From 7a1ea510a9fc43ccbc257601b149a90920332e13 Mon Sep 17 00:00:00 2001 From: Alex Auvolat Date: Fri, 15 Jul 2016 22:39:04 +0200 Subject: Add Lua source, not compiled yet as libc/libm functions remain unimplemented --- src/lib/lualib/lbitlib.c | 233 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 233 insertions(+) create mode 100644 src/lib/lualib/lbitlib.c (limited to 'src/lib/lualib/lbitlib.c') diff --git a/src/lib/lualib/lbitlib.c b/src/lib/lualib/lbitlib.c new file mode 100644 index 0000000..1cb1d5b --- /dev/null +++ b/src/lib/lualib/lbitlib.c @@ -0,0 +1,233 @@ +/* +** $Id: lbitlib.c,v 1.30 2015/11/11 19:08:09 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 /* } */ -- cgit v1.2.3