ARM: zImage: gather some string functions into string.c

This is a small subset of string functions needed by commits to come.
Except for memcpy() which is unchanged from its original location, their
implementation is meant to be small, and -Os is enforced to prevent gcc
from doing pointless loop unrolling.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Dave Martin <dave.martin@linaro.org>
Tested-by: Thomas Abraham <thomas.abraham@linaro.org>

3 files changed, 132 insertions, 41 deletions

diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index 4867647b9796..c20ddc69d950 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -26,6 +26,10 @@ HEAD	= head.o
 OBJS    += misc.o decompress.o
 FONTC   = $(srctree)/drivers/video/console/font_acorn_8x8.c
 
+# string library code (-Os is enforced to keep it much smaller)
+OBJS            += string.o
+CFLAGS_string.o := -Os
+
 #
 # Architecture dependencies
 #
diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
index 832d37236c59..8e2a8fca5ed2 100644
--- a/arch/arm/boot/compressed/misc.c
+++ b/arch/arm/boot/compressed/misc.c
@@ -18,14 +18,9 @@
 
 unsigned int __machine_arch_type;
 
-#define _LINUX_STRING_H_
-
 #include <linux/compiler.h>     /* for inline */
-#include <linux/types.h>        /* for size_t */
-#include <linux/stddef.h>       /* for NULL */
+#include <linux/types.h>
 #include <linux/linkage.h>
-#include <asm/string.h>
-
 
 static void putstr(const char *ptr);
 extern void error(char *x);
@@ -101,41 +96,6 @@ static void putstr(const char *ptr)
         flush();
 }
 
-
-void *memcpy(void *__dest, __const void *__src, size_t __n)
-{
-        int i = 0;
-        unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;
-
-        for (i = __n >> 3; i > 0; i--) {
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-        }
-
-        if (__n & 1 << 2) {
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-                *d++ = *s++;
-        }
-
-        if (__n & 1 << 1) {
-                *d++ = *s++;
-                *d++ = *s++;
-        }
-
-        if (__n & 1)
-                *d++ = *s++;
-
-        return __dest;
-}
-
 /*
  * gzip declarations
  */
diff --git a/arch/arm/boot/compressed/string.c b/arch/arm/boot/compressed/string.c
new file mode 100644
index 000000000000..36e53ef9200f
--- /dev/null
+++ b/arch/arm/boot/compressed/string.c
@@ -0,0 +1,127 @@
+/*
+ * arch/arm/boot/compressed/string.c
+ *
+ * Small subset of simple string routines
+ */
+
+#include <linux/string.h>
+
+void *memcpy(void *__dest, __const void *__src, size_t __n)
+{
+        int i = 0;
+        unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;
+
+        for (i = __n >> 3; i > 0; i--) {
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+        }
+
+        if (__n & 1 << 2) {
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+                *d++ = *s++;
+        }
+
+        if (__n & 1 << 1) {
+                *d++ = *s++;
+                *d++ = *s++;
+        }
+
+        if (__n & 1)
+                *d++ = *s++;
+
+        return __dest;
+}
+
+void *memmove(void *__dest, __const void *__src, size_t count)
+{
+        unsigned char *d = __dest;
+        const unsigned char *s = __src;
+
+        if (__dest == __src)
+                return __dest;
+
+        if (__dest < __src)
+                return memcpy(__dest, __src, count);
+
+        while (count--)
+                d[count] = s[count];
+        return __dest;
+}
+
+size_t strlen(const char *s)
+{
+        const char *sc = s;
+
+        while (*sc != '\0')
+                sc++;
+        return sc - s;
+}
+
+int memcmp(const void *cs, const void *ct, size_t count)
+{
+        const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
+        int res = 0;
+
+        while (su1 < end) {
+                res = *su1++ - *su2++;
+                if (res)
+                        break;
+        }
+        return res;
+}
+
+int strcmp(const char *cs, const char *ct)
+{
+        unsigned char c1, c2;
+        int res = 0;
+
+        do {
+                c1 = *cs++;
+                c2 = *ct++;
+                res = c1 - c2;
+                if (res)
+                        break;
+        } while (c1);
+        return res;
+}
+
+void *memchr(const void *s, int c, size_t count)
+{
+        const unsigned char *p = s;
+
+        while (count--)
+                if ((unsigned char)c == *p++)
+                        return (void *)(p - 1);
+        return NULL;
+}
+
+char *strchr(const char *s, int c)
+{
+        while (*s != (char)c)
+                if (*s++ == '\0')
+                        return NULL;
+        return (char *)s;
+}
+
+#undef memset
+
+void *memset(void *s, int c, size_t count)
+{
+        char *xs = s;
+        while (count--)
+                *xs++ = c;
+        return s;
+}
+
+void __memzero(void *s, size_t count)
+{
+        memset(s, 0, count);
+}