Add bit32 library

4 files changed, 298 insertions, 0 deletions

diff --git a/lbitlib.c b/lbitlib.c
new file mode 100644
index 0000000..4786c0d
--- /dev/null
+++ b/lbitlib.c
@@ -0,0 +1,233 @@
+/*
+** $Id: lbitlib.c,v 1.30.1.1 2017/04/19 17:20:42 roberto Exp $
+** Standard library for bitwise operations
+** See Copyright Notice in lua.h
+*/
+
+#define lbitlib_c
+#define LUA_LIB
+
+#include "lprefix.h"
+
+
+#include "lua.h"
+
+#include "lauxlib.h"
+#include "lualib.h"
+
+
+#if defined(LUA_COMPAT_BITLIB)          /* { */
+
+
+#define pushunsigned(L,n)       lua_pushinteger(L, (lua_Integer)(n))
+#define checkunsigned(L,i)      ((lua_Unsigned)luaL_checkinteger(L,i))
+
+
+/* number of bits to consider in a number */
+#if !defined(LUA_NBITS)
+#define LUA_NBITS       32
+#endif
+
+
+/*
+** a lua_Unsigned with its first LUA_NBITS bits equal to 1. (Shift must
+** be made in two parts to avoid problems when LUA_NBITS is equal to the
+** number of bits in a lua_Unsigned.)
+*/
+#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)))
+
+
+
+static lua_Unsigned andaux (lua_State *L) {
+  int i, n = lua_gettop(L);
+  lua_Unsigned r = ~(lua_Unsigned)0;
+  for (i = 1; i <= n; i++)
+    r &= checkunsigned(L, i);
+  return trim(r);
+}
+
+
+static int b_and (lua_State *L) {
+  lua_Unsigned r = andaux(L);
+  pushunsigned(L, r);
+  return 1;
+}
+
+
+static int b_test (lua_State *L) {
+  lua_Unsigned r = andaux(L);
+  lua_pushboolean(L, r != 0);
+  return 1;
+}
+
+
+static int b_or (lua_State *L) {
+  int i, n = lua_gettop(L);
+  lua_Unsigned r = 0;
+  for (i = 1; i <= n; i++)
+    r |= checkunsigned(L, i);
+  pushunsigned(L, trim(r));
+  return 1;
+}
+
+
+static int b_xor (lua_State *L) {
+  int i, n = lua_gettop(L);
+  lua_Unsigned r = 0;
+  for (i = 1; i <= n; i++)
+    r ^= checkunsigned(L, i);
+  pushunsigned(L, trim(r));
+  return 1;
+}
+
+
+static int b_not (lua_State *L) {
+  lua_Unsigned r = ~checkunsigned(L, 1);
+  pushunsigned(L, trim(r));
+  return 1;
+}
+
+
+static int b_shift (lua_State *L, lua_Unsigned r, lua_Integer 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);
+  }
+  pushunsigned(L, r);
+  return 1;
+}
+
+
+static int b_lshift (lua_State *L) {
+  return b_shift(L, checkunsigned(L, 1), luaL_checkinteger(L, 2));
+}
+
+
+static int b_rshift (lua_State *L) {
+  return b_shift(L, checkunsigned(L, 1), -luaL_checkinteger(L, 2));
+}
+
+
+static int b_arshift (lua_State *L) {
+  lua_Unsigned r = checkunsigned(L, 1);
+  lua_Integer i = luaL_checkinteger(L, 2);
+  if (i < 0 || !(r & ((lua_Unsigned)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) | ~(trim(~(lua_Unsigned)0) >> i));  /* add signal bit */
+    pushunsigned(L, r);
+    return 1;
+  }
+}
+
+
+static int b_rot (lua_State *L, lua_Integer d) {
+  lua_Unsigned r = checkunsigned(L, 1);
+  int i = d & (LUA_NBITS - 1);  /* i = d % NBITS */
+  r = trim(r);
+  if (i != 0)  /* avoid undefined shift of LUA_NBITS when i == 0 */
+    r = (r << i) | (r >> (LUA_NBITS - i));
+  pushunsigned(L, trim(r));
+  return 1;
+}
+
+
+static int b_lrot (lua_State *L) {
+  return b_rot(L, luaL_checkinteger(L, 2));
+}
+
+
+static int b_rrot (lua_State *L) {
