proxmark3/client/deps/liblua/lbitlib.c

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/*
** $Id: lbitlib.c,v 1.18 2013/03/19 13:19:12 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)
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#define LUA_NBITS 32
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#endif
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#define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
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/* macro to trim extra bits */
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#define trim(x) ((x) & ALLONES)
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/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
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#define mask(n) (~((ALLONES << 1) << ((n) - 1)))
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typedef lua_Unsigned b_uint;
static b_uint andaux(lua_State *L) {
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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);
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}
static int b_and(lua_State *L) {
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b_uint r = andaux(L);
lua_pushunsigned(L, r);
return 1;
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}
static int b_test(lua_State *L) {
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b_uint r = andaux(L);
lua_pushboolean(L, r != 0);
return 1;
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}
static int b_or(lua_State *L) {
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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;
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}
static int b_xor(lua_State *L) {
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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;
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}
static int b_not(lua_State *L) {
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b_uint r = ~luaL_checkunsigned(L, 1);
lua_pushunsigned(L, trim(r));
return 1;
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}
static int b_shift(lua_State *L, b_uint r, int i) {
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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;
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}
static int b_lshift(lua_State *L) {
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return b_shift(L, luaL_checkunsigned(L, 1), luaL_checkint(L, 2));
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}
static int b_rshift(lua_State *L) {
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return b_shift(L, luaL_checkunsigned(L, 1), -luaL_checkint(L, 2));
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}
static int b_arshift(lua_State *L) {
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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;
}
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}
static int b_rot(lua_State *L, int i) {
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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;
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}
static int b_lrot(lua_State *L) {
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return b_rot(L, luaL_checkint(L, 2));
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}
static int b_rrot(lua_State *L) {
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return b_rot(L, -luaL_checkint(L, 2));
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}
/*
** 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) {
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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) {
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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;
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}
static int b_replace(lua_State *L) {
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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;
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}
static const luaL_Reg bitlib[] = {
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{"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}
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};
LUAMOD_API int luaopen_bit32(lua_State *L) {
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luaL_newlib(L, bitlib);
return 1;
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}