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mirror of https://github.com/TomHarte/CLK.git synced 2024-11-18 17:06:15 +00:00

Start experimenting with varying return types.

This commit is contained in:
Thomas Harte 2023-11-01 10:03:31 -04:00
parent 430c60111e
commit 78df0d19e4

View File

@ -169,8 +169,15 @@ struct Memory {
return *reinterpret_cast<IntT *>(&memory[address]);
}
template <typename IntT, AccessType type> struct ReturnType;
template <typename IntT> struct ReturnType<IntT, AccessType::Read> { using type = IntT; };
template <typename IntT> struct ReturnType<IntT, AccessType::Write> { using type = IntT &; };
template <typename IntT> struct ReturnType<IntT, AccessType::ReadModifyWrite> { using type = IntT &; };
template <typename IntT> struct ReturnType<IntT, AccessType::PreAuthorised> { using type = IntT &; };
// Entry point for the 8086; simply notes that memory was accessed.
template <typename IntT, AccessType type> IntT &access([[maybe_unused]] InstructionSet::x86::Source segment, uint32_t address) {
template <typename IntT, AccessType type>
typename ReturnType<IntT, type>::type &access(InstructionSet::x86::Source segment, uint32_t address) {
if constexpr (std::is_same_v<IntT, uint16_t>) {
// If this is a 16-bit access that runs past the end of the segment, it'll wrap back
// to the start. So the 16-bit value will need to be a local cache.
@ -183,13 +190,6 @@ struct Memory {
}
auto &value = access<IntT, type>(segment, address, Tag::Accessed);
// For testing purposes: if the CPU indicated it'll only be reading, copy the requested value into a temporary
// location so that any writes will be discarded.
if(type == AccessType::Read) {
*reinterpret_cast<IntT *>(&read_value_) = value;
return *reinterpret_cast<IntT *>(&read_value_);
}
// If the CPU has indicated a write, it should be safe to fuzz the value now.
if(type == AccessType::Write) {
value = IntT(~0);
@ -212,7 +212,6 @@ struct Memory {
static constexpr uint32_t NoWriteBack = 0; // A low byte address of 0 can't require write-back.
uint32_t write_back_address_[2] = {NoWriteBack, NoWriteBack};
uint16_t write_back_value_;
uint16_t read_value_;
};
struct IO {
template <typename IntT> void out([[maybe_unused]] uint16_t port, [[maybe_unused]] IntT value) {}