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better organization for coercion functions between lua_Number and 

integer types + IEEE trick to be used in most platforms, by default
This commit is contained in:
Roberto Ierusalimschy 2010-10-26 17:32:19 -02:00
parent c6b64ffe65
commit 6098e06e09
2 changed files with 71 additions and 31 deletions
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4
lua.h
View File

@ -1,5 +1,5 @@
/*
** $Id: lua.h,v 1.274 2010/09/03 14:14:01 roberto Exp roberto $
** $Id: lua.h,v 1.275 2010/10/25 20:31:11 roberto Exp roberto $
** Lua - A Scripting Language
** Lua.org, PUC-Rio, Brazil (http://www.lua.org)
** See Copyright Notice at the end of this file
@ -107,7 +107,7 @@ typedef LUA_NUMBER lua_Number;
typedef LUA_INTEGER lua_Integer;
/* unsigned integer type */
typedef unsigned LUA_INT32 lua_Unsigned;
typedef LUA_UNSIGNED lua_Unsigned;

98
luaconf.h
View File

@ -1,5 +1,5 @@
/*
** $Id: luaconf.h,v 1.142 2010/07/28 15:51:59 roberto Exp roberto $
** $Id: luaconf.h,v 1.143 2010/09/07 19:21:39 roberto Exp roberto $
** Configuration file for Lua
** See Copyright Notice in lua.h
*/
@ -438,26 +438,28 @@
*/
#define LUA_INTEGER ptrdiff_t
/*
@@ LUA_UNSIGNED is the integral type used by lua_pushunsigned/lua_tounsigned.
** It must have at least 32 bits.
*/
#define LUA_UNSIGNED unsigned LUA_INT32
/*
@@ lua_number2int is a macro to convert lua_Number to int.
@@ lua_number2integer is a macro to convert lua_Number to LUA_INTEGER.
@@ lua_number2uint is a macro to convert a lua_Number to an unsigned
@* LUA_INT32.
@@ lua_uint2number is a macro to convert an unsigned LUA_INT32
@* to a lua_Number.
** CHANGE them if you know a faster way to convert a lua_Number to
** int (with any rounding method and without throwing errors) in your
** system. In Pentium machines, a naive typecast from double to int
** in C is extremely slow, so any alternative is worth trying.
@@ lua_number2uint is a macro to convert a lua_Number to a LUA_UNSIGNED.
@@ lua_uint2number is a macro to convert a LUA_UNSIGNED to a lua_Number.
*/
/* On a Pentium, resort to a trick */
#if defined(LUA_NUMBER_DOUBLE) && !defined(LUA_ANSI) && !defined(__SSE2__) && \
(defined(__i386) || defined (_M_IX86) || defined(__i386__)) /* { */
#if defined(LUA_CORE) /* { */
/* On a Microsoft compiler, use assembler */
#if defined(_MSC_VER) /* { */
#if defined(LUA_NUMBER_DOUBLE) && !defined(LUA_ANSI) && \
!defined(LUA_NOIEEE754TRICK) /* { */
/* On a Microsoft compiler on a Pentium, use assembler to avoid chashes
with a DirectX idiosyncrasy */
#if defined(_MSC_VER) && defined(M_IX86) /* { */
#define lua_number2int(i,n) __asm {__asm fld n __asm fistp i}
#define lua_number2integer(i,n) lua_number2int(i, n)
@ -465,31 +467,69 @@
{__int64 l; __asm {__asm fld n __asm fistp l} i = (unsigned int)l;}
#else /* }{ */
/* the next trick should work on any Pentium, but sometimes clashes
with a DirectX idiosyncrasy */
/* the next trick should work on any machine using IEEE754 with
a 32-bit integer type */
union luai_Cast { double l_d; long l_l; };
#define lua_number2int(i,n) \
{ volatile union luai_Cast u; u.l_d = (n) + 6755399441055744.0; (i) = u.l_l; }
#define lua_number2integer(i,n) lua_number2int(i, n)
#define lua_number2uint(i,n) lua_number2int(i, n)
union luai_Cast { double l_d; LUA_INT32 l_p[2]; };
/*
@@ LUA_IEEEENDIAN is the endianess of doubles in your machine
@@ (0 for little endian, 1 for big endian); if not defined, Lua will
@@ check it dynamically.
*/
#if !defined(LUA_IEEEENDIAN) /* { */
#define LUAI_EXTRAIEEE \
static const union luai_Cast ieeeendian = {-(33.0 + 6755399441055744.0)};
#define LUA_IEEEENDIAN (ieeeendian.l_p[1] == 33)
#else
#define LUAI_EXTRAIEEE /* empty */
#endif /* } */
#define lua_number2int32(i,n,t) \
{ LUAI_EXTRAIEEE \
volatile union luai_Cast u; u.l_d = (n) + 6755399441055744.0; \
(i) = (t)u.l_p[LUA_IEEEENDIAN]; }
#define lua_number2int(i,n) lua_number2int32(i, n, int)
#define lua_number2integer(i,n) lua_number2int32(i, n, LUA_INTEGER)
#define lua_number2uint(i,n) lua_number2int32(i, n, LUA_UNSIGNED)
#endif /* } */
#else /* }{ */
/* this option always works, but may be slow */
#define lua_number2int(i,n) ((i)=(int)(n))
#define lua_number2integer(i,n) ((i)=(LUA_INTEGER)(n))
#define lua_number2uint(i,n) ((i)=(unsigned LUA_INT32)(n))
#endif /* } */
/* on several machines, coercion from unsigned to double is too slow,
so avoid that if possible */
/* the following definitions always work, but may be slow */
#if !defined(lua_number2int)
#define lua_number2int(i,n) ((i)=(int)(n))
#endif
#if !defined(lua_number2integer)
#define lua_number2integer(i,n) ((i)=(LUA_INTEGER)(n))
#endif
#if !defined(lua_number2uint) && (defined(lapi_c) || defined(luaall_c)) /* { */
/* the following definition assures proper modulo behavior */
#if defined(LUA_NUMBER_DOUBLE)
#include <math.h>
#define lua_number2uint(i,n) \
((i)=(LUA_UNSIGNED)((n) - floor((n)/4294967296.0)*4294967296.0))
#else
#define lua_number2uint(i,n) ((i)=(LUA_UNSIGNED)(n))
#endif
#endif /* } */
#if !defined(lua_uint2number)
/* on several machines, coercion from unsigned to double is slow,
so it may be worth to avoid */
#define lua_uint2number(u) \
((LUA_INT32)(u) < 0 ? (lua_Number)(u) : (lua_Number)(LUA_INT32)(u))
#endif
#endif /* } */
/*