test.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>

void dump_line(const unsigned char* buf, int w, int l)
{
#define YYYGET(X)       ( X >= 32 && X <= 126) ? X : '.'
    unsigned int i = 0;
    printf("%08x: ", l);
    for (; i < w; ++i)
        printf((i % 8 == 7) ? "%02x  " : "%02x ", *(buf+i));
    if (w < 0x10)
    {
        for (i = 0; i < 0x10 - w; ++i) printf("   ");
        printf("  ");
    }
    printf ("|");
    for (i = 0; i < w; ++i)
        printf ("%c", YYYGET(*(buf+i)));
    if (w < 0x10)
        for (i = 0; i < 0x10 - w; ++i) printf(" ");
    printf ("|\n");
#undef YYYGET
}

void dump_buffer(const unsigned char* buf, int max)
{
    int l = max / 0x10 + ((max % 0x10) ? 1 : 0);
    printf ("l = %d\n",l);
    int i = 0;
    int w = l - i > 1 ? 0x10 : max;
    const unsigned char* ptr = buf;
    for (; i < l; ++i,w = l - i > 1 ? 0x10 : max - 0x10 * i)
    {
        dump_line(ptr, w, i);
        ptr += w;
    }
}


int main(int argc, char *argv[])
{
    if (argc < 3)
    {
        printf ("Usage: %s FileName, number.\n", argv[0]);
        exit(1);
    }

    int fd = open(argv[1], O_RDONLY);
    if (fd != -1)
    {
        int s = atoi(argv[2]);
        unsigned char* buf = malloc(s+1);
        memset(buf, 0, s+1);
        read(fd, buf, s);
        dump_buffer(buf, s);
    }
    return 0;
}