glibc/sysdeps/mips/submul_1.S

/* MIPS __mpn_submul_1 -- Multiply a limb vector with a single limb and
subtract the product from a second limb vector.

Copyright (C) 1995 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

The GNU MP 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 Library General Public
License for more details.

You should have received a copy of the GNU Library General Public License
along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA.  */

#include <sysdep.h>

/* INPUT PARAMETERS
   res_ptr	$4
   s1_ptr	$5
   size		$6
   s2_limb	$7
*/
#ifdef PIC
	.option pic2
#endif
ENTRY (__mpn_submul_1)
	.set    noreorder
#ifdef PIC
	.cpload t9
#endif
	.set    nomacro

	/* warm up phase 0 */
	lw	$8,0($5)

	/* warm up phase 1 */
	addiu	$5,$5,4
	multu	$8,$7

	addiu	$6,$6,-1
	beq	$6,$0,$LC0
	move	$2,$0		/* zero cy2 */

	addiu	$6,$6,-1
	beq	$6,$0,$LC1
	lw	$8,0($5)	/* load new s1 limb as early as possible */

Loop:	lw	$10,0($4)
	mflo	$3
	mfhi	$9
	addiu	$5,$5,4
	addu	$3,$3,$2	/* add old carry limb to low product limb */
	multu	$8,$7
	lw	$8,0($5)	/* load new s1 limb as early as possible */
	addiu	$6,$6,-1	/* decrement loop counter */
	sltu	$2,$3,$2	/* carry from previous addition -> $2 */
	subu	$3,$10,$3
	sgtu	$10,$3,$10
	addu	$2,$2,$10
	sw	$3,0($4)
	addiu	$4,$4,4
	bne	$6,$0,Loop	/* should be "bnel" */
	addu	$2,$9,$2	/* add high product limb and carry from addition */

	/* cool down phase 1 */
$LC1:	lw	$10,0($4)
	mflo	$3
	mfhi	$9
	addu	$3,$3,$2
	sltu	$2,$3,$2
	multu	$8,$7
	subu	$3,$10,$3
	sgtu	$10,$3,$10
	addu	$2,$2,$10
	sw	$3,0($4)
	addiu	$4,$4,4
	addu	$2,$9,$2	/* add high product limb and carry from addition */

	/* cool down phase 0 */
$LC0:	lw	$10,0($4)
	mflo	$3
	mfhi	$9
	addu	$3,$3,$2
	sltu	$2,$3,$2
	subu	$3,$10,$3
	sgtu	$10,$3,$10
	addu	$2,$2,$10
	sw	$3,0($4)
	j	$31
	addu	$2,$9,$2	/* add high product limb and carry from addition */