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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/*
CSW format
----------
Header Description
Offset Value Type Description
0x00 (note) ASCII 22 bytes "Compressed Square Wave" signature
0x16 0x1A BYTE Terminator code
0x17 0x02 BYTE CSW major revision number
0x18 0x00 BYTE CSW minor revision number
0x19 DWORD Sample rate
0x1D DWORD Total number of pulses (after decompression)
0x21 BYTE Compression type 0x01: RLE 0x02: Z-RLE
0x22 BYTE Flags b0: initial polarity; if set, the signal starts at logical high
0x23 HDR BYTE Header extension length in bytes (0x00)
0x24 ASCII Encoding application description
0x34 BYTE Header extension data (if present HDR>0)
0x34+HDR CSW data
*/
#include "csw_cas.h"
#include "uef_cas.h"
#include <zlib.h>
#include <cassert>
#include <cstring>
static const uint8_t CSW_HEADER[] = { "Compressed Square Wave" };
/*-------------------------------------------------
csw_cassette_identify - identify cassette
-------------------------------------------------*/
static cassette_image::error csw_cassette_identify(cassette_image *cassette, cassette_image::Options *opts)
{
uint8_t header[0x34];
cassette->image_read(header, 0, sizeof(header));
if (memcmp(&header[0], CSW_HEADER, sizeof(CSW_HEADER) - 1)) {
return cassette_image::error::INVALID_IMAGE;
}
opts->bits_per_sample = 8;
opts->channels = 1;
opts->sample_frequency = little_endianize_int16(*(uint32_t*)(header + 0x19));
return cassette_image::error::SUCCESS;
}
/*-------------------------------------------------
csw_cassette_load - load cassette
-------------------------------------------------*/
static cassette_image::error csw_cassette_load(cassette_image *cassette)
{
uint8_t header[0x34];
uint64_t image_size = cassette->image_size();
std::vector<uint8_t> image_data(image_size);
int8_t bit;
uint8_t compression;
int bsize = 0;
size_t csw_data = 0;
size_t sample_count = 0;
uint32_t sample_rate;
std::vector<int8_t> samples;
/* csw header */
cassette->image_read(header, 0, sizeof(header));
if (header[0x16] != 0x1a)
{
LOG_FORMATS("csw_cassette_load: Terminator Code Not Found\n");
return cassette_image::error::INVALID_IMAGE;
}
LOG_FORMATS("CSW Version %d.%d\n", header[0x17], header[0x18]);
switch (header[0x17])
{
case 1:
sample_rate = little_endianize_int16(*(uint32_t*)(header + 0x19));
compression = header[0x1b];
bit = (header[0x1c] & 1) ? 127 : -128;
csw_data = 0x20;
LOG_FORMATS("Sample Rate: %u\n", sample_rate);
LOG_FORMATS("CompressionType: %u Flags: %u\n", header[0x1b], header[0x1c]);
break;
case 2:
sample_rate = little_endianize_int32(*(uint32_t*)(header + 0x19));
compression = header[0x21];
bit = (header[0x22] & 1) ? 127 : -128;
csw_data = (size_t) header[0x23] + 0x34;
LOG_FORMATS("Sample Rate: %u\n", sample_rate);
LOG_FORMATS("Number of Pulses: %u\n", little_endianize_int32(*(uint32_t *)(header + 0x1d)));
LOG_FORMATS("CompressionType: %u Flags: %u\n", header[0x21], header[0x22]);
LOG_FORMATS("Encoder: ");
for (int i = 0; i < 16; i++)
LOG_FORMATS("%c", header[0x24 + i]);
LOG_FORMATS("\n");
break;
default:
LOG_FORMATS("Unsupported Major Version\n");
return cassette_image::error::INVALID_IMAGE;
}
/* csw data */
switch (compression)
{
case 0x01:
/* RLE (Run Length Encoding) */
for (size_t pos = csw_data; pos < image_size; pos++)
{
bsize = image_data[pos];
if (bsize == 0)
{
bsize = little_endianize_int32(*(uint32_t *)(&image_data[pos + 1]));
pos += 4;
}
for (int i = 0; i < bsize; i++)
{
samples.resize(sample_count + 1);
samples[sample_count++] = bit;
}
bit ^= 0xff;
}
break;
case 0x02:
/* Z-RLE (CSW v2.xx only) */
cassette->image_read(&image_data[0], 0, image_size);
std::vector<uint8_t> gz_ptr;
z_stream d_stream;
int err;
gz_ptr.resize(8);
d_stream.next_in = (unsigned char *) &image_data[csw_data];
d_stream.avail_in = image_size - 0x34 - header[0x23];
d_stream.total_in = 0;
d_stream.next_out = &gz_ptr[0];
d_stream.avail_out = 1;
d_stream.total_out = 0;
d_stream.zalloc = nullptr;
d_stream.zfree = nullptr;
d_stream.opaque = nullptr;
d_stream.data_type = 0;
err = inflateInit(&d_stream);
if (err != Z_OK)
{
LOG_FORMATS("inflateInit error: %d\n", err);
return cassette_image::error::INVALID_IMAGE;
}
do
{
d_stream.next_out = &gz_ptr[0];
d_stream.avail_out = 1;
err = inflate(&d_stream, Z_SYNC_FLUSH);
if (err == Z_OK)
{
bsize = gz_ptr[0];
if (bsize == 0)
{
d_stream.avail_out = 4;
d_stream.next_out = &gz_ptr[0];
err = inflate(&d_stream, Z_SYNC_FLUSH);
bsize = little_endianize_int32(*(uint32_t *)(&gz_ptr[0]));
}
for (int i = 0; i < bsize; i++)
{
samples.resize(sample_count + 1);
samples[sample_count++] = bit;
}
bit ^= 0xff;
}
}
while (err == Z_OK);
if (err != Z_STREAM_END)
{
LOG_FORMATS("inflate error: %d\n", err);
return cassette_image::error::INVALID_IMAGE;
}
err = inflateEnd(&d_stream);
if (err != Z_OK)
{
LOG_FORMATS("inflateEnd error: %d\n", err);
return cassette_image::error::INVALID_IMAGE;
}
break;
}
return cassette->put_samples(0, 0.0, (double) sample_count / sample_rate, sample_count, 1, &samples[0], cassette_image::WAVEFORM_8BIT);
}
/*-------------------------------------------------
CassetteFormat csw_cassette_format
-------------------------------------------------*/
const cassette_image::Format csw_cassette_format = {
"csw",
csw_cassette_identify,
csw_cassette_load,
nullptr
};
CASSETTE_FORMATLIST_START(csw_cassette_formats)
CASSETTE_FORMAT(csw_cassette_format)
CASSETTE_FORMATLIST_END
CASSETTE_FORMATLIST_START(bbc_cassette_formats)
CASSETTE_FORMAT(csw_cassette_format)
CASSETTE_FORMAT(uef_cassette_format)
CASSETTE_FORMATLIST_END
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