diff options
Diffstat (limited to '3rdparty/lua/src/lmathlib.c')
-rw-r--r-- | 3rdparty/lua/src/lmathlib.c | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/3rdparty/lua/src/lmathlib.c b/3rdparty/lua/src/lmathlib.c index e0c61a168d9..43810634808 100644 --- a/3rdparty/lua/src/lmathlib.c +++ b/3rdparty/lua/src/lmathlib.c @@ -249,6 +249,15 @@ static int math_type (lua_State *L) { ** =================================================================== */ +/* +** This code uses lots of shifts. ANSI C does not allow shifts greater +** than or equal to the width of the type being shifted, so some shifts +** are written in convoluted ways to match that restriction. For +** preprocessor tests, it assumes a width of 32 bits, so the maximum +** shift there is 31 bits. +*/ + + /* number of binary digits in the mantissa of a float */ #define FIGS l_floatatt(MANT_DIG) @@ -267,20 +276,23 @@ static int math_type (lua_State *L) { /* try to find an integer type with at least 64 bits */ -#if (ULONG_MAX >> 31 >> 31) >= 3 +#if ((ULONG_MAX >> 31) >> 31) >= 3 /* 'long' has at least 64 bits */ #define Rand64 unsigned long +#define SRand64 long #elif !defined(LUA_USE_C89) && defined(LLONG_MAX) /* there is a 'long long' type (which must have at least 64 bits) */ #define Rand64 unsigned long long +#define SRand64 long long -#elif (LUA_MAXUNSIGNED >> 31 >> 31) >= 3 +#elif ((LUA_MAXUNSIGNED >> 31) >> 31) >= 3 -/* 'lua_Integer' has at least 64 bits */ +/* 'lua_Unsigned' has at least 64 bits */ #define Rand64 lua_Unsigned +#define SRand64 lua_Integer #endif @@ -319,23 +331,30 @@ static Rand64 nextrand (Rand64 *state) { } -/* must take care to not shift stuff by more than 63 slots */ - - /* ** Convert bits from a random integer into a float in the ** interval [0,1), getting the higher FIG bits from the ** random unsigned integer and converting that to a float. +** Some old Microsoft compilers cannot cast an unsigned long +** to a floating-point number, so we use a signed long as an +** intermediary. When lua_Number is float or double, the shift ensures +** that 'sx' is non negative; in that case, a good compiler will remove +** the correction. */ /* must throw out the extra (64 - FIGS) bits */ #define shift64_FIG (64 - FIGS) -/* to scale to [0, 1), multiply by scaleFIG = 2^(-FIGS) */ +/* 2^(-FIGS) == 2^-1 / 2^(FIGS-1) */ #define scaleFIG (l_mathop(0.5) / ((Rand64)1 << (FIGS - 1))) static lua_Number I2d (Rand64 x) { - return (lua_Number)(trim64(x) >> shift64_FIG) * scaleFIG; + SRand64 sx = (SRand64)(trim64(x) >> shift64_FIG); + lua_Number res = (lua_Number)(sx) * scaleFIG; + if (sx < 0) + res += l_mathop(1.0); /* correct the two's complement if negative */ + lua_assert(0 <= res && res < 1); + return res; } /* convert a 'Rand64' to a 'lua_Unsigned' */ @@ -471,8 +490,6 @@ static lua_Number I2d (Rand64 x) { #else /* 32 < FIGS <= 64 */ -/* must take care to not shift stuff by more than 31 slots */ - /* 2^(-FIGS) = 1.0 / 2^30 / 2^3 / 2^(FIGS-33) */ #define scaleFIG \ (l_mathop(1.0) / (UONE << 30) / l_mathop(8.0) / (UONE << (FIGS - 33))) @@ -500,12 +517,12 @@ static lua_Number I2d (Rand64 x) { /* convert a 'Rand64' to a 'lua_Unsigned' */ static lua_Unsigned I2UInt (Rand64 x) { - return ((lua_Unsigned)trim32(x.h) << 31 << 1) | (lua_Unsigned)trim32(x.l); + return (((lua_Unsigned)trim32(x.h) << 31) << 1) | (lua_Unsigned)trim32(x.l); } /* convert a 'lua_Unsigned' to a 'Rand64' */ static Rand64 Int2I (lua_Unsigned n) { - return packI((lu_int32)(n >> 31 >> 1), (lu_int32)n); + return packI((lu_int32)((n >> 31) >> 1), (lu_int32)n); } #endif /* } */ |