1 files changed, 143 insertions, 0 deletions
diff --git a/src/string.c b/src/string.c
new file mode 100644
index 0000000..210b2bc
--- /dev/null
+++ b/src/string.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stddef.h>
+#include <string.h>
+
+#include <lib/macros.h>
+
+void *
+memcpy(void *dest, const void *src, size_t n)
+{
+    const char *src_ptr;
+    char *dest_ptr;
+    size_t i;
+
+    dest_ptr = dest;
+    src_ptr = src;
+
+    for (i = 0; i < n; i++) {
+        *dest_ptr = *src_ptr;
+        dest_ptr++;
+        src_ptr++;
+    }
+
+    return dest;
+}
+
+void *
+memmove(void *dest, const void *src, size_t n)
+{
+    const char *src_ptr;
+    char *dest_ptr;
+    size_t i;
+
+    if (dest <= src) {
+        dest_ptr = dest;
+        src_ptr = src;
+
+        for (i = 0; i < n; i++) {
+            *dest_ptr = *src_ptr;
+            dest_ptr++;
+            src_ptr++;
+        }
+    } else {
+        dest_ptr = dest + n - 1;
+        src_ptr = src + n - 1;
+
+        for (i = 0; i < n; i++) {
+            *dest_ptr = *src_ptr;
+            dest_ptr--;
+            src_ptr--;
+        }
+    }
+
+    return dest;
+}
+
+char *
+strcpy(char *dest, const char *src)
+{
+    char *tmp;
+
+    tmp = dest;
+
+    while ((*dest = *src) != '\0') {
+        dest++;
+        src++;
+    }
+
+    return tmp;
+}
+
+size_t
+strlen(const char *s)
+{
+    const char *start;
+
+    start = s;
+
+    while (*s != '\0') {
+        s++;
+    }
+
+    return (s - start);
+}
+
+int
+strcmp(const char *s1, const char *s2)
+{
+    char c1, c2;
+
+    while ((c1 = *s1) == (c2 = *s2)) {
+        if (c1 == '\0') {
+            return 0;
+        }
+
+        s1++;
+        s2++;
+    }
+
+    return (int)c1 - (int)c2;
+}
+
+int
+strncmp(const char *s1, const char *s2, size_t n)
+{
+    char c1, c2;
+
+    if (unlikely(n == 0)) {
+        return 0;
+    }
+
+    while ((n != 0) && (c1 = *s1) == (c2 = *s2)) {
+        if (c1 == '\0') {
+            return 0;
+        }
+
+        n--;
+        s1++;
+        s2++;
+    }
+
+    return (int)c1 - (int)c2;
+}