a simple bit table program use an array of 8 chars as a bit map

bitmap.c

/*
 * @Copyright chm <prehistoricpenguin@qq.com>
 *
 * a simple bit table program
 * use an array of 8 chars as a bit map,illuminated as below:
 *   7 6 5 4 3 2 1 0
 *    <---------------
 *	0 0 0 0 0 0 0 0 | 0
 *	0 0 0 0 0 0 0 0 | 1
 *	0 0 0 0 0 0 0 0 | 2
 *	0 0 0 0 0 0 0 0 | 3
 *	0 0 0 0 0 0 0 0 | 4
 *	0 0 0 0 0 0 0 0 | 5
 *	0 0 0 0 0 0 0 0 | 6
 *	0 0 0 0 0 0 0 0 | 7
 *					^
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>

#define TABLEROWS 			8
#define TABLECOLUMNS 		8
#define getX(val) 			(val >> 3)
#define getY(val) 			(val & 0x7)
#define setBit(val,idx) 	(val |= (0x1 << idx))
#define getBit(val,idx) 	((val >> idx) & 0x1)
unsigned char tbl[TABLEROWS];

int setValue(int);
void printTable();
void initTable();

int main()
{
    int index;
    initTable();
    printf("Table initialized as below:\n");
    printTable();
    while (1)
    {
        printf("please input a value(0~63,EOF to exit):\n");
        if (EOF == scanf("%d", &index))
            break;
        assert( index >= 0 && index <= 63);
        if (setValue(index) == 0)
            fprintf(stderr, "error:bit %d is already setted!\n", index);
        else
        {
            printf("bit set sucessful\n");
            printTable();
        }
    }

    return EXIT_SUCCESS;
}

void initTable()
{
    memset(tbl, 0, sizeof(tbl));
}

void printTable()
{
    int i, j;

    printf("<---------------\n");
    for (i = 0; i < TABLEROWS; ++i)
    {
        for (j = TABLECOLUMNS - 1; j >= 0; --j)
            printf("%d ", getBit(tbl[i], j));
        printf("|\n");
    }
    printf("                ^\n");
}

int setValue(int idx)
{
    int x = getX(idx),
        y = getY(idx);

    /*
     * bit is already setted
     */
    if (getBit(tbl[x], y))
        return 0;
    else
    {
        setBit(tbl[x], y);
        return 1;
    }
}