mirror of
https://github.com/TomHarte/CLK.git
synced 2024-06-09 17:29:36 +00:00
100 lines
2.1 KiB
C++
100 lines
2.1 KiB
C++
//
|
||
// Bitplanes.hpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 26/11/2021.
|
||
// Copyright © 2021 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#pragma once
|
||
|
||
#include <cstdint>
|
||
|
||
#include "DMADevice.hpp"
|
||
|
||
namespace Amiga {
|
||
|
||
struct BitplaneData: public std::array<uint16_t, 6> {
|
||
BitplaneData &operator <<= (int c) {
|
||
(*this)[0] <<= c;
|
||
(*this)[1] <<= c;
|
||
(*this)[2] <<= c;
|
||
(*this)[3] <<= c;
|
||
(*this)[4] <<= c;
|
||
(*this)[5] <<= c;
|
||
return *this;
|
||
}
|
||
|
||
void clear() {
|
||
std::fill(begin(), end(), 0);
|
||
}
|
||
};
|
||
|
||
class Bitplanes: public DMADevice<6, 2> {
|
||
public:
|
||
using DMADevice::DMADevice;
|
||
|
||
bool advance_dma(int cycle);
|
||
void do_end_of_line();
|
||
void set_control(uint16_t);
|
||
|
||
private:
|
||
bool is_high_res_ = false;
|
||
int plane_count_ = 0;
|
||
|
||
BitplaneData next;
|
||
};
|
||
|
||
template <typename SourceT> constexpr SourceT bitplane_swizzle(SourceT value) {
|
||
return
|
||
(value&0x21) |
|
||
((value&0x02) << 2) |
|
||
((value&0x04) >> 1) |
|
||
((value&0x08) << 1) |
|
||
((value&0x10) >> 2);
|
||
}
|
||
|
||
class BitplaneShifter {
|
||
public:
|
||
/// Installs a new set of output pixels.
|
||
void set(
|
||
const BitplaneData &previous,
|
||
const BitplaneData &next,
|
||
int odd_delay,
|
||
int even_delay);
|
||
|
||
/// Shifts either two pixels (in low-res mode) or four pixels (in high-res).
|
||
void shift(bool high_res) {
|
||
constexpr int shifts[] = {16, 32};
|
||
|
||
data_[1] = (data_[1] << shifts[high_res]) | (data_[0] >> (64 - shifts[high_res]));
|
||
data_[0] <<= shifts[high_res];
|
||
}
|
||
|
||
/// @returns The next four pixels to output; in low-resolution mode only two
|
||
/// of them will be unique.
|
||
///
|
||
/// The value is arranges so that MSB = first pixel to output, LSB = last.
|
||
///
|
||
/// Each byte is swizzled to provide easier playfield separation, being in the form:
|
||
/// b6, b7 = 0;
|
||
/// b3–b5: planes 1, 3 and 5;
|
||
/// b0–b2: planes 0, 2 and 4.
|
||
uint32_t get(bool high_res) {
|
||
if(high_res) {
|
||
return uint32_t(data_[1] >> 32);
|
||
} else {
|
||
uint32_t result = uint16_t(data_[1] >> 48);
|
||
result = ((result & 0xff00) << 8) | (result & 0x00ff);
|
||
result |= result << 8;
|
||
return result;
|
||
}
|
||
}
|
||
|
||
private:
|
||
std::array<uint64_t, 2> data_{};
|
||
|
||
};
|
||
|
||
}
|