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// license:BSD-3-Clause
// copyright-holders:Robbbert
/********************************************************************
Support for Goldstar FC-100 cassette images
We don't actually have any info on the cassette frequencies, so
it's all a guess.
********************************************************************/
#include <assert.h>
#include "fc100_cas.h"
#define WAVEENTRY_LOW -32768
#define WAVEENTRY_HIGH 32767
#define FC100_WAV_FREQUENCY 9600
#define FC100_HEADER_BYTES 16
// image size
static int fc100_image_size;
static int fc100_put_samples(int16_t *buffer, int sample_pos, int count, int level)
{
if (buffer)
{
for (int i=0; i<count; i++)
buffer[sample_pos + i] = level;
}
return count;
}
static int fc100_output_bit(int16_t *buffer, int sample_pos, bool bit)
{
int samples = 0;
if (bit)
{
samples += fc100_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_LOW);
samples += fc100_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_HIGH);
samples += fc100_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_LOW);
samples += fc100_put_samples(buffer, sample_pos + samples, 2, WAVEENTRY_HIGH);
}
else
{
samples += fc100_put_samples(buffer, sample_pos + samples, 4, WAVEENTRY_LOW);
samples += fc100_put_samples(buffer, sample_pos + samples, 4, WAVEENTRY_HIGH);
}
return samples;
}
static int fc100_output_byte(int16_t *buffer, int sample_pos, uint8_t byte)
{
int samples = 0;
uint8_t i;
/* start */
samples += fc100_output_bit (buffer, sample_pos + samples, 0);
/* data */
for (i = 0; i<8; i++)
samples += fc100_output_bit (buffer, sample_pos + samples, (byte >> i) & 1);
/* stop */
for (i = 0; i<4; i++)
samples += fc100_output_bit (buffer, sample_pos + samples, 1);
return samples;
}
static int fc100_handle_cassette(int16_t *buffer, const uint8_t *bytes)
{
uint32_t sample_count = 0;
uint32_t byte_count = 0;
uint32_t i;
/* start */
for (i=0; i<2155; i++)
sample_count += fc100_output_bit(buffer, sample_count, 1);
/* header */
for (int i=0; i<FC100_HEADER_BYTES; i++)
sample_count += fc100_output_byte(buffer, sample_count, bytes[i]);
byte_count = FC100_HEADER_BYTES;
/* pause */
for (i=0; i<1630; i++)
sample_count += fc100_output_bit(buffer, sample_count, 1);
/* data */
for (i=byte_count; i<fc100_image_size; i++)
sample_count += fc100_output_byte(buffer, sample_count, bytes[i]);
return sample_count;
}
/*******************************************************************
Generate samples for the tape image
********************************************************************/
static int fc100_cassette_fill_wave(int16_t *buffer, int length, uint8_t *bytes)
{
return fc100_handle_cassette(buffer, bytes);
}
/*******************************************************************
Calculate the number of samples needed for this tape image
********************************************************************/
static int fc100_cassette_calculate_size_in_samples(const uint8_t *bytes, int length)
{
fc100_image_size = length;
return fc100_handle_cassette(nullptr, bytes);
}
static const struct CassetteLegacyWaveFiller fc100_legacy_fill_wave =
{
fc100_cassette_fill_wave, /* fill_wave */
-1, /* chunk_size */
0, /* chunk_samples */
fc100_cassette_calculate_size_in_samples, /* chunk_sample_calc */
FC100_WAV_FREQUENCY, /* sample_frequency */
0, /* header_samples */
0 /* trailer_samples */
};
static cassette_image::error fc100_cassette_identify(cassette_image *cassette, struct CassetteOptions *opts)
{
return cassette_legacy_identify(cassette, opts, &fc100_legacy_fill_wave);
}
static cassette_image::error fc100_cassette_load(cassette_image *cassette)
{
return cassette_legacy_construct(cassette, &fc100_legacy_fill_wave);
}
static const struct CassetteFormat fc100_cassette_image_format =
{
"cas",
fc100_cassette_identify,
fc100_cassette_load,
nullptr
};
CASSETTE_FORMATLIST_START(fc100_cassette_formats)
CASSETTE_FORMAT(fc100_cassette_image_format)
CASSETTE_FORMATLIST_END
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