dnl  IBM POWER mpn_submul_1 -- Multiply a limb vector with a limb and subtract

dnl  the result from a second limb vector.

dnl  Copyright 1992, 1994, 1999-2001 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/.

dnl  INPUT PARAMETERS

dnl  res_ptr	r3

dnl  s1_ptr	r4

dnl  size	r5

dnl  s2_limb	r6

dnl  The POWER architecture has no unsigned 32x32->64 bit multiplication

dnl  instruction.  To obtain that operation, we have to use the 32x32->64

dnl  signed multiplication instruction, and add the appropriate compensation to

dnl  the high limb of the result.  We add the multiplicand if the multiplier

dnl  has its most significant bit set, and we add the multiplier if the

dnl  multiplicand has its most significant bit set.  We need to preserve the

dnl  carry flag between each iteration, so we have to compute the compensation

dnl  carefully (the natural, srai+and doesn't work).  Since all POWER can

dnl  branch in zero cycles, we use conditional branches for the compensation.

include(`../config.m4')

ASM_START()

PROLOGUE(mpn_submul_1)

	cal	3,-4(3)

	l	0,0(4)

	cmpi	0,6,0

	mtctr	5

	mul	9,0,6

	srai	7,0,31

	and	7,7,6

	mfmq	11

	cax	9,9,7

	l	7,4(3)

	sf	8,11,7		C add res_limb

	a	11,8,11		C invert cy (r11 is junk)

	blt	Lneg

Lpos:	bdz	Lend

Lploop:	lu	0,4(4)

	stu	8,4(3)

	cmpi	0,0,0

	mul	10,0,6

	mfmq	0

	ae	11,0,9		C low limb + old_cy_limb + old cy

	l	7,4(3)

	aze	10,10		C propagate cy to new cy_limb

	sf	8,11,7		C add res_limb

	a	11,8,11		C invert cy (r11 is junk)

	bge	Lp0

	cax	10,10,6		C adjust high limb for negative limb from s1

Lp0:	bdz	Lend0

	lu	0,4(4)

	stu	8,4(3)

	cmpi	0,0,0

	mul	9,0,6

	mfmq	0

	ae	11,0,10

	l	7,4(3)

	aze	9,9

	sf	8,11,7

	a	11,8,11		C invert cy (r11 is junk)

	bge	Lp1

	cax	9,9,6		C adjust high limb for negative limb from s1

Lp1:	bdn	Lploop

	b	Lend

Lneg:	cax	9,9,0

	bdz	Lend

Lnloop:	lu	0,4(4)

	stu	8,4(3)

	cmpi	0,0,0

	mul	10,0,6

	mfmq	7

	ae	11,7,9

	l	7,4(3)

	ae	10,10,0		C propagate cy to new cy_limb

	sf	8,11,7		C add res_limb

	a	11,8,11		C invert cy (r11 is junk)

	bge	Ln0

	cax	10,10,6		C adjust high limb for negative limb from s1

Ln0:	bdz	Lend0

	lu	0,4(4)

	stu	8,4(3)

	cmpi	0,0,0

	mul	9,0,6

	mfmq	7

	ae	11,7,10

	l	7,4(3)

	ae	9,9,0		C propagate cy to new cy_limb

	sf	8,11,7		C add res_limb

	a	11,8,11		C invert cy (r11 is junk)

	bge	Ln1

	cax	9,9,6		C adjust high limb for negative limb from s1

Ln1:	bdn	Lnloop

	b	Lend

Lend0:	cal	9,0(10)

Lend:	st	8,4(3)

	aze	3,9

	br

EPILOGUE(mpn_submul_1)