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authormaedhros <maedhros@openttd.org>2007-01-14 19:06:11 +0000
committermaedhros <maedhros@openttd.org>2007-01-14 19:06:11 +0000
commitc1364599db5ef7bbf8cf6a17fee2079651c4c355 (patch)
treef7a2ab466d8e492c406f5a6e7e47f73fb2e77c27 /src
parent238ccd26fbfad7889586ce0022acc4529d317df8 (diff)
downloadopenttd-c1364599db5ef7bbf8cf6a17fee2079651c4c355.tar.xz
(svn r8123) -Fix (r117): FindFirstBit now really returns the first bit. Fixes bug FS#538.
Diffstat (limited to 'src')
-rw-r--r--src/misc.cpp20
1 files changed, 11 insertions, 9 deletions
diff --git a/src/misc.cpp b/src/misc.cpp
index 39714bb55..921e267b1 100644
--- a/src/misc.cpp
+++ b/src/misc.cpp
@@ -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;
}