Lua: Add bitop

A few people have written custom C commands because bit
manipulation isn't exposed through Lua.  Let's give
them Mike Pall's bitop.

This adds bitop 1.0.2 (2012-05-08) from http://bitop.luajit.org/

bitop is imported as "bit" into the global namespace.

New Lua commands: bit.tobit, bit.tohex, bit.bnot, bit.band, bit.bor, bit.bxor,
bit.lshift, bit.rshift, bit.arshift, bit.rol, bit.ror, bit.bswap

Verification of working (the asserts would abort on error, so (nil) is correct):
127.0.0.1:6379> eval "assert(bit.tobit(1) == 1); assert(bit.band(1) == 1); assert(bit.bxor(1,2) == 3); assert(bit.bor(1,2,4,8,16,32,64,128) == 255)" 0
(nil)
127.0.0.1:6379> eval 'assert(0x7fffffff == 2147483647, "broken hex literals"); assert(0xffffffff == -1 or 0xffffffff == 2^32-1, "broken hex literals"); assert(tostring(-1) == "-1", "broken tostring()"); assert(tostring(0xffffffff) == "-1" or tostring(0xffffffff) == "4294967295", "broken tostring()")' 0
(nil)

Tests also integrated into the scripting tests and can be run with:
./runtest --single unit/scripting

Tests are excerpted from `bittest.lua` included in the bitop distribution.

deps/lua/src/Makefile

@@ -27,7 +27,8 @@ CORE_O=	lapi.o lcode.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o lmem.o \
 	lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o ltm.o  \
 	lundump.o lvm.o lzio.o strbuf.o
 LIB_O=	lauxlib.o lbaselib.o ldblib.o liolib.o lmathlib.o loslib.o ltablib.o \
-	lstrlib.o loadlib.o linit.o lua_cjson.o lua_struct.o lua_cmsgpack.o
+	lstrlib.o loadlib.o linit.o lua_cjson.o lua_struct.o lua_cmsgpack.o \
+	lua_bit.o
 
 LUA_T=	lua
 LUA_O=	lua.o

deps/lua/src/lua_bit.c

+/*
+** Lua BitOp -- a bit operations library for Lua 5.1/5.2.
+** http://bitop.luajit.org/
+**
+** Copyright (C) 2008-2012 Mike Pall. All rights reserved.
+**
+** Permission is hereby granted, free of charge, to any person obtaining
+** a copy of this software and associated documentation files (the
+** "Software"), to deal in the Software without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Software, and to
+** permit persons to whom the Software is furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be
+** included in all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+**
+** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
+*/
+
+#define LUA_BITOP_VERSION	"1.0.2"
+
+#define LUA_LIB
+#include "lua.h"
+#include "lauxlib.h"
+
+#ifdef _MSC_VER
+/* MSVC is stuck in the last century and doesn't have C99's stdint.h. */
+typedef __int32 int32_t;
+typedef unsigned __int32 uint32_t;
+typedef unsigned __int64 uint64_t;
+#else
+#include <stdint.h>
+#endif
+
+typedef int32_t SBits;
+typedef uint32_t UBits;
+
+typedef union {
+  lua_Number n;
+#ifdef LUA_NUMBER_DOUBLE
+  uint64_t b;
+#else
+  UBits b;
+#endif
+} BitNum;
+
+/* Convert argument to bit type. */
+static UBits barg(lua_State *L, int idx)
+{
+  BitNum bn;
+  UBits b;
+#if LUA_VERSION_NUM < 502
+  bn.n = lua_tonumber(L, idx);
+#else
+  bn.n = luaL_checknumber(L, idx);
+#endif
+#if defined(LUA_NUMBER_DOUBLE)
+  bn.n += 6755399441055744.0;  /* 2^52+2^51 */
+#ifdef SWAPPED_DOUBLE
+  b = (UBits)(bn.b >> 32);
+#else
+  b = (UBits)bn.b;
+#endif
+#elif defined(LUA_NUMBER_INT) || defined(LUA_NUMBER_LONG) || \
+      defined(LUA_NUMBER_LONGLONG) || defined(LUA_NUMBER_LONG_LONG) || \
+      defined(LUA_NUMBER_LLONG)
+  if (sizeof(UBits) == sizeof(lua_Number))
+    b = bn.b;
+  else
+    b = (UBits)(SBits)bn.n;
+#elif defined(LUA_NUMBER_FLOAT)
+#error "A 'float' lua_Number type is incompatible with this library"
+#else
+#error "Unknown number type, check LUA_NUMBER_* in luaconf.h"
+#endif
+#if LUA_VERSION_NUM < 502
+  if (b == 0 && !lua_isnumber(L, idx)) {
+    luaL_typerror(L, idx, "number");
+  }
+#endif
+  return b;
+}
+
+/* Return bit type. */
+#define BRET(b)  lua_pushnumber(L, (lua_Number)(SBits)(b)); return 1;
+
+static int bit_tobit(lua_State *L) { BRET(barg(L, 1)) }
+static int bit_bnot(lua_State *L) { BRET(~barg(L, 1)) }
+
+#define BIT_OP(func, opr) \
+  static int func(lua_State *L) { int i; UBits b = barg(L, 1); \
+    for (i = lua_gettop(L); i > 1; i--) b opr barg(L, i); BRET(b) }
+BIT_OP(bit_band, &=)
+BIT_OP(bit_bor, |=)
+BIT_OP(bit_bxor, ^=)
+
+#define bshl(b, n)  (b << n)
+#define bshr(b, n)  (b >> n)
+#define bsar(b, n)  ((SBits)b >> n)
+#define brol(b, n)  ((b << n) | (b >> (32-n)))
+#define bror(b, n)  ((b << (32-n)) | (b >> n))
+#define BIT_SH(func, fn) \
+  static int func(lua_State *L) { \
+    UBits b = barg(L, 1); UBits n = barg(L, 2) & 31; BRET(fn(b, n)) }
+BIT_SH(bit_lshift, bshl)
+BIT_SH(bit_rshift, bshr)
+BIT_SH(bit_arshift, bsar)
+BIT_SH(bit_rol, brol)
+BIT_SH(bit_ror, bror)
+
+static int bit_bswap(lua_State *L)
+{
+  UBits b = barg(L, 1);
+  b = (b >> 24) | ((b >> 8) & 0xff00) | ((b & 0xff00) << 8) | (b << 24);
+  BRET(b)
+}
+
+static int bit_tohex(lua_State *L)
+{
+  UBits b = barg(L, 1);
+  SBits n = lua_isnone(L, 2) ? 8 : (SBits)barg(L, 2);
+  const char *hexdigits = "0123456789abcdef";
+  char buf[8];
+  int i;
+  if (n < 0) { n = -n; hexdigits = "0123456789ABCDEF"; }
+  if (n > 8) n = 8;
+  for (i = (int)n; --i >= 0; ) { buf[i] = hexdigits[b & 15]; b >>= 4; }
+  lua_pushlstring(L, buf, (size_t)n);
+  return 1;
+}
+
+static const struct luaL_Reg bit_funcs[] = {
+  { "tobit",	bit_tobit },
+  { "bnot",	bit_bnot },
+  { "band",	bit_band },
+  { "bor",	bit_bor },
+  { "bxor",	bit_bxor },
+  { "lshift",	bit_lshift },
+  { "rshift",	bit_rshift },
+  { "arshift",	bit_arshift },
+  { "rol",	bit_rol },
+  { "ror",	bit_ror },
+  { "bswap",	bit_bswap },
+  { "tohex",	bit_tohex },
+  { NULL, NULL }
+};
+
+/* Signed right-shifts are implementation-defined per C89/C99.
+** But the de facto standard are arithmetic right-shifts on two's
+** complement CPUs. This behaviour is required here, so test for it.
+*/
+#define BAD_SAR		(bsar(-8, 2) != (SBits)-2)
+
+LUALIB_API int luaopen_bit(lua_State *L)
+{
+  UBits b;
+  lua_pushnumber(L, (lua_Number)1437217655L);
+  b = barg(L, -1);
+  if (b != (UBits)1437217655L || BAD_SAR) {  /* Perform a simple self-test. */
+    const char *msg = "compiled with incompatible luaconf.h";
+#ifdef LUA_NUMBER_DOUBLE
+#ifdef _WIN32
+    if (b == (UBits)1610612736L)
+      msg = "use D3DCREATE_FPU_PRESERVE with DirectX";
+#endif
+    if (b == (UBits)1127743488L)
+      msg = "not compiled with SWAPPED_DOUBLE";
+#endif
+    if (BAD_SAR)
+      msg = "arithmetic right-shift broken";
+    luaL_error(L, "bit library self-test failed (%s)", msg);
+  }
+#if LUA_VERSION_NUM < 502
+  luaL_register(L, "bit", bit_funcs);
+#else
+  luaL_newlib(L, bit_funcs);
+#endif
+  return 1;
+}
+

