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// license:BSD-3-Clause
// copyright-holders:Sandro Ronco
/********************************************************************
Support for Videoton TVC .cas files
http://tvc.homeserver.hu/html/konvertformatum.html
********************************************************************/
#include "tvc_cas.h"
#include <cassert>
#define TVC64_BIT0_FREQ 1812
#define TVC64_BIT1_FREQ 2577
#define TVC64_PRE_FREQ 2128
#define TVC64_SYNC_FREQ 1359
#define WAVE_AMPLITUDE 0x3fffffff
#define TVC64_HEADER_BYTES 0x90
#define TVC64_HEADER_BYTES 0x90
static void tvc64_emit_level(cassette_image *cass, double &time, int freq, int level)
{
double period = 1.0 / freq;
cass->put_sample(0, time, period, level * WAVE_AMPLITUDE);
time += period;
}
static cassette_image::error tvc64_output_byte(cassette_image *cass, double &time, uint8_t byte)
{
for (int i=0; i<8; i++)
{
if ((byte>>i) & 0x01)
{
tvc64_emit_level(cass, time, TVC64_BIT1_FREQ*2, +1);
tvc64_emit_level(cass, time, TVC64_BIT1_FREQ*2, -1);
}
else
{
tvc64_emit_level(cass, time, TVC64_BIT0_FREQ*2, +1);
tvc64_emit_level(cass, time, TVC64_BIT0_FREQ*2, -1);
}
}
return cassette_image::error::SUCCESS;
}
static int tvc64_output_predata(cassette_image *cass, double &time, int number)
{
for (int i=0; i<number; i++)
{
tvc64_emit_level(cass, time, TVC64_PRE_FREQ*2, +1);
tvc64_emit_level(cass, time, TVC64_PRE_FREQ*2, -1);
}
return (int)cassette_image::error::SUCCESS;
}
static uint16_t tvc64_calc_crc(const uint8_t *bytes, int size)
{
uint16_t crc = 0;
for (int i=0; i<size; i++)
{
for (int b=0; b<8; b++)
{
uint8_t al = (bytes[i] & (1<<b)) ? 0x80 : 0x00;
al ^= ((crc>>8) & 0xff);
if (al & 0x80)
crc ^= 0x0810;
crc <<= 1;
if (al & 0x80) crc += 1;
}
}
return crc;
}
static cassette_image::error tvc64_cassette_load(cassette_image *cassette)
{
uint8_t tmp_buff[512];
int buff_idx = 0;
double time = 0.0;
uint8_t header[TVC64_HEADER_BYTES];
cassette->image_read(header, 0, TVC64_HEADER_BYTES);
uint16_t cas_size = (header[0x83]<<8) | header[0x82];
// tape header
tmp_buff[buff_idx++] = 0x00;
tmp_buff[buff_idx++] = 0x6a;
tmp_buff[buff_idx++] = 0xff; // head sector
tmp_buff[buff_idx++] = 0x11; // not puffered
tmp_buff[buff_idx++] = 0x00; // not write protected
tmp_buff[buff_idx++] = 0x01; // 1 sector
tmp_buff[buff_idx++] = 0x00; // sector number
tmp_buff[buff_idx++] = 0x12; // head size
tmp_buff[buff_idx++] = 0x01; // name size
tmp_buff[buff_idx++] = ' '; // name
tmp_buff[buff_idx++] = 0x00;
tmp_buff[buff_idx++] = header[0x81]; // type
tmp_buff[buff_idx++] = header[0x82]; // size LSB
tmp_buff[buff_idx++] = header[0x83]; // size MSB
tmp_buff[buff_idx++] = header[0x84]; // autostart
// sector fill
for (int i=0; i<10 ; i++)
tmp_buff[buff_idx++] = 0x00;
tmp_buff[buff_idx++] = 0x00; // file version
tmp_buff[buff_idx++] = 0x00; // no last sector
