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Add initial support for the Basis-108.

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This commit is contained in:
dg
2023-03-27 23:07:59 +00:00
parent cebc7c6cd2
commit 27a04ee22b
5 changed files with 105 additions and 164 deletions
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2
README.md
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@@ -106,7 +106,7 @@ people who've had it work).
| [Acorn DFS](doc/disk-acorndfs.md) | 🦄 | 🦖* | |
| [Ampro Little Board](doc/disk-ampro.md) | 🦖 | 🦖* | |
| [Agat](doc/disk-agat.md) | 🦖 | | Soviet Union Apple-II-like computer |
| [Apple II](doc/disk-apple2.md) | 🦄 | 🦄 | |
| [Apple II](doc/disk-apple2.md) | 🦄 | 🦄 | also the Basis-108 clone |
| [Amiga](doc/disk-amiga.md) | 🦄 | 🦄 | |
| [Commodore 64 1541/1581](doc/disk-c64.md) | 🦄 | 🦄 | and probably the other formats |
| [Brother 120kB](doc/disk-brother.md) | 🦄 | 🦄 | |

8
arch/apple2/apple2.proto
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@@ -2,7 +2,10 @@ syntax = "proto2";
import "lib/common.proto";
message Apple2DecoderProto {}
message Apple2DecoderProto {
optional uint32 side_one_track_offset = 1
[ default = 0, (help) = "offset to apply to track numbers on side 1" ];
}
message Apple2EncoderProto
{
@@ -13,4 +16,7 @@ message Apple2EncoderProto
/* Apple II disk drives spin at 300rpm. */
optional double rotational_period_ms = 2
[ default = 200.0, (help) = "rotational period on the real device" ];
optional uint32 side_one_track_offset = 3
[ default = 0, (help) = "offset to apply to track numbers on side 1" ];
}

