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(svn r8123) -Fix (r117): FindFirstBit now really returns the first bit. Fixes bug FS#538.

This commit is contained in:
maedhros 2007-01-14 19:06:11 +00:00
parent 04d2d80891
commit d289816deb
1 changed files with 11 additions and 9 deletions
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20
src/misc.cpp
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@ -266,16 +266,18 @@ void InitializeLandscapeVariables(bool only_constants)
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;
}