diff options
Diffstat (limited to 'common/math.h')
| -rw-r--r-- | common/math.h | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/common/math.h b/common/math.h index ebe01fbaf5..f787b84fa6 100644 --- a/common/math.h +++ b/common/math.h @@ -26,6 +26,31 @@ #define COMMON_MATH_H #include "common/scummsys.h" +#ifdef _MSC_VER +// HACK: +// intrin.h on MSVC includes setjmp.h, which will fail compiling due to our +// forbidden symbol colde. Since we also can not assure that defining +// FORBIDDEN_SYMBOL_EXCEPTION_setjmp and FORBIDDEN_SYMBOL_EXCEPTION_longjmp +// will actually allow the symbols, since forbidden.h might be included +// earlier already we need to undefine them here... +#undef setjmp +#undef longjmp +#include <intrin.h> +// ...and redefine them here so no code can actually use it. +// This could be resolved by including intrin.h on MSVC in scummsys.h before +// the forbidden.h include. This might make sense, in case we use MSVC +// extensions like _BitScanReverse in more places. But for now this hack should +// be ok... +#ifndef FORBIDDEN_SYMBOL_EXCEPTION_setjmp +#undef setjmp +#define setjmp(a) FORBIDDEN_SYMBOL_REPLACEMENT +#endif + +#ifndef FORBIDDEN_SYMBOL_EXCEPTION_longjmp +#undef longjmp +#define longjmp(a,b) FORBIDDEN_SYMBOL_REPLACEMENT +#endif +#endif #ifndef M_SQRT1_2 #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */ @@ -50,6 +75,28 @@ struct Complex { float re, im; }; +#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) +inline int intLog2(uint32 v) { + // This is a slightly optimized implementation of log2 for natural numbers + // targeting gcc. It also saves some binary size over our fallback + // implementation, since it does not need any table. + if (v == 0) + return -1; + else + // This is really "sizeof(unsigned int) * CHAR_BIT - 1" but using 8 + // instead of CHAR_BIT is sane enough and it saves us from including + // limits.h + return (sizeof(unsigned int) * 8 - 1) - __builtin_clz(v); +} +#elif defined(_MSC_VER) +inline int intLog2(uint32 v) { + unsigned long result = 0; + unsigned char nonZero = _BitScanReverse(&result, v); + // _BitScanReverse stores the position of the MSB set in case its result + // is non zero, thus we can just return it as is. + return nonZero ? result : -1; +} +#else // See http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup static const char LogTable256[256] = { #define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n @@ -58,7 +105,7 @@ static const char LogTable256[256] = { LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7) }; -inline uint32 intLog2(uint32 v) { +inline int intLog2(uint32 v) { register uint32 t, tt; if ((tt = v >> 16)) @@ -66,6 +113,7 @@ inline uint32 intLog2(uint32 v) { else return (t = v >> 8) ? 8 + LogTable256[t] : LogTable256[v]; } +#endif inline float rad2deg(float rad) { return rad * 180.0 / M_PI; |