apple1js/js/ram.ts
2023-08-05 18:31:27 -07:00

62 lines
1.7 KiB
TypeScript

/* Copyright 2010-2023 Will Scullin <scullin@scullinsteel.com>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
import { base64_decode, base64_encode } from "./base64";
import { allocMemPages } from "./util";
import type { byte } from "./types";
export interface RAMState {
start: byte;
end: byte;
mem: string;
}
export default class RAM {
mem: Uint8Array | byte[];
constructor(private start_page: byte, private end_page: byte) {
this.mem = allocMemPages(end_page - start_page + 1);
for (var page = 0; page <= end_page; page++) {
for (var off = 0; off < 0x100; off++) {
this.mem[page * 0x100 + off] = 0; // Math.floor(Math.random()*256);
}
}
}
start() {
return this.start_page;
}
end() {
return this.end_page;
}
read(page: byte, off: byte) {
return this.mem[(page - this.start_page) * 0x100 + off];
}
write(page: byte, off: byte, val: byte) {
this.mem[(page - this.start_page) * 0x100 + off] = val;
}
getState(): RAMState {
return {
start: this.start_page,
end: this.end_page,
mem: base64_encode(this.mem),
};
}
setState(state: RAMState) {
this.start_page = state.start;
this.end_page = state.end;
this.mem = base64_decode(state.mem);
}
}