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https://github.com/lua/lua
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reorganization of '#if's for sellecting a type for 'Rand64' +
comments
This commit is contained in:
Roberto Ierusalimschy
parent
e64e20ac81
commit
3e7415e846
87
lmathlib.c
87
lmathlib.c
@ -1,5 +1,5 @@
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/*
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** $Id: lmathlib.c,v 1.130 2018/04/06 15:41:29 roberto Exp roberto $
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** $Id: lmathlib.c,v 1.131 2018/04/06 17:52:42 roberto Exp roberto $
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** Standard mathematical library
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** See Copyright Notice in lua.h
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*/
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@ -257,27 +257,45 @@ static int math_type (lua_State *L) {
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#endif
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#if (!defined(LUA_USE_C89) && defined(LLONG_MAX) && !defined(LUA_DEBUG)) \
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|| defined(Rand64) /* { */
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/*
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** Assume long long.
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** LUA_RAND32 forces the use of 32-bit integers in the implementation
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** of the PRN generator (mainly for testing).
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*/
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#if !defined(LUA_RAND32) && !defined(Rand64)
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/* try to find an integer type with at least 64 bits */
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#if (LONG_MAX >> 31 >> 31) >= 1
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/* 'long' has at least 64 bits */
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#define Rand64 unsigned long
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#elif !defined(LUA_USE_C89) && defined(LLONG_MAX)
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/* there is a 'long long' type (which must have at least 64 bits) */
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#define Rand64 unsigned long long
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#elif (LUA_MAXINTEGER >> 31 >> 31) >= 1
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/* 'lua_Integer' has at least 64 bits */
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#define Rand64 LUA_UNSIGNED
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#endif
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#if !defined(Rand64)
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/* a 64-bit value */
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typedef unsigned long long Rand64;
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#endif
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#if defined(Rand64) /* { */
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/*
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** Standard implementation, using 64-bit integers.
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** If 'Rand64' has more than 64 bits, the extra bits do not interfere
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** with the 64 initial bits, except in a right shift. Otherwise, we just
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** have to make sure we never use them.
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** with the 64 initial bits, except in a right shift. Moreover, the
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** final result has to discard the extra bits.
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*/
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/* avoid using extra bits when needed */
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#define trim64(x) ((x) & 0xffffffffffffffffU)
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#define trim64(x) ((x) & 0xffffffffffffffffu)
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/* rotate left 'x' by 'n' bits */
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@ -315,24 +333,23 @@ static lua_Number I2d (Rand64 x) {
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/* convert a 'Rand64' to a 'lua_Unsigned' */
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#define I2UInt(x) ((lua_Unsigned)trim64(x))
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/* convert a 'lua_Unsigned' to an 'Rand64' */
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/* convert a 'lua_Unsigned' to a 'Rand64' */
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#define Int2I(x) ((Rand64)(x))
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#else /* no long long }{ */
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#else /* no 'Rand64' }{ */
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/*
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** Use two 32-bit integers to represent a 64-bit quantity.
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*/
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#if LUAI_BITSINT >= 32
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/* get an integer with at least 32 bits */
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#if (INT_MAX >> 30) >= 1
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typedef unsigned int lu_int32;
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#else
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typedef unsigned long lu_int32;
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#endif
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/* a 64-bit value */
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/*
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** Use two 32-bit integers to represent a 64-bit quantity.
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*/
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typedef struct Rand64 {
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lu_int32 h; /* higher half */
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lu_int32 l; /* lower half */
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@ -342,17 +359,18 @@ typedef struct Rand64 {
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/*
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** If 'lu_int32' has more than 32 bits, the extra bits do not interfere
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** with the 32 initial bits, except in a right shift and comparisons.
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** Otherwise, we just have to make sure we never use them.
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** Moreover, the final result has to discard the extra bits.
