kolibrios-gitea/drivers/ddk/string/_strncat.S

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/* _strncat() Author: Kees J. Bot */
/* 1 Jan 1994 */
/* char *_strncat(char *s1, const char *s2, size_t edx) */
/* Append string s2 to s1. */
/* */
#include "asm.h"
ENTRY(_strncat)
push %ebp
movl %esp, %ebp
push %esi
push %edi
movl 8(%ebp), %edi /* String s1 */
movl $-1, %ecx
xorb %al, %al /* Null byte */
cld
repne scasb /* Look for the zero byte in s1 */
decl %edi /* Back one up (and clear 'Z' flag) */
push %edi /* Save end of s1 */
movl 12(%ebp), %edi /* edi = string s2 */
movl %edx, %ecx /* Maximum count */
repne scasb /* Look for the end of s2 */
jne no0
incl %ecx /* Exclude null byte */
no0:
subl %ecx, %edx /* Number of bytes in s2 */
movl %edx, %ecx
movl 12(%ebp), %esi /* esi = string s2 */
pop %edi /* edi = end of string s1 */
rep movsb /* Copy bytes */
stosb /* Add a terminating null */
movl 8(%ebp), %eax /* Return s1 */
pop %edi
pop %esi
pop %ebp
ret