mirror of
https://github.com/whscullin/apple2js.git
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c9b7987c4c
Before, the offset for `FLAGS` in `2mg.ts` was `0x0A`, which is incorrect according to the spec at: https://apple2.org.za/gswv/a2zine/Docs/DiskImage_2MG_Info.txt Now, all of the fields in the 2mg header are described, including their lengths and any constraints. These constraints are enforced by `read2MGHeader` and tested by new tests.
103 lines
2.6 KiB
TypeScript
103 lines
2.6 KiB
TypeScript
import { byte, memory, word } from './types';
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/*eslint no-console: 0*/
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const hex_digits = '0123456789ABCDEF';
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const bin_digits = '01';
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/** Returns a random byte. */
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export function garbage(): byte {
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return (Math.random() * 0x100) & 0xff;
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}
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export const testables = {
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garbage
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};
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/**
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* Returns an array or Uint8Array of `size` bytes filled as if the computer
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* was just powered on.
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*/
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export function allocMem(size: number) {
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const result = new Uint8Array(size);
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for (let idx = 0; idx < size; idx++) {
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result[idx] = (idx & 0x02) ? 0x00 : 0xff;
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}
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// Borrowed from AppleWin (https://github.com/AppleWin/AppleWin)
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for (let idx = 0; idx < size; idx += 0x200) {
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result[idx + 0x28] = garbage();
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result[idx + 0x29] = garbage();
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result[idx + 0x68] = garbage();
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result[idx + 0x69] = garbage();
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}
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return result;
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}
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/** Returns an array or Uint8Array of 256 * `pages` bytes. */
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export function allocMemPages(pages: number): memory {
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return allocMem(pages << 8);
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}
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/** Returns a new Uint8Array for the input array. */
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export function bytify(ary: number[]): memory {
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return new Uint8Array(ary);
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}
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/** Returns a new Uint8Array with the concatenated data from the inputs. */
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export function concat(...arys: Array<byte[] | Uint8Array>) {
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const result = new Uint8Array(arys.reduce((l, ary) => l + ary.length, 0));
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let offset = 0;
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for (let i = 0; i < arys.length; i++) {
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result.set(arys[i], offset);
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offset += arys[i].length;
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}
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return result;
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}
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/** Writes to the console. */
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export function debug(...args: unknown[]): void {
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console.log(...args);
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}
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/**
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* Returns a string of hex digits (all caps).
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* @param v the value to encode
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* @param n the number of nibbles. If `n` is missing, it is guessed from the value
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* of `v`. If `v` < 256, it is assumed to be 2 nibbles, otherwise 4.
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*/
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export function toHex(v: byte | word | number, n?: number) {
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if (!n) {
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n = v < 256 ? 2 : 4;
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}
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let result = '';
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for (let idx = 0; idx < n; idx++) {
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result = hex_digits[v & 0x0f] + result;
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v >>= 4;
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}
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return result;
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}
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/**
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* Returns a string of 8 binary digits.
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* @param v the value to encode
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*/
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export function toBinary(v: byte) {
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let result = '';
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for (let idx = 0; idx < 8; idx++) {
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result = bin_digits[v & 0x01] + result;
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v >>= 1;
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}
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return result;
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}
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/** Packs a 32-bit integer into a string in little-endian order. */
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export function numToString(num: number) {
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let result = '';
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for (let idx = 0; idx < 4; idx++) {
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result += String.fromCharCode(num & 0xff);
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num >>= 8;
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}
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return result;
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}
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