/*
**  HEXDUMP.C - Dump a file.
**
**  Usage: hexdump file_name [start] [length]
**
**  e.g. hexdump temp.txt
**
**  "start" is zero-based.
**
**  The output format is similar to that used on a VAX machine, except
**  that the ordering isn't screwed up to make up for the screwed
**  little-endian cpu.
**
**  This program was written by Paul Edwards
**  It was modified by:
**  Bob Stout
**  Andrew Clarke
**
**  This program is released to the public domain
*/

#include 
#include 
#include 
#include 

static void dodump(FILE * fp, long start, long count);
static void skipb(FILE * fp, long start);

main(int argc, char **argv)
{
    FILE *fp;
    long start, count;

    if (argc < 2)
    {
        puts("Usage: HEXDUMP file_name [start] [length]");
        return (EXIT_FAILURE);
    }
    if (argc > 2)
    {
        start = strtol(*(argv + 2), NULL, 0);
    }
    else
    {
        start = 0L;
    }
    if (argc > 3)
    {
        count = strtol(*(argv + 3), NULL, 0);
    }
    else
    {
        count = -1L;
    }
    fp = fopen(*(argv + 1), "rb");
    if (fp == NULL)
    {
        printf("unable to open file %s for input\n", *(argv + 1));
        return (EXIT_FAILURE);
    }
    skipb(fp, start);
    dodump(fp, start, count);
    return (EXIT_SUCCESS);
}

static void dodump(FILE * fp, long start, long count)
{
    int c, pos1, pos2;
    long x = 0L;
    char prtln[100];

    while (((c = fgetc(fp)) != EOF) && (x != count))
    {
        if (x % 16 == 0)
        {
            memset(prtln, ' ', sizeof prtln);
            sprintf(prtln, "%0.6X   ", start + x);
            pos1 = 8;
            pos2 = 45;
        }
        sprintf(prtln + pos1, "%0.2X", c);
        if (isprint(c))
        {
            sprintf(prtln + pos2, "%c", c);
        }
        else
        {
            sprintf(prtln + pos2, ".");
        }
        pos1 += 2;
        *(prtln + pos1) = ' ';
        pos2++;
        if (x % 4 == 3)
        {
            *(prtln + pos1++) = ' ';
        }
        if (x % 16 == 15)
        {
            printf("%s\n", prtln);
        }
        x++;
    }
    if (x % 16 != 0)
    {
        printf("%s\n", prtln);
    }
    return;
}

static void skipb(FILE * fp, long start)
{
    long x = 0;

    while (x < start)
    {
        fgetc(fp);
        x++;
    }
    return;
}
@EOT:

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