foundation, Inc.

dnl  This file is part of the GNU MP Library.

dnl

dnl  The GNU MP Library is free software; you can redistribute it and/or modify

dnl  it under the terms of either:

dnl

dnl    * the GNU Lesser General Public License as published by the Free

dnl      Software Foundation; either version 3 of the License, or (at your

dnl      option) any later version.

dnl

dnl  or

dnl

dnl    * the GNU General Public License as published by the Free Software

dnl      Foundation; either version 2 of the License, or (at your option) any

dnl      later version.

dnl

dnl  or both in parallel, as here.

dnl

dnl  The GNU MP Library is distributed in the hope that it will be useful, but

dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

dnl  for more details.

dnl

dnl  You should have received copies of the GNU General Public License and the

dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,

dnl  see https://www.gnu.org/licenses/.

include(`../config.m4')

C	     cycles/limb

C AMD K8,K9	10

C AMD K10	10

C Intel P4	33

C Intel core2	13.25

C Intel corei	14

C Intel atom	42

C VIA nano	43

C A quick adoption of the 32-bit K7 code.

C INPUT PARAMETERS

C rp		rdi

C up		rsi

C n		rdx

C divisor	rcx

ABI_SUPPORT(DOS64)

ABI_SUPPORT(STD64)

ASM_START()

	TEXT

	ALIGN(16)

PROLOGUE(mpn_divexact_1)

	FUNC_ENTRY(4)

	push	%rbx

	mov	%rcx, %rax

	xor	R32(%rcx), R32(%rcx)	C shift count

	mov	%rdx, %r8

	bt	$0, R32(%rax)

	jnc	L(evn)			C skip bsfq unless divisor is even

L(odd):	mov	%rax, %rbx

	shr	R32(%rax)

	and	$127, R32(%rax)		C d/2, 7 bits

	LEA(	binvert_limb_table, %rdx)

	movzbl	(%rdx,%rax), R32(%rax)	C inv 8 bits

	mov	%rbx, %r11		C d without twos

	lea	(%rax,%rax), R32(%rdx)	C 2*inv

	imul	R32(%rax), R32(%rax)	C inv*inv

	imul	R32(%rbx), R32(%rax)	C inv*inv*d

	sub	R32(%rax), R32(%rdx)	C inv = 2*inv - inv*inv*d, 16 bits

	lea	(%rdx,%rdx), R32(%rax)	C 2*inv

	imul	R32(%rdx), R32(%rdx)	C inv*inv

	imul	R32(%rbx), R32(%rdx)	C inv*inv*d

	sub	R32(%rdx), R32(%rax)	C inv = 2*inv - inv*inv*d, 32 bits

	lea	(%rax,%rax), %r10	C 2*inv

	imul	%rax, %rax		C inv*inv

	imul	%rbx, %rax		C inv*inv*d

	sub	%rax, %r10		C inv = 2*inv - inv*inv*d, 64 bits

	lea	(%rsi,%r8,8), %rsi	C up end

	lea	-8(%rdi,%r8,8), %rdi	C rp end

	neg	%r8			C -n

	mov	(%rsi,%r8,8), %rax	C up[0]

	inc	%r8

	jz	L(one)

	mov	(%rsi,%r8,8), %rdx	C up[1]

	shrd	R8(%rcx), %rdx, %rax

	xor	R32(%rbx), R32(%rbx)

	jmp	L(ent)

L(evn):	bsf	%rax, %rcx

	shr	R8(%rcx), %rax

	jmp	L(odd)

	ALIGN(8)

L(top):

	C rax	q

	C rbx	carry bit, 0 or 1

	C rcx	shift

	C rdx

	C rsi	up end

	C rdi	rp end

	C r8	counter, limbs, negative

	C r10	d^(-1) mod 2^64

	C r11	d, shifted down

	mul	%r11			C carry limb in rdx	0 10

	mov	-8(%rsi,%r8,8), %rax	C

	mov	(%rsi,%r8,8), %r9	C

	shrd	R8(%rcx), %r9, %rax	C

	nop				C

	sub	%rbx, %rax		C apply carry bit

	setc	%bl			C

	sub	%rdx, %rax		C apply carry limb	5

	adc	$0, %rbx		C			6

L(ent):	imul	%r10, %rax		C			6

	mov	%rax, (%rdi,%r8,8)	C

	inc	%r8			C

	jnz	L(top)

	mul	%r11			C carry limb in rdx

	mov	-8(%rsi), %rax		C up high limb

	shr	R8(%rcx), %rax

	sub	%rbx, %rax		C apply carry bit

	sub	%rdx, %rax		C apply carry limb

	imul	%r10, %rax

	mov	%rax, (%rdi)

	pop	%rbx

	FUNC_EXIT()

	ret

L(one):	shr	R8(%rcx), %rax

	imul	%r10, %rax

	mov	%rax, (%rdi)

	pop	%rbx

	FUNC_EXIT()

	ret

EPILOGUE()