//
// hex -- File hex dump tool.
//
// 30-Mar-2009 tvb www.LeapSecond.com/tools
//

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <memory.h>

#define SAFE(c) ( (c >= ' ' && c <= '~') ? c : '.' )
int WIDE = 16;
int FULL = 0;
time_t Mtime;

// Dump given array in hex.

void hex_dump (unsigned char *buf, long size)
{
    long i;     // current buffer index
    long n;     // bytes left in buffer
    int j;

    for (i = 0; i < size; i += WIDE) {
        n = size - i;

        // (1) Display address on left.

        if (FULL) {
            printf("%.8lX:", i);        // display all lines in "full" mode

        } else {
            char *pl = &buf[i - WIDE];  // previous line
            char *cl = &buf[i];         // current line
            char *nl = &buf[i + WIDE];  // next line

            // If current line is the same as previous line then skip it.
            if (n >= WIDE && i >= WIDE && memcmp(cl, pl, WIDE) == 0) {
                continue;
            }

            // If current line is the same as next line then mark it.
            if (n >= 2 * WIDE && memcmp(cl, nl, WIDE) == 0) {
                printf("%.8lX*", i);

            // Otherwise display current line as usual.
            } else {
                printf("%.8lX:", i);
            }
        }

        // (2) Display bytes in hexadecimal format.

        for (j = 0; j < WIDE; j += 1) {
            if (j < n) {
                printf(" %.2X", buf[i + j]);
            } else {
                printf(" --");   // file not mod-16; partial last line
            }
        }

        // (3) Display bytes as ascii characters on right.

        printf("  ");
        for (j = 0; j < WIDE; j += 1) {
            if (j < n) {
                printf("%c", SAFE(buf[i + j]));
            }
        }
        printf("\n");
    }
    printf("%.8lX: end (%ld bytes) mtime %ld\n", size, size, Mtime);
}

// Read entire binary file into array.

char *read_file (char *path, long *size)
{
    char *buf;
    FILE *f;
    struct _stat st;

    f = fopen(path, "rb");
    if (NULL == f) {
        fprintf(stderr, "%s: open failed\n", path);
        exit(1);
    }
    if (_fstat(_fileno(f), &st) != 0) {
        fprintf(stderr, "%s: fstat failed\n", path);
        exit(1);
    }
    Mtime = st.st_mtime;
    if (st.st_size == 0) {
        buf = NULL;

    } else {
        buf = malloc(st.st_size);
        if (NULL == buf) {
            fprintf(stderr, "%s: malloc failed (%ld bytes).\n", path, st.st_size);
            exit(1);
        }
        if (fread(buf, st.st_size, 1, f) != 1) {
            fprintf(stderr, "%s: read error (size=%ld)\n", path, st.st_size);
            exit(1);
        }
    }
    *size = st.st_size;
    fclose(f);
    return buf;
}

void main (int argc, char *argv[])
{
    char *buf;
    long size;

    if (argc < 2) {
        fprintf(stderr, "Usage: hexdump [file]\n");
        exit(1);
    }
    if (argc > 2) {
        WIDE = atoi(argv[2]);
        if (WIDE < 0) {
            WIDE = -WIDE;
            FULL = 1;
        }
        if (WIDE <= 1) {
            WIDE = 1;
        }
    }

    buf = read_file(argv[1], &size);
    hex_dump(buf, size);
    if (buf != NULL) {
        free(buf);
    }
}