diff options
Diffstat (limited to 'libc/string/i386/strncat.c')
-rw-r--r-- | libc/string/i386/strncat.c | 73 |
1 files changed, 49 insertions, 24 deletions
diff --git a/libc/string/i386/strncat.c b/libc/string/i386/strncat.c index 3872679d5..640b0d213 100644 --- a/libc/string/i386/strncat.c +++ b/libc/string/i386/strncat.c @@ -32,30 +32,55 @@ #include <string.h> -/* Experimentally off - libc_hidden_proto(strncat) */ -char *strncat(char * dest, - const char * src, size_t count) +#undef strncat +//#define strncat TESTING +char *strncat(char * dest, const char * src, size_t count) { - int d0, d1, d2, d3; - __asm__ __volatile__( - "repne\n\t" - "scasb\n\t" - "decl %1\n\t" - "movl %8,%3\n" - "incl %3\n" - "1:\tdecl %3\n\t" - "jz 2f\n" - "lodsb\n\t" - "stosb\n\t" - "testb %%al,%%al\n\t" - "jne 1b\n" - "jmp 3f\n" - "2:\txorl %2,%2\n\t" - "stosb\n" - "3:" - : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) - : "0" (src),"1" (dest),"2" (0),"3" (0xffffffff), "g" (count) - : "memory"); - return dest; + int esi, edi, eax, ecx, edx; + __asm__ __volatile__( + " xorl %%eax, %%eax\n" + " incl %%edx\n" + " pushl %%edi\n" /* save dest */ + " repne; scasb\n" + " decl %%edi\n" /* edi => NUL in dest */ + /* count-- */ + "1: decl %%edx\n" + /* if count reached 0, store NUL and bail out */ + " movl %%edx, %%eax\n" + " jz 2f\n" + /* else copy a char */ + " lodsb\n" + "2: stosb\n" + " testb %%al, %%al\n" + " jnz 1b\n" + /* end of loop */ + " popl %%eax\n" /* restore dest into eax */ + : "=&S" (esi), "=&D" (edi), "=&a" (eax), "=&c" (ecx), "=&d" (edx) + : "0" (src), "1" (dest), "3" (0xffffffff), "4" (count) + : "memory" + ); + return (char *)eax; } +#ifndef strncat libc_hidden_def(strncat) +#else +/* Uncomment TESTING, gcc -m32 -Os strncat.c -o strncat + * and run ./strncat + */ +int main() +{ + char buf[99]; + + strcpy(buf, "abc"); buf[4] = '*'; strncat(buf, "def", 0); + printf(strcmp(buf, "abc") == 0 && buf[4] == '*' ? "ok\n" : "BAD!\n"); + + strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def", 50); + printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n"); + + strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def", -1); + printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n"); + + strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def123", 3); + printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n"); +} +#endif |