dnl  x86-64 mpn_div_qr_2n_pi1

dnl  -- Divide an mpn number by a normalized 2-limb number,

dnl     using a single-limb inverse.

dnl  Copyright 2007, 2008, 2010-2012 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		c/l

C INPUT PARAMETERS

define(`qp',		`%rdi')

define(`rp',		`%rsi')

define(`up_param',	`%rdx')

define(`un',		`%rcx')

define(`d1',		`%r8')

define(`d0',		`%r9')

define(`di_param',	`8(%rsp)')

define(`di',		`%r10')

define(`up',		`%r11')

define(`u2',		`%rbx')

define(`u1',		`%r12')

define(`t1',		`%r13')

define(`t0',		`%r14')

define(`md1',		`%r15')

C TODO

C * Store qh in the same stack slot as di_param, instead of pushing

C   it. (we could put it in register %rbp, but then we would need to

C   save and restore that instead, which doesn't seem like a win).

ABI_SUPPORT(DOS64)

ABI_SUPPORT(STD64)

ASM_START()

	TEXT

	ALIGN(16)

PROLOGUE(mpn_div_qr_2n_pi1)

	FUNC_ENTRY(4)

IFDOS(`	mov	56(%rsp), %r8	')

IFDOS(`	mov	64(%rsp), %r9	')

IFDOS(`define(`di_param', `72(%rsp)')')

	mov	di_param, di

	mov	up_param, up

	push	%r15

	push	%r14

	push	%r13

	push	%r12

	push	%rbx

	mov	-16(up, un, 8), u1

	mov	-8(up, un, 8), u2

	mov	u1, t0

	mov	u2, t1

	sub	d0, t0

	sbb	d1, t1

	cmovnc  t0, u1

	cmovnc	t1, u2

	C push qh which is !carry

	sbb	%rax, %rax

	inc	%rax

	push	%rax

	lea	-2(un), un

	mov	d1, md1

	neg	md1

	jmp	L(next)

	ALIGN(16)

L(loop):

	C udiv_qr_3by2 (q,u2,u1,u2,u1,n0, d1,d0,di)

	C Based on the optimized divrem_2.asm code.

	mov	di, %rax

	mul	u2

	mov	u1, t0

	add	%rax, t0	C q0 in t0

	adc	u2, %rdx

	mov	%rdx, t1	C q in t1

	imul	md1, %rdx

	mov	d0, %rax

	lea	(%rdx, u1), u2

	mul	t1

	mov	(up, un, 8), u1

	sub	d0, u1

	sbb	d1, u2

	sub	%rax, u1

	sbb	%rdx, u2

	xor	R32(%rax), R32(%rax)

	xor	R32(%rdx), R32(%rdx)

	cmp	t0, u2

	cmovnc	d0, %rax

	cmovnc	d1, %rdx

	adc	$0, t1

	nop

	add	%rax, u1

	adc	%rdx, u2

	cmp	d1, u2

	jae	L(fix)

L(bck):

	mov	t1, (qp, un, 8)

L(next):

	sub	$1, un

	jnc	L(loop)

L(end):

	mov	u2, 8(rp)

	mov	u1, (rp)

	C qh on stack

	pop	%rax

	pop	%rbx

	pop	%r12

	pop	%r13

	pop	%r14

	pop	%r15

	FUNC_EXIT()

	ret

L(fix):	C Unlikely update. u2 >= d1

	seta	%dl

	cmp	d0, u1

	setae	%al

	orb	%dl, %al		C "orb" form to placate Sun tools

	je	L(bck)

	inc	t1

	sub	d0, u1

	sbb	d1, u2

	jmp	L(bck)

EPILOGUE()