glibc/sysdeps/m68k/m68020/submul_1.S

/* mc68020 __mpn_submul_1 -- Multiply a limb vector with a limb and subtract
   the result from a second limb vector.

Copyright (C) 1992, 1994, 1996, 1998 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. */

/*
  INPUT PARAMETERS
  res_ptr	(sp + 4)
  s1_ptr	(sp + 8)
  s1_size	(sp + 12)
  s2_limb	(sp + 16)
*/

#include "sysdep.h"
#include "asm-syntax.h"

	TEXT
ENTRY(__mpn_submul_1)

#define res_ptr a0
#define s1_ptr a1
#define s1_size d2
#define s2_limb d4

/* Save used registers on the stack.  */
	moveml	R(d2)-R(d5),MEM_PREDEC(sp)

/* Copy the arguments to registers.  Better use movem?  */
	movel	MEM_DISP(sp,20),R(res_ptr)
	movel	MEM_DISP(sp,24),R(s1_ptr)
	movel	MEM_DISP(sp,28),R(s1_size)
	movel	MEM_DISP(sp,32),R(s2_limb)

	eorw	#1,R(s1_size)
	clrl	R(d1)
	clrl	R(d5)
	lsrl	#1,R(s1_size)
	bcc	L(L1)
	subql	#1,R(s1_size)
	subl	R(d0),R(d0)	/* (d0,cy) <= (0,0) */

L(Loop:)
	movel	MEM_POSTINC(s1_ptr),R(d3)
	mulul	R(s2_limb),R(d1):R(d3)
	addxl	R(d0),R(d3)
	addxl	R(d5),R(d1)
	subl	R(d3),MEM_POSTINC(res_ptr)
L(L1:)	movel	MEM_POSTINC(s1_ptr),R(d3)
	mulul	R(s2_limb),R(d0):R(d3)
	addxl	R(d1),R(d3)
	addxl	R(d5),R(d0)
	subl	R(d3),MEM_POSTINC(res_ptr)

	dbf	R(s1_size),L(Loop)
	addxl	R(d5),R(d0)
	subl	#0x10000,R(s1_size)
	bcc	L(Loop)

/* Restore used registers from stack frame.  */
	moveml	MEM_POSTINC(sp),R(d2)-R(d5)

	rts
END(__mpn_submul_1)