1 /* mc68020 __mpn_rshift -- Shift right a low-level natural-number integer.
3 Copyright (C) 1996 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 Library General Public License as published by
9 the Free Software Foundation; either version 2 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 Library General Public
15 License for more details.
17 You should have received a copy of the GNU Library 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. */
31 #include "asm-syntax.h"
40 GLOBL C_SYMBOL_NAME(__mpn_rshift)
42 C_SYMBOL_NAME(__mpn_rshift:)
44 /* Save used registers on the stack. */
45 moveml R(d2)-R(d6)/R(a2),MEM_PREDEC(sp)
47 /* Copy the arguments to registers. */
48 movel MEM_DISP(sp,28),R(res_ptr)
49 movel MEM_DISP(sp,32),R(s_ptr)
50 movel MEM_DISP(sp,36),R(s_size)
51 movel MEM_DISP(sp,40),R(cnt)
56 cmpl R(res_ptr),R(s_ptr)
57 bls L(Lspecial) /* jump if res_ptr >= s_ptr */
58 #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
59 lea MEM_INDX1(res_ptr,s_size,l,4),R(a2)
60 #else /* not mc68020 */
63 lea MEM_INDX(res_ptr,d0,l),R(a2)
66 bls L(Lspecial) /* jump if s_ptr >= res_ptr + s_size */
71 movel MEM_POSTINC(s_ptr),R(d2)
73 lsll R(d5),R(d0) /* compute carry limb */
84 movel MEM_POSTINC(s_ptr),R(d2)
88 movel R(d1),MEM_POSTINC(res_ptr)
91 movel MEM_POSTINC(s_ptr),R(d1)
95 movel R(d2),MEM_POSTINC(res_ptr)
99 subl #0x10000,R(s_size)
103 movel R(d1),MEM(res_ptr) /* store most significant limb */
105 /* Restore used registers from stack frame. */
106 moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
109 /* We loop from most significant end of the arrays, which is only
110 permissible if the source and destination don't overlap, since the
111 function is documented to work for overlapping source and destination. */
114 #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
115 lea MEM_INDX1(s_ptr,s_size,l,4),R(s_ptr)
116 lea MEM_INDX1(res_ptr,s_size,l,4),R(res_ptr)
117 #else /* not mc68000 */
118 movel R(s_size),R(d0)
120 addl R(s_size),R(s_ptr)
121 addl R(s_size),R(res_ptr)
124 clrl R(d0) /* initialize carry */
131 movel MEM_PREDEC(s_ptr),R(d2)
133 movel R(d2),MEM_PREDEC(res_ptr)
135 movel MEM_PREDEC(s_ptr),R(d2)
137 movel R(d2),MEM_PREDEC(res_ptr)
139 dbf R(s_size),L(LLoop)
140 roxrl #1,R(d0) /* save cy in msb */
141 subl #0x10000,R(s_size)
143 addl R(d0),R(d0) /* restore cy */
147 /* Restore used registers from stack frame. */
148 moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)