blob: 31cdd118e9186cbb947d06207588a261ed0a6adc [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001 .file "shr_Xsig.S"
2/*---------------------------------------------------------------------------+
3 | shr_Xsig.S |
4 | |
5 | 12 byte right shift function |
6 | |
7 | Copyright (C) 1992,1994,1995 |
8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
9 | Australia. E-mail billm@jacobi.maths.monash.edu.au |
10 | |
11 | Call from C as: |
12 | void shr_Xsig(Xsig *arg, unsigned nr) |
13 | |
14 | Extended shift right function. |
15 | Fastest for small shifts. |
16 | Shifts the 12 byte quantity pointed to by the first arg (arg) |
17 | right by the number of bits specified by the second arg (nr). |
18 | |
19 +---------------------------------------------------------------------------*/
20
21#include "fpu_emu.h"
22
23.text
24ENTRY(shr_Xsig)
25 push %ebp
26 movl %esp,%ebp
27 pushl %esi
28 movl PARAM2,%ecx
29 movl PARAM1,%esi
30 cmpl $32,%ecx /* shrd only works for 0..31 bits */
31 jnc L_more_than_31
32
33/* less than 32 bits */
34 pushl %ebx
35 movl (%esi),%eax /* lsl */
36 movl 4(%esi),%ebx /* midl */
37 movl 8(%esi),%edx /* msl */
38 shrd %cl,%ebx,%eax
39 shrd %cl,%edx,%ebx
40 shr %cl,%edx
41 movl %eax,(%esi)
42 movl %ebx,4(%esi)
43 movl %edx,8(%esi)
44 popl %ebx
45 popl %esi
46 leave
47 ret
48
49L_more_than_31:
50 cmpl $64,%ecx
51 jnc L_more_than_63
52
53 subb $32,%cl
54 movl 4(%esi),%eax /* midl */
55 movl 8(%esi),%edx /* msl */
56 shrd %cl,%edx,%eax
57 shr %cl,%edx
58 movl %eax,(%esi)
59 movl %edx,4(%esi)
60 movl $0,8(%esi)
61 popl %esi
62 leave
63 ret
64
65L_more_than_63:
66 cmpl $96,%ecx
67 jnc L_more_than_95
68
69 subb $64,%cl
70 movl 8(%esi),%eax /* msl */
71 shr %cl,%eax
72 xorl %edx,%edx
73 movl %eax,(%esi)
74 movl %edx,4(%esi)
75 movl %edx,8(%esi)
76 popl %esi
77 leave
78 ret
79
80L_more_than_95:
81 xorl %eax,%eax
82 movl %eax,(%esi)
83 movl %eax,4(%esi)
84 movl %eax,8(%esi)
85 popl %esi
86 leave
87 ret