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(svn r11616) -Fix [FS#1526]: sometimes large values could go off the chart.

This commit is contained in:
rubidium 2007-12-10 22:26:24 +00:00
parent ac7c79f039
commit a1dbb10c26
2 changed files with 9 additions and 8 deletions
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15
src/core/bitmath_func.cpp
View File

@ -45,7 +45,7 @@ uint8 FindFirstBit(uint32 x)
}
/**
* Search the last set bit in a 32 bit variable.
* Search the last set bit in a 64 bit variable.
*
* This algorithm is a static implementation of a log
* conguence search algorithm. It checks the second half
@ -55,17 +55,18 @@ uint8 FindFirstBit(uint32 x)
* @param x The value to search
* @return The position of the last bit set
*/
uint8 FindLastBit(uint32 x)
uint8 FindLastBit(uint64 x)
{
if (x == 0) return 0;
uint8 pos = 0;
if ((x & 0xffff0000) != 0) { x >>= 16; pos += 16; }
if ((x & 0x0000ff00) != 0) { x >>= 8; pos += 8; }
if ((x & 0x000000f0) != 0) { x >>= 4; pos += 4; }
if ((x & 0x0000000c) != 0) { x >>= 2; pos += 2; }
if ((x & 0x00000002) != 0) { pos += 1; }
if ((x & 0xffffffff00000000ULL) != 0) { x >>= 32; pos += 32; }
if ((x & 0x00000000ffff0000ULL) != 0) { x >>= 16; pos += 16; }
if ((x & 0x000000000000ff00ULL) != 0) { x >>= 8; pos += 8; }
if ((x & 0x00000000000000f0ULL) != 0) { x >>= 4; pos += 4; }
if ((x & 0x000000000000000cULL) != 0) { x >>= 2; pos += 2; }
if ((x & 0x0000000000000002ULL) != 0) { pos += 1; }
return pos;
}

2
src/core/bitmath_func.hpp
View File

@ -211,7 +211,7 @@ static inline uint8 FindFirstBit2x64(const int value)
}
uint8 FindFirstBit(uint32 x);
uint8 FindLastBit(uint32 x);
uint8 FindLastBit(uint64 x);
/**
* Clear the first bit in an integer.