feat(libc): add freestanding types and string helpers

src/string.c

@@ -0,0 +1,69 @@
+#include "string.h"
+
+void* memset(void* dest, int value, usize count)
+{
+    uint8* target = (uint8*)dest;
+    for (usize i = 0; i < count; i++)
+        target[i] = (uint8)value;
+    return dest;
+}
+
+void* memcpy(void* dest, const void* src, usize count)
+{
+    uint8* target = (uint8*)dest;
+    const uint8* source = (const uint8*)src;
+    for (usize i = 0; i < count; i++)
+        target[i] = source[i];
+    return dest;
+}
+
+void* memmove(void* dest, const void* src, usize count)
+{
+    uint8* target = (uint8*)dest;
+    const uint8* source = (const uint8*)src;
+    if (target < source) {
+        for (usize i = 0; i < count; i++)
+            target[i] = source[i];
+    } else {
+        for (usize i = count; i > 0; i--)
+            target[i - 1] = source[i - 1];
+    }
+    return dest;
+}
+
+int memcmp(const void* a, const void* b, usize count)
+{
+    const uint8* left = (const uint8*)a;
+    const uint8* right = (const uint8*)b;
+    for (usize i = 0; i < count; i++) {
+        if (left[i] != right[i])
+            return (int)left[i] - (int)right[i];
+    }
+    return 0;
+}
+
+usize strlen(const char* str)
+{
+    usize length = 0;
+    while (str[length])
+        length++;
+    return length;
+}
+
+int strcmp(const char* a, const char* b)
+{
+    while (*a && (*a == *b)) {
+        a++;
+        b++;
+    }
+    return (int)(uint8)*a - (int)(uint8)*b;
+}
+
+int strncmp(const char* a, const char* b, usize count)
+{
+    for (usize i = 0; i < count; i++) {
+        if (a[i] != b[i] || a[i] == 0)
+            return (int)(uint8)a[i] - (int)(uint8)b[i];
+    }
+    return 0;
+}