08_boolarray_lib.c

#include <limits.h>
#include <stdio.h>

#include "lua.h"
#include "lauxlib.h"

#define BITS_PER_WORD (CHAR_BIT * sizeof(unsigned int))
#define I_WORD(i) ((unsigned int)(i) / BITS_PER_WORD)
#define I_BIT(i) (1 << ((unsigned int) (i) % BITS_PER_WORD))

typedef struct NumArray {
	int size;
	unsigned int values[1];
} NumArray;

static int newarray(lua_State *L) {
	int i, n;
	size_t nbytes;
	NumArray *a;

	n = luaL_checkinteger(L, 1);
	luaL_argcheck(L, n >= 1, 1, "invalid size");	//check : n >= 1
	nbytes = sizeof(NumArray) + I_WORD(n - 1) * sizeof(unsigned int);
	a = (NumArray *)lua_newuserdata(L, nbytes);

	a -> size = n;
	for(i = 0; i <= I_WORD(n - 1); i++)
		a -> values[i] = 0;	//初始化数组

	return 1;
}

static int setarray(lua_State *L) {
	NumArray *a = (NumArray *) lua_touserdata(L, 1);
	int index = (int) luaL_checkinteger(L, 2) - 1;

	luaL_argcheck(L, a != NULL, 1, "'array' exception");
	luaL_argcheck(L, index >= 0 && index < a->size, 2, "index out of range");
	luaL_checkany(L, 3);

	if(lua_toboolean(L, 3)) {
		a->values[I_WORD(index)] |= I_BIT(index);	//设置bit
	} else {
		a->values[I_WORD(index)] &= ~I_BIT(index);	//重置bit
	}

	return 0;
}

static int getarray(lua_State *L) {
	NumArray *a = (NumArray *) lua_touserdata(L, 1);
	int index = (int) luaL_checkinteger(L, 2) - 1;

	luaL_argcheck(L, a != NULL, 1, "'array' exception");
	luaL_argcheck(L, index >= 0 && index < a->size, 2, "index out of range");

	lua_pushboolean(L, a->values[I_WORD(index)] & I_BIT(index));

	return 1;
}

static int getsize(lua_State *L) {
	NumArray *a = (NumArray *) lua_touserdata(L, 1);

	luaL_argcheck(L, a != NULL, 1, "'array' exception");

	lua_pushnumber(L, a->size);

	return 1;
}

static const struct luaL_Reg arraylib [] = {
	{"new", newarray},
	{"set", setarray},
	{"get", getarray},
	{"size", getsize},
	{NULL, NULL}
};

int luaopen_boolarray(lua_State *L) {
	luaL_newlib(L, arraylib);
	return 1;
}