1 files changed, 177 insertions, 91 deletions

diff --git a/apps/plugins/lua/lbitlib.c b/apps/plugins/lua/lbitlib.c
index 76c8d1d39b..31c7b66f12 100644
--- a/apps/plugins/lua/lbitlib.c
+++ b/apps/plugins/lua/lbitlib.c
@@ -1,126 +1,212 @@
-/* Bitwise operations library */
-/* (c) Reuben Thomas 2000-2008 */
-/* bitlib is copyright Reuben Thomas 2000-2008, and is released under the MIT
-   license, like Lua (see http://www.lua.org/copyright.html; it's
-   basically the same as the BSD license). There is no warranty. */
+/*
+** $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
+*/
 
-#include "config.h"
+#define lbitlib_c
+#define LUA_LIB
 
 #include "lua.h"
+
 #include "lauxlib.h"
 #include "lualib.h"
-#include <limits.h>
 
 
-/* FIXME: Assume lua_Integer is ptrdiff_t */
-#define LUA_INTEGER_MAX INTPTR_MAX
-#define LUA_INTEGER_MIN INTPTR_MIN
+/* number of bits to consider in a number */
+#if !defined(LUA_NBITS)
+#define LUA_NBITS       32
+#endif
 
-/* FIXME: Assume size_t is an unsigned lua_Integer */
-typedef size_t lua_UInteger;
-#define LUA_UINTEGER_MAX UINT_MAX
 
+#define ALLONES         (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1))
 
-/* Bit type size and limits */
+/* macro to trim extra bits */
+#define trim(x)         ((x) & ALLONES)
 
-#define BIT_BITS (CHAR_BIT * sizeof(lua_Integer))
 
-/* This code may give warnings if BITLIB_FLOAT_* are too big to fit in
-   long, but that doesn't matter since in that case they won't be
-   used. */
-#define BIT_MAX  (LUA_INTEGER_MAX)
+/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */
+#define mask(n)         (~((ALLONES << 1) << ((n) - 1)))
 
-#define BIT_MIN  (LUA_INTEGER_MIN)
 
-#define BIT_UMAX (LUA_UINTEGER_MAX)
+typedef lua_Unsigned b_uint;
 
 
-/* Define TOBIT to get a bit value */
-#ifdef BUILTIN_CAST
-#define 
-#define TOBIT(L, n, res)                    \
-  ((void)(res), luaL_checkinteger((L), (n)))
-#else
 
-#define TOBIT(L, n, res)                                            \
-  ((lua_Integer)(((res) = luaL_checknumber(L, (n)) % BIT_UMAX), \
-                 (res) > BIT_MAX ? ((res) -= BIT_UMAX, (res) -= 1) : \
-                 ((res) < BIT_MIN ? ((res) += BIT_UMAX, (res) += 1) : (res))))
-#endif
+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);
+}
 
 
-#define BIT_TRUNCATE(i)                         \
-  ((i) & BIT_UMAX)
+static int b_and (lua_State *L) {
+  b_uint r = andaux(L);
+  lua_pushunsigned(L, r);
+  return 1;
+}
 
 
-/* Operations
+static int b_test (lua_State *L) {
+  b_uint r = andaux(L);
+  lua_pushboolean(L, r != 0);
+  return 1;
+}
 
-   The macros MONADIC and VARIADIC only deal with bitwise operations.
 
-   LOGICAL_SHIFT truncates its left-hand operand before shifting so
-   that any extra bits at the most-significant end are not shifted
-   into the result.
+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;
+}
 
-   ARITHMETIC_SHIFT does not truncate its left-hand operand, so that
-   the sign bits are not removed and right shift work properly.
-   */
-  
-#define MONADIC(name, op)                                       \
-  static int bit_ ## name(lua_State *L) {                       \
-    lua_Number f;                                               \
-    lua_pushinteger(L, BIT_TRUNCATE(op TOBIT(L, 1, f)));        \
-    return 1;                                                   \
-  }
 
-#define VARIADIC(name, op)                      \
-  static int bit_ ## name(lua_State *L) {       \
-    lua_Number f;                               \
-    int n = lua_gettop(L), i;                   \
-    lua_Integer w = TOBIT(L, 1, f);             \
-    for (i = 2; i <= n; i++)                    \
-      w op TOBIT(L, i, f);                      \
-    lua_pushinteger(L, BIT_TRUNCATE(w));        \
-    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;
+}
 
-#define LOGICAL_SHIFT(name, op)                                         \
-  static int bit_ ## name(lua_State *L) {                               \
-    lua_Number f;                                                       \
-    lua_pushinteger(L, BIT_TRUNCATE(BIT_TRUNCATE((lua_UInteger)TOBIT(L, 1, f)) op \
-                                    (unsigned)luaL_checknumber(L, 2))); \
-    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));
+}
 
-#define ARITHMETIC_SHIFT(name, op)                                      \
-  static int bit_ ## name(lua_State *L) {                               \
-    lua_Number f;                                                       \
-    lua_pushinteger(L, BIT_TRUNCATE((lua_Integer)TOBIT(L, 1, f) op      \
-                                    (unsigned)luaL_checknumber(L, 2))); \
-    return 1;                                                           \
+
+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;
+}
+
 
-MONADIC(bnot,  ~)
-VARIADIC(band, &=)
-VARIADIC(bor,  |=)
-VARIADIC(bxor, ^=)
-ARITHMETIC_SHIFT(lshift,  <<)
-LOGICAL_SHIFT(rshift,     >>)
-ARITHMETIC_SHIFT(arshift, >>)
-
-static const struct luaL_reg bitlib[] = {
-  {"bnot",    bit_bnot},
-  {"band",    bit_band},
-  {"bor",     bit_bor},
-  {"bxor",    bit_bxor},
-  {"lshift",  bit_lshift},
-  {"rshift",  bit_rshift},
-  {"arshift", bit_arshift},
+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}
 };
 
-LUALIB_API int luaopen_bit (lua_State *L) {
-  luaL_register(L, "bit", bitlib);
-  lua_pushnumber(L, BIT_BITS);
-  lua_setfield(L, -2, "bits");
+
+
+LUAMOD_API int luaopen_bit32 (lua_State *L) {
+  luaL_newlib(L, bitlib);
   return 1;
 }
+