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-rw-r--r--kernel/string.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/kernel/string.c b/kernel/string.c
new file mode 100644
index 0000000..d99e612
--- /dev/null
+++ b/kernel/string.c
@@ -0,0 +1,104 @@
+#include "types.h"
+
+void*
+memset(void *dst, int c, uint n)
+{
+ char *cdst = (char *) dst;
+ int i;
+ for(i = 0; i < n; i++){
+ cdst[i] = c;
+ }
+ return dst;
+}
+
+int
+memcmp(const void *v1, const void *v2, uint n)
+{
+ const uchar *s1, *s2;
+
+ s1 = v1;
+ s2 = v2;
+ while(n-- > 0){
+ if(*s1 != *s2)
+ return *s1 - *s2;
+ s1++, s2++;
+ }
+
+ return 0;
+}
+
+void*
+memmove(void *dst, const void *src, uint n)
+{
+ const char *s;
+ char *d;
+
+ s = src;
+ d = dst;
+ if(s < d && s + n > d){
+ s += n;
+ d += n;
+ while(n-- > 0)
+ *--d = *--s;
+ } else
+ while(n-- > 0)
+ *d++ = *s++;
+
+ return dst;
+}
+
+// memcpy exists to placate GCC. Use memmove.
+void*
+memcpy(void *dst, const void *src, uint n)
+{
+ return memmove(dst, src, n);
+}
+
+int
+strncmp(const char *p, const char *q, uint n)
+{
+ while(n > 0 && *p && *p == *q)
+ n--, p++, q++;
+ if(n == 0)
+ return 0;
+ return (uchar)*p - (uchar)*q;
+}
+
+char*
+strncpy(char *s, const char *t, int n)
+{
+ char *os;
+
+ os = s;
+ while(n-- > 0 && (*s++ = *t++) != 0)
+ ;
+ while(n-- > 0)
+ *s++ = 0;
+ return os;
+}
+
+// Like strncpy but guaranteed to NUL-terminate.
+char*
+safestrcpy(char *s, const char *t, int n)
+{
+ char *os;
+
+ os = s;
+ if(n <= 0)
+ return os;
+ while(--n > 0 && (*s++ = *t++) != 0)
+ ;
+ *s = 0;
+ return os;
+}
+
+int
+strlen(const char *s)
+{
+ int n;
+
+ for(n = 0; s[n]; n++)
+ ;
+ return n;
+}
+