bool_array.h

//
// Created by Swift Sheng on 10/1/24.
//

// have this user defined data type working, then creating object capability

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <signal.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"
#include "llimits.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 BitArray {
    int size;
    unsigned int values[1]; /* variable part */
} BitArray;

static int newarray (lua_State *L) {
    int i;
    size_t nbytes;
    BitArray *a;

    int n = (int)luaL_checkinteger(L, 1); /* number of bits */
    luaL_argcheck(L, n >= 1, 1, "invalid size");
    nbytes = sizeof(BitArray) + I_WORD(n - 1)*sizeof(unsigned int);
    a = (BitArray *)lua_newuserdata(L, nbytes);

    a->size = n;
    for (i = 0; i <= I_WORD(n - 1); i++)
        a->values[i] = 0; /* initialize array */

    return 1; /* new userdata is already on the stack */
}

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

    luaL_argcheck(L, a != NULL, 1, "'array' expected");
    luaL_argcheck(L, 0 <= index && 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); /* set bit */
    else
        a->values[I_WORD(index)] &= ~I_BIT(index); /* reset bit */
    return 0;
}

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

    luaL_argcheck(L, a != NULL, 1, "'array' expected");
    luaL_argcheck(L, 0 <= index && 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) {
    BitArray *a = (BitArray *)lua_touserdata(L, 1);
    luaL_argcheck(L, a != NULL, 1, "'array' expected");
    lua_pushinteger(L, a->size);
    return 1;
}

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

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