ceph/src/civetweb/src/third_party/lua-5.3.3/src/lbitlib.c

   1 /*
   2 ** $Id: lbitlib.c,v 1.30 2015/11/11 19:08:09 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 "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
  22 #define pushunsigned(L,n)       lua_pushinteger(L, (lua_Integer)(n))
  23 #define checkunsigned(L,i)      ((lua_Unsigned)luaL_checkinteger(L,i))
  24
  25
  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++)
  53     r &= checkunsigned(L, i);
  54   return trim(r);
  55 }
  56
  57
  58 static int b_and (lua_State *L) {
  59   lua_Unsigned r = andaux(L);
  60   pushunsigned(L, r);
  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++)
  76     r |= checkunsigned(L, i);
  77   pushunsigned(L, trim(r));
  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++)
  86     r ^= checkunsigned(L, i);
  87   pushunsigned(L, trim(r));
  88   return 1;
  89 }
  90
  91
  92 static int b_not (lua_State *L) {
  93   lua_Unsigned r = ~checkunsigned(L, 1);
  94   pushunsigned(L, trim(r));
  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   }
 111   pushunsigned(L, r);
 112   return 1;
 113 }
 114
 115
 116 static int b_lshift (lua_State *L) {
 117   return b_shift(L, checkunsigned(L, 1), luaL_checkinteger(L, 2));
 118 }
 119
 120
 121 static int b_rshift (lua_State *L) {
 122   return b_shift(L, checkunsigned(L, 1), -luaL_checkinteger(L, 2));
 123 }
 124
 125
 126 static int b_arshift (lua_State *L) {
 127   lua_Unsigned r = checkunsigned(L, 1);
 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 */
 135     pushunsigned(L, r);
 136     return 1;
 137   }
 138 }
 139
 140
 141 static int b_rot (lua_State *L, lua_Integer d) {
 142   lua_Unsigned r = checkunsigned(L, 1);
 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));
 147   pushunsigned(L, trim(r));
 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;
 182   lua_Unsigned r = trim(checkunsigned(L, 1));
 183   int f = fieldargs(L, 2, &w);
 184   r = (r >> f) & mask(w);
 185   pushunsigned(L, r);
 186   return 1;
 187 }
 188
 189
 190 static int b_replace (lua_State *L) {
 191   int w;
 192   lua_Unsigned r = trim(checkunsigned(L, 1));
 193   lua_Unsigned v = trim(checkunsigned(L, 2));
 194   int f = fieldargs(L, 3, &w);
 195   lua_Unsigned m = mask(w);
 196   r = (r & ~(m << f)) | ((v & m) << f);
 197   pushunsigned(L, r);
 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                                  /* } */