// see: see the physical bits in a file
// usage: see [filename]
// sort of like the `od' command, but only supports binary output

// $ echo foobar > foo.txt; see foo.txt
// 01100110 01101111 01101111 01100010
// 01100001 01110010 00001010
// $

// bugs:
//   - assumes big-endianness of machine
//   - only allows one file to be seen at a time
//   - no command line options
//   - generally untested

#include <stdio.h>

int main(int argc, char **argv)
{
        FILE *fp;
        if (argc > 1)
        {
                if ((fp = fopen(argv[1], "r")) == NULL)
                {
                        fprintf(stderr, "see: could not open file `%s': ");
                        perror(NULL);
                        return -1;
                }
        }
        else
                fp = stdin;

        unsigned currbyte;
        signed currbit;

        int col = 0;
        int maxcols = 4;

        while ((currbyte = fgetc(fp)) != EOF)
        {
                for (currbit = 7; currbit >= 0; currbit--)
                {
                        if ( (currbyte >> currbit) & 1 )
                                putchar('1');
                        else
                                putchar('0');
                }
                putchar(' ');

                if (++col == maxcols)
                {
                        col = 0;
                        putchar('\n');
                }
        }

        if (col > 0)
                putchar('\n');

        return 0;
}