hexcodec.h

hexadecimal encoding/decoding header library.

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void hex_encode( unsigned char *dest, unsigned char *src, size_t len )

hex_encode() function encode the len bytes from src and copy encoded bytes to the dest.

Parameters

• *dest: dest size must be greater than len * 2.
• *src: source string.
• len: byte length of src.

int hex_decode( char *dest, unsigned char *src, size_t len )

hex_encode() function encode the len bytes from src and copy encoded bytes to the dest.

Parameters

• *dest: dest size must be greater than len / 2.
• *src: encoded string.
• len: byte length of src. (this value must be multiples of two.)

Return Values

returns 0 on success, or -1 on failure.

Errors

• EINVAL: len value is not multiples of two.
• EILSEQ: src contained an illegal character.

Usage

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "hexcodec.h"

int main (int argc, const char * argv[])
{
    char *src = " !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
    size_t len = strlen( src );
    size_t hlen = len * 2;
    char *enc = alloca( hlen + 1 );
    char *dec = alloca( len + 1 );
    
    // encode
    printf("encode:\n\t%s\n", src );
    hex_encode( (unsigned char*)enc, (unsigned char*)src, len );
    enc[hlen] = 0;
    printf("\t%s\n\n", enc );
    
    // decode
    printf("decode:\n\t%s\n", enc );
    assert( hex_decode( dec, (unsigned char*)enc, hlen ) == 0 );
    dec[len] = 0;
    printf("\t%s\n", dec );
    
    assert( memcmp( src, dec, len ) == 0 );
    
    return 0;
}