helpers.function

#ifdef _MSC_VER
#include <basetsd.h>
typedef UINT32 uint32_t;
#else
#include <inttypes.h>
#endif

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_ULONG_BE
#define GET_ULONG_BE(n,b,i)                             \
{                                                       \
    (n) = ( (unsigned long) (b)[(i)    ] << 24 )        \
        | ( (unsigned long) (b)[(i) + 1] << 16 )        \
        | ( (unsigned long) (b)[(i) + 2] <<  8 )        \
        | ( (unsigned long) (b)[(i) + 3]       );       \
}
#endif

#ifndef PUT_ULONG_BE
#define PUT_ULONG_BE(n,b,i)                             \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

int unhexify(unsigned char *obuf, const char *ibuf)
{
    unsigned char c, c2;
    int len = strlen(ibuf) / 2;
    assert(!(strlen(ibuf) %1)); // must be even number of bytes

    while (*ibuf != 0)
    {
        c = *ibuf++;
        if( c >= '0' && c <= '9' )
            c -= '0';
        else if( c >= 'a' && c <= 'f' )
            c -= 'a' - 10;
        else if( c >= 'A' && c <= 'F' )
            c -= 'A' - 10;
        else
            assert( 0 );

        c2 = *ibuf++;
        if( c2 >= '0' && c2 <= '9' )
            c2 -= '0';
        else if( c2 >= 'a' && c2 <= 'f' )
            c2 -= 'a' - 10;
        else if( c2 >= 'A' && c2 <= 'F' )
            c2 -= 'A' - 10;
        else
            assert( 0 );

        *obuf++ = ( c << 4 ) | c2;
    }

    return len;
}

void hexify(unsigned char *obuf, const unsigned char *ibuf, int len)
{
    unsigned char l, h;

    while (len != 0)
    {
        h = (*ibuf) / 16;
        l = (*ibuf) % 16;

        if( h < 10 )
            *obuf++ = '0' + h;
        else
            *obuf++ = 'a' + h - 10;

        if( l < 10 )
            *obuf++ = '0' + l;
        else
            *obuf++ = 'a' + l - 10;

        ++ibuf;
        len--;
    }
}

/**
 * This function just returns data from rand().
 * Although predictable and often similar on multiple
 * runs, this does not result in identical random on
 * each run. So do not use this if the results of a
 * test depend on the random data that is generated.
 *
 * rng_state shall be NULL.
 */
static int rnd_std_rand( void *rng_state )
{
    if( rng_state != NULL )
        rng_state  = NULL;

    return( rand() );
}

/**
 * This function only returns zeros
 *
 * rng_state shall be NULL.
 */
static int rnd_zero_rand( void *rng_state )
{
    if( rng_state != NULL )
        rng_state  = NULL;

    return( 0 );
}

typedef struct
{
    unsigned char *buf;
    int length;
    int per_call;
} rnd_buf_info;

/**
 * This function returns random based on a buffer it receives.
 *
 * rng_state shall be a pointer to a rnd_buf_info structure.
 * 
 * The number of bytes released from the buffer on each call to
 * the random function is specified by per_call. (Can be between
 * 1 and 4)
 *
 * After the buffer is empty it will return rand();
 */
static int rnd_buffer_rand( void *rng_state )
{
    rnd_buf_info *info = (rnd_buf_info *) rng_state;
    int res;

    if( rng_state == NULL )
        return( rand() );

    if( info->per_call > 4 )
        info->per_call = 4;
    else if( info->per_call < 1 )
        info->per_call = 1;

    res = rand();

    if( info->length >= info->per_call )
    {
        memcpy( &res, info->buf, info->per_call );
        info->buf += info->per_call;
        info->length -= info->per_call;
    }
    else if( info->length > 0 )
    {
        memcpy( &res, info->buf, info->length );
        info->length = 0;
    }

    return( res );
}

/**
 * Info structure for the pseudo random function
 *
 * Key should be set at the start to a test-unique value.
 * Do not forget endianness!
 * State( v0, v1 ) should be set to zero.
 */
typedef struct
{
    uint32_t key[16];
    uint32_t v0, v1;
} rnd_pseudo_info;

/**
 * This function returns random based on a pseudo random function.
 * This means the results should be identical on all systems.
 * Pseudo random is based on the XTEA encryption algorithm to
 * generate pseudorandom.
 *
 * rng_state shall be a pointer to a rnd_pseudo_info structure.
 */
static int rnd_pseudo_rand( void *rng_state )
{
    rnd_pseudo_info *info = (rnd_pseudo_info *) rng_state;
    uint32_t i, *k, sum = 0, delta=0x9E3779B9;

    if( rng_state == NULL )
        return( rand() );

    k = info->key;
    for( i = 0; i < 32; i++ )
    {
        info->v0 += (((info->v1 << 4) ^ (info->v1 >> 5)) + info->v1) ^ (sum + k[sum & 3]);
        sum += delta;
        info->v1 += (((info->v0 << 4) ^ (info->v0 >> 5)) + info->v0) ^ (sum + k[(sum>>11) & 3]);
    }

    return( info->v0 );
}