From b84e3d0f20e81199fa4c7cc736689e2651c99107 Mon Sep 17 00:00:00 2001 From: Philippe Teuwen 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