apple1js/js/ram.js

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/* -*- mode: JavaScript; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* Copyright 2010-2019Will 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';
export default function RAM(sp, ep) {
var mem;
var start_page = sp;
var end_page = ep;
mem = allocMemPages(ep - sp + 1);
for (var page = 0; page <= ep; page++) {
for (var off = 0; off < 0x100; off++) {
mem[page * 0x100 + off] = 0; // Math.floor(Math.random()*256);
}
}
return {
start: function() {
return start_page;
},
end: function() {
return end_page;
},
read: function(page, off) {
return mem[(page - start_page) * 0x100 + off];
},
write: function(page, off, val) {
mem[(page - start_page) * 0x100 + off] = val;
},
getState: function() {
return {
start: start_page,
end: end_page,
mem: base64_encode(mem)
};
},
setState: function(state) {
start_page = state.start;
end_page = state.end;
mem = base64_decode(state.mem);
}
};
}