[libc] Reduce overall code size by externalising strncmp()

Typical saving is 20-30 bytes in each file using strncmp().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/x86/core/x86_string.c b/src/arch/x86/core/x86_string.c
index 59e0eaae1523840e0b14bb287f90981d9cfcb59e..962a7d84df766ba51dfaaafb4a9ae64ddaafd595 100644 (file)
--- a/src/arch/x86/core/x86_string.c
+++ b/src/arch/x86/core/x86_string.c
@@ -104,3 +104,41 @@ void * __memmove ( void *dest, const void *src, size_t len ) {
                return __memcpy_reverse ( dest, src, len );
        }
 }
+
+/**
+ * Compare strings (up to a specified length)
+ *
+ * @v str1             First string
+ * @v str2             Second string
+ * @v len              Maximum length
+ * @ret diff           Difference
+ */
+int strncmp ( const char *str1, const char *str2, size_t len ) {
+       const void *discard_S;
+       const void *discard_D;
+       size_t discard_c;
+       int diff;
+
+       __asm__ __volatile__ ( "\n1:\n\t"
+                              "dec %2\n\t"
+                              "js 2f\n\t"
+                              "lodsb\n\t"
+                              "scasb\n\t"
+                              "jne 3f\n\t"
+                              "testb %b3, %b3\n\t"
+                              "jnz 1b\n\t"
+                              /* Equal */
+                              "\n2:\n\t"
+                              "xor %3, %3\n\t"
+                              "jmp 4f\n\t"
+                              /* Not equal; CF indicates difference */
+                              "\n3:\n\t"
+                              "sbb %3, %3\n\t"
+                              "orb $1, %b3\n\t"
+                              "\n4:\n\t"
+                              : "=&S" ( discard_S ), "=&D" ( discard_D ),
+                                "=&c" ( discard_c ), "=&a" ( diff )
+                              : "0" ( str1 ), "1" ( str2 ), "2" ( len ) );
+
+       return diff;
+}

diff --git a/src/arch/x86/include/bits/string.h b/src/arch/x86/include/bits/string.h
index 5736295ab42f738e3ede990f5b9b0a2cff8b64aa..75a1f01a88428212d40f2c1bfb9ac5e35e5d3a55 100644 (file)
--- a/src/arch/x86/include/bits/string.h
+++ b/src/arch/x86/include/bits/string.h
@@ -230,27 +230,8 @@ return dest;
 }
 
 #define __HAVE_ARCH_STRNCMP
-static inline int strncmp(const char * cs,const char * ct,size_t count)
-{
-register int __res;
-int d0, d1, d2;
-__asm__ __volatile__(
-       "1:\tdecl %3\n\t"
-       "js 2f\n\t"
-       "lodsb\n\t"
-       "scasb\n\t"
-       "jne 3f\n\t"
-       "testb %%al,%%al\n\t"
-       "jne 1b\n"
-       "2:\txorl %%eax,%%eax\n\t"
-       "jmp 4f\n"
-       "3:\tsbbl %%eax,%%eax\n\t"
-       "orb $1,%%al\n"
-       "4:"
-                    :"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
-                    :"1" (cs),"2" (ct),"3" (count));
-return __res;
-}
+
+extern int strncmp ( const char *str1, const char *str2, size_t len );
 
 #define __HAVE_ARCH_STRLEN
 static inline size_t strlen(const char * s)