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*/
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/* avoid using extra bits when needed */
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#define trim32(x) ((x) & 0xffffffffU)
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#define trim32(x) ((x) & 0xffffffffu)
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/*
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** basic operations on 'Rand64' values
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*/
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/* build a new Rand64 value */
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static Rand64 packI (lu_int32 h, lu_int32 l) {
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Rand64 result;
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result.h = h;
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@ -360,16 +378,19 @@ static Rand64 packI (lu_int32 h, lu_int32 l) {
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return result;
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}
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/* return i << n */
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static Rand64 Ishl (Rand64 i, int n) {
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lua_assert(n > 0 && n < 32);
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return packI((i.h << n) | (trim32(i.l) >> (32 - n)), i.l << n);
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}
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/* i1 ^= i2 */
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static void Ixor (Rand64 *i1, Rand64 i2) {
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i1->h ^= i2.h;
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i1->l ^= i2.l;
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}
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/* return i1 + i2 */
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static Rand64 Iadd (Rand64 i1, Rand64 i2) {
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Rand64 result = packI(i1.h + i2.h, i1.l + i2.l);
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if (trim32(result.l) < trim32(i1.l)) /* carry? */
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@ -377,14 +398,17 @@ static Rand64 Iadd (Rand64 i1, Rand64 i2) {
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return result;
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}
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/* return i * 5 */
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static Rand64 times5 (Rand64 i) {
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return Iadd(Ishl(i, 2), i); /* i * 5 == (i << 2) + i */
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}
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/* return i * 9 */
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static Rand64 times9 (Rand64 i) {
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return Iadd(Ishl(i, 3), i); /* i * 9 == (i << 3) + i */
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}
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/* return 'i' rotated left 'n' bits */
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static Rand64 rotl (Rand64 i, int n) {
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lua_assert(n > 0 && n < 32);
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return packI((i.h << n) | (trim32(i.l) >> (32 - n)),
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@ -416,7 +440,7 @@ static Rand64 nextrand (Rand64 *state) {
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/*
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** Converts an 'Rand64' into a float.
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** Converts a 'Rand64' into a float.
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*/
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/* an unsigned 1 with proper type */
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@ -452,11 +476,12 @@ static lua_Number I2d (Rand64 x) {
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}
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/* convert a 'Rand64' to a 'lua_Unsigned' */
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static lua_Unsigned I2UInt (Rand64 x) {
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return ((lua_Unsigned)x.h << 31 << 1) | (lua_Unsigned)trim32(x.l);
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return ((lua_Unsigned)trim32(x.h) << 31 << 1) | (lua_Unsigned)trim32(x.l);
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}
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/* convert a 'lua_Unsigned' to a 'Rand64' */
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static Rand64 Int2I (lua_Unsigned n) {
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return packI((lu_int32)(n >> 31 >> 1), (lu_int32)n);
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}
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@ -479,7 +504,7 @@ typedef struct {
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** division). To get a uniform projection into [0, n], we first compute
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** 'lim', the smallest Mersenne number not smaller than 'n'. We then
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** project 'ran' into the interval [0, lim]. If the result is inside
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** [0, n], we are done. Otherwise, we try with another 'ran' until we
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** [0, n], we are done. Otherwise, we try with another 'ran', until we
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** have a result inside the interval.
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*/
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static lua_Unsigned project (lua_Unsigned ran, lua_Unsigned n,
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@ -492,15 +517,15 @@ static lua_Unsigned project (lua_Unsigned ran, lua_Unsigned n,
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lim |= (lim >> 4);
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lim |= (lim >> 8);
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lim |= (lim >> 16);
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#if (LUA_MAXINTEGER >> 30 >> 2) > 0
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#if (LUA_MAXINTEGER >> 30 >> 1) > 0
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lim |= (lim >> 32); /* integer type has more than 32 bits */
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#endif
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}
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lua_assert((lim & (lim + 1)) == 0 /* 'lim + 1' is a power of 2 */
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&& lim >= n /* not smaller than 'n' */
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&& (lim == 0 || (lim >> 1) < n)); /* it is the smallest one */
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while ((ran &= lim) > n)
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ran = I2UInt(nextrand(state->s));
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lua_assert((lim & (lim + 1)) == 0 /* 'lim + 1' is a power of 2, */
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&& lim >= n /* not smaller than 'n', */
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&& (lim == 0 || (lim >> 1) < n)); /* and it is the smallest one */
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while ((ran &= lim) > n) /* project 'ran' into [0..lim] */
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ran = I2UInt(nextrand(state->s)); /* not inside [0..n]? try again */
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return ran;
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}
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6
ltests.h
6
ltests.h
@ -1,5 +1,5 @@
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/*
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** $Id: ltests.h,v 2.57 2018/04/11 16:49:36 roberto Exp roberto $
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** $Id: ltests.h,v 2.58 2018/04/19 15:42:41 roberto Exp roberto $
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** Internal Header for Debugging of the Lua Implementation
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** See Copyright Notice in lua.h
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*/
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@ -49,6 +49,10 @@
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#define LUA_USE_JUMPTABLE 0
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/* use 32-bit integers in random generator */
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#define LUA_RAND32
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/* memory-allocator control variables */
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typedef struct Memcontrol {
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unsigned long numblocks;
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