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commit 1a92c2b354bd08031a744cb39125a8c5d04349c3
parent fe0d54d37edd3d28d42a01db013e04cc12e97f2f
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Fri, 17 Dec 2010 11:26:14 -0200

allows number of bits used by the library to be changed from outside

Diffstat:
Mlbitlib.c | 25++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/lbitlib.c b/lbitlib.c @@ -1,5 +1,5 @@ /* -** $Id: lbitlib.c,v 1.13 2010/11/22 18:06:33 roberto Exp roberto $ +** $Id: lbitlib.c,v 1.14 2010/11/29 15:19:28 roberto Exp roberto $ ** Standard library for bitwise operations ** See Copyright Notice in lua.h */ @@ -14,15 +14,18 @@ /* number of bits to consider in a number */ -#define NBITS 32 +#if !defined(LUA_NBITS) +#define LUA_NBITS 32 +#endif -#define ALLONES (~(((~(lua_Unsigned)0) << (NBITS - 1)) << 1)) + +#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 <= NBITS) */ +/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */ #define mask(n) (~((ALLONES << 1) << ((n) - 1))) @@ -84,11 +87,11 @@ static int b_shift (lua_State *L, b_uint r, int i) { if (i < 0) { /* shift right? */ i = -i; r = trim(r); - if (i >= NBITS) r = 0; + if (i >= LUA_NBITS) r = 0; else r >>= i; } else { /* shift left */ - if (i >= NBITS) r = 0; + if (i >= LUA_NBITS) r = 0; else r <<= i; r = trim(r); } @@ -110,10 +113,10 @@ static int b_rshift (lua_State *L) { 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 << (NBITS - 1)))) + if (i < 0 || !(r & ((b_uint)1 << (LUA_NBITS - 1)))) return b_shift(L, r, -i); else { /* arithmetic shift for 'negative' number */ - if (i >= NBITS) r = ALLONES; + if (i >= LUA_NBITS) r = ALLONES; else r = trim((r >> i) | ~(~(b_uint)0 >> i)); /* add signal bit */ lua_pushunsigned(L, r); @@ -124,9 +127,9 @@ static int b_arshift (lua_State *L) { static int b_rot (lua_State *L, int i) { b_uint r = luaL_checkunsigned(L, 1); - i &= (NBITS - 1); /* i = i % NBITS */ + i &= (LUA_NBITS - 1); /* i = i % NBITS */ r = trim(r); - r = (r << i) | (r >> (NBITS - i)); + r = (r << i) | (r >> (LUA_NBITS - i)); lua_pushunsigned(L, trim(r)); return 1; } @@ -151,7 +154,7 @@ static int fieldargs (lua_State *L, int farg, int *width) { int w = luaL_optint(L, farg + 1, 1); luaL_argcheck(L, 0 <= f, farg, "field cannot be netative"); luaL_argcheck(L, 0 < w, farg + 1, "width must be positive"); - if (f + w > NBITS) + if (f + w > LUA_NBITS) luaL_error(L, "trying to access non-existent bits"); *width = w; return f;