+  return b_rot(L, -luaL_checkinteger(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) {
+  lua_Integer f = luaL_checkinteger(L, farg);
+  lua_Integer w = luaL_optinteger(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 = (int)w;
+  return (int)f;
+}
+
+
+static int b_extract (lua_State *L) {
+  int w;
+  lua_Unsigned r = trim(checkunsigned(L, 1));
+  int f = fieldargs(L, 2, &w);
+  r = (r >> f) & mask(w);
+  pushunsigned(L, r);
+  return 1;
+}
+
+
+static int b_replace (lua_State *L) {
+  int w;
+  lua_Unsigned r = trim(checkunsigned(L, 1));
+  lua_Unsigned v = trim(checkunsigned(L, 2));
+  int f = fieldargs(L, 3, &w);
+  lua_Unsigned m = mask(w);
+  r = (r & ~(m << f)) | ((v & m) << f);
+  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;
+}
+
+
+#else                                   /* }{ */
+
+
+LUAMOD_API int luaopen_bit32 (lua_State *L) {
+  return luaL_error(L, "library 'bit32' has been deprecated");
+}
+
+#endif                                  /* } */
diff --git a/rockspecs/bit32-5.3.5-1.rockspec b/rockspecs/bit32-5.3.5-1.rockspec
new file mode 100644
index 0000000..be2f5a7
--- /dev/null
+++ b/rockspecs/bit32-5.3.5-1.rockspec
@@ -0,0 +1,28 @@
+package = "bit32"
+version = "5.3.5-1"
+source = {
+   url = "git://github.com/keplerproject/lua-compat-5.3/archive/v0.9.zip",
+   dir = "lua-compat-5.3-0.9",
+}
+description = {
+   summary = "Lua 5.2 bit manipulation library",
+   detailed = [[
+      bit32 is the native Lua 5.2 bit manipulation library, in the version
+      from Lua 5.3; it is compatible with Lua 5.1, 5.2 and 5.3.
+   ]],
+   homepage = "http://www.lua.org/manual/5.2/manual.html#6.7",
+   license = "MIT"
+}
+dependencies = {
+   "lua >= 5.1, < 5.5"
+}
+build = {
+   type = "builtin",
+   modules = {
+      bit32 = {
+         sources = { "lbitlib.c" },
+         defines = { "LUA_COMPAT_BITLIB" },
+         incdirs = { "c-api" },
+      }
+   }
+}
diff --git a/rockspecs/bit32-scm-1.rockspec b/rockspecs/bit32-scm-1.rockspec
new file mode 100644
index 0000000..cce77de
--- /dev/null
+++ b/rockspecs/bit32-scm-1.rockspec
@@ -0,0 +1,28 @@
+package = "bit32"
+version = "scm-1"
+source = {
+   url = "https://github.com/keplerproject/lua-compat-5.3/archive/master.zip",
+   branch = "lua-compat-5.3-master",
+}
+description = {
+   summary = "Lua 5.2 bit manipulation library",
+   detailed = [[
+      bit32 is the native Lua 5.2 bit manipulation library, in the version
+      from Lua 5.3; it is compatible with Lua 5.1, 5.2 and 5.3.
+   ]],
+   homepage = "http://www.lua.org/manual/5.2/manual.html#6.7",
+   license = "MIT"
+}
+dependencies = {
+   "lua >= 5.1, < 5.5"
+}
+build = {
+   type = "builtin",
+   modules = {
+      bit32 = {
+         sources = { "lbitlib.c" },
+         defines = { "LUA_COMPAT_BITLIB" },
+         incdirs = { "c-api" },
+      }
+   }
+}
diff --git a/tests/test-bit32.lua b/tests/test-bit32.lua
new file mode 100755
index 0000000..cc91e52
--- /dev/null
+++ b/tests/test-bit32.lua
@@ -0,0 +1,9 @@
+#!/usr/bin/env lua
+
+local bit32 = require("bit32")
+
+
+assert(bit32.bnot(0) == 2^32-1)
+assert(bit32.band(1, 3, 5) == 1)
+assert(bit32.bor(1, 3, 5) == 7)
+