paw: spkg: Add more string functions

Signed-off-by: Chloe M. <chloe@mensia.org>

paw/spkg/head/string.h

@@ -22,4 +22,35 @@
  */
 LONG RtlMemCmp(const VOID *Buffer1, const VOID *Buffer2, USIZE Length);
 
+/*
+ * Obtain the length in bytes of a '\0' terminated string
+ *
+ * @String: String to obtain length from
+ *
+ * Returns zero on failure
+ */
+USIZE RtlStrLen(const CHAR *String);
+
+/*
+ * Fill n bytes of a buffer with a value
+ *
+ * @Buffer:     Pointer to buffer to fill
+ * @SetValue:   Value to fill with
+ * @Length:     Number of bytes to fill
+ *
+ * Returns @Buffer on success, otherwise NULL on failure
+ */
+VOID *RtlMemSet(VOID *Buffer, LONG SetValue, USIZE Length);
+
+/*
+ * Copy n bytes of one buffer to another
+ *
+ * @Dest: Destination buffer
+ * @Soruce: Source buffer
+ * @Length: Length of buffers
+ *
+ * Returns @Dest on suucess, otherwise NULL on failure
+ */
+VOID *RtlMemCpy(VOID *Dest, const VOID *Source, USIZE Length);
+
 #endif  /* !_SPKG_STRING_H_ */

paw/spkg/lib/memcpy.c

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: RtlMemCpy() implementation
+ * Author:      Chloe M.
+ */
+
+#include <string.h>
+
+VOID *
+RtlMemCpy(VOID *Dest, const VOID *Source, USIZE Length)
+{
+    if (Dest == NULL || Source == NULL) {
+        return NULL;
+    }
+
+    for (USIZE Idx = 0; Idx < Length; ++Idx) {
+        ((UCHAR *)Dest)[Idx] = ((UCHAR *)Source)[Idx];
+    }
+
+    return Dest;
+}

paw/spkg/lib/memset.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: RtlMemSet() implementation
+ * Author:      Chloe M.
+ */
+
+#include <string.h>
+
+#ifndef __x86_64__
+#error "64-bit only"
+#else
+#define WORD_SHIFT 3
+#endif  /* !__x86_64__ */
+
+VOID *
+RtlMemSet(VOID *Buffer, LONG SetValue, USIZE Length)
+{
+    USIZE WordCount;
+    USIZE *WordBuffer;
+    CHAR *ByteBuffer = (CHAR *)Buffer;
+    USIZE Index;
+
+    if (Buffer == NULL || Length == 0) {
+        return NULL;
+    }
+
+    /* How many words can this fit? */
+    WordCount = Length / sizeof(USIZE);
+    WordBuffer = (USIZE *)Buffer;
+
+    /* Fill as many words as we can */
+    for (Index = 0; Index < WordCount; ++Index) {
+        WordBuffer[Index] = SetValue;
+    }
+
+    /* Fill the rest */
+    Index <<= WORD_SHIFT;
+    for (; Index < Length; ++Index) {
+        ByteBuffer[Index] = SetValue;
+    }
+
+    return Buffer;
+}

paw/spkg/lib/strlen.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: RtlStrLen() implementation
+ * Author:      Chloe M.
+ */
+
+#include <string.h>
+
+USIZE
+RtlStrLen(const CHAR *String)
+{
+    USIZE Length = 0;
+
+    if (String == NULL) {
+        return 0;
+    }
+
+    while (String[Length++] != '\0')
+        ;
+
+    return Length;
+}