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MMC mostly completed.

master
Bryan Miller 5 years ago
parent
commit
d873bd773c
1 changed files with 56 additions and 4 deletions
  1. +56
    -4
      chip/mmc.js

+ 56
- 4
chip/mmc.js View File

@@ -26,9 +26,13 @@ class Bank{
}
}



class MMC{
constructor(){
this.__banks = [];
this.__addr = 0;
this.__bnkidx = 0;
}

get size(){
@@ -39,10 +43,58 @@ class MMC{

get banks(){return this.__banks.length;}

// TODO: Add a get/set for the memory address. This should handle banking and memory address offsets.
// TODO: Add a get/set for memory data at the current address.
// TODO: Add method for adding memory modules}
// TODO: Add a connection between a memory address and the triggering of bank switching.
get address(){return this.__addr;}
set address(a){
if (a >= 0 && a < this.size){
this.__addr = a;
offset = 0;
for (let b=0; b < this.__banks.length; b++){
if (a >= offset && a < offset + this.__banks[b].mem.size){
this.__bnkidx = b;
this.__banks[b].mem.address = a - offset;
break;
} else {
offset += this.__banks[b].mem.size;
}
}
}
}

get byte(){return (this.__banks.length > 0) ? this.__banks[this.__bnkidx].mem.byte : -1;}
set byte(b){
if (this.__banks.length > 0){
this.__banks[this.__bnkidx].mem.byte = b;
}
}

connectMemory(mem, addroff){
addroff = (typeof(addroff) === 'number' && addroff >= 0) ? addroff : -1;
if (addroff < 0 || addroff === this.size){
this.__banks.push(new Bank(mem));
} else {
offset = 0;
for (let b=0; b < this.__banks.length; b++){
if (addroff === offset){
if (this.__banks[b].mem.size !== mem.size)
throw new RangeError("Memory modules assigned to the same bank must be the same byte size.");
this.__banks[b].addMemModule(mem);
offset = -1;
break;
} else {
offset += this.__banks[b].mem.size;
}
}
if (offset >= 0)
throw new RangeError("Cannot align memory module to bank at address " + addroff);
}
return this;
}
mmSwitchCallback(){
return (function(byte){
// TODO: Check the bits to determin which bank and bank index is being switched on.
}).bind(this);
}
}

module.exports = MMC;

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