mirror of https://github.com/stella-emu/stella.git
138 lines
4.1 KiB
C++
138 lines
4.1 KiB
C++
//============================================================================
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//
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// SSSS tt lll lll
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// SS SS tt ll ll
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// SS tttttt eeee ll ll aaaa
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// SSSS tt ee ee ll ll aa
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// SS tt eeeeee ll ll aaaaa -- "An Atari 2600 VCS Emulator"
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// SS SS tt ee ll ll aa aa
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// SSSS ttt eeeee llll llll aaaaa
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//
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// Copyright (c) 1995-2019 by Bradford W. Mott, Stephen Anthony
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// and the Stella Team
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//
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// See the file "License.txt" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//============================================================================
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#ifndef MT24LC256_HXX
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#define MT24LC256_HXX
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class System;
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#include "Control.hxx"
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#include "bspf.hxx"
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/**
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Emulates a Microchip Technology Inc. 24LC256, a 32KB Serial Electrically
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Erasable PROM accessed using the I2C protocol. Thanks to J. Payson
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(aka Supercat) for the bulk of this code.
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@author Stephen Anthony & J. Payson
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*/
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class MT24LC256
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{
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public:
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/**
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Create a new 24LC256 with its data stored in the given file
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@param filename Data file containing the EEPROM data
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@param system The system using the controller of this device
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@param callback Called to pass messages back to the parent controller
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*/
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MT24LC256(const string& filename, const System& system,
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const Controller::onMessageCallback& callback);
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~MT24LC256();
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public:
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// Sizes of the EEPROM
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static constexpr uInt32 FLASH_SIZE = 32_KB;
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static constexpr uInt32 PAGE_SIZE = 64;
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static constexpr uInt32 PAGE_NUM = FLASH_SIZE / PAGE_SIZE;
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// Initial state value of flash EEPROM
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static constexpr uInt8 INITIAL_VALUE = 0xff;
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/** Read boolean data from the SDA line */
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bool readSDA() const { return jpee_mdat && jpee_sdat; }
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/** Write boolean data to the SDA and SCL lines */
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void writeSDA(bool state);
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void writeSCL(bool state);
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/** Called when the system is being reset */
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void systemReset();
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/** Erase entire EEPROM to known state ($FF) */
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void eraseAll();
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/** Erase the pages used by the current ROM to known state ($FF) */
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void eraseCurrent();
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/** Returns true if the page is used by the current ROM */
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bool isPageUsed(uInt32 page) const;
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private:
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// I2C access code provided by Supercat
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void jpee_init();
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void jpee_data_start();
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void jpee_data_stop();
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void jpee_clock_fall();
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bool jpee_timercheck(int mode);
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void jpee_logproc(const char* const st) { cerr << " " << st << endl; }
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void update();
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private:
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// The system of the parent controller
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const System& mySystem;
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// Sends messages back to the parent class
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// Currently used for indicating read/write access
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Controller::onMessageCallback myCallback;
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// The EEPROM data
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std::array<uInt8, FLASH_SIZE> myData;
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// Track which pages are used
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std::array<bool, PAGE_NUM> myPageHit;
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// Cached state of the SDA and SCL pins on the last write
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bool mySDA, mySCL;
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// Indicates that a timer has been set and hasn't expired yet
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bool myTimerActive;
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// Indicates when the timer was set
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uInt64 myCyclesWhenTimerSet;
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// Indicates when the SDA and SCL pins were set/written
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uInt64 myCyclesWhenSDASet, myCyclesWhenSCLSet;
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// The file containing the EEPROM data
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string myDataFile;
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// Indicates if a valid EEPROM data file exists/was successfully loaded
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bool myDataFileExists;
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// Indicates if the EEPROM has changed since class invocation
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bool myDataChanged;
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// Required for I2C functionality
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Int32 jpee_mdat, jpee_sdat, jpee_mclk;
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Int32 jpee_sizemask, jpee_pagemask, jpee_smallmode, jpee_logmode;
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Int32 jpee_pptr, jpee_state, jpee_nb;
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uInt32 jpee_address, jpee_ad_known;
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std::array<uInt8, 70> jpee_packet;
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private:
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// Following constructors and assignment operators not supported
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MT24LC256() = delete;
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MT24LC256(const MT24LC256&) = delete;
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MT24LC256(MT24LC256&&) = delete;
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MT24LC256& operator=(const MT24LC256&) = delete;
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MT24LC256& operator=(MT24LC256&&) = delete;
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};
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#endif
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