[PATCH] 3% tighter packs for free
From: Nicolas Pitre <hidden>
Date: 2016-06-15 22:42:21
Subsystem:
the rest · Maintainer:
Linus Torvalds
This patch makes for 3.4% smaller pack with the git repository, and a bit more than 3% smaller pack with the kernel repository. And so with _no_ measurable CPU difference. Signed-off-by: Nicolas Pitre <redacted> ---
diff --git a/diff-delta.c b/diff-delta.c
index aaee7be..1188b31 100644
--- a/diff-delta.c
+++ b/diff-delta.c@@ -136,7 +136,8 @@ void *diff_delta(void *from_buf, unsigne unsigned long *delta_size, unsigned long max_size) { - unsigned int i, outpos, outsize, inscnt, hash_shift; + unsigned int i, outpos, outsize, hash_shift; + int inscnt; const unsigned char *ref_data, *ref_top, *data, *top; unsigned char *out; struct index *entry, **hash;
@@ -222,6 +223,20 @@ void *diff_delta(void *from_buf, unsigne unsigned char *op; if (inscnt) { + while (moff && ref_data[moff-1] == data[-1]) { + if (msize == 0x10000) + break; + /* we can match one byte back */ + msize++; + moff--; + data--; + outpos--; + if (--inscnt) + continue; + outpos--; /* remove count slot */ + inscnt--; /* make it -1 */ + break; + } out[outpos - inscnt - 1] = inscnt; inscnt = 0; }