/*******************************************************************
Generate samples for 1 byte
********************************************************************/
static inline int kc_cas_byte(int16_t *buffer, int sample_pos, uint8_t data)
{
int samples = 0;
// write the byte
for ( int i = 0; i < 8; i++ )
{
if ( data & 0x01 )
{
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_BIT_1 );
}
else
{
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_BIT_0 );
}
data >>= 1;
}
// byte separator
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_SEPARATOR);
return samples;
}
/*******************************************************************
Generate samples for 1 byte
********************************************************************/
INLINE int kc_cas_byte(INT16 *buffer, int sample_pos, UINT8 data)
{
int samples = 0;
// write the byte
for ( int i = 0; i < 8; i++ )
{
if ( data & 0x01 )
{
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_BIT_1 );
}
else
{
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_BIT_0 );
}
data >>= 1;
}
// byte separator
samples += kc_cas_cycle( buffer, sample_pos + samples, FREQ_SEPARATOR);
return samples;
}
static int kc_handle_cass(int16_t *buffer, const uint8_t *casdata, int type)
{
int data_pos = (type == KC_IMAGE_KCC || type == KC_IMAGE_KCM) ? 0 : 16;
int sample_count = 0;
int block_id = 1;
// 1 sec of silence at start
sample_count += kc_cas_silence(buffer, sample_count, KC_WAV_FREQUENCY);
// 8000 cycles of BIT_1 for synchronization
for (int i=0; i<8000; i++)
sample_count += kc_cas_cycle( buffer, sample_count, FREQ_BIT_1);
// on the entire file
while( data_pos < kc_image_size )
{
uint8_t checksum = 0;
// 200 cycles of BIT_1 every block
for (int i=0; i<200; i++)
sample_count += kc_cas_cycle( buffer, sample_count, FREQ_BIT_1);
// separator
sample_count += kc_cas_cycle( buffer, sample_count, FREQ_SEPARATOR);
// in TAP and TP2 file the first byte is the ID
if (type == KC_IMAGE_TAP || type == KC_IMAGE_TP2 || type == KC_IMAGE_KCM)
block_id = casdata[data_pos++];
// is the last block ?
if (data_pos + 128 >= kc_image_size && type == KC_IMAGE_KCC)
block_id = 0xff;
// write the block ID
sample_count += kc_cas_byte( buffer, sample_count, block_id );
// write the 128 bytes of the block
for (int i=0; i<128; i++)
{
uint8_t data = 0;
if (data_pos < kc_image_size)
data = casdata[data_pos++];
// calculate the checksum
checksum += data;
// write a byte
sample_count += kc_cas_byte( buffer, sample_count, data );
}
// TP2 and KCM files also have the checksum byte
if (type == KC_IMAGE_TP2 || type == KC_IMAGE_KCM)
checksum = casdata[data_pos++];
// 8bit checksum
sample_count += kc_cas_byte( buffer, sample_count, checksum );
// more TAP and TP2 can be combined into the same file
if ((type == KC_IMAGE_TAP || type == KC_IMAGE_TP2) && block_id == 0xff && data_pos < kc_image_size)
{
if (casdata[data_pos] == 0xc3 || casdata[data_pos] == 0x4b)
{
sample_count += kc_cas_silence(buffer, sample_count, KC_WAV_FREQUENCY/10);
data_pos += 16;
}
}
block_id++;
}
sample_count += kc_cas_cycle( buffer, sample_count, FREQ_SEPARATOR);
// 1 sec of silence
sample_count += kc_cas_silence(buffer, sample_count, KC_WAV_FREQUENCY);
return sample_count;
}