167
arch/apple2/decoder.cc
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@@ -5,6 +5,8 @@
#include "decoders/decoders.h"
#include "sector.h"
#include "apple2.h"
#include "arch/apple2/apple2.pb.h"
#include "lib/decoders/decoders.pb.h"
#include "bytes.h"
#include "fmt/format.h"
#include <string.h>
@@ -12,22 +14,25 @@
const FluxPattern SECTOR_RECORD_PATTERN(24, APPLE2_SECTOR_RECORD);
const FluxPattern DATA_RECORD_PATTERN(24, APPLE2_DATA_RECORD);
const FluxMatchers ANY_RECORD_PATTERN({ &SECTOR_RECORD_PATTERN, &DATA_RECORD_PATTERN });
const FluxMatchers ANY_RECORD_PATTERN(
{&SECTOR_RECORD_PATTERN, &DATA_RECORD_PATTERN});
static int decode_data_gcr(uint8_t gcr)
{
switch (gcr)
{
#define GCR_ENTRY(gcr, data) \
case gcr: return data;
#include "data_gcr.h"
#undef GCR_ENTRY
#define GCR_ENTRY(gcr, data) \
case gcr: \
return data;
#include "data_gcr.h"
#undef GCR_ENTRY
}
return -1;
}
/* This is extremely inspired by the MESS implementation, written by Nathan Woods
* and R. Belmont: https://github.com/mamedev/mame/blob/7914a6083a3b3a8c243ae6c3b8cb50b023f21e0e/src/lib/formats/ap2_dsk.cpp
/* This is extremely inspired by the MESS implementation, written by Nathan
* Woods and R. Belmont:
* https://github.com/mamedev/mame/blob/7914a6083a3b3a8c243ae6c3b8cb50b023f21e0e/src/lib/formats/ap2_dsk.cpp
*/
static Bytes decode_crazy_data(const uint8_t* inp, Sector::Status& status)
{
@@ -47,9 +52,11 @@ static Bytes decode_crazy_data(const uint8_t* inp, Sector::Status& status)
{
/* 3 * 2 bit */
output[i + 0] = ((checksum >> 1) & 0x01) | ((checksum << 1) & 0x02);
output[i + 86] = ((checksum >> 3) & 0x01) | ((checksum >> 1) & 0x02);
output[i + 86] =
((checksum >> 3) & 0x01) | ((checksum >> 1) & 0x02);
if ((i + 172) < APPLE2_SECTOR_LENGTH)
output[i + 172] = ((checksum >> 5) & 0x01) | ((checksum >> 3) & 0x02);
output[i + 172] =
((checksum >> 5) & 0x01) | ((checksum >> 3) & 0x02);
}
}
@@ -67,88 +74,102 @@ static uint8_t combine(uint16_t word)
class Apple2Decoder : public Decoder
{
public:
Apple2Decoder(const DecoderProto& config):
Decoder(config)
{}
Apple2Decoder(const DecoderProto& config): Decoder(config) {}
nanoseconds_t advanceToNextRecord() override
{
return seekToPattern(ANY_RECORD_PATTERN);
}
{
return seekToPattern(ANY_RECORD_PATTERN);
}
void decodeSectorRecord() override
{
if (readRaw24() != APPLE2_SECTOR_RECORD)
return;
{
if (readRaw24() != APPLE2_SECTOR_RECORD)
return;
/* Read header. */
/* Read header. */
auto header = toBytes(readRawBits(8*8)).slice(0, 8);
ByteReader br(header);
auto header = toBytes(readRawBits(8 * 8)).slice(0, 8);
ByteReader br(header);
uint8_t volume = combine(br.read_be16());
_sector->logicalTrack = combine(br.read_be16());
_sector->logicalSector = combine(br.read_be16());
uint8_t checksum = combine(br.read_be16());
uint8_t volume = combine(br.read_be16());
_sector->logicalTrack = combine(br.read_be16());
_sector->logicalSide = _sector->physicalSide;
_sector->logicalSector = combine(br.read_be16());
uint8_t checksum = combine(br.read_be16());
// If the checksum is correct, upgrade the sector from MISSING
// to DATA_MISSING in anticipation of its data record
if (checksum == (volume ^ _sector->logicalTrack ^ _sector->logicalSector))
_sector->status = Sector::DATA_MISSING; /* unintuitive but correct */
}
// If the checksum is correct, upgrade the sector from MISSING
// to DATA_MISSING in anticipation of its data record
if (checksum ==
(volume ^ _sector->logicalTrack ^ _sector->logicalSector))
_sector->status =
Sector::DATA_MISSING; /* unintuitive but correct */
if (_sector->logicalSide == 1)
_sector->logicalTrack -= _config.apple2().side_one_track_offset();
/* Sanity check. */
if (_sector->logicalTrack > 100)
{
_sector->status = Sector::MISSING;
return;
}
}
void decodeDataRecord() override
{
/* Check ID. */
{
/* Check ID. */
if (readRaw24() != APPLE2_DATA_RECORD)
return;
if (readRaw24() != APPLE2_DATA_RECORD)
return;
// Sometimes there's a 1-bit gap between APPLE2_DATA_RECORD and
// the data itself. This has been seen on real world disks
// such as the Apple II Operating System Kit from Apple2Online.
// However, I haven't seen it described in any of the various
// references.
//
// This extra '0' bit would not affect the real disk interface,
// as it was a '1' reaching the top bit of a shift register
// that triggered a byte to be available, but it affects the
// way the data is read here.
//
// While the floppies tested only seemed to need this applied
// to the first byte of the data record, applying it
// consistently to all of them doesn't seem to hurt, and
// simplifies the code.
// Sometimes there's a 1-bit gap between APPLE2_DATA_RECORD and
// the data itself. This has been seen on real world disks
// such as the Apple II Operating System Kit from Apple2Online.
// However, I haven't seen it described in any of the various
// references.
//
// This extra '0' bit would not affect the real disk interface,
// as it was a '1' reaching the top bit of a shift register
// that triggered a byte to be available, but it affects the
// way the data is read here.
//
// While the floppies tested only seemed to need this applied
// to the first byte of the data record, applying it
// consistently to all of them doesn't seem to hurt, and
// simplifies the code.
/* Read and decode data. */
/* Read and decode data. */
auto readApple8 = [&]() {
auto result = 0;
while((result & 0x80) == 0) {
auto b = readRawBits(1);
if(b.empty()) break;
result = (result << 1) | b[0];
}
return result;
};
auto readApple8 = [&]()
{
auto result = 0;
while ((result & 0x80) == 0)
{
auto b = readRawBits(1);
if (b.empty())
break;
result = (result << 1) | b[0];
}
return result;
};
constexpr unsigned recordLength = APPLE2_ENCODED_SECTOR_LENGTH+2;
uint8_t bytes[recordLength];
for(auto &byte : bytes) {
byte = readApple8();
}
constexpr unsigned recordLength = APPLE2_ENCODED_SECTOR_LENGTH + 2;
uint8_t bytes[recordLength];
for (auto& byte : bytes)
{
byte = readApple8();
}
// Upgrade the sector from MISSING to BAD_CHECKSUM.
// If decode_crazy_data succeeds, it upgrades the sector to
// OK.
_sector->status = Sector::BAD_CHECKSUM;
_sector->data = decode_crazy_data(&bytes[0], _sector->status);
}
// Upgrade the sector from MISSING to BAD_CHECKSUM.
// If decode_crazy_data succeeds, it upgrades the sector to
// OK.
_sector->status = Sector::BAD_CHECKSUM;
_sector->data = decode_crazy_data(&bytes[0], _sector->status);
}
};
std::unique_ptr<Decoder> createApple2Decoder(const DecoderProto& config)
{
return std::unique_ptr<Decoder>(new Apple2Decoder(config));
return std::unique_ptr<Decoder>(new Apple2Decoder(config));
}

