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1 | # _strnlen() Author: Kees J. Bot 1 Jan 1994 |
1 | /* _strnlen() Author: Kees J. Bot */ |
- | 2 | /* 1 Jan 1994 */ |
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2 | 3 | ||
3 | # size_t _strnlen(const char *s, size_t ecx) |
4 | /* size_t _strnlen(const char *s, size_t ecx) */ |
- | 5 | /* Return the length of a string. */ |
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- | 6 | /* */ |
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4 | # Return the length of a string. |
- | |
5 | - | ||
6 | .intel_syntax |
7 | #include "asm.h" |
7 | - | ||
8 | .globl __strnlen |
- | |
9 | - | ||
10 | .text |
8 | |
11 | .align 16 |
- | |
12 | __strnlen: |
9 | ENTRY(_strnlen) |
13 | push ebp |
10 | push %ebp |
14 | mov ebp, esp |
11 | movl %esp, %ebp |
15 | push edi |
12 | push %edi |
16 | mov edi, [ebp+8] # edi = string |
13 | movl 8(%ebp), %edi /* edi = string */ |
17 | xorb al, al # Look for a zero byte |
14 | xorb %al, %al /* Look for a zero byte */ |
18 | mov edx, ecx # Save maximum count |
15 | movl %ecx, %edx /* Save maximum count */ |
19 | cmpb cl, 1 # 'Z' bit must be clear if ecx = 0 |
- | |
- | 16 | cmpb $1, %cl /* 'Z' bit must be clear if ecx = 0 */ |
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20 | cld |
17 | cld |
21 | repne |
18 | |
22 | scasb # Look for zero |
19 | repne scasb /* Look for zero */ |
23 | jne no0 |
20 | jne no0 |
24 | inc ecx # Don't count zero byte |
21 | incl %ecx /* Don't count zero byte */ |
25 | no0: |
22 | no0: |
26 | mov eax, edx |
23 | movl %edx, %eax |
27 | sub eax, ecx # Compute bytes scanned |
24 | subl %ecx, %eax /* Compute bytes scanned */ |
28 | pop edi |
25 | pop %edi |