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authorDenis Vlasenko <vda.linux@googlemail.com>2008-12-20 01:34:52 +0000
committerDenis Vlasenko <vda.linux@googlemail.com>2008-12-20 01:34:52 +0000
commitbd7510cc6b7ea453c1bc1c12949174f6324a6bdc (patch)
tree60cc6c9ef264264b208b3b70a7a2f54fc986fde4 /libc/string/i386/strncpy.c
parenta0da3cfbbff226c7792be30e2bb277386e7cd086 (diff)
string/i386/strncpy: faster i386 version (same code size), testing code
string/i386/*: formatiing and commentary tidying up
Diffstat (limited to 'libc/string/i386/strncpy.c')
-rw-r--r--libc/string/i386/strncpy.c55
1 files changed, 37 insertions, 18 deletions
diff --git a/libc/string/i386/strncpy.c b/libc/string/i386/strncpy.c
index 76aa6ae1b..ba0c41063 100644
--- a/libc/string/i386/strncpy.c
+++ b/libc/string/i386/strncpy.c
@@ -32,25 +32,44 @@
#include <string.h>
-/* Experimentally off - libc_hidden_proto(strncpy) */
+#undef strncpy
+//#define strncpy TESTING
char *strncpy(char * dest, const char * src, size_t count)
{
- int d0, d1, d2, d3;
- __asm__ __volatile__(
- "incl %2\n"
- "1:\n"
- "decl %2\n"
- "jz 2f\n"
- "lodsb\n\t"
- "stosb\n\t"
- "testb %%al,%%al\n\t"
- "jne 1b\n\t"
- "decl %2\n"
- "rep\n\t"
- "stosb\n"
- "2:"
- : "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3)
- :"0" (src),"1" (dest),"2" (count) : "memory");
- return dest;
+ int esi, edi, ecx, eax;
+ __asm__ __volatile__(
+ "1: subl $1, %%ecx\n" /* not dec! it doesnt set CF */
+ " jc 2f\n"
+ " lodsb\n"
+ " stosb\n"
+ " testb %%al, %%al\n"
+ " jnz 1b\n"
+ " rep; stosb\n"
+ "2:\n"
+ : "=&S" (esi), "=&D" (edi), "=&c" (ecx), "=&a" (eax)
+ : "0" (src), "1" (dest), "2" (count)
+ : "memory"
+ );
+ return dest;
}
+#ifndef strncpy
libc_hidden_def(strncpy)
+#else
+/* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os strncpy.c -o strncpy
+ * and run ./strncpy
+ */
+int main()
+{
+ static char str[99];
+
+ str[3] = '*'; str[4] = 0; strncpy(str, "abc", 3);
+ printf(strcmp(str, "abc*") == 0 ? "ok\n" : "BAD!\n");
+
+ str[4] = '*'; str[5] = '+'; strncpy(str, "abc", 5);
+ printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
+ "ok\n" : "BAD!\n");
+ strncpy(str, "abc", 0); /* should do nothing */
+ printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
+ "ok\n" : "BAD!\n");
+}
+#endif