game of life

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

typedef struct cell_t_ {
    struct cell_t_ *neighbours[8];
    int on;
} cell_t;

typedef struct world_t_ {
    cell_t **array;
    int width;
    int height;
    void *mem;
} world_t;

void printworld(world_t *world, FILE *pOutput)
{
    int x, y;

    for(y = 0; y < world->height; y++) {
        for(x = 0; x < world->width; x++) {
            fprintf(pOutput, "%c", (world->array[y][x]).on ? 254 : ' ');
        }
        fputc((int)'\n', pOutput);
    }
    fflush(pOutput);
}

void randomizeworld(world_t *world)
{
    int x, y;

    for(y = 0; y < world->height; y++) {
        for(x = 0; x < world->width; x++) {
            (world->array[y][x]).on = rand() & 1;
        }
    }
}

void updateworld(world_t *world)
{
    int x, y, i, neighbours;

    for(y = 0; y < world->height; y++) {
        for(x = 0; x < world->width; x++, neighbours = 0) {
            for(i = 0; i < 8; i++)
                if((world->array[y][x].neighbours[i]) && ((world->array[y][x]).neighbours[i]->on & 1))
                    neighbours++;

            if((neighbours < 2) || (neighbours > 3))
                (world->array[y][x]).on |= 2;
            else if(neighbours == 3)
                (world->array[y][x]).on |= 4;
        }
    }

    for(y = 0; y < world->height; y++) {
        for(x = 0; x < world->width; x++) {
            if(world->array[y][x].on & 4)
                world->array[y][x].on = 1;
            else if(world->array[y][x].on & 2)
                world->array[y][x].on = 0;
        }
    }
}

void destroyworld(world_t *world)
{
    free(world->mem);
}

int createworld(world_t *world, int width, int height)
{
    int i, j;
    unsigned long base   = sizeof(cell_t *) * height;
    unsigned long rowlen = sizeof(cell_t)   * width;

    if(!(world->mem = calloc(base + (rowlen * height), 1)))
        return 0;

    world->array  = world->mem;
    world->width  = width;
    world->height = height;

    for(i = 0; i < height; i++) {
        world->array[i] = world->mem + base + (i * rowlen);
    }

    for(i = 0; i < height; i++) {
        for(j = 0; j < width; j++) {
            if(j != 0) {
                (world->array[i][j]).neighbours[3] = &(world->array[i][j - 1]);
            }

            if(i != 0) {
                (world->array[i][j]).neighbours[1] = &(world->array[i - 1][j]);
            }

            if(j != (width - 1)) {
                (world->array[i][j]).neighbours[4] = &(world->array[i][j + 1]);
            }

            if(i != (height - 1)) {
                (world->array[i][j]).neighbours[6] = &(world->array[i + 1][j]);
            }

            if((i != 0) && (j != 0)) {
                (world->array[i][j]).neighbours[0] = &(world->array[i - 1][j - 1]);
            }

            if((i != (height - 1)) && (j != (width - 1))) {
                (world->array[i][j]).neighbours[7] = &(world->array[i + 1][j + 1]);
            }

            if((i != (height - 1)) && (j != 0)) {
                (world->array[i][j]).neighbours[5] = &(world->array[i + 1][j - 1]);
            }

            if((i != 0) && (j != (width - 1))) {
                (world->array[i][j]).neighbours[2] = &(world->array[i - 1][j + 1]);
            }
        }
    }

    return 1;
}

int main(int argc, char *argv[]) {
    world_t gameoflife;

    if(createworld(&gameoflife, 79, 24)) {
        randomizeworld(&gameoflife);
        do {
            printworld(&gameoflife, stdout);
            getchar();
            fflush(stdin);
            updateworld(&gameoflife);
        }while(1);
        destroyworld(&gameoflife);
    }

    return 0;
}