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-rw-r--r--apps/plugins/lua/lbitlib.c268
1 files changed, 91 insertions, 177 deletions
diff --git a/apps/plugins/lua/lbitlib.c b/apps/plugins/lua/lbitlib.c
index 31c7b66f12..76c8d1d39b 100644
--- a/apps/plugins/lua/lbitlib.c
+++ b/apps/plugins/lua/lbitlib.c
@@ -1,212 +1,126 @@
1/* 1/* Bitwise operations library */
2** $Id: lbitlib.c,v 1.18.1.2 2013/07/09 18:01:41 roberto Exp $ 2/* (c) Reuben Thomas 2000-2008 */
3** Standard library for bitwise operations 3/* bitlib is copyright Reuben Thomas 2000-2008, and is released under the MIT
4** See Copyright Notice in lua.h 4 license, like Lua (see http://www.lua.org/copyright.html; it's
5*/ 5 basically the same as the BSD license). There is no warranty. */
6 6
7#define lbitlib_c 7#include "config.h"
8#define LUA_LIB
9 8
10#include "lua.h" 9#include "lua.h"
11
12#include "lauxlib.h" 10#include "lauxlib.h"
13#include "lualib.h" 11#include "lualib.h"
12#include <limits.h>
14 13
15 14
16/* number of bits to consider in a number */ 15/* FIXME: Assume lua_Integer is ptrdiff_t */
17#if !defined(LUA_NBITS) 16#define LUA_INTEGER_MAX INTPTR_MAX
18#define LUA_NBITS 32 17#define LUA_INTEGER_MIN INTPTR_MIN
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 18
19/* FIXME: Assume size_t is an unsigned lua_Integer */
20typedef size_t lua_UInteger;
21#define LUA_UINTEGER_MAX UINT_MAX
31 22
32typedef lua_Unsigned b_uint;
33 23
24/* Bit type size and limits */
34 25
26#define BIT_BITS (CHAR_BIT * sizeof(lua_Integer))
35 27
36static b_uint andaux (lua_State *L) { 28/* This code may give warnings if BITLIB_FLOAT_* are too big to fit in
37 int i, n = lua_gettop(L); 29 long, but that doesn't matter since in that case they won't be
38 b_uint r = ~(b_uint)0; 30 used. */
39 for (i = 1; i <= n; i++) 31#define BIT_MAX (LUA_INTEGER_MAX)
40 r &= luaL_checkunsigned(L, i);
41 return trim(r);
42}
43 32
33#define BIT_MIN (LUA_INTEGER_MIN)
44 34
45static int b_and (lua_State *L) { 35#define BIT_UMAX (LUA_UINTEGER_MAX)
46 b_uint r = andaux(L);
47 lua_pushunsigned(L, r);
48 return 1;
49}
50 36
51 37
52static int b_test (lua_State *L) { 38/* Define TOBIT to get a bit value */
53 b_uint r = andaux(L); 39#ifdef BUILTIN_CAST
54 lua_pushboolean(L, r != 0); 40#define
55 return 1; 41#define TOBIT(L, n, res) \
56} 42 ((void)(res), luaL_checkinteger((L), (n)))
43#else
57 44
45#define TOBIT(L, n, res) \
46 ((lua_Integer)(((res) = luaL_checknumber(L, (n)) % BIT_UMAX), \
47 (res) > BIT_MAX ? ((res) -= BIT_UMAX, (res) -= 1) : \
48 ((res) < BIT_MIN ? ((res) += BIT_UMAX, (res) += 1) : (res))))
49#endif
58 50
59static 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 51
52#define BIT_TRUNCATE(i) \
53 ((i) & BIT_UMAX)
68 54
69static 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 55
56/* Operations
78 57
79static int b_not (lua_State *L) { 58 The macros MONADIC and VARIADIC only deal with bitwise operations.
80 b_uint r = ~luaL_checkunsigned(L, 1);
81 lua_pushunsigned(L, trim(r));
82 return 1;
83}
84 59
60 LOGICAL_SHIFT truncates its left-hand operand before shifting so
61 that any extra bits at the most-significant end are not shifted
62 into the result.
85 63
86static int b_shift (lua_State *L, b_uint r, int i) { 64 ARITHMETIC_SHIFT does not truncate its left-hand operand, so that
87 if (i < 0) { /* shift right? */ 65 the sign bits are not removed and right shift work properly.