// updates the header CRC
uint16_t crc = tvc64_calc_crc(tmp_buff, buff_idx);
tmp_buff[buff_idx++] = crc & 0xff;
tmp_buff[buff_idx++] = (crc>>8) & 0xff;
// 2 sec silence
tvc64_emit_level(cassette, time, 2, 0);
// 10240 pre data cycles
tvc64_output_predata(cassette, time, 10240);
// 1 synchro cycle
tvc64_emit_level(cassette, time, TVC64_SYNC_FREQ*2, +1);
tvc64_emit_level(cassette, time, TVC64_SYNC_FREQ*2, -1);
// header data
for (int i=0; i<buff_idx; i++)
tvc64_output_byte(cassette, time, tmp_buff[i]);
// 5 post data cycles
tvc64_output_predata(cassette, time, 5);
// 1 sec silence
tvc64_emit_level(cassette, time, 1, 0);
// 5120 pre data cycles
tvc64_output_predata(cassette, time, 5120);
// 1 synchro cycle
tvc64_emit_level(cassette, time, TVC64_SYNC_FREQ*2, +1);
tvc64_emit_level(cassette, time, TVC64_SYNC_FREQ*2, -1);
// first data sector contain the data header
buff_idx = 0;
tmp_buff[buff_idx++] = 0x00;
tmp_buff[buff_idx++] = 0x6a;
tmp_buff[buff_idx++] = 0x00; // data sector
tmp_buff[buff_idx++] = 0x11; // not puffered
tmp_buff[buff_idx++] = 0x00; // not write protected
tmp_buff[buff_idx++] = (uint8_t)((cas_size / 256) + ((cas_size % 256) > 0 ? 1 : 0)); // number of sectors
uint8_t sect_num = 1;
int sector_num = cas_size / 256;
for (int i=0; i<=sector_num; i++)
{
tmp_buff[buff_idx++] = sect_num++; // sector number
// sector size
if (i == sector_num)
tmp_buff[buff_idx++] = cas_size % 256;
else
tmp_buff[buff_idx++] = 0x00;
// sector data
int sector_size = (i == sector_num) ? (cas_size % 256) : 256;
for (int z=0; z < sector_size; z++)
cassette->image_read(&tmp_buff[buff_idx++], TVC64_HEADER_BYTES + i*256 + z, 1);
if (i == sector_num || ((i+1) == sector_num && (cas_size % 256 ) == 0))
tmp_buff[buff_idx++] = 0xff; // last sector
else
tmp_buff[buff_idx++] = 0x00; // no last sector
// sector crc
crc = tvc64_calc_crc(tmp_buff, buff_idx);
tmp_buff[buff_idx++] = crc & 0xff;
tmp_buff[buff_idx++] = (crc>>8) & 0xff;
// output the sector
for (int z=0; z<buff_idx; z++)
tvc64_output_byte(cassette, time, tmp_buff[z]);
buff_idx = 0;
}
// 5 post data cycles
tvc64_output_predata(cassette, time, 5);
// 1 sec silence
tvc64_emit_level(cassette, time, 1, 0);
return cassette_image::error::SUCCESS;
}
static cassette_image::error tvc64_cassette_identify(cassette_image *cassette, cassette_image::Options *opts)
{
uint8_t byte;
cassette->image_read(&byte, 0, 1);
if (byte == 0x11)
{
opts->bits_per_sample = 16;
opts->channels = 1;
opts->sample_frequency = 44100;
return cassette_image::error::SUCCESS;
}
return cassette_image::error::INVALID_IMAGE;
}
static const cassette_image::Format tvc64_cassette_image_format =
{
"cas",
tvc64_cassette_identify,
tvc64_cassette_load,
nullptr
};
CASSETTE_FORMATLIST_START(tvc64_cassette_formats)
CASSETTE_FORMAT(tvc64_cassette_image_format)
CASSETTE_FORMATLIST_END
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