Files
fluxengine/arch/amiga/encoder.cc
David Given d0ed5b32f7 Add support for 528-byte sectors. Adjust the post-index gap to (try?) and fit
all the data in one revolution. I think my write clock is a bit slow.
2019-12-14 21:49:31 +01:00

127 lines
3.4 KiB
C++

#include "globals.h"
#include "record.h"
#include "decoders/decoders.h"
#include "encoders/encoders.h"
#include "amiga.h"
#include "crc.h"
#include "sectorset.h"
#include "writer.h"
FlagGroup amigaEncoderFlags;
static DoubleFlag clockRateUs(
{ "--clock-rate" },
"Encoded data clock rate (microseconds).",
2.00);
static DoubleFlag postIndexGapMs(
{ "--post-index-gap" },
"Post-index gap before first sector header (milliseconds).",
0.5);
static int charToInt(char c)
{
if (isdigit(c))
return c - '0';
return 10 + tolower(c) - 'a';
}
static void write_bits(std::vector<bool>& bits, unsigned& cursor, const std::vector<bool>& src)
{
for (bool bit : src)
{
if (cursor < bits.size())
bits[cursor++] = bit;
}
}
static void write_bits(std::vector<bool>& bits, unsigned& cursor, uint64_t data, int width)
{
cursor += width;
for (int i=0; i<width; i++)
{
unsigned pos = cursor - i - 1;
if (pos < bits.size())
bits[pos] = data & 1;
data >>= 1;
}
}
static void write_interleaved_bytes(std::vector<bool>& bits, unsigned& cursor, const Bytes& bytes)
{
assert(!(bytes.size() & 3));
Bytes interleaved = amigaInterleave(bytes);
encodeMfm(bits, cursor, interleaved);
}
static void write_interleaved_bytes(std::vector<bool>& bits, unsigned& cursor, uint32_t data)
{
Bytes b(4);
ByteWriter bw(b);
bw.write_be32(data);
write_interleaved_bytes(bits, cursor, b);
}
static void write_sector(std::vector<bool>& bits, unsigned& cursor, const Sector* sector)
{
if ((sector->data.size() != 512) && (sector->data.size() != 528))
Error() << "unsupported sector size --- you must pick 512 or 528";
write_bits(bits, cursor, AMIGA_SECTOR_RECORD, 6*8);
std::vector<bool> headerBits(20*16);
unsigned headerCursor = 0;
Bytes header =
{
0xff, /* Amiga 1.0 format byte */
(uint8_t) ((sector->logicalTrack<<1) | sector->logicalSide),
(uint8_t) sector->logicalSector,
(uint8_t) (AMIGA_SECTORS_PER_TRACK - sector->logicalSector)
};
write_interleaved_bytes(headerBits, headerCursor, header);
Bytes recoveryInfo(16);
if (sector->data.size() == 528)
recoveryInfo = sector->data.slice(512, 16);
write_interleaved_bytes(headerBits, headerCursor, recoveryInfo);
std::vector<bool> dataBits(512*16);
unsigned dataCursor = 0;
write_interleaved_bytes(dataBits, dataCursor, sector->data);
write_bits(bits, cursor, headerBits);
uint32_t headerChecksum = amigaChecksum(toBytes(headerBits));
write_interleaved_bytes(bits, cursor, headerChecksum);
uint32_t dataChecksum = amigaChecksum(toBytes(dataBits));
write_interleaved_bytes(bits, cursor, dataChecksum);
write_bits(bits, cursor, dataBits);
}
std::unique_ptr<Fluxmap> AmigaEncoder::encode(
int physicalTrack, int physicalSide, const SectorSet& allSectors)
{
if ((physicalTrack < 0) || (physicalTrack >= AMIGA_TRACKS_PER_DISK))
return std::unique_ptr<Fluxmap>();
int bitsPerRevolution = 200000.0 / clockRateUs;
std::vector<bool> bits(bitsPerRevolution);
unsigned cursor = 0;
fillBitmapTo(bits, cursor, postIndexGapMs * 1000 / clockRateUs, { true, false });
for (int sectorId=0; sectorId<AMIGA_SECTORS_PER_TRACK; sectorId++)
{
const auto& sectorData = allSectors.get(physicalTrack, physicalSide, sectorId);
write_sector(bits, cursor, sectorData);
}
if (cursor >= bits.size())
Error() << "track data overrun";
fillBitmapTo(bits, cursor, bits.size(), { true, false });
std::unique_ptr<Fluxmap> fluxmap(new Fluxmap);
fluxmap->appendBits(bits, clockRateUs*1e3);
return fluxmap;
}