88 i = -i; 66 */
89 r = trim(r); 67
90 if (i >= LUA_NBITS) r = 0; 68#define MONADIC(name, op) \
91 else r >>= i; 69 static int bit_ ## name(lua_State *L) { \
92 } 70 lua_Number f; \
93 else { /* shift left */ 71 lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f))); \
94 if (i >= LUA_NBITS) r = 0; 72 return 1; \
95 else r <<= i;
96 r = trim(r);
97 } 73 }
98 lua_pushunsigned(L, r);
99 return 1;
100}
101
102
103static int b_lshift (lua_State *L) {
104 return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));
105}
106
107
108static int b_rshift (lua_State *L) {
109 return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));
110}
111 74
112 75#define VARIADIC(name, op) \
113static int b_arshift (lua_State *L) { 76 static int bit_ ## name(lua_State *L) { \
114 b_uint r = luaL_checkunsigned(L, 1); 77 lua_Number f; \
115 int i = luaL_checkint(L, 2); 78 int n = lua_gettop(L), i; \
116 if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1)))) 79 lua_Integer w = TOBIT(L, 1, f); \
117 return b_shift(L, r, -i); 80 for (i = 2; i <= n; i++) \
118 else { /* arithmetic shift for 'negative' number */ 81 w op TOBIT(L, i, f); \
119 if (i >= LUA_NBITS) r = ALLONES; 82 lua_pushinteger(L, BIT_TRUNCATE(w)); \
120 else 83 return 1; \
121 r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */
122 lua_pushunsigned(L, r);
123 return 1;
124 } 84 }
125}
126
127
128static 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 if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */
133 r = (r << i) | (r >> (LUA_NBITS - i));
134 lua_pushunsigned(L, trim(r));
135 return 1;
136}
137
138 85
139static int b_lrot (lua_State *L) { 86#define LOGICAL_SHIFT(name, op) \
140 return b_rot(L, luaL_checkint(L, 2)); 87 static int bit_ ## name(lua_State *L) { \
141} 88 lua_Number f; \
142 89 lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \
143 90 (unsigned)luaL_checknumber(L, 2))); \
144static int b_rrot (lua_State *L) { 91 return 1; \
145 return b_rot(L, -luaL_checkint(L, 2)); 92 }
146}
147
148
149/*
150** get field and width arguments for field-manipulation functions,
151** checking whether they are valid.
152** ('luaL_error' called without 'return' to avoid later warnings about
153** 'width' being used uninitialized.)
154*/
155static int fieldargs (lua_State *L, int farg, int *width) {
156 int f = luaL_checkint(L, farg);
157 int w = luaL_optint(L, farg + 1, 1);
158 luaL_argcheck(L, 0 <= f, farg, "field cannot be negative");
159 luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");
160 if (f + w > LUA_NBITS)
161 luaL_error(L, "trying to access non-existent bits");
162 *width = w;
163 return f;
164}
165
166
167static int b_extract (lua_State *L) {
168 int w;
169 b_uint r = luaL_checkunsigned(L, 1);
170 int f = fieldargs(L, 2, &w);
171 r = (r >> f) & mask(w);
172 lua_pushunsigned(L, r);
173 return 1;
174}
175
176
177static int b_replace (lua_State *L) {
178 int w;
179 b_uint r = luaL_checkunsigned(L, 1);
180 b_uint v = luaL_checkunsigned(L, 2);
181 int f = fieldargs(L, 3, &w);
182 int m = mask(w);
183 v &= m; /* erase bits outside given width */
184 r = (r & ~(m << f)) | (v << f);
185 lua_pushunsigned(L, r);
186 return 1;
187}
188 93
94#define ARITHMETIC_SHIFT(name, op) \
95 static int bit_ ## name(lua_State *L) { \
96 lua_Number f; \
97 lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op \
98 (unsigned)luaL_checknumber(L, 2))); \
99 return 1; \
100 }
189 101
190static const luaL_Reg bitlib[] = { 102MONADIC(bnot, ~)
191 {"arshift", b_arshift}, 103VARIADIC(band, &=)
192 {"band", b_and}, 104VARIADIC(bor, |=)
193 {"bnot", b_not}, 105VARIADIC(bxor, ^=)
194 {"bor", b_or}, 106ARITHMETIC_SHIFT(lshift, <<)
195 {"bxor", b_xor}, 107LOGICAL_SHIFT(rshift, >>)
196 {"btest", b_test}, 108ARITHMETIC_SHIFT(arshift, >>)
197 {"extract", b_extract}, 109
198 {"lrotate", b_lrot}, 110static const struct luaL_reg bitlib[] = {
199 {"lshift", b_lshift}, 111 {"bnot", bit_bnot},
200 {"replace", b_replace}, 112 {"band", bit_band},
201 {"rrotate", b_rrot}, 113 {"bor", bit_bor},
202 {"rshift", b_rshift}, 114 {"bxor", bit_bxor},
115 {"lshift", bit_lshift},
116 {"rshift", bit_rshift},
117 {"arshift", bit_arshift},
203 {NULL, NULL} 118 {NULL, NULL}
204}; 119};
205 120
206 121LUALIB_API int luaopen_bit (lua_State *L) {
207 122 luaL_register(L, "bit", bitlib);
208LUAMOD_API int luaopen_bit32 (lua_State *L) { 123 lua_pushnumber(L, BIT_BITS);
209 luaL_newlib(L, bitlib); 124 lua_setfield(L, -2, "bits");
210 return 1; 125 return 1;
211} 126}
212
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