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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/*********************************************************************
formats/apd_dsk.c
Archimedes Protected Disk Image format
APD file structure
------------------
The APD file is a GZip compressed version of the original APD file.
Compressed file always starts:
1F 8B 08 00 00 00 00 00 00 0B EC BD
^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^
| | | | | | | | | |
| | | | | | | | | +- OS
| | | | | | | | +---- xfl
| | | | +--+--+--+------- time
| | | +------------------- gzip flags
| | +---------------------- gzip compression*
| |
+--+------------------------- gzip header
* Compression method: 8 is the only supported format
Original APD file structure:
0 - 7 "APDX0001" identifier
8 - B t0sd - Track 0 SD length in bits
C - F t0dd - Track 0 DD length in bits
10 - 13 t0qd - Track 0 QD length in bits
14 - 1F t1sd - Track 1 SD length in bits
20 - 23 t1dd - Track 1 DD length in bits
24 - 27 t1qd - Track 1 QD length in bits
... ... repeated to Track 159
77C - 787 Track 160 (blank)
7C4 - 7CF Track 166 (blank)
7D0 Track 0 SD data
+ (t0sd + 7) >> 3 Track 0 DD data
+ (t0dd + 7) >> 3 Track 0 QD data
+ (t0qd + 7) >> 3 Track 1 SD data
+ (t1sd + 7) >> 3 Track 1 DD data
+ (t1dd + 7) >> 3 Track 1 QD data
SD data is big-endian raw FM words
DD/QD data is big-endian raw MFM words
As far as I can tell, the tracks are always sequential, so
physical tracks translate as:
Physical APD
-------------- -------
Side 0 Track 0 > Track 0
Side 1 Track 0 > Track 1
Side 0 Track 1 > Track 2
etc.
*********************************************************************/
#include <zlib.h>
#include "formats/apd_dsk.h"
static const uint8_t APD_HEADER[8] = { 'A', 'P', 'D', 'X', '0', '0', '0', '1' };
static const uint8_t GZ_HEADER[2] = { 0x1f, 0x8b };
apd_format::apd_format()
{
}
const char *apd_format::name() const
{
return "apd";
}
const char *apd_format::description() const
{
return "Archimedes Protected Disk Image";
}
const char *apd_format::extensions() const
{
return "apd";
}
int apd_format::identify(io_generic *io, uint32_t form_factor)
{
uint64_t size = io_generic_size(io);
std::vector<uint8_t> img(size);
io_generic_read(io, &img[0], 0, size);
int err;
std::vector<uint8_t> gz_ptr(8);
z_stream d_stream;
if (!memcmp(&img[0], GZ_HEADER, sizeof(GZ_HEADER))) {
d_stream.zalloc = nullptr;
d_stream.zfree = nullptr;
d_stream.opaque = nullptr;
d_stream.next_in = &img[0];
d_stream.avail_in = size;
d_stream.next_out = &gz_ptr[0];
d_stream.avail_out = 8;
err = inflateInit2(&d_stream, MAX_WBITS | 16);
if (err != Z_OK) return 0;
err = inflate(&d_stream, Z_SYNC_FLUSH);
if (err != Z_OK) return 0;
err = inflateEnd(&d_stream);
if (err != Z_OK) return 0;
img = gz_ptr;
}
if (!memcmp(&img[0], APD_HEADER, sizeof(APD_HEADER))) {
return 100;
}
return 0;
}
bool apd_format::load(io_generic *io, uint32_t form_factor, floppy_image *image)
{
uint64_t size = io_generic_size(io);
std::vector<uint8_t> img(size);
io_generic_read(io, &img[0], 0, size);
int err;
std::vector<uint8_t> gz_ptr;
z_stream d_stream;
int inflate_size = (img[size - 1] << 24) | (img[size - 2] << 16) | (img[size - 3] << 8) | img[size - 4];
uint8_t *in_ptr = &img[0];
if (!memcmp(&img[0], GZ_HEADER, sizeof(GZ_HEADER))) {
gz_ptr.resize(inflate_size);
d_stream.zalloc = nullptr;
d_stream.zfree = nullptr;
d_stream.opaque = nullptr;
d_stream.next_in = in_ptr;
d_stream.avail_in = size;
d_stream.next_out = &gz_ptr[0];
d_stream.avail_out = inflate_size;
err = inflateInit2(&d_stream, MAX_WBITS | 16);
if (err != Z_OK) {
osd_printf_error("inflateInit2 error: %d\n", err);
return false;
}
err = inflate(&d_stream, Z_FINISH);
if (err != Z_STREAM_END && err != Z_OK) {
osd_printf_error("inflate error: %d\n", err);
return false;
}
err = inflateEnd(&d_stream);
if (err != Z_OK) {
osd_printf_error("inflateEnd error: %d\n", err);
return false;
}
size = inflate_size;
img = gz_ptr;
}
int data = 0x7d0;
for (int track = 0; track < 166; track++) {
uint32_t sdlen = little_endianize_int32(*(uint32_t *)(&img[(track * 12) + 8 + 0x0]));
uint32_t ddlen = little_endianize_int32(*(uint32_t *)(&img[(track * 12) + 8 + 0x4]));
uint32_t qdlen = little_endianize_int32(*(uint32_t *)(&img[(track * 12) + 8 + 0x8]));
if (sdlen > 0) {
generate_track_from_bitstream(track / 2, track % 2, &img[data], sdlen, image);
data += (sdlen + 7) >> 3;
}
if (ddlen > 0) {
generate_track_from_bitstream(track / 2, track % 2, &img[data], ddlen, image);
data += (ddlen + 7) >> 3;
}
if (qdlen > 0) {
generate_track_from_bitstream(track / 2, track % 2, &img[data], qdlen, image);
data += (qdlen + 7) >> 3;
}
}
image->set_variant(floppy_image::DSDD);
return true;
}
bool apd_format::supports_save() const
{
return false;
}
const floppy_format_type FLOPPY_APD_FORMAT = &floppy_image_format_creator<apd_format>;
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