Mercurial > hg > openttd
changeset 5663:613ac0e6c3c4 draft
(svn r8123) -Fix (r117): FindFirstBit now really returns the first bit. Fixes bug FS#538.
author | maedhros <maedhros@openttd.org> |
---|---|
date | Sun, 14 Jan 2007 19:06:11 +0000 |
parents | 4548b7616c70 |
children | 6e382104fb68 |
files | src/misc.cpp |
diffstat | 1 files changed, 11 insertions(+), 9 deletions(-) [+] |
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line diff
--- a/src/misc.cpp +++ b/src/misc.cpp @@ -266,16 +266,18 @@ int FindFirstBit(uint32 value) { - // This is much faster than the one that was before here. - // Created by Darkvater.. blame him if it is wrong ;) - // Btw, the macro FINDFIRSTBIT is better to use when your value is - // not more than 128. + // The macro FIND_FIRST_BIT is better to use when your value is + // not more than 128. byte i = 0; - if (value & 0xffff0000) { value >>= 16; i += 16; } - if (value & 0x0000ff00) { value >>= 8; i += 8; } - if (value & 0x000000f0) { value >>= 4; i += 4; } - if (value & 0x0000000c) { value >>= 2; i += 2; } - if (value & 0x00000002) { i += 1; } + + if (value == 0) return 0; + + if ((value & 0x0000ffff) == 0) { value >>= 16; i += 16; } + if ((value & 0x000000ff) == 0) { value >>= 8; i += 8; } + if ((value & 0x0000000f) == 0) { value >>= 4; i += 4; } + if ((value & 0x00000003) == 0) { value >>= 2; i += 2; } + if ((value & 0x00000001) == 0) { i += 1; } + return i; }