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7c673cae | 1 | /* |
11fdf7f2 | 2 | ** $Id: lbitlib.c,v 1.30 2015/11/11 19:08:09 roberto Exp $ |
7c673cae FG |
3 | ** Standard library for bitwise operations |
4 | ** See Copyright Notice in lua.h | |
5 | */ | |
6 | ||
7 | #define lbitlib_c | |
8 | #define LUA_LIB | |
9 | ||
10 | #include "lprefix.h" | |
11 | ||
12 | ||
13 | #include "lua.h" | |
14 | ||
15 | #include "lauxlib.h" | |
16 | #include "lualib.h" | |
17 | ||
18 | ||
19 | #if defined(LUA_COMPAT_BITLIB) /* { */ | |
20 | ||
21 | ||
11fdf7f2 TL |
22 | #define pushunsigned(L,n) lua_pushinteger(L, (lua_Integer)(n)) |
23 | #define checkunsigned(L,i) ((lua_Unsigned)luaL_checkinteger(L,i)) | |
24 | ||
25 | ||
7c673cae FG |
26 | /* number of bits to consider in a number */ |
27 | #if !defined(LUA_NBITS) | |
28 | #define LUA_NBITS 32 | |
29 | #endif | |
30 | ||
31 | ||
32 | /* | |
33 | ** a lua_Unsigned with its first LUA_NBITS bits equal to 1. (Shift must | |
34 | ** be made in two parts to avoid problems when LUA_NBITS is equal to the | |
35 | ** number of bits in a lua_Unsigned.) | |
36 | */ | |
37 | #define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1)) | |
38 | ||
39 | ||
40 | /* macro to trim extra bits */ | |
41 | #define trim(x) ((x) & ALLONES) | |
42 | ||
43 | ||
44 | /* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */ | |
45 | #define mask(n) (~((ALLONES << 1) << ((n) - 1))) | |
46 | ||
47 | ||
48 | ||
49 | static lua_Unsigned andaux (lua_State *L) { | |
50 | int i, n = lua_gettop(L); | |
51 | lua_Unsigned r = ~(lua_Unsigned)0; | |
52 | for (i = 1; i <= n; i++) | |
11fdf7f2 | 53 | r &= checkunsigned(L, i); |
7c673cae FG |
54 | return trim(r); |
55 | } | |
56 | ||
57 | ||
58 | static int b_and (lua_State *L) { | |
59 | lua_Unsigned r = andaux(L); | |
11fdf7f2 | 60 | pushunsigned(L, r); |
7c673cae FG |
61 | return 1; |
62 | } | |
63 | ||
64 | ||
65 | static int b_test (lua_State *L) { | |
66 | lua_Unsigned r = andaux(L); | |
67 | lua_pushboolean(L, r != 0); | |
68 | return 1; | |
69 | } | |
70 | ||
71 | ||
72 | static int b_or (lua_State *L) { | |
73 | int i, n = lua_gettop(L); | |
74 | lua_Unsigned r = 0; | |
75 | for (i = 1; i <= n; i++) | |
11fdf7f2 TL |
76 | r |= checkunsigned(L, i); |
77 | pushunsigned(L, trim(r)); | |
7c673cae FG |
78 | return 1; |
79 | } | |
80 | ||
81 | ||
82 | static int b_xor (lua_State *L) { | |
83 | int i, n = lua_gettop(L); | |
84 | lua_Unsigned r = 0; | |
85 | for (i = 1; i <= n; i++) | |
11fdf7f2 TL |
86 | r ^= checkunsigned(L, i); |
87 | pushunsigned(L, trim(r)); | |
7c673cae FG |
88 | return 1; |
89 | } | |
90 | ||
91 | ||
92 | static int b_not (lua_State *L) { | |
11fdf7f2 TL |
93 | lua_Unsigned r = ~checkunsigned(L, 1); |
94 | pushunsigned(L, trim(r)); | |
7c673cae FG |
95 | return 1; |
96 | } | |
97 | ||
98 | ||
99 | static int b_shift (lua_State *L, lua_Unsigned r, lua_Integer i) { | |
100 | if (i < 0) { /* shift right? */ | |
101 | i = -i; | |
102 | r = trim(r); | |
103 | if (i >= LUA_NBITS) r = 0; | |
104 | else r >>= i; | |
105 | } | |
106 | else { /* shift left */ | |
107 | if (i >= LUA_NBITS) r = 0; | |
108 | else r <<= i; | |
109 | r = trim(r); | |
110 | } | |
11fdf7f2 | 111 | pushunsigned(L, r); |
7c673cae FG |
112 | return 1; |
113 | } | |
114 | ||
115 | ||
116 | static int b_lshift (lua_State *L) { | |
11fdf7f2 | 117 | return b_shift(L, checkunsigned(L, 1), luaL_checkinteger(L, 2)); |
7c673cae FG |
118 | } |
119 | ||
120 | ||
121 | static int b_rshift (lua_State *L) { | |
11fdf7f2 | 122 | return b_shift(L, checkunsigned(L, 1), -luaL_checkinteger(L, 2)); |
7c673cae FG |
123 | } |
124 | ||
