1/* mc68020 __mpn_lshift -- Shift left a low-level natural-number integer.
2
3Copyright (C) 1996, 1998 Free Software Foundation, Inc.
4
5This file is part of the GNU MP Library.
6
7The GNU MP Library is free software; you can redistribute it and/or modify
8it under the terms of the GNU Lesser General Public License as published by
9the Free Software Foundation; either version 2.1 of the License, or (at your
10option) any later version.
11
12The GNU MP Library is distributed in the hope that it will be useful, but
13WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
15License for more details.
16
17You should have received a copy of the GNU Lesser General Public License
18along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
19the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20MA 02111-1307, USA. */
21
22/*
23  INPUT PARAMETERS
24  res_ptr	(sp + 4)
25  s_ptr		(sp + 8)
26  s_size	(sp + 16)
27  cnt		(sp + 12)
28*/
29
30#include "sysdep.h"
31#include "asm-syntax.h"
32
33#define res_ptr a1
34#define s_ptr a0
35#define s_size d6
36#define cnt d4
37
38	TEXT
39ENTRY(__mpn_lshift)
40
41/* Save used registers on the stack.  */
42	moveml	R(d2)-R(d6)/R(a2),MEM_PREDEC(sp)
43
44/* Copy the arguments to registers.  */
45	movel	MEM_DISP(sp,28),R(res_ptr)
46	movel	MEM_DISP(sp,32),R(s_ptr)
47	movel	MEM_DISP(sp,36),R(s_size)
48	movel	MEM_DISP(sp,40),R(cnt)
49
50	moveql	#1,R(d5)
51	cmpl	R(d5),R(cnt)
52	bne	L(Lnormal)
53	cmpl	R(s_ptr),R(res_ptr)
54	bls	L(Lspecial)		/* jump if s_ptr >= res_ptr */
55#if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
56	lea	MEM_INDX1(s_ptr,s_size,l,4),R(a2)
57#else /* not mc68020 */
58	movel	R(s_size),R(d0)
59	asll	#2,R(d0)
60	lea	MEM_INDX(s_ptr,d0,l),R(a2)
61#endif
62	cmpl	R(res_ptr),R(a2)
63	bls	L(Lspecial)		/* jump if res_ptr >= s_ptr + s_size */
64
65L(Lnormal:)
66	moveql	#32,R(d5)
67	subl	R(cnt),R(d5)
68
69#if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
70	lea	MEM_INDX1(s_ptr,s_size,l,4),R(s_ptr)
71	lea	MEM_INDX1(res_ptr,s_size,l,4),R(res_ptr)
72#else /* not mc68000 */
73	movel	R(s_size),R(d0)
74	asll	#2,R(d0)
75	addl	R(s_size),R(s_ptr)
76	addl	R(s_size),R(res_ptr)
77#endif
78	movel	MEM_PREDEC(s_ptr),R(d2)
79	movel	R(d2),R(d0)
80	lsrl	R(d5),R(d0)		/* compute carry limb */
81
82	lsll	R(cnt),R(d2)
83	movel	R(d2),R(d1)
84	subql	#1,R(s_size)
85	beq	L(Lend)
86	lsrl	#1,R(s_size)
87	bcs	L(L1)
88	subql	#1,R(s_size)
89
90L(Loop:)
91	movel	MEM_PREDEC(s_ptr),R(d2)
92	movel	R(d2),R(d3)
93	lsrl	R(d5),R(d3)
94	orl	R(d3),R(d1)
95	movel	R(d1),MEM_PREDEC(res_ptr)
96	lsll	R(cnt),R(d2)
97L(L1:)
98	movel	MEM_PREDEC(s_ptr),R(d1)
99	movel	R(d1),R(d3)
100	lsrl	R(d5),R(d3)
101	orl	R(d3),R(d2)
102	movel	R(d2),MEM_PREDEC(res_ptr)
103	lsll	R(cnt),R(d1)
104
105	dbf	R(s_size),L(Loop)
106	subl	#0x10000,R(s_size)
107	bcc	L(Loop)
108
109L(Lend:)
110	movel	R(d1),MEM_PREDEC(res_ptr) /* store least significant limb */
111
112/* Restore used registers from stack frame.  */
113	moveml	MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
114	rts
115
116/* We loop from least significant end of the arrays, which is only
117   permissible if the source and destination don't overlap, since the
118   function is documented to work for overlapping source and destination.  */
119
120L(Lspecial:)
121	clrl	R(d0)			/* initialize carry */
122	eorw	#1,R(s_size)
123	lsrl	#1,R(s_size)
124	bcc	L(LL1)
125	subql	#1,R(s_size)
126
127L(LLoop:)
128	movel	MEM_POSTINC(s_ptr),R(d2)
129	addxl	R(d2),R(d2)
130	movel	R(d2),MEM_POSTINC(res_ptr)
131L(LL1:)
132	movel	MEM_POSTINC(s_ptr),R(d2)
133	addxl	R(d2),R(d2)
134	movel	R(d2),MEM_POSTINC(res_ptr)
135
136	dbf	R(s_size),L(LLoop)
137	addxl	R(d0),R(d0)		/* save cy in lsb */
138	subl	#0x10000,R(s_size)
139	bcs	L(LLend)
140	lsrl	#1,R(d0)		/* restore cy */
141	bra	L(LLoop)
142
143L(LLend:)
144/* Restore used registers from stack frame.  */
145	moveml	MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
146	rts
147END(__mpn_lshift)
148