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1 /* Bitwise operations library */
2 /* (c) Reuben Thomas 2000-2008 */
3 /* See README for license */
4
5 #include <lua.h>
6 #include <lauxlib.h>
7 #include <limits.h>
8
9 #include "pm3_bit_limits.h"
10
11
12 /* FIXME: Assumes lua_Integer is ptrdiff_t */
13 #define LUA_INTEGER_MAX PTRDIFF_MAX
14 #define LUA_INTEGER_MIN PTRDIFF_MIN
15
16 /* FIXME: Assumes size_t is an unsigned lua_Integer */
17 typedef size_t lua_UInteger;
18 #define LUA_UINTEGER_MAX SIZE_MAX
19
20
21 /* Bit type size and limits */
22
23 #define BIT_BITS \
24 (CHAR_BIT * sizeof(lua_Integer) > BITLIB_FLOAT_BITS ? \
25 BITLIB_FLOAT_BITS : (CHAR_BIT * sizeof(lua_Integer)))
26
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 \
31 (CHAR_BIT * sizeof(lua_Integer) > BITLIB_FLOAT_BITS ? BITLIB_FLOAT_MAX : LUA_INTEGER_MAX)
32
33 #define BIT_MIN \
34 (CHAR_BIT * sizeof(lua_Integer) > BITLIB_FLOAT_BITS ? BITLIB_FLOAT_MIN : LUA_INTEGER_MIN)
35
36 #define BIT_UMAX \
37 (CHAR_BIT * sizeof(lua_Integer) > BITLIB_FLOAT_BITS ? BITLIB_FLOAT_UMAX : LUA_UINTEGER_MAX)
38
39
40 /* Define TOBIT to get a bit value */
41 #ifdef BUILTIN_CAST
42 #define
43 #define TOBIT(L, n, res) \
44 ((void)(res), luaL_checkinteger((L), (n)))
45 #else
46 #include <stdint.h>
47 #include <math.h>
48
49 /* FIXME: Assumes lua_Number fits in a double (use of fmod). */
50 #define TOBIT(L, n, res) \
51 ((lua_Integer)(((res) = fmod(luaL_checknumber(L, (n)), (double)BIT_UMAX + 1.0)), \
52 (res) > BIT_MAX ? ((res) -= (double)BIT_UMAX, (res) -= 1) : \
53 ((res) < BIT_MIN ? ((res) += (double)BIT_UMAX, (res) += 1) : (res))))
54 #endif
55
56
57 #define BIT_TRUNCATE(i) \
58 ((i) & BIT_UMAX)
59
60
61 /* Operations
62
63 The macros MONADIC and VARIADIC only deal with bitwise operations.
64
65 LOGICAL_SHIFT truncates its left-hand operand before shifting so
66 that any extra bits at the most-significant end are not shifted
67 into the result.
68
69 ARITHMETIC_SHIFT does not truncate its left-hand operand, so that
70 the sign bits are not removed and right shift work properly.
71 */
72
73 #define MONADIC(name, op) \
74 static int bit_ ## name(lua_State *L) { \
75 lua_Number f; \
76 lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f))); \
77 return 1; \
78 }
79
80 #define VARIADIC(name, op) \
81 static int bit_ ## name(lua_State *L) { \
82 lua_Number f; \
83 int n = lua_gettop(L), i; \
84 lua_Integer w = TOBIT(L, 1, f); \
85 for (i = 2; i <= n; i++) \
86 w op TOBIT(L, i, f); \
87 lua_pushinteger(L, BIT_TRUNCATE(w)); \
88 return 1; \
89 }
90
91 #define LOGICAL_SHIFT(name, op) \
92 static int bit_ ## name(lua_State *L) { \
93 lua_Number f; \
94 lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \
95 (unsigned)luaL_checknumber(L, 2))); \
96 return 1; \
97 }
98
99 #define ARITHMETIC_SHIFT(name, op) \
100 static int bit_ ## name(lua_State *L) { \
101 lua_Number f; \
102 lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op \
103 (unsigned)luaL_checknumber(L, 2))); \
104 return 1; \
105 }
106
107 MONADIC(cast, +)
108 MONADIC(bnot, ~)
109 VARIADIC(band, &=)
110 VARIADIC(bor, |=)
111 VARIADIC(bxor, ^=)
112 ARITHMETIC_SHIFT(lshift, <<)
113 LOGICAL_SHIFT(rshift, >>)
114 ARITHMETIC_SHIFT(arshift, >>)
115
116 static const struct luaL_Reg bitlib[] = {
117 {"cast", bit_cast},
118 {"bnot", bit_bnot},
119 {"band", bit_band},
120 {"bor", bit_bor},
121 {"bxor", bit_bxor},
122 {"lshift", bit_lshift},
123 {"rshift", bit_rshift},
124 {"arshift", bit_arshift},
125 {NULL, NULL}
126 };
127
128 LUALIB_API int luaopen_bit (lua_State *L) {
129 luaL_newlib(L, bitlib);
130 //luaL_register(L, "bit", bitlib);
131 lua_pushnumber(L, BIT_BITS);
132 lua_setfield(L, -2, "bits");
133 return 1;
134 }
135
136 /**
137 LUALIB_API int luaopen_bit (lua_State *L) {
138 luaL_register(L, "bit", bitlib);
139 lua_pushnumber(L, BIT_BITS);
140 lua_setfield(L, -2, "bits");
141 return 1;
142 }
143 **/
144 /*
145 ** Open bit library
146 */
147 int set_bit_library (lua_State *L) {
148
149 luaL_requiref(L, "bit", luaopen_bit, 1);
150 lua_pop(L, 1);
151 return 1;
152 }
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