51 lines
1.1 KiB
TypeScript
51 lines
1.1 KiB
TypeScript
import { byte, memory, Memory, Restorable } from './types';
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import { allocMemPages } from './util';
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export interface RAMState {
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/** Copy of contents. */
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mem: memory;
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}
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/**
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* Represents RAM from the start page `sp` to end page `ep`. The memory
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* is addressed by `page` and `offset`.
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*/
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export default class RAM implements Memory, Restorable<RAMState> {
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private start_page: byte;
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private end_page: byte;
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private mem: memory;
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constructor(sp: byte, ep: byte) {
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this.start_page = sp;
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this.end_page = ep;
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this.mem = allocMemPages(ep - sp + 1);
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}
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public start(): byte {
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return this.start_page;
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}
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public end(): byte {
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return this.end_page;
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}
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public read(page: byte, offset: byte) {
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return this.mem[(page - this.start_page) << 8 | offset];
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}
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public write(page: byte, offset: byte, val: byte) {
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this.mem[(page - this.start_page) << 8 | offset] = val;
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}
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public getState(): RAMState {
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return {
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mem: new Uint8Array(this.mem)
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};
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}
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public setState(state: RAMState) {
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this.mem = new Uint8Array(state.mem);
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}
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}
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