FS#8961 - Anti-Aliased Fonts.
[kugel-rb/myfork.git] / apps / plugins / lua / lbitlib.c
blobdcb5b9d82809ba2fa2f70578661a911355b7d0df
1 /* Bitwise operations library */
2 /* (c) Reuben Thomas 2000-2008 */
3 /* bitlib is copyright Reuben Thomas 2000-2008, and is released under the MIT
4 license, like Lua (see http://www.lua.org/copyright.html; it's
5 basically the same as the BSD license). There is no warranty. */
7 #include "config.h"
9 #include "lua.h"
10 #include "lauxlib.h"
11 #include <limits.h>
14 /* FIXME: Assume lua_Integer is ptrdiff_t */
15 #define LUA_INTEGER_MAX INTPTR_MAX
16 #define LUA_INTEGER_MIN INTPTR_MIN
18 /* FIXME: Assume size_t is an unsigned lua_Integer */
19 typedef size_t lua_UInteger;
20 #define LUA_UINTEGER_MAX UINT_MAX
23 /* Bit type size and limits */
25 #define BIT_BITS (CHAR_BIT * sizeof(lua_Integer))
27 /* This code may give warnings if BITLIB_FLOAT_* are too big to fit in
28 long, but that doesn't matter since in that case they won't be
29 used. */
30 #define BIT_MAX (LUA_INTEGER_MAX)
32 #define BIT_MIN (LUA_INTEGER_MIN)
34 #define BIT_UMAX (LUA_UINTEGER_MAX)
37 /* Define TOBIT to get a bit value */
38 #ifdef BUILTIN_CAST
39 #define
40 #define TOBIT(L, n, res) \
41 ((void)(res), luaL_checkinteger((L), (n)))
42 #else
44 #define TOBIT(L, n, res) \
45 ((lua_Integer)(((res) = luaL_checknumber(L, (n)) % BIT_UMAX), \
46 (res) > BIT_MAX ? ((res) -= BIT_UMAX, (res) -= 1) : \
47 ((res) < BIT_MIN ? ((res) += BIT_UMAX, (res) += 1) : (res))))
48 #endif
51 #define BIT_TRUNCATE(i) \
52 ((i) & BIT_UMAX)
55 /* Operations
57 The macros MONADIC and VARIADIC only deal with bitwise operations.
59 LOGICAL_SHIFT truncates its left-hand operand before shifting so
60 that any extra bits at the most-significant end are not shifted
61 into the result.
63 ARITHMETIC_SHIFT does not truncate its left-hand operand, so that
64 the sign bits are not removed and right shift work properly.
67 #define MONADIC(name, op) \
68 static int bit_ ## name(lua_State *L) { \
69 lua_Number f; \
70 lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f))); \
71 return 1; \
74 #define VARIADIC(name, op) \
75 static int bit_ ## name(lua_State *L) { \
76 lua_Number f; \
77 int n = lua_gettop(L), i; \
78 lua_Integer w = TOBIT(L, 1, f); \
79 for (i = 2; i <= n; i++) \
80 w op TOBIT(L, i, f); \
81 lua_pushinteger(L, BIT_TRUNCATE(w)); \
82 return 1; \
85 #define LOGICAL_SHIFT(name, op) \
86 static int bit_ ## name(lua_State *L) { \
87 lua_Number f; \
88 lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \
89 (unsigned)luaL_checknumber(L, 2))); \
90 return 1; \
93 #define ARITHMETIC_SHIFT(name, op) \
94 static int bit_ ## name(lua_State *L) { \
95 lua_Number f; \
96 lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op \
97 (unsigned)luaL_checknumber(L, 2))); \
98 return 1; \
101 MONADIC(bnot, ~)
102 VARIADIC(band, &=)
103 VARIADIC(bor, |=)
104 VARIADIC(bxor, ^=)
105 ARITHMETIC_SHIFT(lshift, <<)
106 LOGICAL_SHIFT(rshift, >>)
107 ARITHMETIC_SHIFT(arshift, >>)
109 static const struct luaL_reg bitlib[] = {
110 {"bnot", bit_bnot},
111 {"band", bit_band},
112 {"bor", bit_bor},
113 {"bxor", bit_bxor},
114 {"lshift", bit_lshift},
115 {"rshift", bit_rshift},
116 {"arshift", bit_arshift},
117 {NULL, NULL}
120 LUALIB_API int luaopen_bit (lua_State *L) {
121 luaL_register(L, "bit", bitlib);
122 lua_pushnumber(L, BIT_BITS);
123 lua_setfield(L, -2, "bits");
124 return 1;