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121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
//
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// MemorySlotHandler.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 03/01/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#ifndef MemorySlotHandler_hpp
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#define MemorySlotHandler_hpp
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#include "../../ClockReceiver/ClockReceiver.hpp"
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#include "../../Analyser/Dynamic/ConfidenceCounter.hpp"
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#include <array>
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#include <cstddef>
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#include <cstdint>
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#include <string>
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#include <vector>
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/*
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Design assumptions:
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- to-ROM writes and paging events are 'rare', so virtual call costs aren't worrisome;
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- ROM type variety is sufficiently slender that most of it can be built into the MSX.
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Part of the motivation is also that the MSX has four logical slots, the ROM, RAM plus two
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things plugged in. So even if the base class were templated to remove the virtual call,
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there'd just be a switch on what to call.
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*/
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namespace MSX {
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class MemorySlot {
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public:
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MemorySlot();
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/// Attempts to write the argument as the secondary paging selection.
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void set_secondary_paging(uint8_t);
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/// @returns The value most recently provided to @c set_secondary_paging.
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uint8_t secondary_paging() const;
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/// Indicates whether this slot supports secondary paging.
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bool supports_secondary_paging = false;
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/// @returns A pointer to the area of memory currently underneath @c address that
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/// should be read
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const uint8_t *read_pointer(int segment) const;
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/// @returns A pointer to the area of memory currently underneath @c address.
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uint8_t *write_pointer(int segment) const;
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/// Sets the value most-recently written to one of the standard
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/// memory mapping ports, FC–FF.
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void apply_mapping(uint8_t port, uint8_t value);
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/// Copies an underlying source buffer.
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void set_source(const std::vector<uint8_t> &source);
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/// Provides a reference to the internal source storage.
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const std::vector<uint8_t> &source() const;
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/// Maps the content from @c source_address in the buffer previously
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/// supplied to @c set_source to the region indicated by
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/// @c destination_address and @c length within @c subslot.
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void map(
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int subslot,
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std::size_t source_address,
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uint16_t destination_address,
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std::size_t length);
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/// Marks the region indicated by @c destination_address and @c length
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/// as unmapped. In practical terms that means that a @c MemorySlotHandler
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/// will be used to field accesses to that area, allowing for areas that are not
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/// backed by memory to be modelled.
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void unmap(
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int subslot,
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uint16_t destination_address,
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std::size_t length);
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private:
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std::vector<uint8_t> source_;
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uint8_t *read_pointers_[4][8];
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uint8_t *write_pointers_[4][8];
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uint8_t secondary_paging_ = 0;
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using MemoryChunk = std::array<uint8_t, 8192>;
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inline static MemoryChunk unmapped{0xff};
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inline static MemoryChunk scratch;
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};
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class MemorySlotHandler {
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public:
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virtual ~MemorySlotHandler() {}
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/*! Advances time by @c half_cycles. */
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virtual void run_for([[maybe_unused]] HalfCycles half_cycles) {}
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/*! Announces an attempt to write @c value to @c address. */
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virtual void write(uint16_t address, uint8_t value, bool pc_is_outside_bios) = 0;
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/*! Seeks the result of a read at @c address; this is used only if the area is unmapped. */
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virtual uint8_t read([[maybe_unused]] uint16_t address) { return 0xff; }
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/*! @returns The probability that this handler is correct for the data it owns. */
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float get_confidence() {
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return confidence_counter_.get_confidence();
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}
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virtual std::string debug_type() {
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return "";
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}
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protected:
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Analyser::Dynamic::ConfidenceCounter confidence_counter_;
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};
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}
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#endif /* MemorySlotHandler_hpp */
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