/lua/lbitlib.c
C | 212 lines | 147 code | 51 blank | 14 comment | 17 complexity | db303cadee91312e2f365e0b8fe5998e MD5 | raw file
Possible License(s): GPL-3.0, GPL-2.0
- /*
- ** $Id: lbitlib.c,v 1.18.1.2 2013/07/09 18:01:41 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);
- if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */
- 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.
- ** ('luaL_error' called without 'return' to avoid later warnings about
- ** 'width' being used uninitialized.)
- */
- 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;
- }