src/scripting.c

@@ -536,6 +536,7 @@ void luaLoadLib(lua_State *lua, const char *libname, lua_CFunction luafunc) {
 LUALIB_API int (luaopen_cjson) (lua_State *L);
 LUALIB_API int (luaopen_struct) (lua_State *L);
 LUALIB_API int (luaopen_cmsgpack) (lua_State *L);
+LUALIB_API int (luaopen_bit) (lua_State *L);
 
 void luaLoadLibraries(lua_State *lua) {
     luaLoadLib(lua, "", luaopen_base);
@@ -546,6 +547,7 @@ void luaLoadLibraries(lua_State *lua) {
     luaLoadLib(lua, "cjson", luaopen_cjson);
     luaLoadLib(lua, "struct", luaopen_struct);
     luaLoadLib(lua, "cmsgpack", luaopen_cmsgpack);
+    luaLoadLib(lua, "bit", luaopen_bit);
 
 #if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
     luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);

tests/unit/scripting.tcl

@@ -184,6 +184,25 @@ start_server {tags {"scripting"}} {
         set e
     } {*against a key*}
 
+    test {EVAL - Numerical sanity check from bitop} {
+        r eval {assert(0x7fffffff == 2147483647, "broken hex literals");
+                assert(0xffffffff == -1 or 0xffffffff == 2^32-1,
+                    "broken hex literals");
+                assert(tostring(-1) == "-1", "broken tostring()");
+                assert(tostring(0xffffffff) == "-1" or
+                    tostring(0xffffffff) == "4294967295",
+                    "broken tostring()")
+        } 0
+    } {}
+
+    test {EVAL - Verify minimal bitop functionality} {
+        r eval {assert(bit.tobit(1) == 1);
+                assert(bit.band(1) == 1);
+                assert(bit.bxor(1,2) == 3);
+                assert(bit.bor(1,2,4,8,16,32,64,128) == 255)
+        } 0
+    } {}
+
     test {SCRIPTING FLUSH - is able to clear the scripts cache?} {
         r set mykey myval
         set v [r evalsha fd758d1589d044dd850a6f05d52f2eefd27f033f 1 mykey]