1 /* mc68020 __gmpn_rshift -- Shift right a low-level natural-number integer.
3 Copyright (C) 1996, 1999, 2000 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 2.1 of the License, or (at your
10 option) any later version.
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20 MA 02111-1307, USA. */
30 #include "asm-syntax.h"
39 GLOBL C_SYMBOL_NAME(__gmpn_rshift)
41 C_SYMBOL_NAME(__gmpn_rshift:)
43 /* Save used registers on the stack. */
44 moveml R(d2)-R(d6)/R(a2),MEM_PREDEC(sp)
46 /* Copy the arguments to registers. */
47 movel MEM_DISP(sp,28),R(res_ptr)
48 movel MEM_DISP(sp,32),R(s_ptr)
49 movel MEM_DISP(sp,36),R(s_size)
50 movel MEM_DISP(sp,40),R(cnt)
55 cmpl R(res_ptr),R(s_ptr)
56 bls L(Lspecial) /* jump if res_ptr >= s_ptr */
57 #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
58 lea MEM_INDX1(res_ptr,s_size,l,4),R(a2)
59 #else /* not mc68020 */
62 lea MEM_INDX(res_ptr,d0,l),R(a2)
65 bls L(Lspecial) /* jump if s_ptr >= res_ptr + s_size */
70 movel MEM_POSTINC(s_ptr),R(d2)
72 lsll R(d5),R(d0) /* compute carry limb */
83 movel MEM_POSTINC(s_ptr),R(d2)
87 movel R(d1),MEM_POSTINC(res_ptr)
90 movel MEM_POSTINC(s_ptr),R(d1)
94 movel R(d2),MEM_POSTINC(res_ptr)
98 subl #0x10000,R(s_size)
102 movel R(d1),MEM(res_ptr) /* store most significant limb */
104 /* Restore used registers from stack frame. */
105 moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
108 /* We loop from most significant end of the arrays, which is only
109 permissable if the source and destination don't overlap, since the
110 function is documented to work for overlapping source and destination. */
113 #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
114 lea MEM_INDX1(s_ptr,s_size,l,4),R(s_ptr)
115 lea MEM_INDX1(res_ptr,s_size,l,4),R(res_ptr)
116 #else /* not mc68000 */
117 movel R(s_size),R(d0)
119 addl R(s_size),R(s_ptr)
120 addl R(s_size),R(res_ptr)
123 clrl R(d0) /* initialize carry */
130 movel MEM_PREDEC(s_ptr),R(d2)
132 movel R(d2),MEM_PREDEC(res_ptr)
134 movel MEM_PREDEC(s_ptr),R(d2)
136 movel R(d2),MEM_PREDEC(res_ptr)
138 dbf R(s_size),L(LLoop)
139 roxrl #1,R(d0) /* save cy in msb */
140 subl #0x10000,R(s_size)
142 addl R(d0),R(d0) /* restore cy */
146 /* Restore used registers from stack frame. */
147 moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
149 EPILOG(__gmpn_rshift)