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more explicit casts when converting an integer to a random float

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(to ensure computations are done with all bits)
This commit is contained in:
Roberto Ierusalimschy 2018-03-11 11:48:09 -03:00
parent 9e3db70482
commit e3388ebfad
1 changed files with 5 additions and 3 deletions
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8
lmathlib.c
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@ -1,5 +1,5 @@
/* /*
** $Id: lmathlib.c,v 1.122 2018/03/09 15:05:13 roberto Exp roberto $ ** $Id: lmathlib.c,v 1.123 2018/03/09 19:23:39 roberto Exp roberto $
** Standard mathematical library ** Standard mathematical library
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -373,7 +373,7 @@ static I xorshift128plus (I *state) {
/* do not need bits from higher half */ /* do not need bits from higher half */
#define maskHF 0 #define maskHF 0
#define maskLOW (~(~1U << (FIGS - 1))) /* use FIG bits */ #define maskLOW (~(~1U << (FIGS - 1))) /* use FIG bits */
#define shiftFIG (0.5 / (1U << (FIGS - 1))) /* 2^(-FIG) */ #define shiftFIG (l_mathop(0.5) / (1U << (FIGS - 1))) /* 2^(-FIG) */
#else /* 32 < FIGS <= 64 */ #else /* 32 < FIGS <= 64 */
@ -393,7 +393,9 @@ static I xorshift128plus (I *state) {
#define twoto32 l_mathop(4294967296.0) /* 2^32 */ #define twoto32 l_mathop(4294967296.0) /* 2^32 */
static lua_Number I2d (I x) { static lua_Number I2d (I x) {
return ((x.h & maskHF) * twoto32 + (x.l & maskLOW)) * shiftFIG; lua_Number h = (lua_Number)(x.h & maskHF);
lua_Number l = (lua_Number)(x.l & maskLOW);
return (h * twoto32 + l) * shiftFIG;
} }
static lua_Unsigned I2UInt (I x) { static lua_Unsigned I2UInt (I x) {