1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/* BEGIN CSTYLED */
/*
** $Id: lbitlib.c,v 1.18.1.2 2013/07/09 18:01:41 roberto Exp $
** Standard library for bitwise operations
** See Copyright Notice in lua.h
*/
#define lbitlib_c
#define LUA_LIB
#include <sys/lua/lua.h>
#include <sys/lua/lauxlib.h>
#include <sys/lua/lualib.h>
/* number of bits to consider in a number */
#if !defined(LUA_NBITS)
#define LUA_NBITS 32
#endif
#define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
/* macro to trim extra bits */
#define trim(x) ((x) & ALLONES)
/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
#define mask(n) (~((ALLONES << 1) << ((n) - 1)))
typedef lua_Unsigned b_uint;
static b_uint andaux (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = ~(b_uint)0;
for (i = 1; i <= n; i++)
r &= luaL_checkunsigned(L, i);
return trim(r);
}
static int b_and (lua_State *L) {
b_uint r = andaux(L);
lua_pushunsigned(L, r);
return 1;
}
static int b_test (lua_State *L) {
b_uint r = andaux(L);
lua_pushboolean(L, r != 0);
return 1;
}
static int b_or (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = 0;
for (i = 1; i <= n; i++)
r |= luaL_checkunsigned(L, i);
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_xor (lua_State *L) {
int i, n = lua_gettop(L);
b_uint r = 0;
for (i = 1; i <= n; i++)
r ^= luaL_checkunsigned(L, i);
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_not (lua_State *L) {
b_uint r = ~luaL_checkunsigned(L, 1);
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_shift (lua_State *L, b_uint r, int i) {
if (i < 0) { /* shift right? */
i = -i;
r = trim(r);
if (i >= LUA_NBITS) r = 0;
else r >>= i;
}
else { /* shift left */
if (i >= LUA_NBITS) r = 0;
else r <<= i;
r = trim(r);
}
lua_pushunsigned(L, r);
return 1;
}
static int b_lshift (lua_State *L) {
return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));
}
static int b_rshift (lua_State *L) {
return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));
}
static int b_arshift (lua_State *L) {
b_uint r = luaL_checkunsigned(L, 1);
int i = luaL_checkint(L, 2);
if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1))))
return b_shift(L, r, -i);
else { /* arithmetic shift for 'negative' number */
if (i >= LUA_NBITS) r = ALLONES;
else
r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */
lua_pushunsigned(L, r);
return 1;
}
}
static int b_rot (lua_State *L, int i) {
b_uint r = luaL_checkunsigned(L, 1);
i &= (LUA_NBITS - 1); /* i = i % NBITS */
r = trim(r);
if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */
r = (r << i) | (r >> (LUA_NBITS - i));
lua_pushunsigned(L, trim(r));
return 1;
}
static int b_lrot (lua_State *L) {
return b_rot(L, luaL_checkint(L, 2));
}
static int b_rrot (lua_State *L) {
return b_rot(L, -luaL_checkint(L, 2));
}
/*
** get field and width arguments for field-manipulation functions,
** checking whether they are valid.
** ('luaL_error' called without 'return' to avoid later warnings about
** 'width' being used uninitialized.)
*/
static int fieldargs (lua_State *L, int farg, int *width) {
int f = luaL_checkint(L, farg);
int w = luaL_optint(L, farg + 1, 1);
luaL_argcheck(L, 0 <= f, farg, "field cannot be negative");
luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");
if (f + w > LUA_NBITS)
luaL_error(L, "trying to access non-existent bits");
*width = w;
return f;
}
static int b_extract (lua_State *L) {
int w;
b_uint r = luaL_checkunsigned(L, 1);
int f = fieldargs(L, 2, &w);
r = (r >> f) & mask(w);
lua_pushunsigned(L, r);
return 1;
}
static int b_replace (lua_State *L) {
int w;
b_uint r = luaL_checkunsigned(L, 1);
b_uint v = luaL_checkunsigned(L, 2);
int f = fieldargs(L, 3, &w);
int m = mask(w);
v &= m; /* erase bits outside given width */
r = (r & ~(m << f)) | (v << f);
lua_pushunsigned(L, r);
return 1;
}
static const luaL_Reg bitlib[] = {
{"arshift", b_arshift},
{"band", b_and},
{"bnot", b_not},
{"bor", b_or},
{"bxor", b_xor},
{"btest", b_test},
{"extract", b_extract},
{"lrotate", b_lrot},
{"lshift", b_lshift},
{"replace", b_replace},
{"rrotate", b_rrot},
{"rshift", b_rshift},
{NULL, NULL}
};
LUAMOD_API int luaopen_bit32 (lua_State *L) {
luaL_newlib(L, bitlib);
return 1;
}
/* END CSTYLED */
|