90
src/formats/apple2.textpb
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@@ -1,4 +1,5 @@
comment: 'Apple II 140kB DOS 3.3 5.25" 40 track SSSD'
include: '_apple2'
image_reader {
filename: "apple2.img"
@@ -22,94 +23,5 @@ image_writer {
type: IMG
}
decoder {
apple2 {}
}
encoder {
apple2 {}
}
tpi: 48
option {
name: "appledos"
comment: "specifies AppleDOS soft sector skew for filesystem access and images"
message: "compensating for AppleDOS soft sector skew"
config {
image_reader {
filesystem_sector_order: true
}
image_writer {
filesystem_sector_order: true
}
layout {
layoutdata {
filesystem {
sector: 0
sector: 14
sector: 13
sector: 12
sector: 11
sector: 10
sector: 9
sector: 8
sector: 7
sector: 6
sector: 5
sector: 4
sector: 3
sector: 2
sector: 1
sector: 15
}
}
}
}
}
option {
name: "prodos"
comment: "specifies ProDOS soft sector skew for filesystem access and images"
message: "compensating for ProDOS soft sector skew"
config {
image_reader {
filesystem_sector_order: true
}
image_writer {
filesystem_sector_order: true
}
filesystem {
type: PRODOS
}
layout {
layoutdata {
filesystem {
sector: 0
sector: 2
sector: 4
sector: 6
sector: 8
sector: 10
sector: 12
sector: 14
sector: 1
sector: 3
sector: 5
sector: 7
sector: 9
sector: 11
sector: 13
sector: 15
}
}
}
}
}

2
src/formats/build.mk
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@@ -1,6 +1,7 @@
FORMATS = \
_acornadfs8 \
_acornadfs32 \
_apple2 \
_atari \
_micropolis \
_northstar \
@@ -27,6 +28,7 @@ FORMATS = \
atarist740 \
atarist800 \
atarist820 \
basis640 \
bk800 \
brother120 \
brother240 \