From b84e3d0f20e81199fa4c7cc736689e2651c99107 Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <yobibe@gmail.com>
Date: Wed, 2 May 2012 10:02:56 +0000
Subject: [PATCH] nfc-utils: smaller oddparity code
---
utils/nfc-utils.c | 22 ++--------------------
1 file changed, 2 insertions(+), 20 deletions(-)
diff --git a/utils/nfc-utils.c b/utils/nfc-utils.c
index 9278f05..ce72465 100644
--- a/utils/nfc-utils.c
+++ b/utils/nfc-utils.c
@@ -36,29 +36,11 @@
#include "nfc-utils.h"
-static const uint8_t OddParity[256] = {
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
- 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
-};
-
uint8_t
oddparity (const uint8_t bt)
{
- return OddParity[bt];
+ // cf http://graphics.stanford.edu/~seander/bithacks.html#ParityParallel
+ return (0x9669 >> ((bt ^ (bt >> 4)) & 0xF)) & 1;
}
void