1/* mc68020 __mpn_submul_1 -- Multiply a limb vector with a limb and subtract
2   the result from a second limb vector.
3
4Copyright (C) 1992, 1994, 1996, 1998 Free Software Foundation, Inc.
5
6This file is part of the GNU MP Library.
7
8The GNU MP Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 2.1 of the License, or (at your
11option) any later version.
12
13The GNU MP Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
20the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21MA 02111-1307, USA. */
22
23/*
24  INPUT PARAMETERS
25  res_ptr	(sp + 4)
26  s1_ptr	(sp + 8)
27  s1_size	(sp + 12)
28  s2_limb	(sp + 16)
29*/
30
31#include "sysdep.h"
32#include "asm-syntax.h"
33
34	TEXT
35ENTRY(__mpn_submul_1)
36
37#define res_ptr a0
38#define s1_ptr a1
39#define s1_size d2
40#define s2_limb d4
41
42/* Save used registers on the stack.  */
43	moveml	R(d2)-R(d5),MEM_PREDEC(sp)
44
45/* Copy the arguments to registers.  Better use movem?  */
46	movel	MEM_DISP(sp,20),R(res_ptr)
47	movel	MEM_DISP(sp,24),R(s1_ptr)
48	movel	MEM_DISP(sp,28),R(s1_size)
49	movel	MEM_DISP(sp,32),R(s2_limb)
50
51	eorw	#1,R(s1_size)
52	clrl	R(d1)
53	clrl	R(d5)
54	lsrl	#1,R(s1_size)
55	bcc	L(L1)
56	subql	#1,R(s1_size)
57	subl	R(d0),R(d0)	/* (d0,cy) <= (0,0) */
58
59L(Loop:)
60	movel	MEM_POSTINC(s1_ptr),R(d3)
61	mulul	R(s2_limb),R(d1):R(d3)
62	addxl	R(d0),R(d3)
63	addxl	R(d5),R(d1)
64	subl	R(d3),MEM_POSTINC(res_ptr)
65L(L1:)	movel	MEM_POSTINC(s1_ptr),R(d3)
66	mulul	R(s2_limb),R(d0):R(d3)
67	addxl	R(d1),R(d3)
68	addxl	R(d5),R(d0)
69	subl	R(d3),MEM_POSTINC(res_ptr)
70
71	dbf	R(s1_size),L(Loop)
72	addxl	R(d5),R(d0)
73	subl	#0x10000,R(s1_size)
74	bcc	L(Loop)
75
76/* Restore used registers from stack frame.  */
77	moveml	MEM_POSTINC(sp),R(d2)-R(d5)
78
79	rts
80END(__mpn_submul_1)
81