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comparison lib/lua/lua-5.2.2/lbitlib.c @ 1866:41cc4dd3c122

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Lua 5.2.2 added.
author Nomad
date Wed, 16 Oct 2013 13:34:26 +0200
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1848:3b39b70e8e93 1866:41cc4dd3c122
1 /*
2 ** $Id: lbitlib.c,v 1.18 2013/03/19 13:19:12 roberto Exp $
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 "lua.h"
11
12 #include "lauxlib.h"
13 #include "lualib.h"
14
15
16 /* number of bits to consider in a number */
17 #if !defined(LUA_NBITS)
18 #define LUA_NBITS 32
19 #endif
20
21
22 #define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
23
24 /* macro to trim extra bits */
25 #define trim(x) ((x) & ALLONES)
26
27
28 /* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
29 #define mask(n) (~((ALLONES << 1) << ((n) - 1)))
30
31
32 typedef lua_Unsigned b_uint;
33
34
35
36 static b_uint andaux (lua_State *L) {
37 int i, n = lua_gettop(L);
38 b_uint r = ~(b_uint)0;
39 for (i = 1; i <= n; i++)
40 r &= luaL_checkunsigned(L, i);
41 return trim(r);
42 }
43
44
45 static int b_and (lua_State *L) {
46 b_uint r = andaux(L);
47 lua_pushunsigned(L, r);
48 return 1;
49 }
50
51
52 static int b_test (lua_State *L) {
53 b_uint r = andaux(L);
54 lua_pushboolean(L, r != 0);
55 return 1;
56 }
57
58
59 static int b_or (lua_State *L) {
60 int i, n = lua_gettop(L);
61 b_uint r = 0;
62 for (i = 1; i <= n; i++)
63 r |= luaL_checkunsigned(L, i);
64 lua_pushunsigned(L, trim(r));
65 return 1;
66 }
67
68
69 static int b_xor (lua_State *L) {
70 int i, n = lua_gettop(L);
71 b_uint r = 0;
72 for (i = 1; i <= n; i++)
73 r ^= luaL_checkunsigned(L, i);
74 lua_pushunsigned(L, trim(r));
75 return 1;
76 }
77
78
79 static int b_not (lua_State *L) {
80 b_uint r = ~luaL_checkunsigned(L, 1);
81 lua_pushunsigned(L, trim(r));
82 return 1;
83 }
84
85
86 static int b_shift (lua_State *L, b_uint r, int i) {
87 if (i < 0) { /* shift right? */
88 i = -i;
89 r = trim(r);
90 if (i >= LUA_NBITS) r = 0;
91 else r >>= i;
92 }
93 else { /* shift left */
94 if (i >= LUA_NBITS) r = 0;
95 else r <<= i;
96 r = trim(r);
97 }
98 lua_pushunsigned(L, r);
99 return 1;
100 }
101
102
103 static int b_lshift (lua_State *L) {
104 return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));
105 }
106
107
108 static int b_rshift (lua_State *L) {
109 return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));
110 }
111
112
113 static int b_arshift (lua_State *L) {
114 b_uint r = luaL_checkunsigned(L, 1);
115 int i = luaL_checkint(L, 2);
116 if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1))))
117 return b_shift(L, r, -i);
118 else { /* arithmetic shift for 'negative' number */
119 if (i >= LUA_NBITS) r = ALLONES;
120 else
121 r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */
122 lua_pushunsigned(L, r);
123 return 1;
124 }
125 }
126
127
128 static int b_rot (lua_State *L, int i) {
129 b_uint r = luaL_checkunsigned(L, 1);
130 i &= (LUA_NBITS - 1); /* i = i % NBITS */
131 r = trim(r);
132 r = (r << i) | (r >> (LUA_NBITS - i));
133 lua_pushunsigned(L, trim(r));
134 return 1;
135 }
136
137
138 static int b_lrot (lua_State *L) {
139 return b_rot(L, luaL_checkint(L, 2));
140 }
141
142
143 static int b_rrot (lua_State *L) {
144 return b_rot(L, -luaL_checkint(L, 2));
145 }
146
147
148 /*
149 ** get field and width arguments for field-manipulation functions,
150 ** checking whether they are valid.
151 ** ('luaL_error' called without 'return' to avoid later warnings about
152 ** 'width' being used uninitialized.)
153 */
154 static int fieldargs (lua_State *L, int farg, int *width) {
155 int f = luaL_checkint(L, farg);
156 int w = luaL_optint(L, farg + 1, 1);
157 luaL_argcheck(L, 0 <= f, farg, "field cannot be negative");
158 luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");
159 if (f + w > LUA_NBITS)
160 luaL_error(L, "trying to access non-existent bits");
161 *width = w;
162 return f;
163 }
164
165
166 static int b_extract (lua_State *L) {
167 int w;
168 b_uint r = luaL_checkunsigned(L, 1);
169 int f = fieldargs(L, 2, &w);
170 r = (r >> f) & mask(w);
171 lua_pushunsigned(L, r);
172 return 1;
173 }
174
175
176 static int b_replace (lua_State *L) {
177 int w;
178 b_uint r = luaL_checkunsigned(L, 1);
179 b_uint v = luaL_checkunsigned(L, 2);
180 int f = fieldargs(L, 3, &w);
181 int m = mask(w);
182 v &= m; /* erase bits outside given width */
183 r = (r & ~(m << f)) | (v << f);
184 lua_pushunsigned(L, r);
185 return 1;
186 }
187
188
189 static const luaL_Reg bitlib[] = {
190 {"arshift", b_arshift},
191 {"band", b_and},
192 {"bnot", b_not},
193 {"bor", b_or},
194 {"bxor", b_xor},
195 {"btest", b_test},
196 {"extract", b_extract},
197 {"lrotate", b_lrot},
198 {"lshift", b_lshift},
199 {"replace", b_replace},
200 {"rrotate", b_rrot},
201 {"rshift", b_rshift},
202 {NULL, NULL}
203 };
204
205
206
207 LUAMOD_API int luaopen_bit32 (lua_State *L) {
208 luaL_newlib(L, bitlib);
209 return 1;
210 }
211