mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-25 16:31:42 +00:00
65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
//
|
|
// DMADevice.hpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 14/09/2021.
|
|
// Copyright © 2021 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#ifndef DMADevice_hpp
|
|
#define DMADevice_hpp
|
|
|
|
#include <array>
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
|
|
#include "Flags.hpp"
|
|
|
|
namespace Amiga {
|
|
|
|
class Chipset;
|
|
|
|
class DMADeviceBase {
|
|
public:
|
|
DMADeviceBase(Chipset &chipset, uint16_t *ram, size_t word_size) :
|
|
chipset_(chipset), ram_(ram), ram_mask_(uint32_t(word_size - 1)) {}
|
|
|
|
void posit_interrupt(Amiga::InterruptFlag);
|
|
|
|
protected:
|
|
Chipset &chipset_;
|
|
uint16_t *const ram_ = nullptr;
|
|
const uint32_t ram_mask_ = 0;
|
|
};
|
|
|
|
template <size_t num_addresses> class DMADevice: public DMADeviceBase {
|
|
public:
|
|
using DMADeviceBase::DMADeviceBase;
|
|
|
|
/// Writes the word @c value to the address register @c id, shifting it by @c shift (0 or 16) first.
|
|
template <int id, int shift> void set_pointer(uint16_t value) {
|
|
static_assert(id < num_addresses);
|
|
static_assert(shift == 0 || shift == 16);
|
|
byte_pointer_[id] = (byte_pointer_[id] & (0xffff'0000 >> shift)) | uint32_t(value << shift);
|
|
pointer_[id] = byte_pointer_[id] >> 1;
|
|
}
|
|
|
|
template <int id, int shift> uint16_t get_pointer() {
|
|
// Restore the original least-significant bit.
|
|
const uint32_t source = (pointer_[id] << 1) | (byte_pointer_[id] & 1);
|
|
return uint16_t(source >> shift);
|
|
}
|
|
|
|
protected:
|
|
// These are shifted right one to provide word-indexing pointers;
|
|
// subclasses should use e.g. ram_[pointer_[0] & ram_mask_] directly.
|
|
std::array<uint32_t, num_addresses> pointer_{};
|
|
|
|
private:
|
|
std::array<uint32_t, num_addresses> byte_pointer_{};
|
|
};
|
|
|
|
}
|
|
|
|
#endif /* DMADevice_hpp */
|