1/* i80386 __mpn_sub_n -- Add two limb vectors of the same length > 0 and store
2 sum in a third limb vector.
3 Copyright (C) 1992-2024 Free Software Foundation, Inc.
4 This file is part of the GNU MP Library.
5
6 The GNU MP Library is free software; you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or (at your
9 option) any later version.
10
11 The GNU MP Library is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
14 License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with the GNU MP Library; see the file COPYING.LIB. If not,
18 see <https://www.gnu.org/licenses/>. */
19
20#include <sysdep.h>
21#include "asm-syntax.h"
22
23#define PARMS 4+8 /* space for 2 saved regs */
24#define RES PARMS
25#define S1 RES+4
26#define S2 S1+4
27#define SIZE S2+4
28
29 .text
30ENTRY (__mpn_sub_n)
31
32 pushl %edi
33 cfi_adjust_cfa_offset (4)
34 pushl %esi
35 cfi_adjust_cfa_offset (4)
36
37 movl RES(%esp),%edi
38 cfi_rel_offset (edi, 4)
39 movl S1(%esp),%esi
40 cfi_rel_offset (esi, 0)
41 movl S2(%esp),%edx
42 movl SIZE(%esp),%ecx
43 movl %ecx,%eax
44 shrl $3,%ecx /* compute count for unrolled loop */
45 negl %eax
46 andl $7,%eax /* get index where to start loop */
47 jz L(oop) /* necessary special case for 0 */
48 incl %ecx /* adjust loop count */
49 shll $2,%eax /* adjustment for pointers... */
50 subl %eax,%edi /* ... since they are offset ... */
51 subl %eax,%esi /* ... by a constant when we ... */
52 subl %eax,%edx /* ... enter the loop */
53 shrl $2,%eax /* restore previous value */
54#ifdef PIC
55/* Calculate start address in loop for PIC. Due to limitations in some
56 assemblers, Loop-L0-3 cannot be put into the leal */
57 call L(0)
58 cfi_adjust_cfa_offset (4)
59L(0): leal (%eax,%eax,8),%eax
60 addl (%esp),%eax
61 addl $(L(oop)-L(0)-3),%eax
62 addl $4,%esp
63 cfi_adjust_cfa_offset (-4)
64#else
65/* Calculate start address in loop for non-PIC. */
66 leal (L(oop) - 3)(%eax,%eax,8),%eax
67#endif
68 jmp *%eax /* jump into loop */
69 ALIGN (3)
70L(oop): movl (%esi),%eax
71 sbbl (%edx),%eax
72 movl %eax,(%edi)
73 movl 4(%esi),%eax
74 sbbl 4(%edx),%eax
75 movl %eax,4(%edi)
76 movl 8(%esi),%eax
77 sbbl 8(%edx),%eax
78 movl %eax,8(%edi)
79 movl 12(%esi),%eax
80 sbbl 12(%edx),%eax
81 movl %eax,12(%edi)
82 movl 16(%esi),%eax
83 sbbl 16(%edx),%eax
84 movl %eax,16(%edi)
85 movl 20(%esi),%eax
86 sbbl 20(%edx),%eax
87 movl %eax,20(%edi)
88 movl 24(%esi),%eax
89 sbbl 24(%edx),%eax
90 movl %eax,24(%edi)
91 movl 28(%esi),%eax
92 sbbl 28(%edx),%eax
93 movl %eax,28(%edi)
94 leal 32(%edi),%edi
95 leal 32(%esi),%esi
96 leal 32(%edx),%edx
97 decl %ecx
98 jnz L(oop)
99
100 sbbl %eax,%eax
101 negl %eax
102
103 popl %esi
104 cfi_adjust_cfa_offset (-4)
105 cfi_restore (esi)
106 popl %edi
107 cfi_adjust_cfa_offset (-4)
108 cfi_restore (edi)
109
110 ret
111END (__mpn_sub_n)
112

source code of glibc/sysdeps/i386/sub_n.S