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gerrit-public.fairphone.software / kernel / msm-4.19 / 71b2ccc3a2fd6c27e3cd9b4239670005978e94ce / . / arch / x86_64 / lib / memset.S
blob: ad397f2c7de8fa7c73185793ba973bdfaed39b0b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/* Copyright 2002 Andi Kleen, SuSE Labs */
2/*
3 * ISO C memset - set a memory block to a byte value.
4 *
5 * rdi destination
6 * rsi value (char)
7 * rdx count (bytes)
8 *
9 * rax original destination
10 */
11 .globl __memset
12 .globl memset
13 .p2align 4
14memset:
15__memset:
Andi Kleen7bcd3f32006-02-03 21:51:02 +0100[diff] [blame]16 movq %rdi,%r10
17 movq %rdx,%r11
18
19 /* expand byte value */
20 movzbl %sil,%ecx
21 movabs $0x0101010101010101,%rax
22 mul %rcx /* with rax, clobbers rdx */
23
24 /* align dst */
25 movl %edi,%r9d
26 andl $7,%r9d
27 jnz .Lbad_alignment
28.Lafter_bad_alignment:
29
30 movl %r11d,%ecx
31 shrl $6,%ecx
32 jz .Lhandle_tail
33
34 .p2align 4
35.Lloop_64:
36 decl %ecx
37 movq %rax,(%rdi)
38 movq %rax,8(%rdi)
39 movq %rax,16(%rdi)
40 movq %rax,24(%rdi)
41 movq %rax,32(%rdi)
42 movq %rax,40(%rdi)
43 movq %rax,48(%rdi)
44 movq %rax,56(%rdi)
45 leaq 64(%rdi),%rdi
46 jnz .Lloop_64
47
48 /* Handle tail in loops. The loops should be faster than hard
49 to predict jump tables. */
50 .p2align 4
51.Lhandle_tail:
52 movl %r11d,%ecx
53 andl $63&(~7),%ecx
54 jz .Lhandle_7
55 shrl $3,%ecx
56 .p2align 4
57.Lloop_8:
58 decl %ecx
59 movq %rax,(%rdi)
60 leaq 8(%rdi),%rdi
61 jnz .Lloop_8
62
63.Lhandle_7:
64 movl %r11d,%ecx
65 andl $7,%ecx
66 jz .Lende
67 .p2align 4
68.Lloop_1:
69 decl %ecx
70 movb %al,(%rdi)
71 leaq 1(%rdi),%rdi
72 jnz .Lloop_1
73
74.Lende:
75 movq %r10,%rax
76 ret
77
78.Lbad_alignment:
79 cmpq $7,%r11
80 jbe .Lhandle_7
81 movq %rax,(%rdi) /* unaligned store */
82 movq $8,%r8
83 subq %r9,%r8
84 addq %r8,%rdi
85 subq %r8,%r11
86 jmp .Lafter_bad_alignment
87
88 /* Some CPUs run faster using the string instructions.
89 It is also a lot simpler. Use this when possible */
90
91#include <asm/cpufeature.h>
92
93 .section .altinstructions,"a"
94 .align 8
95 .quad memset
96 .quad memset_c
97 .byte X86_FEATURE_REP_GOOD
98 .byte memset_c_end-memset_c
99 .byte memset_c_end-memset_c
100 .previous
101
102 .section .altinstr_replacement,"ax"
103 /* rdi destination
104 * rsi value
105 * rdx count
106 */
107memset_c:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]108 movq %rdi,%r9
109 movl %edx,%r8d
110 andl $7,%r8d
111 movl %edx,%ecx
112 shrl $3,%ecx
113 /* expand byte value */
114 movzbl %sil,%esi
115 movabs $0x0101010101010101,%rax
116 mulq %rsi /* with rax, clobbers rdx */
117 rep
118 stosq
119 movl %r8d,%ecx
120 rep
121 stosb
122 movq %r9,%rax
123 ret
Andi Kleen7bcd3f32006-02-03 21:51:02 +0100[diff] [blame]124memset_c_end:
125 .previous