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Location: cpp/openttd-patchpack/source/src/core/bitmath_func.cpp - annotation
r9583:b6e25a00b908
2.0 KiB
text/x-c
(svn r13621) -Fix: building roadbits in the wrong direction on bridges or building roadbits from underneath the bridge to the bridgehead is impossible, so don't silently ignore that error when building over houses and industries is not ignored.
r7971:5de6852fd5c5 r7971:5de6852fd5c5 r9111:983de9c5a848 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r8000:8bece5ad1135 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r7971:5de6852fd5c5 r8000:8bece5ad1135 r8000:8bece5ad1135 r8055:1270040d620c r8000:8bece5ad1135 r8000:8bece5ad1135 r8005:db909f00ebe3 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8055:1270040d620c r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 r8055:1270040d620c r8055:1270040d620c r8055:1270040d620c r8055:1270040d620c r8055:1270040d620c r8055:1270040d620c r8000:8bece5ad1135 r8000:8bece5ad1135 r8000:8bece5ad1135 | /* $Id$ */
/** @file bitmath_func.cpp Functions related to bit mathematics. */
#include "../stdafx.h"
#include "bitmath_func.hpp"
const uint8 _ffb_64[64] = {
0, 0, 1, 0, 2, 0, 1, 0,
3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0,
3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0,
3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0,
3, 0, 1, 0, 2, 0, 1, 0,
};
/**
* Search the first set bit in a 32 bit variable.
*
* This algorithm is a static implementation of a log
* conguence search algorithm. It checks the first half
* if there is a bit set search there further. And this
* way further. If no bit is set return 0.
*
* @param x The value to search
* @return The position of the first bit set
*/
uint8 FindFirstBit(uint32 x)
{
if (x == 0) return 0;
/* The macro FIND_FIRST_BIT is better to use when your x is
not more than 128. */
uint8 pos = 0;
if ((x & 0x0000ffff) == 0) { x >>= 16; pos += 16; }
if ((x & 0x000000ff) == 0) { x >>= 8; pos += 8; }
if ((x & 0x0000000f) == 0) { x >>= 4; pos += 4; }
if ((x & 0x00000003) == 0) { x >>= 2; pos += 2; }
if ((x & 0x00000001) == 0) { pos += 1; }
return pos;
}
/**
* 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
* if there is a bit set search there further. And this
* way further. If no bit is set return 0.
*
* @param x The value to search
* @return The position of the last bit set
*/
uint8 FindLastBit(uint64 x)
{
if (x == 0) return 0;
uint8 pos = 0;
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;
}
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