| 58 | #endif |
| 59 | |
| 60 | SDL_FORCE_INLINE int |
| 61 | SDL_MostSignificantBitIndex32(Uint32 x) |
| 62 | { |
| 63 | #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) |
| 64 | /* Count Leading Zeroes builtin in GCC. |
| 65 | * http://gcc.gnu.org/onlinedocs/gcc-4.3.4/gcc/Other-Builtins.html |
| 66 | */ |
| 67 | if (x == 0) { |
| 68 | return -1; |
| 69 | } |
| 70 | return 31 - __builtin_clz(x); |
| 71 | #elif defined(__WATCOMC__) && defined(__386__) |
| 72 | if (x == 0) { |
| 73 | return -1; |
| 74 | } |
| 75 | return 31 - _SDL_clz_watcom(x); |
| 76 | #else |
| 77 | /* Based off of Bit Twiddling Hacks by Sean Eron Anderson |
| 78 | * <seander@cs.stanford.edu>, released in the public domain. |
| 79 | * http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog |
| 80 | */ |
| 81 | const Uint32 b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000}; |
| 82 | const int S[] = {1, 2, 4, 8, 16}; |
| 83 | |
| 84 | int msbIndex = 0; |
| 85 | int i; |
| 86 | |
| 87 | if (x == 0) { |
| 88 | return -1; |
| 89 | } |
| 90 | |
| 91 | for (i = 4; i >= 0; i--) |
| 92 | { |
| 93 | if (x & b[i]) |
| 94 | { |
| 95 | x >>= S[i]; |
| 96 | msbIndex |= S[i]; |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | return msbIndex; |
| 101 | #endif |
| 102 | } |
| 103 | |
| 104 | SDL_FORCE_INLINE SDL_bool |
| 105 | SDL_HasExactlyOneBitSet32(Uint32 x) |
no outgoing calls
no test coverage detected