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bus: Perform open bus reads for unmapped addresses.

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Fixes F-Zero X (cartridge version).
This commit is contained in:
Tyler J. Stachecki 2016-07-17 20:09:45 -04:00
parent d8f264eb09
commit 3900be4776
2 changed files with 43 additions and 8 deletions
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36
bus/controller.c
View file

@ -34,6 +34,10 @@ struct bus_controller_mapping {
uint32_t length;
};
static int bus_open_read(void *opaque, uint32_t address, uint32_t *word);
static int bus_dead_write(void *opaque, uint32_t address, uint32_t word,
uint32_t dqm);
// Initializes the bus component.
int bus_init(struct bus_controller *bus) {
unsigned i;
@ -82,11 +86,33 @@ int bus_init(struct bus_controller *bus) {
create_memory_map(&bus->map);
for (i = 0; i < NUM_MAPPINGS; i++)
if (map_address_range(&bus->map, mappings[i].address, mappings[i].length,
instances[i], mappings[i].read, mappings[i].write))
return 1;
for (i = 0; i < NUM_MAPPINGS; i++) {
memory_rd_function rd = mappings[i].read;
memory_wr_function wr = mappings[i].write;
void *instance = instances[i];
if (instance == bus->dd && bus->dd->ipl_rom == NULL) {
rd = bus_open_read;
wr = bus_dead_write;
instance = NULL;
}
if (map_address_range(&bus->map, mappings[i].address, mappings[i].length,
instances[i], rd, wr))
return 1;
}
return 0;
}
// Open read (happens for non-mapped addresses)
static int bus_open_read(void *opaque, uint32_t address, uint32_t *word) {
*word = (address >> 16) | (address & 0xFFFF0000);
return 0;
}
static int bus_dead_write(void *opaque, uint32_t address, uint32_t word,
uint32_t dqm) {
return 0;
}
@ -103,7 +129,7 @@ int bus_read_word(void *component, uint32_t address, uint32_t *word) {
else if ((node = resolve_mapped_address(&bus->map, address)) == NULL) {
debug("bus_read_word: Failed to access: 0x%.8X\n", address);
*word = 0x00000000U;
*word = (address >> 16) | (address & 0xFFFF0000);
return 0;
}

15
pi/controller.c
View file

@ -130,8 +130,17 @@ static int pi_dma_write(struct pi_controller *pi) {
else if (pi->rom) {
if (source + length > pi->rom_size) {
unsigned i;
// TODO: Check for correctness against hardware.
// Is this the right address to use for open bus?
for (i = (pi->regs[PI_CART_ADDR_REG] + pi->rom_size + 3) & ~0x3;
i < pi->regs[PI_CART_ADDR_REG] + length; i += 4) {
uint32_t word = (i >> 16) | (i & 0xFFFF0000);
memcpy(pi->bus->ri->ram + dest + i, &word, sizeof(word));
}
length = pi->rom_size - source;
//assert(0);
}
// TODO: Very hacky.
@ -164,8 +173,8 @@ int read_cart_rom(void *opaque, uint32_t address, uint32_t *word) {
// TODO: Need to figure out correct behaviour.
// Should this even happen to begin with?
if (pi->rom == NULL || offset > pi->rom_size - sizeof(*word)) {
*word = 0;
if (pi->rom == NULL || offset > (pi->rom_size - sizeof(*word))) {
*word = (address >> 16) | (address & 0xFFFF0000);
return 0;
}