1/* mc68020 __mpn_submul_1 -- Multiply a limb vector with a limb and subtract
2 *                           the result from a second limb vector.
3 *
4 *      Copyright (C) 1992, 1994, 1996, 1998,
5 *                    2001 Free Software Foundation, Inc.
6 *
7 * This file is part of GnuPG.
8 *
9 * GnuPG is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 3 of the License, or
12 * (at your option) any later version.
13 *
14 * GnuPG is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, see <http://www.gnu.org/licenses/>.
21 *
22 * Note: This code is heavily based on the GNU MP Library.
23 *	 Actually it's the same code with only minor changes in the
24 *	 way the data is stored; this is to support the abstraction
25 *	 of an optional secure memory allocation which may be used
26 *	 to avoid revealing of sensitive data due to paging etc.
27 *	 The GNU MP Library itself is published under the LGPL;
28 *	 however I decided to publish this code under the plain GPL.
29 */
30
31
32
33
34#include "sysdep.h"
35#include "asm-syntax.h"
36
37/*******************
38 * mpi_limb_t
39 * mpihelp_submul_1( mpi_ptr_t res_ptr,      (sp + 4)
40 *		     mpi_ptr_t s1_ptr,	     (sp + 8)
41 *		     mpi_size_t s1_size,     (sp + 12)
42 *		     mpi_limb_t s2_limb)     (sp + 16)
43 */
44
45
46	TEXT
47	ALIGN
48	GLOBL	C_SYMBOL_NAME(mpihelp_submul_1)
49
50C_SYMBOL_NAME(mpihelp_submul_1:)
51PROLOG(mpihelp_submul_1)
52
53#define res_ptr a0
54#define s1_ptr a1
55#define s1_size d2
56#define s2_limb d4
57
58/* Save used registers on the stack.  */
59	moveml	R(d2)-R(d5),MEM_PREDEC(sp)
60
61/* Copy the arguments to registers.  Better use movem?	*/
62	movel	MEM_DISP(sp,20),R(res_ptr)
63	movel	MEM_DISP(sp,24),R(s1_ptr)
64	movel	MEM_DISP(sp,28),R(s1_size)
65	movel	MEM_DISP(sp,32),R(s2_limb)
66
67	eorw	#1,R(s1_size)
68	clrl	R(d1)
69	clrl	R(d5)
70	lsrl	#1,R(s1_size)
71	bcc	L(L1)
72	subql	#1,R(s1_size)
73	subl	R(d0),R(d0)	/* (d0,cy) <= (0,0) */
74
75L(Loop:)
76	movel	MEM_POSTINC(s1_ptr),R(d3)
77	mulul	R(s2_limb),R(d1):R(d3)
78	addxl	R(d0),R(d3)
79	addxl	R(d5),R(d1)
80	subl	R(d3),MEM_POSTINC(res_ptr)
81L(L1:)	movel	MEM_POSTINC(s1_ptr),R(d3)
82	mulul	R(s2_limb),R(d0):R(d3)
83	addxl	R(d1),R(d3)
84	addxl	R(d5),R(d0)
85	subl	R(d3),MEM_POSTINC(res_ptr)
86
87	dbf	R(s1_size),L(Loop)
88	addxl	R(d5),R(d0)
89	subl	#0x10000,R(s1_size)
90	bcc	L(Loop)
91
92/* Restore used registers from stack frame.  */
93	moveml	MEM_POSTINC(sp),R(d2)-R(d5)
94
95	rts
96EPILOG(mpihelp_submul_1)
97
98
99