source/libs/luajit/lbitlib.c

   1 /*
   2 ** $Id: lbitlib.c,v 1.16 2011/06/20 16:35:23 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 #include "lj_obj.h"
  16 #include "lj_state.h"
  17
  18 /* http://lua-users.org/lists/lua-l/2011-01/msg01039.html */
  19 typedef unsigned int lua_Unsigned;
  20 #define LUA_UNSIGNED unsigned LUA_INT32
  21
  22
  23 #if !defined(lua_unsigned2number)
  24 /* on several machines, coercion from unsigned to double is slow,
  25    so it may be worth to avoid */
  26 #define lua_unsigned2number(u)  \
  27     (((u) <= (lua_Unsigned)INT_MAX) ? (lua_Number)(int)(u) : (lua_Number)( unsigned int )(u))
  28 #endif
  29
  30 #if !defined(lua_lock)
  31 #define lua_lock(L)     ((void) 0)
  32 #define lua_unlock(L)   ((void) 0)
  33 #endif
  34
  35
  36 LUA_API void lua_pushunsigned (lua_State *L, lua_Unsigned u) {
  37   lua_Number n=0;
  38   lua_lock(L);
  39 /*  printf("u=%d,%u,%x\n",u,u,u);
  40   printf("INT_MAX=%d %u %x, (lua_Unsigned)INT_MAX=%d %u %x (unsigned int)INT_MAX=%d %u %x\n",
  41                             INT_MAX,INT_MAX,INT_MAX,
  42                             (lua_Unsigned)INT_MAX,(lua_Unsigned)INT_MAX,(lua_Unsigned)INT_MAX,
  43                             (unsigned int)INT_MAX,(unsigned int)INT_MAX,(unsigned int)INT_MAX);
  44   printf("((u) <= (lua_Unsigned)INT_MAX) :%d\n",(((unsigned int)u) <= (lua_Unsigned)INT_MAX));
  45   printf("(lua_Number)(int)(u) =%d,%u,%x\n",(lua_Number)(int)(u),(lua_Number)(int)(u),(lua_Number)(int)(u));
  46   printf("(lua_Number)(u) =%f,%u,%x\n",(lua_Number)(u),(lua_Number)(u),(lua_Number)(u));
  47   printf("u=%d,%u,%x\n",u,u,u);
  48 */
  49   /*printf("n=%d,%u,%x u=%d,%u,%x\n",n,n,n,u,u,u);    */
  50   n = lua_unsigned2number(u);
  51 /*  printf("n=%f \n",n);
  52   printf("u=%d %u %x n=%d %u %x\n",u,u,u,n,n,n);
  53   printf("n=%d %u %x\n",n,n,n);
  54   printf("u=%d,%u,%x\n",u,u,u);
  55 */
  56 /*  setintptrV(L->top, n);
  57   incr_top(L);
  58   setnumV(L->top, n);
  59 */
  60   setnumV(L->top, n);
  61   if (LJ_UNLIKELY(tvisnan(L->top)))
  62     setnanV(L->top);  /* Canonicalize injected NaNs. */
  63   incr_top(L);
  64   /*setnvalue(L->top, n);
  65   api_incr_top(L);
  66   */
  67   lua_unlock(L);
  68 }
  69
  70
  71
  72
  73
  74
  75 #define luaL_checkunsigned (lua_Unsigned) luaL_checkinteger
  76 /*#define lua_pushunsigned lua_pushinteger*/
  77
  78
  79
  80 /* number of bits to consider in a number */
  81 #if !defined(LUA_NBITS)
  82 #define LUA_NBITS       32
  83 #endif
  84
  85
  86 #define ALLONES         (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
  87
  88 /* macro to trim extra bits */
  89 #define trim(x)         ((x) & ALLONES)
  90
  91
  92 /* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
  93 #define mask(n)         (~((ALLONES << 1) << ((n) - 1)))
  94
  95
  96 typedef lua_Unsigned b_uint;
  97
  98
  99
 100 static b_uint andaux (lua_State *L) {
 101   int i, n = lua_gettop(L);
 102   b_uint r = ~(b_uint)0;
 103 /*  printf("1 r=%d,%u,%x\n",r,r,r);*/
 104   for (i = 1; i <= n; i++)
 105     r &= luaL_checkunsigned(L, i);
 106 /*  printf("2 r=%d,%u,%x\n",r,r,r);
 107   printf("3 r=%d,%u,%x\n",trim(r),trim(r),trim(r));
 108 */
 109   return trim(r);
 110 }
 111
 112
 113 static int b_and (lua_State *L) {
 114   b_uint r = andaux(L);
 115 /*  printf("4 r=%d,%u,%x\n",r,r,r);*/
 116   lua_pushunsigned(L, r);
 117   return 1;
 118 }
 119
 120
 121 static int b_test (lua_State *L) {
 122   b_uint r = andaux(L);
 123   lua_pushboolean(L, r != 0);
 124   return 1;
 125 }
 126
 127
 128 static int b_or (lua_State *L) {
 129   int i, n = lua_gettop(L);
 130   b_uint r = 0;
 131   for (i = 1; i <= n; i++)
 132     r |= luaL_checkunsigned(L, i);
 133   lua_pushunsigned(L, trim(r));
 134   return 1;
 135 }
 136
 137
 138 static int b_xor (lua_State *L) {
