1 files changed, 257 insertions, 0 deletions

diff --git a/arch/i386/lib/string.c b/arch/i386/lib/string.c
new file mode 100644
index 000000000000..2c773fefa3dd
--- /dev/null
+++ b/arch/i386/lib/string.c
@@ -0,0 +1,257 @@
+/*
+ * Most of the string-functions are rather heavily hand-optimized,
+ * see especially strsep,strstr,str[c]spn. They should work, but are not
+ * very easy to understand. Everything is done entirely within the register
+ * set, making the functions fast and clean. String instructions have been
+ * used through-out, making for "slightly" unclear code :-)
+ *
+ * AK: On P4 and K7 using non string instruction implementations might be faster
+ * for large memory blocks. But most of them are unlikely to be used on large
+ * strings.
+ */
+
+#include <linux/string.h>
+#include <linux/module.h>
+
+#ifdef __HAVE_ARCH_STRCPY
+char *strcpy(char * dest,const char *src)
+{
+        int d0, d1, d2;
+        asm volatile( "1:\tlodsb\n\t"
+                "stosb\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b"
+                : "=&S" (d0), "=&D" (d1), "=&a" (d2)
+                :"0" (src),"1" (dest) : "memory");
+        return dest;
+}
+EXPORT_SYMBOL(strcpy);
+#endif
+
+#ifdef __HAVE_ARCH_STRNCPY
+char *strncpy(char * dest,const char *src,size_t count)
+{
+        int d0, d1, d2, d3;
+        asm volatile( "1:\tdecl %2\n\t"
+                "js 2f\n\t"
+                "lodsb\n\t"
+                "stosb\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b\n\t"
+                "rep\n\t"
+                "stosb\n"
+                "2:"
+                : "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3)
+                :"0" (src),"1" (dest),"2" (count) : "memory");
+        return dest;
+}
+EXPORT_SYMBOL(strncpy);
+#endif
+
+#ifdef __HAVE_ARCH_STRCAT
+char *strcat(char * dest,const char * src)
+{
+        int d0, d1, d2, d3;
+        asm volatile( "repne\n\t"
+                "scasb\n\t"
+                "decl %1\n"
+                "1:\tlodsb\n\t"
+                "stosb\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b"
+                : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3)
+                : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu): "memory");
+        return dest;
+}
+EXPORT_SYMBOL(strcat);
+#endif
+
+#ifdef __HAVE_ARCH_STRNCAT
+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"
+                "1:\tdecl %3\n\t"
+                "js 2f\n\t"
+                "lodsb\n\t"
+                "stosb\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b\n"
+                "2:\txorl %2,%2\n\t"
+                "stosb"
+                : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3)
+                : "0" (src),"1" (dest),"2" (0),"3" (0xffffffffu), "g" (count)
+                : "memory");
+        return dest;
+}
+EXPORT_SYMBOL(strncat);
+#endif
+
+#ifdef __HAVE_ARCH_STRCMP
+int strcmp(const char * cs,const char * ct)
+{
+        int d0, d1;
+        int res;
+        asm volatile( "1:\tlodsb\n\t"
+                "scasb\n\t"
+                "jne 2f\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b\n\t"
+                "xorl %%eax,%%eax\n\t"
+                "jmp 3f\n"
+                "2:\tsbbl %%eax,%%eax\n\t"
+                "orb $1,%%al\n"
+                "3:"
+                :"=a" (res), "=&S" (d0), "=&D" (d1)
+                :"1" (cs),"2" (ct)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strcmp);
+#endif
+
+#ifdef __HAVE_ARCH_STRNCMP
+int strncmp(const char * cs,const char * ct,size_t count)
+{
+        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)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strncmp);
+#endif
+
+#ifdef __HAVE_ARCH_STRCHR
+char *strchr(const char * s, int c)
+{
+        int d0;
+        char * res;
+        asm volatile( "movb %%al,%%ah\n"
+                "1:\tlodsb\n\t"
+                "cmpb %%ah,%%al\n\t"
+                "je 2f\n\t"
+                "testb %%al,%%al\n\t"
+                "jne 1b\n\t"
+                "movl $1,%1\n"
+                "2:\tmovl %1,%0\n\t"
+                "decl %0"
+                :"=a" (res), "=&S" (d0)
+                :"1" (s),"0" (c)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strchr);
+#endif
+
+#ifdef __HAVE_ARCH_STRRCHR
+char *strrchr(const char * s, int c)
+{
+        int d0, d1;
+        char * res;
+        asm volatile( "movb %%al,%%ah\n"
+                "1:\tlodsb\n\t"
+                "cmpb %%ah,%%al\n\t"
+                "jne 2f\n\t"
+                "leal -1(%%esi),%0\n"
+                "2:\ttestb %%al,%%al\n\t"
+                "jne 1b"
+                :"=g" (res), "=&S" (d0), "=&a" (d1)
+                :"0" (0),"1" (s),"2" (c)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strrchr);
+#endif
+
+#ifdef __HAVE_ARCH_STRLEN
+size_t strlen(const char * s)
+{
+        int d0;
+        int res;
+        asm volatile( "repne\n\t"
+                "scasb\n\t"
+                "notl %0\n\t"
+                "decl %0"
+                :"=c" (res), "=&D" (d0)
+                :"1" (s),"a" (0), "0" (0xffffffffu)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strlen);
+#endif
+
+#ifdef __HAVE_ARCH_MEMCHR
+void *memchr(const void *cs,int c,size_t count)
+{
+        int d0;
+        void *res;
+        if (!count)
+                return NULL;
+        asm volatile( "repne\n\t"
+                "scasb\n\t"
+                "je 1f\n\t"
+                "movl $1,%0\n"
+                "1:\tdecl %0"
+                :"=D" (res), "=&c" (d0)
+                :"a" (c),"0" (cs),"1" (count)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(memchr);
+#endif
+
+#ifdef __HAVE_ARCH_MEMSCAN
+void *memscan(void * addr, int c, size_t size)
+{
+        if (!size)
+                return addr;
+        asm volatile("repnz; scasb\n\t"
+            "jnz 1f\n\t"
+            "dec %%edi\n"
+            "1:"
+            : "=D" (addr), "=c" (size)
+            : "0" (addr), "1" (size), "a" (c)
+            : "memory");
+        return addr;
+}
+EXPORT_SYMBOL(memscan);
+#endif
+
+#ifdef __HAVE_ARCH_STRNLEN
+size_t strnlen(const char *s, size_t count)
+{
+        int d0;
+        int res;
+        asm volatile( "movl %2,%0\n\t"
+                "jmp 2f\n"
+                "1:\tcmpb $0,(%0)\n\t"
+                "je 3f\n\t"
+                "incl %0\n"
+                "2:\tdecl %1\n\t"
+                "cmpl $-1,%1\n\t"
+                "jne 1b\n"
+                "3:\tsubl %2,%0"
+                :"=a" (res), "=&d" (d0)
+                :"c" (s),"1" (count)
+                :"memory");
+        return res;
+}
+EXPORT_SYMBOL(strnlen);
+#endif