125 | ||
126 | static int b_arshift (lua_State *L) { | |
11fdf7f2 | 127 | lua_Unsigned r = checkunsigned(L, 1); |
7c673cae FG |
128 | lua_Integer i = luaL_checkinteger(L, 2); |
129 | if (i < 0 || !(r & ((lua_Unsigned)1 << (LUA_NBITS - 1)))) | |
130 | return b_shift(L, r, -i); | |
131 | else { /* arithmetic shift for 'negative' number */ | |
132 | if (i >= LUA_NBITS) r = ALLONES; | |
133 | else | |
134 | r = trim((r >> i) | ~(trim(~(lua_Unsigned)0) >> i)); /* add signal bit */ | |
11fdf7f2 | 135 | pushunsigned(L, r); |
7c673cae FG |
136 | return 1; |
137 | } | |
138 | } | |
139 | ||
140 | ||
141 | static int b_rot (lua_State *L, lua_Integer d) { | |
11fdf7f2 | 142 | lua_Unsigned r = checkunsigned(L, 1); |
7c673cae FG |
143 | int i = d & (LUA_NBITS - 1); /* i = d % NBITS */ |
144 | r = trim(r); | |
145 | if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */ | |
146 | r = (r << i) | (r >> (LUA_NBITS - i)); | |
11fdf7f2 | 147 | pushunsigned(L, trim(r)); |
7c673cae FG |
148 | return 1; |
149 | } | |
150 | ||
151 | ||
152 | static int b_lrot (lua_State *L) { | |
153 | return b_rot(L, luaL_checkinteger(L, 2)); | |
154 | } | |
155 | ||
156 | ||
157 | static int b_rrot (lua_State *L) { | |
158 | return b_rot(L, -luaL_checkinteger(L, 2)); | |
159 | } | |
160 | ||
161 | ||
162 | /* | |
163 | ** get field and width arguments for field-manipulation functions, | |
164 | ** checking whether they are valid. | |
165 | ** ('luaL_error' called without 'return' to avoid later warnings about | |
166 | ** 'width' being used uninitialized.) | |
167 | */ | |
168 | static int fieldargs (lua_State *L, int farg, int *width) { | |
169 | lua_Integer f = luaL_checkinteger(L, farg); | |
170 | lua_Integer w = luaL_optinteger(L, farg + 1, 1); | |
171 | luaL_argcheck(L, 0 <= f, farg, "field cannot be negative"); | |
172 | luaL_argcheck(L, 0 < w, farg + 1, "width must be positive"); | |
173 | if (f + w > LUA_NBITS) | |
174 | luaL_error(L, "trying to access non-existent bits"); | |
175 | *width = (int)w; | |
176 | return (int)f; | |
177 | } | |
178 | ||
179 | ||
180 | static int b_extract (lua_State *L) { | |
181 | int w; | |
11fdf7f2 | 182 | lua_Unsigned r = trim(checkunsigned(L, 1)); |
7c673cae FG |
183 | int f = fieldargs(L, 2, &w); |
184 | r = (r >> f) & mask(w); | |
11fdf7f2 | 185 | pushunsigned(L, r); |
7c673cae FG |
186 | return 1; |
187 | } | |
188 | ||
189 | ||
190 | static int b_replace (lua_State *L) { | |
191 | int w; | |
11fdf7f2 TL |
192 | lua_Unsigned r = trim(checkunsigned(L, 1)); |
193 | lua_Unsigned v = trim(checkunsigned(L, 2)); | |
7c673cae | 194 | int f = fieldargs(L, 3, &w); |
11fdf7f2 TL |
195 | lua_Unsigned m = mask(w); |
196 | r = (r & ~(m << f)) | ((v & m) << f); | |
197 | pushunsigned(L, r); | |
7c673cae FG |
198 | return 1; |
199 | } | |
200 | ||
201 | ||
202 | static const luaL_Reg bitlib[] = { | |
203 | {"arshift", b_arshift}, | |
204 | {"band", b_and}, | |
205 | {"bnot", b_not}, | |
206 | {"bor", b_or}, | |
207 | {"bxor", b_xor}, | |
208 | {"btest", b_test}, | |
209 | {"extract", b_extract}, | |
210 | {"lrotate", b_lrot}, | |
211 | {"lshift", b_lshift}, | |
212 | {"replace", b_replace}, | |
213 | {"rrotate", b_rrot}, | |
214 | {"rshift", b_rshift}, | |
215 | {NULL, NULL} | |
216 | }; | |
217 | ||
218 | ||
219 | ||
220 | LUAMOD_API int luaopen_bit32 (lua_State *L) { | |
221 | luaL_newlib(L, bitlib); | |
222 | return 1; | |
223 | } | |
224 | ||
225 | ||
226 | #else /* }{ */ | |
227 | ||
228 | ||
229 | LUAMOD_API int luaopen_bit32 (lua_State *L) { | |
230 | return luaL_error(L, "library 'bit32' has been deprecated"); | |
231 | } | |
232 | ||
233 | #endif /* } */ |