hex.c

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/*
 * hex.c
 *
 * Part of librfn (a general utility library from redfelineninja.org.uk)
 *
 * Copyright (C) 2012 Daniel Thompson <daniel@redfelineninja.org.uk> 
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 */

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

#include "librfn.h"

static inline char hexchar(char h)
{
        if (h < 10)
                return '0' + h;

        return 'a' - 10 + h;
}

int hex_dump_to_file(FILE *f, unsigned char *p, size_t sz)
{
        size_t oldsz = sz;

        while (sz > 0) {
                for (int i=0;
                     i<16 && sz > 0;
                     i++, sz--, p++)
                        fprintf(f, "%c%c", hexchar(*p >> 4), hexchar(*p & 0xf));
                fprintf(f, "\n");
        }

        return oldsz;
}

int hex_dump(unsigned char *p, size_t sz)
{
        return hex_dump_to_file(stdout, p, sz);
}

static inline int nibble(char h)
{
        if (h <= '9')
                return h - '0';

        return (h & ~('a' - 'A')) - 'A' + 10;
}


int hex_get_byte(const char *s, const char **p)
{
    next_line:
        if (s) {
                char *q = strchr(s, ':');
                if (q)
                        s = q+1;
        } else {
                s = *p;
                if (!s)
                        return -1;
        }

        while (isspace((int) *s))
                if (*s++ == '\n')
                        goto next_line;

        /* lazy evaluation ensures we don't read past end of string */
        if ('0' == s[0] && 'x' == s[1])
                s += 2;

        if (isxdigit((int) s[0]) && isxdigit((int) s[1])) {
                *p = s + 2;
                return 16 * nibble(s[0]) | nibble(s[1]);
        }

        /* jump to the next line (if there is one) */
        s = *p = strchr(s, '\n');
        if (s++)
                goto next_line;

        return -1;
}