This patch removes floating point operations used by Lua 5.1 by
changing the type of Lua numbers from double to long.  It implements
division and modulus so that x == (x / y) * y + x % y.  The
exponentiation function returns zero for negative exponents.  The
patch removes the difftime function, and the math module should not be
used.  The string.format function no longer handles the floating point
directives %e, %E, %f, %g, and %G.  By removing the definition of
LUA_NUMBER_INTEGRAL in src/luaconf.h, one obtains a Lua number
implementation based on doubles.

John D. Ramsdell
May 2, 2006

diff -ur olua-5.1/src/linit.c lua-5.1/src/linit.c
--- olua-5.1/src/linit.c	2005-12-29 10:32:11.000000000 -0500
+++ lua-5.1/src/linit.c	2006-05-02 07:30:15.000000000 -0400
@@ -21,7 +21,9 @@
   {LUA_IOLIBNAME, luaopen_io},
   {LUA_OSLIBNAME, luaopen_os},
   {LUA_STRLIBNAME, luaopen_string},
+#if !defined LUA_NUMBER_INTEGRAL
   {LUA_MATHLIBNAME, luaopen_math},
+#endif
   {LUA_DBLIBNAME, luaopen_debug},
   {NULL, NULL}
 };
diff -ur olua-5.1/src/lmathlib.c lua-5.1/src/lmathlib.c
--- olua-5.1/src/lmathlib.c	2005-08-26 13:36:32.000000000 -0400
+++ lua-5.1/src/lmathlib.c	2006-05-02 07:30:15.000000000 -0400
@@ -252,8 +252,10 @@
   luaL_register(L, LUA_MATHLIBNAME, mathlib);
   lua_pushnumber(L, PI);
   lua_setfield(L, -2, "pi");
+#if !defined LUA_NUMBER_INTEGRAL
   lua_pushnumber(L, HUGE_VAL);
   lua_setfield(L, -2, "huge");
+#endif
 #if defined(LUA_COMPAT_MOD)
   lua_getfield(L, -1, "fmod");
   lua_setfield(L, -2, "mod");
diff -ur olua-5.1/src/loslib.c lua-5.1/src/loslib.c
--- olua-5.1/src/loslib.c	2006-01-27 08:54:31.000000000 -0500
+++ lua-5.1/src/loslib.c	2006-05-02 07:30:15.000000000 -0400
@@ -185,11 +185,13 @@
 }
 
 
+#if !defined LUA_NUMBER_INTEGRAL
 static int os_difftime (lua_State *L) {
   lua_pushnumber(L, difftime((time_t)(luaL_checknumber(L, 1)),
                              (time_t)(luaL_optnumber(L, 2, 0))));
   return 1;
 }
+#endif
 
 /* }====================================================== */
 
@@ -215,7 +217,9 @@
 static const luaL_Reg syslib[] = {
   {"clock",     os_clock},
   {"date",      os_date},
+#if !defined LUA_NUMBER_INTEGRAL
   {"difftime",  os_difftime},
+#endif
   {"execute",   os_execute},
   {"exit",      os_exit},
   {"getenv",    os_getenv},
diff -ur olua-5.1/src/lstrlib.c lua-5.1/src/lstrlib.c
--- olua-5.1/src/lstrlib.c	2005-12-29 10:32:11.000000000 -0500
+++ lua-5.1/src/lstrlib.c	2006-05-02 07:30:15.000000000 -0400
@@ -780,11 +780,13 @@
           sprintf(buff, form, (unsigned LUA_INTFRM_T)luaL_checknumber(L, arg));
           break;
         }
+#if !defined LUA_NUMBER_INTEGRAL
         case 'e':  case 'E': case 'f':
         case 'g': case 'G': {
           sprintf(buff, form, (double)luaL_checknumber(L, arg));
           break;
         }
+#endif
         case 'q': {
           addquoted(L, &b, arg);
           continue;  /* skip the 'addsize' at the end */
diff -ur olua-5.1/src/luaconf.h lua-5.1/src/luaconf.h
--- olua-5.1/src/luaconf.h	2006-02-10 12:44:06.000000000 -0500
+++ lua-5.1/src/luaconf.h	2006-05-02 07:45:46.000000000 -0400
@@ -128,8 +128,9 @@
 ** CHANGE that if ptrdiff_t is not adequate on your machine. (On most
 ** machines, ptrdiff_t gives a good choice between int or long.)
 */
-#define LUA_INTEGER	ptrdiff_t
 
+/* Changed to long for use with integral Lua numbers. */
+#define LUA_INTEGER	long
 
 /*
 @@ LUA_API is a mark for all core API functions.
@@ -488,14 +489,31 @@
 ** ===================================================================
 */
 
+/* Define LUA_NUMBER_INTEGRAL to produce a system that uses no
+   floating point operations by changing the type of Lua numbers from
+   double to long.  It implements division and modulus so that 
+
+   x == (x / y) * y + x % y.  
+   
+   The exponentiation function returns zero for negative exponents.
+   Defining LUA_NUMBER_INTEGRAL also removes the difftime function,
+   and the math module should not be used.  The string.format function
+   no longer handles the floating point directives %e, %E, %f, %g, and
+   %G. */
+
+#define LUA_NUMBER_INTEGRAL
+#if defined LUA_NUMBER_INTEGRAL
+#define LUA_NUMBER	long
+#else
 #define LUA_NUMBER_DOUBLE
 #define LUA_NUMBER	double
+#endif
 
