223 lines
2.7 KiB
Plaintext
223 lines
2.7 KiB
Plaintext
; The OS/K Team licenses this file to you under the MIT license.
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; See the LICENSE file in the project root for more information.
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;
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; int strnlen(char *, int)
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;
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strnlen:
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mov ecx, ax1
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scasb ax0, zero
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sub eax, ax1, ecx
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ret
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;
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; int strlen(char *)
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;
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strlen:
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mov ecx, STRLEN_MAX
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mov edx, ecx
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scasb ax0, zero
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sub eax, edx, ecx
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ret
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;
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; void strcpy(char *, const char *)
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;
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strcpy:
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.l:
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mov ecx, b[ax1]
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mov b[ax0], ecx
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jrcxz .r
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inc ax0
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inc ax1
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jmp .l
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.r:
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ret
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;
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; void strncpy(char *, const char *, int)
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;
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strncpy:
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mov ecx, ax2
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jrcxz .r
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.l:
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mov b[ax0], b[ax1]
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inc ax0
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inc ax1
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loop .l
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.r:
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ret
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;
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; void strnzcpy(char *, const char *, int)
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;
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strnzcpy:
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mov ecx, ax2
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jrcxz .r
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.l:
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mov eax, b[ax1]
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mov b[ax0], eax
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jraxz .r
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inc ax0
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inc ax1
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loop .l
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.z:
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nul b[ax0]
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.r:
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ret
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;
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; int strcmp(const char *str1, const char *str2)
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;
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; Returns:
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; 0 if the contents of both strings are equal
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; >0 if the first character that does not match has a greater value in str1 than in str2
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; <0 if the first character that does not match has a lower value in str1 than in str2
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;
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strcmp:
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nul esi
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.l:
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movzx eax, b[ax0+esi]
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movzx edx, b[ax1+esi]
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bne eax, edx, .r
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; both zero?
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add ecx, eax, edx
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jrcxz .r
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inc esi
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jmp .l
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.r:
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sub eax, edx
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ret
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;
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; int strncmp(const char *str1, const char *str2, int maxn)
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;
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strncmp:
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mov ecx, ax2
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jrcxz .r
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.l:
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movzx eax, b[ax0]
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movzx edx, b[ax1]
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bne eax, edx, .r
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inc ax0
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inc ax1
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loop .l
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.r:
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sub eax, edx
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ret
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;
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; char *strchrnul(const char *str, int ch)
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;
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strchrnul:
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mov ecx, STRLEN_MAX
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scasb ax0, ax1
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mov eax, ax0
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ret
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;
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; char *strchr(const char *str, int ch)
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;
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strchr:
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mov ecx, STRLEN_MAX
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scasb ax0, ax1
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bnz b[ax0], .r
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nul eax
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ret
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.r:
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mov eax, ax0
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ret
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;
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; void strrev(char *buf, const char *str)
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;
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; buf and src must NOT overlap
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;
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strrev:
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bzr b[ax1], .z
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; save str's location
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mov esi, ax1
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; go to str's end, just before
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; the null terminator
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mov ecx, STRLEN_MAX
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scasb ax1, zero
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dec ax1
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.l:
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; copy, going backward though str
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; and forward through buf
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mov b[ax0], b[ax1]
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beq ax1, esi, .r
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inc ax0
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dec ax1
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jmp .l
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.r:
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nul b[ax0+1]
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ret
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.z:
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nul b[ax0]
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ret
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;
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; void strrev2(char *str)
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;
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; Inverses str
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;
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strrev2:
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bzr b[ax0], .r
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mov ax1, ax0
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; go to str's end, just before
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; the null terminator
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mov ecx, STRLEN_MAX
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scasb ax1, zero
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dec ax1
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; increase ax0 while decreasing ax1, performing exchanges
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.l:
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blteu ax1, ax0, .r
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xchg b[ax0], b[ax1]
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inc ax0
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dec ax1
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jmp .l
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.r:
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ret
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