89 lines
1.7 KiB
C
89 lines
1.7 KiB
C
#include "bus.h"
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
|
|
#include "cpu.h"
|
|
#include "cartridge.h"
|
|
|
|
struct Bus* createBus()
|
|
{
|
|
struct Bus* bus = (struct Bus*)malloc(sizeof(struct Bus));
|
|
if (bus == NULL)
|
|
{
|
|
fprintf(stderr, "Failed to create Bus object, aborting.");
|
|
exit(1);
|
|
}
|
|
|
|
// 2KB of memory, equates to 2048 Bytes (0x800)
|
|
bus->ram = (Byte*)malloc(0x800);
|
|
if (bus->ram == NULL)
|
|
{
|
|
fprintf(stderr, "Failed to allocate memory for NES RAM, aborting.");
|
|
exit(1);
|
|
}
|
|
|
|
// Create CPU and attach it
|
|
bus->cpu = createCPU(bus);
|
|
|
|
// Create and insert cartridge
|
|
bus->cartridge = createCartridge(bus, "roms/nestest.nes");
|
|
|
|
printf("Reset vector: $%x\n", ((Word)readCartridge(bus->cartridge, 0xFFFD) << 8) | (readCartridge(bus->cartridge, 0xFFFC)));
|
|
|
|
return bus;
|
|
}
|
|
|
|
void destroyBus(struct Bus* bus)
|
|
{
|
|
destroyCartridge(bus->cartridge);
|
|
destroyCPU(bus->cpu);
|
|
|
|
free(bus->ram);
|
|
free(bus);
|
|
}
|
|
|
|
Byte readBus(struct Bus* bus, Word addr)
|
|
{
|
|
Byte val = 0;
|
|
|
|
// Return from the appropriate device depending on the address
|
|
if (addr <= 0x1FFF) // RAM (or one of the mirrored addresses)
|
|
{
|
|
val = bus->ram[addr & 0x7FF];
|
|
}
|
|
else if (0x4020 <= addr && addr <= 0xFFFF) // Cartridge space
|
|
{
|
|
val = readCartridge(bus->cartridge, addr);
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "Access violation at $%x", addr);
|
|
exit(1);
|
|
}
|
|
|
|
return val;
|
|
}
|
|
|
|
void writeBus(struct Bus* bus, Word addr, Byte val)
|
|
{
|
|
// writeCartridge to the appropriate memory or device
|
|
if (addr <= 0x1FFF) // RAM (or one of the mirrored addresses)
|
|
{
|
|
bus->ram[addr & 0x7FF] = val;
|
|
}
|
|
else if (0x4020 <= addr && addr <= 0xFFFF) // Cartridge space
|
|
{
|
|
writeCartridge(bus->cartridge, addr, val);
|
|
}
|
|
else
|
|
{
|
|
fprintf(stderr, "Access violation at $%x", addr);
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
|
|
void tick(struct Bus* bus)
|
|
{
|
|
tickInstr(bus->cpu);
|
|
} |