 /*
 @@ LUAI_UACNUMBER is the result of an 'usual argument conversion'
 @* over a number.
 */
-#define LUAI_UACNUMBER	double
+#define LUAI_UACNUMBER	LUA_NUMBER
 
 
 /*
@@ -505,11 +523,20 @@
 @@ LUAI_MAXNUMBER2STR is maximum size of previous conversion.
 @@ lua_str2number converts a string to a number.
 */
+#if defined LUA_NUMBER_INTEGRAL
+#define LUA_NUMBER_SCAN		"%ld"
+#define LUA_NUMBER_FMT		"%ld"
+#else
 #define LUA_NUMBER_SCAN		"%lf"
 #define LUA_NUMBER_FMT		"%.14g"
+#endif
 #define lua_number2str(s,n)	sprintf((s), LUA_NUMBER_FMT, (n))
 #define LUAI_MAXNUMBER2STR	32 /* 16 digits, sign, point, and \0 */
+#if defined LUA_NUMBER_INTEGRAL
+#define lua_str2number(s,p)	strtol((s), (p), 10)
+#else
 #define lua_str2number(s,p)	strtod((s), (p))
+#endif
 
 
 /*
@@ -520,9 +547,36 @@
 #define luai_numadd(a,b)	((a)+(b))
 #define luai_numsub(a,b)	((a)-(b))
 #define luai_nummul(a,b)	((a)*(b))
+#if defined LUA_NUMBER_INTEGRAL
+#define luai_numdiv(a,b)	\
+  (-1/2?			\
+   (a)/(b):			\
+   ((a)<0==(b)<0||(a)%(b)==0?	\
+    (a)/(b):			\
+    (a)/(b)-1))
+#define luai_nummod(a,b)	\
+  (-1/2?			\
+   (a)%(b):			\
+   ((a)<0==(b)<0||(a)%(b)==0?	\
+    (a)%(b):			\
+    (a)%(b)+(b)))
+#define luai_lnumdiv(a,b)	\
+  ((b)==0?			\
+   (luaG_runerror(L,"divide by zero"),0): \
+   luai_numdiv(a,b))
+#define luai_lnummod(a,b)	\
+  ((b)==0?			\
+   (luaG_runerror(L,"modulo by zero"),0): \
+   luai_nummod(a,b))
+LUA_NUMBER luai_ipow(LUA_NUMBER, LUA_NUMBER);
+#define luai_numpow(a,b)	(luai_ipow(a,b))
+#else
 #define luai_numdiv(a,b)	((a)/(b))
 #define luai_nummod(a,b)	((a) - floor((a)/(b))*(b))
+#define luai_lnumdiv(a,b)	(luai_numdiv(a,b))
+#define luai_lnummod(a,b)	(luai_nummod(a,b))
 #define luai_numpow(a,b)	(pow(a,b))
+#endif
 #define luai_numunm(a)		(-(a))
 #define luai_numeq(a,b)		((a)==(b))
 #define luai_numlt(a,b)		((a)<(b))
diff -ur olua-5.1/src/lvm.c lua-5.1/src/lvm.c
--- olua-5.1/src/lvm.c	2006-01-23 14:51:43.000000000 -0500
+++ lua-5.1/src/lvm.c	2006-05-02 07:30:15.000000000 -0400
@@ -27,6 +27,25 @@
 #include "lvm.h"
 
 
+#if defined LUA_NUMBER_INTEGRAL
+LUA_NUMBER luai_ipow(LUA_NUMBER a, LUA_NUMBER b) {
+  if (b < 0)
+    return 0;
+  else if (b == 0)
+    return 1;
+  else {
+    LUA_NUMBER c = 1;
+    for (;;) {
+      if (b & 1)
+	c *= a;
+      b = b >> 1;
+      if (b == 0)
+	return c;
+      a *= a;
+    }
+  }
+}
+#endif
 
 /* limit for table tag-method chains (to avoid loops) */
 #define MAXTAGLOOP	100
@@ -321,8 +340,8 @@
       case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
       case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
       case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
-      case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
-      case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
+      case TM_DIV: setnvalue(ra, luai_lnumdiv(nb, nc)); break;
+      case TM_MOD: setnvalue(ra, luai_lnummod(nb, nc)); break;
       case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
       case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
       default: lua_assert(0); break;
@@ -479,11 +498,11 @@
         continue;
       }
       case OP_DIV: {
-        arith_op(luai_numdiv, TM_DIV);
+        arith_op(luai_lnumdiv, TM_DIV);
         continue;
       }
       case OP_MOD: {
-        arith_op(luai_nummod, TM_MOD);
+        arith_op(luai_lnummod, TM_MOD);
         continue;
       }
       case OP_POW: {