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Diffstat (limited to 'private/crt32/string/i386/strncat.asm')
| -rw-r--r-- | private/crt32/string/i386/strncat.asm | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/private/crt32/string/i386/strncat.asm b/private/crt32/string/i386/strncat.asm new file mode 100644 index 000000000..b6060bb12 --- /dev/null +++ b/private/crt32/string/i386/strncat.asm @@ -0,0 +1,117 @@ + page ,132 + title strncat - append n chars of string1 to string2 +;*** +;strncat.asm - append n chars of string to new string +; +; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved. +; +;Purpose: +; defines strncat() - appends n characters of string onto +; end of other string +; +;Revision History: +; 10-25-83 RN initial version +; 08-05-87 SKS Fixed bug: extra null was stored if n > strlen(back) +; 05-18-88 SJM Add model-independent (large model) ifdef +; 08-04-88 SJM convert to cruntime/ add 32-bit support +; 08-23-88 JCR Minor 386 cleanup +; 10-26-88 JCR General cleanup for 386-only code +; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright. +; 05-10-91 GJF Back to _cdecl, sigh... +; +;******************************************************************************* + + .xlist + include cruntime.inc + .list + +page +;*** +;char *strncat(front, back, count) - append count chars of back onto front +; +;Purpose: +; Appends at most count characters of the string back onto the +; end of front, and ALWAYS terminates with a null character. +; If count is greater than the length of back, the length of back +; is used instead. (Unlike strncpy, this routine does not pad out +; to count characters). +; +; Algorithm: +; char * +; strncat (front, back, count) +; char *front, *back; +; unsigned count; +; { +; char *start = front; +; +; while (*front++) +; ; +; front--; +; while (count--) +; if (!(*front++ = *back++)) +; return(start); +; *front = '\0'; +; return(start); +; } +; +;Entry: +; char *front - string to append onto +; char *back - string to append +; unsigned count - count of max characters to append +; +;Exit: +; returns a pointer to string appended onto (front). +; +;Uses: +; +;Exceptions: +; +;******************************************************************************* + + CODESEG + + public strncat +strncat proc \ + uses edi esi, \ + front:ptr byte, \ + back:ptr byte, \ + count:IWORD + + + mov edi,[front] ; di=pointer to dest + + mov edx,edi ; save return value in dx + xor eax,eax ; search value: null byte (assumed zero below!) + or ecx,-1 ; cx = -1, so won't stop scan +repne scasb ; find null byte + dec edi ; di points to dest null terminator + mov esi,edi ; si " " " " " + + mov edi,[back] ; di points to source + + push edi ; save back pointer + mov ecx,[count] ; cx = count bytes negatively +repne scasb ; find null byte & get source length + jne short nonull + inc ecx ; do NOT count null byte in length +nonull: + ; cx=count of difference in bytes in source + ; with reference (without null) + sub ecx,[count] ; take the difference of bytes counted to expected + neg ecx ; away from expected + mov edi,esi ; di=pointer to dest null terminator + pop esi ; restore pointer to source +rep movsb ; concatenate the strings + ; WARNING: AL must be zero at this point! + stosb ; attach null byte + + mov eax,edx ; return value: dest addr + +ifdef _STDCALL_ + ret 2*DPSIZE + ISIZE ; _stdcall return +else + ret ; _cdecl return +endif + +strncat endp + end |