- v = ((struct ulong_wrapper *)src)->v;
- ((struct ulong_wrapper *)dst)->v = v;
- dst += sizeof(unsigned long);
- src += sizeof(unsigned long);
-
- if (dst < end) {
+ if (offset >= WORDSIZE) {
+ /* The source and destination words don't overlap. */
+
+ /* To improve branch prediction, one iteration of this
+ * loop is unrolled. Most matches are short and will
+ * fail the first check. But if that check passes, then
+ * it becomes increasing likely that the match is long
+ * and we'll need to continue copying. */
+
+ copy_word_unaligned(src, dst);
+ src += WORDSIZE;
+ dst += WORDSIZE;
+
+ if (dst < end) {
+ do {
+ copy_word_unaligned(src, dst);
+ src += WORDSIZE;
+ dst += WORDSIZE;
+ } while (dst < end);
+ }
+ return;
+ } else if (offset == 1) {
+
+ /* Offset 1 matches are equivalent to run-length
+ * encoding of the previous byte. This case is common
+ * if the data contains many repeated bytes. */
+
+ machine_word_t v = repeat_byte(*(dst - 1));