blob: 07bbbf2982c15bb595c67ff85b402df29cc88de8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
package nes
// CPU memory map is:
// Address range | Size | Device
// --------------------------------------------------
// $0000-$07FF | $0800 | 2 KB internal RAM
// $0800-$0FFF | $0800 | Mirror of $0000-$07FF
// $1000-$17FF | $0800 | Mirror of $0000-$07FF
// $1800-1FFF | $0800 | Mirror of $0000-$07FF
// $2000-2007 | $0008 | PPU registers
// $2008-$3FFF | $1FF8 | Mirrors of $2000-$2007 (repeats every 8 bytes)
// $4000-4017 | $0018 | APU and I/O registers
// $4018-$401F | $0008 | APU and I/O functionality thats normally disabled (CPU test mode)
// $4020-$FFFF | $BFE0 | Unmapped, available for cartridge
// - $6000-$7FFF | $2000 | Usually cartridge RAM (if present)
// - $8000-$FFFF | $8000 | Usually cartridge ROM (if present)
// wow i put way too much effort into making that table
func (n *Console) Read(addr uint16) uint8 {
switch {
case addr < 0x2000: // internal RAM and mirrors
return n.RAM[addr&0x7FF]
case addr >= 0x4020: // cartridge
return n.Cart.Mapper.CPURead(addr)
default:
return 0
}
}
func (n *Console) Write(addr uint16, v uint8) {
switch {
case addr < 0x2000:
n.RAM[addr&0x7FF] = v
case addr >= 0x4020:
n.Cart.Mapper.CPUWrite(addr, v)
}
}
|