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

static	void	disp(char *buf, int length, int dir)
{
	int	i, j, mask;

	for (i = 0; i < length; i++) {
		mask = dir ? 0x001 : 0x080;

		for (j = 0; j < 8; j++) {
			printf("%s", (*buf & mask) ? "**" : "  ");

			if (dir) {
				mask <<= 1;
			} else {
				mask >>= 1;
			}
		}

		buf++;
	}

	return;
}

int	main(int argc, char *argv[])
{
	int	i, result, size, asize, width, step, dir, rem;
	FILE	*fp;
	char	*buf;

	/* usage */
	if (argc < 3) {
		printf("usage: %s [width(byte)] [filename]\n", argv[0]);
		result = EXIT_FAILURE;
		goto fin0;
	}

	/* get width */
	width = atoi(argv[1]);
	if (!width) {
		printf("bad width!\n");
		goto fin0;
	}

	/* file open */
	fp = fopen(argv[2], "rb");
	if (fp == NULL) {
		printf("file open error\n");
		goto fin0;
	}

	/* get file size */
	fseek(fp, 0, SEEK_END);
	size = asize = ftell(fp);
	fseek(fp, 0, SEEK_SET);

	/* round-up */
	rem = asize % width;
	if (rem) asize += width - rem;

	/* allocate memory */
	buf = malloc(asize);
	if (buf == NULL) {
		printf("malloc() failed\n");
		goto fin0;
	}

	/* clear */
	memset(buf, 0, asize);

	/* read file */
	if (fread(buf, 1, size, fp) < size) {
		printf("fread() failed\n");
		goto fin1;
	}

	/* display */
	if (width < 0) {
		step = -width;
		dir = 1;
	} else {
		step = width;
		dir = 0;
	}

	for (i = 0; i < size; i += step) {
		printf("%08x: ", i);
		disp(buf + i, step, dir);
		printf("\n");
	}

	result = EXIT_SUCCESS;

 fin1:
	free(buf);
 fin0:
	return result;
}