 139   int i, n = lua_gettop(L);
 140   b_uint r = 0;
 141   for (i = 1; i <= n; i++)
 142     r ^= luaL_checkunsigned(L, i);
 143   lua_pushunsigned(L, trim(r));
 144   return 1;
 145 }
 146
 147
 148 static int b_not (lua_State *L) {
 149   b_uint r = ~luaL_checkunsigned(L, 1);
 150   lua_pushunsigned(L, trim(r));
 151   return 1;
 152 }
 153
 154
 155 static int b_shift (lua_State *L, b_uint r, int i) {
 156   if (i < 0) {  /* shift right? */
 157     i = -i;
 158     r = trim(r);
 159     if (i >= LUA_NBITS) r = 0;
 160     else r >>= i;
 161   }
 162   else {  /* shift left */
 163     if (i >= LUA_NBITS) r = 0;
 164     else r <<= i;
 165     r = trim(r);
 166   }
 167   lua_pushunsigned(L, r);
 168   return 1;
 169 }
 170
 171
 172 static int b_lshift (lua_State *L) {
 173   return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));
 174 }
 175
 176
 177 static int b_rshift (lua_State *L) {
 178   return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));
 179 }
 180
 181
 182 static int b_arshift (lua_State *L) {
 183   b_uint r = luaL_checkunsigned(L, 1);
 184   int i = luaL_checkint(L, 2);
 185   if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1))))
 186     return b_shift(L, r, -i);
 187   else {  /* arithmetic shift for 'negative' number */
 188     if (i >= LUA_NBITS) r = ALLONES;
 189     else
 190       r = trim((r >> i) | ~(~(b_uint)0 >> i));  /* add signal bit */
 191     lua_pushunsigned(L, r);
 192     return 1;
 193   }
 194 }
 195
 196
 197 static int b_rot (lua_State *L, int i) {
 198   b_uint r = luaL_checkunsigned(L, 1);
 199   i &= (LUA_NBITS - 1);  /* i = i % NBITS */
 200   r = trim(r);
 201   r = (r << i) | (r >> (LUA_NBITS - i));
 202   lua_pushunsigned(L, trim(r));
 203   return 1;
 204 }
 205
 206
 207 static int b_lrot (lua_State *L) {
 208   return b_rot(L, luaL_checkint(L, 2));
 209 }
 210
 211
 212 static int b_rrot (lua_State *L) {
 213   return b_rot(L, -luaL_checkint(L, 2));
 214 }
 215
 216
 217 /*
 218 ** get field and width arguments for field-manipulation functions,
 219 ** checking whether they are valid
 220 */
 221 static int fieldargs (lua_State *L, int farg, int *width) {
 222   int f = luaL_checkint(L, farg);
 223   int w = luaL_optint(L, farg + 1, 1);
 224   luaL_argcheck(L, 0 <= f, farg, "field cannot be negative");
 225   luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");
 226   if (f + w > LUA_NBITS)
 227     luaL_error(L, "trying to access non-existent bits");
 228   *width = w;
 229   return f;
 230 }
 231
 232
 233 static int b_extract (lua_State *L) {
 234   int w;
 235   b_uint r = luaL_checkunsigned(L, 1);
 236   int f = fieldargs(L, 2, &w);
 237   r = (r >> f) & mask(w);
 238   lua_pushunsigned(L, r);
 239   return 1;
 240 }
 241
 242
 243 static int b_replace (lua_State *L) {
 244   int w;
 245   b_uint r = luaL_checkunsigned(L, 1);
 246   b_uint v = luaL_checkunsigned(L, 2);
 247   int f = fieldargs(L, 3, &w);
 248   int m = mask(w);
 249   v &= m;  /* erase bits outside given width */
 250   r = (r & ~(m << f)) | (v << f);
 251   lua_pushunsigned(L, r);
 252   return 1;
 253 }
 254
 255
 256 static const luaL_Reg bitlib[] = {
 257   {"arshift", b_arshift},
 258   {"band", b_and},
 259   {"bnot", b_not},
 260   {"bor", b_or},
 261   {"bxor", b_xor},
 262   {"btest", b_test},
 263   {"extract", b_extract},
 264   {"lrotate", b_lrot},
 265   {"lshift", b_lshift},
 266   {"replace", b_replace},
 267   {"rrotate", b_rrot},
 268   {"rshift", b_rshift},
 269   {NULL, NULL}
 270 };
 271
 272
 273
 274 /* http://lua-users.org/lists/lua-l/2011-01/msg01039.html */
 275
 276 /*LUAMOD_API int luaopen_bit32 (lua_State *L) {*/
 277 /*  luaL_newlib(L, bitlib);*/
 278 /*  return 1;*/
 279 /*} */
 280
 281 int luaopen_bit32 (lua_State *L) {
 282   luaL_register(L, "bit32", bitlib);
 283   return 1;
 284 }
 285
 286
 287