From 82eea9ed69886a4eaf41a1124b292635ca60fe9a Mon Sep 17 00:00:00 2001 From: Maurus Cuelenaere Date: Mon, 1 Jun 2009 22:02:18 +0000 Subject: Lua: add bitlib (makes bitwise operators possible) git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21164 a1c6a512-1295-4272-9138-f99709370657 --- apps/plugins/lua/lbitlib.c | 125 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 apps/plugins/lua/lbitlib.c (limited to 'apps/plugins/lua/lbitlib.c') diff --git a/apps/plugins/lua/lbitlib.c b/apps/plugins/lua/lbitlib.c new file mode 100644 index 0000000000..f7e4619377 --- /dev/null +++ b/apps/plugins/lua/lbitlib.c @@ -0,0 +1,125 @@ +/* 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 +#include +#include + + +/* 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; +} -- cgit v1.2.3