/*** $Id: lbitlib.c,v 1.16 2011/06/20 16:35:23 roberto Exp $** Standard library for bitwise operations** See Copyright Notice in lua.h*/ #define lbitlib_c#define LUA_LIB #include "lua.h" #include "lauxlib.h"#include "lualib.h"  /* number of bits to consider in a number */#if !defined(LUA_NBITS)#define LUA_NBITS	32#endif  #define ALLONES		(~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1)) /* macro to trim extra bits */#define trim(x)		((x) & ALLONES)  /* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */#define mask(n)		(~((ALLONES << 1) << ((n) - 1)))  typedef lua_Unsigned b_uint;   static b_uint andaux (lua_State *L) {  int i, n = lua_gettop(L);  b_uint r = ~(b_uint)0;  for (i = 1; i <= n; i++)    r &= luaL_checkunsigned(L, i);  return trim(r);}  static int b_and (lua_State *L) {  b_uint r = andaux(L);  lua_pushunsigned(L, r);  return 1;}  static int b_test (lua_State *L) {  b_uint r = andaux(L);  lua_pushboolean(L, r != 0);  return 1;}  static int b_or (lua_State *L) {  int i, n = lua_gettop(L);  b_uint r = 0;  for (i = 1; i <= n; i++)    r |= luaL_checkunsigned(L, i);  lua_pushunsigned(L, trim(r));  return 1;}  static int b_xor (lua_State *L) {  int i, n = lua_gettop(L);  b_uint r = 0;  for (i = 1; i <= n; i++)    r ^= luaL_checkunsigned(L, i);  lua_pushunsigned(L, trim(r));  return 1;}  static int b_not (lua_State *L) {  b_uint r = ~luaL_checkunsigned(L, 1);  lua_pushunsigned(L, trim(r));  return 1;}  static int b_shift (lua_State *L, b_uint r, int i) {  if (i < 0) {  /* shift right? */    i = -i;    r = trim(r);    if (i >= LUA_NBITS) r = 0;    else r >>= i;  }  else {  /* shift left */    if (i >= LUA_NBITS) r = 0;    else r <<= i;    r = trim(r);  }  lua_pushunsigned(L, r);  return 1;}  static int b_lshift (lua_State *L) {  return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));}  static int b_rshift (lua_State *L) {  return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));}  static int b_arshift (lua_State *L) {  b_uint r = luaL_checkunsigned(L, 1);  int i = luaL_checkint(L, 2);  if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1))))    return b_shift(L, r, -i);  else {  /* arithmetic shift for 'negative' number */    if (i >= LUA_NBITS) r = ALLONES;    else      r = trim((r >> i) | ~(~(b_uint)0 >> i));  /* add signal bit */    lua_pushunsigned(L, r);    return 1;  }}  static int b_rot (lua_State *L, int i) {  b_uint r = luaL_checkunsigned(L, 1);  i &= (LUA_NBITS - 1);  /* i = i % NBITS */  r = trim(r);  r = (r << i) | (r >> (LUA_NBITS - i));  lua_pushunsigned(L, trim(r));  return 1;}  static int b_lrot (lua_State *L) {  return b_rot(L, luaL_checkint(L, 2));}  static int b_rrot (lua_State *L) {  return b_rot(L, -luaL_checkint(L, 2));}  /*** get field and width arguments for field-manipulation functions,** checking whether they are valid*/static int fieldargs (lua_State *L, int farg, int *width) {  int f = luaL_checkint(L, farg);  int w = luaL_optint(L, farg + 1, 1);  luaL_argcheck(L, 0 <= f, farg, "field cannot be negative");  luaL_argcheck(L, 0 < w, farg + 1, "width must be positive");  if (f + w > LUA_NBITS)    luaL_error(L, "trying to access non-existent bits");  *width = w;  return f;}  static int b_extract (lua_State *L) {  int w;  b_uint r = luaL_checkunsigned(L, 1);  int f = fieldargs(L, 2, &w);  r = (r >> f) & mask(w);  lua_pushunsigned(L, r);  return 1;}  static int b_replace (lua_State *L) {  int w;  b_uint r = luaL_checkunsigned(L, 1);  b_uint v = luaL_checkunsigned(L, 2);  int f = fieldargs(L, 3, &w);  int m = mask(w);  v &= m;  /* erase bits outside given width */  r = (r & ~(m << f)) | (v << f);  lua_pushunsigned(L, r);  return 1;}  static const luaL_Reg bitlib[] = {  {"arshift", b_arshift},  {"band", b_and},  {"bnot", b_not},  {"bor", b_or},  {"bxor", b_xor},  {"btest", b_test},  {"extract", b_extract},  {"lrotate", b_lrot},  {"lshift", b_lshift},  {"replace", b_replace},  {"rrotate", b_rrot},  {"rshift", b_rshift},  {NULL, NULL}};   LUAMOD_API int luaopen_bit32 (lua_State *L) {  luaL_newlib(L, bitlib);  return 1;}