glibc/sysdeps/powerpc/submul_1.S

/* Multiply a limb vector by a single limb, for PowerPC.
   Copyright (C) 1993-1995, 1997, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C 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 C 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 C 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>
#include <bp-sym.h>
#include <bp-asm.h>

/* mp_limb_t mpn_submul_1 (mp_ptr res_ptr, mp_srcptr s1_ptr,
                           mp_size_t s1_size, mp_limb_t s2_limb)
   Calculate res-s1*s2 and put result back in res; return carry.  */

ENTRY (BP_SYM (__mpn_submul_1))
#if __BOUNDED_POINTERS__
	slwi r10,r5,2		/* convert limbs to bytes */
	CHECK_BOUNDS_BOTH_WIDE (r3, r8, r9, r10)
	CHECK_BOUNDS_BOTH_WIDE (r4, r8, r9, r10)
#endif
	mtctr	r5

	lwz	r0,0(r4)
	mullw	r7,r0,r6
	mulhwu	r10,r0,r6
	lwz     r9,0(r3)
	subf 	r8,r7,r9
	addc    r7,r7,r8		# invert cy (r7 is junk)
	addi	r3,r3,-4		# adjust res_ptr
	bdz	L(1)

L(0):	lwzu	r0,4(r4)
	stwu	r8,4(r3)
	mullw	r8,r0,r6
	adde	r7,r8,r10
	mulhwu	r10,r0,r6
	lwz     r9,4(r3)
	addze   r10,r10
	subf    r8,r7,r9
	addc    r7,r7,r8		# invert cy (r7 is junk)
	bdnz	L(0)

L(1):	stw	r8,4(r3)
	addze	r3,r10
	blr
END (BP_SYM (__mpn_submul_1))