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io: i really ought to be working on the ppu and apu by now

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Signed-off-by: Amneesh Singh <natto@weirdnatto.in>
This commit is contained in:
Amneesh Singh
2024-06-13 03:53:25 +05:30
parent 933b622493
commit 08cc582f23
17 changed files with 1751 additions and 78 deletions
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28
src/bus.cc
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@@ -3,16 +3,28 @@
#include <memory>
namespace matar {
static constexpr uint32_t IO_START = 0x4000000;
static constexpr uint32_t IO_END = 0x40003FE;
Bus::Bus(const Memory& memory)
: memory(std::make_shared<Memory>(memory)) {}
uint8_t
Bus::read_byte(uint32_t address) {
if (address >= IO_START && address <= IO_END)
return io.read_byte(address);
return memory->read(address);
}
void
Bus::write_byte(uint32_t address, uint8_t byte) {
if (address >= IO_START && address <= IO_END) {
io.write_byte(address, byte);
return;
}
memory->write(address, byte);
}
@@ -21,6 +33,9 @@ Bus::read_halfword(uint32_t address) {
if (address & 0b01)
glogger.warn("Reading a non aligned halfword address");
if (address >= IO_START && address <= IO_END)
return io.read_halfword(address);
return read_byte(address) | read_byte(address + 1) << 8;
}
@@ -29,6 +44,11 @@ Bus::write_halfword(uint32_t address, uint16_t halfword) {
if (address & 0b01)
glogger.warn("Writing to a non aligned halfword address");
if (address >= IO_START && address <= IO_END) {
io.write_halfword(address, halfword);
return;
}
write_byte(address, halfword & 0xFF);
write_byte(address + 1, halfword >> 8 & 0xFF);
}
@@ -38,6 +58,9 @@ Bus::read_word(uint32_t address) {
if (address & 0b11)
glogger.warn("Reading a non aligned word address");
if (address >= IO_START && address <= IO_END)
return io.read_word(address);
return read_byte(address) | read_byte(address + 1) << 8 |
read_byte(address + 2) << 16 | read_byte(address + 3) << 24;
}
@@ -47,6 +70,11 @@ Bus::write_word(uint32_t address, uint32_t word) {
if (address & 0b11)
glogger.warn("Writing to a non aligned word address");
if (address >= IO_START && address <= IO_END) {
io.write_word(address, word);
return;
}
write_byte(address, word & 0xFF);
write_byte(address + 1, word >> 8 & 0xFF);
write_byte(address + 2, word >> 16 & 0xFF);