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apple2js
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Fix sector wrap issue, validate sector

This commit is contained in:
Will Scullin 2022-08-20 08:31:34 -07:00
parent 04ef236601
commit fec0e14465
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GPG Key ID: 26DCD1042C6638CD
1 changed files with 22 additions and 9 deletions
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31
js/formats/format_utils.ts
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@ -335,7 +335,7 @@ export interface TrackNibble {
* @param sector sector number to read
* @returns An array of sector data bytes.
*/
export function findSector(disk: NibbleDisk, track: byte, sector: byte): TrackNibble | null {
export function findSector(disk: NibbleDisk, track: byte, sector: byte): TrackNibble {
const _sector = disk.format === 'po' ? _PO[sector] : _DO[sector];
let val, state = 0;
let idx = 0;
@ -385,7 +385,22 @@ export function findSector(disk: NibbleDisk, track: byte, sector: byte): TrackNi
break;
case 4: // Data
if (s === _sector && t === track) {
return { track, sector, nibble: idx };
// Save start of data
const nibble = idx;
// Do checksum on data
let last = 0;
for (let jdx = 0; jdx < 0x156; jdx++) {
last = detrans62[_readNext() - 0x80] ^ last;
}
const checkSum = detrans62[_readNext() - 0x80] ^ last;
// Validate checksum before returning
if (!checkSum) {
return { track, sector, nibble };
} else {
debug('Invalid data checksum:', toHex(last), toHex(track), toHex(sector), toHex(checkSum));
}
_skipBytes(3); // Skip footer
}
else
_skipBytes(0x159); // Skip data, checksum and footer
@ -395,7 +410,7 @@ export function findSector(disk: NibbleDisk, track: byte, sector: byte): TrackNi
break;
}
}
return null;
throw new Error(`Unable to locate track ${track}, sector ${sector}`);
}
/**
@ -410,20 +425,17 @@ export function findSector(disk: NibbleDisk, track: byte, sector: byte): TrackNi
*/
export function readSector(disk: NibbleDisk, track: byte, sector: byte): Uint8Array {
const trackNibble = findSector(disk, track, sector);
if (!trackNibble) {
return new Uint8Array(0);
}
const { nibble } = trackNibble;
const cur = disk.tracks[track];
let idx = nibble;
function _readNext() {
const _readNext = () => {
const result = cur[idx++];
if (nibble >= cur.length) {
if (idx >= cur.length) {
idx = 0;
}
return result;
}
};
const data = new Uint8Array(256);
const data2 = [];
@ -443,6 +455,7 @@ export function readSector(disk: NibbleDisk, track: byte, sector: byte): Uint8Ar
const checkSum = detrans62[_readNext() - 0x80] ^ last;
if (checkSum) {
debug('Invalid data checksum:', toHex(last), toHex(track), toHex(sector), toHex(checkSum));
throw new Error(`Unable to read track ${track}, sector ${sector}`);
}
for (let kdx = 0, jdx = 0x55; kdx < 0x100; kdx++) {
data[kdx] <<= 1;