util/nvmutil swap(): Only handle the nvm area

The 128-byte nvm area is all that we need to handle,
since that is the only thing we actually work on in
nvmutil, based on checksum verification; the latter
implies that bytes must be in the correct order.

The swap() function previously worked on the entire
block, e.g. 4KB on 8KB files, 8KB on 16KB files and
64KB on 128KB files, and it did this twice, so it would
have operated on anywhere between 8KB to 128KB of data.

It now only operates on 256 bytes at a maximum, or 128
bytes if only handling one block. This is a significant
performance optimisation, on big endian host CPUs.

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/util/nvmutil/nvmutil.c b/util/nvmutil/nvmutil.c
index 8e1fef4f..8350504b 100644
--- a/util/nvmutil/nvmutil.c
+++ b/util/nvmutil/nvmutil.c
@@ -437,6 +437,6 @@ swap(int partnum) /* swaps bytes in words, not pointers. */
 	size_t w, x;
 	uint8_t *n = (uint8_t *) gbe[partnum];
 
-	for (w = nf * ((uint8_t *) &e)[0], x = 1; w < nf; w += 2, x += 2)
+	for (w = nf * ((uint8_t *) &e)[0], x = 1; w < 128; w += 2, x += 2)
 		n[w] ^= n[x], n[x] ^= n[w], n[w] ^= n[x];
 }