BYTE cartridge_read_ram123(WORD addr)
{
switch (mem_cartridge_type) {
case CARTRIDGE_VIC20_GENERIC:
vic20_cpu_last_data = generic_ram123_read(addr);
break;
case CARTRIDGE_VIC20_UM:
vic20_cpu_last_data = vic_um_ram123_read(addr);
break;
case CARTRIDGE_VIC20_FP:
vic20_cpu_last_data = vic_fp_ram123_read(addr);
break;
case CARTRIDGE_VIC20_MEGACART:
vic20_cpu_last_data = megacart_ram123_read(addr);
break;
case CARTRIDGE_VIC20_FINAL_EXPANSION:
vic20_cpu_last_data = finalexpansion_ram123_read(addr);
break;
default:
vic20_cpu_last_data = vic20_v_bus_last_data;
break;
}
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
static BYTE via_read(WORD addr)
{
if ( (addr & 0x30) == 0x00 ) { /* $910x (unconnected V-bus) */
vic20_cpu_last_data = vic20_v_bus_last_data;
} else {
BYTE temp_bus = 0xff;
if (addr & 0x10) { /* $911x (VIA2) */
temp_bus &= via2_read(addr);
}
if (addr & 0x20) { /* $912x (VIA1) */
temp_bus &= via1_read(addr);
}
vic20_cpu_last_data = temp_bus;
}
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
static BYTE read_unconnected_v_bus(WORD addr)
{
vic20_cpu_last_data = vic20_v_bus_last_data;
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
static BYTE chargen_read(WORD addr)
{
vic20_cpu_last_data = vic20memrom_chargen_read(addr);
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
static BYTE ram_read_v_bus(WORD addr)
{
vic20_cpu_last_data = mem_ram[addr];
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
BYTE zero_read(WORD addr)
{
vic20_cpu_last_data = mem_ram[addr & 0xff];
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
static inline BYTE io_read(io_source_list_t *list, WORD addr)
{
io_source_list_t *current = list->next;
int io_source_counter = 0;
BYTE realval = 0;
BYTE retval = 0;
unsigned int lowest_order = 0xffffffff;
while (current) {
if (current->device->read != NULL) {
if ((addr >= current->device->start_address) && (addr <= current->device->end_address)) {
retval = current->device->read((WORD)(addr & current->device->address_mask));
if (current->device->io_source_valid) {
if (current->device->io_source_prio == 1) {
return retval;
}
if (io_source_collision_handling == IO_COLLISION_METHOD_DETACH_LAST) {
if (current->device->order < lowest_order) {
lowest_order = current->device->order;
realval = retval;
}
}
if (io_source_collision_handling == IO_COLLISION_METHOD_AND_WIRES) {
realval &= retval;
}
if (current->device->io_source_prio != -1) {
io_source_counter++;
}
}
}
}
current = current->next;
}
if (io_source_counter == 0) {
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
if (io_source_counter == 1) {
vic20_cpu_last_data = retval;
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
if (io_source_collision_handling == IO_COLLISION_METHOD_DETACH_ALL) {
io_source_msg_detach_all(addr, io_source_counter, list);
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
if (io_source_collision_handling == IO_COLLISION_METHOD_DETACH_LAST) {
io_source_msg_detach_last(addr, io_source_counter, list, lowest_order);
vic20_cpu_last_data = realval;
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
if (io_source_collision_handling == IO_COLLISION_METHOD_AND_WIRES) {
io_source_log_collisions(addr, io_source_counter, list);
vic20_cpu_last_data = realval;
vic20_mem_v_bus_read(addr);
return vic20_cpu_last_data;
}
return vic20_cpu_last_data;
}