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/* Bitwise operations library */
/* (c) Reuben Thomas 2000-2008 */
/* bitlib is copyright Reuben Thomas 2000-2008, and is released under the MIT
license, like Lua (see http://www.lua.org/copyright.html; it's
basically the same as the BSD license). There is no warranty. */
#include "config.h"
#include "lua.h"
#include "lauxlib.h"
#include <limits.h>
/* FIXME: Assume lua_Integer is ptrdiff_t */
#define LUA_INTEGER_MAX INTPTR_MAX
#define LUA_INTEGER_MIN INTPTR_MIN
/* FIXME: Assume size_t is an unsigned lua_Integer */
typedef size_t lua_UInteger;
#define LUA_UINTEGER_MAX UINT_MAX
/* Bit type size and limits */
#define BIT_BITS (CHAR_BIT * sizeof(lua_Integer))
/* This code may give warnings if BITLIB_FLOAT_* are too big to fit in
long, but that doesn't matter since in that case they won't be
used. */
#define BIT_MAX (LUA_INTEGER_MAX)
#define BIT_MIN (LUA_INTEGER_MIN)
#define BIT_UMAX (LUA_UINTEGER_MAX)
/* Define TOBIT to get a bit value */
#ifdef BUILTIN_CAST
#define
#define TOBIT(L, n, res) \
((void)(res), luaL_checkinteger((L), (n)))
#else
#define TOBIT(L, n, res) \
((lua_Integer)(((res) = luaL_checknumber(L, (n)) % BIT_UMAX), \
(res) > BIT_MAX ? ((res) -= BIT_UMAX, (res) -= 1) : \
((res) < BIT_MIN ? ((res) += BIT_UMAX, (res) += 1) : (res))))
#endif
#define BIT_TRUNCATE(i) \
((i) & BIT_UMAX)
/* Operations
The macros MONADIC and VARIADIC only deal with bitwise operations.
LOGICAL_SHIFT truncates its left-hand operand before shifting so
that any extra bits at the most-significant end are not shifted
into the result.
ARITHMETIC_SHIFT does not truncate its left-hand operand, so that
the sign bits are not removed and right shift work properly.
*/
#define MONADIC(name, op) \
static int bit_ ## name(lua_State *L) { \
lua_Number f; \
lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f))); \
return 1; \
}
#define VARIADIC(name, op) \
static int bit_ ## name(lua_State *L) { \
lua_Number f; \
int n = lua_gettop(L), i; \
lua_Integer w = TOBIT(L, 1, f); \
for (i = 2; i <= n; i++) \
w op TOBIT(L, i, f); \
lua_pushinteger(L, BIT_TRUNCATE(w)); \
return 1; \
}
#define LOGICAL_SHIFT(name, op) \
static int bit_ ## name(lua_State *L) { \
lua_Number f; \
lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \
(unsigned)luaL_checknumber(L, 2))); \
return 1; \
}
#define ARITHMETIC_SHIFT(name, op) \
static int bit_ ## name(lua_State *L) { \
lua_Number f; \
lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op \
(unsigned)luaL_checknumber(L, 2))); \
return 1; \
}
MONADIC(bnot, ~)
VARIADIC(band, &=)
VARIADIC(bor, |=)
VARIADIC(bxor, ^=)
ARITHMETIC_SHIFT(lshift, <<)
LOGICAL_SHIFT(rshift, >>)
ARITHMETIC_SHIFT(arshift, >>)
static const struct luaL_reg bitlib[] = {
{"bnot", bit_bnot},
{"band", bit_band},
{"bor", bit_bor},
{"bxor", bit_bxor},
{"lshift", bit_lshift},
{"rshift", bit_rshift},
{"arshift", bit_arshift},
{NULL, NULL}
};
LUALIB_API int luaopen_bit (lua_State *L) {
luaL_register(L, "bit", bitlib);
lua_pushnumber(L, BIT_BITS);
lua_setfield(L, -2, "bits");
return 1;
}
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