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