128 lines
3.9 KiB
C++
128 lines
3.9 KiB
C++
// Pi1541 - A Commodore 1541 disk drive emulator
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// Copyright(C) 2018 Stephen White
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//
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// This file is part of Pi1541.
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//
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// Pi1541 is free software : you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Pi1541 is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Pi1541. If not, see <http://www.gnu.org/licenses/>.
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#ifndef DRIVE_H
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#define DRIVE_H
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#include "m6522.h"
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#include "DiskImage.h"
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#include <stdlib.h>
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class Drive
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{
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public:
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Drive();
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void SetVIA(m6522* pVIA)
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{
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m_pVIA = pVIA;
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pVIA->GetPortB()->SetPortOut(this, OnPortOut);
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}
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static void OnPortOut(void*, unsigned char status);
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bool Update();
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void Insert(DiskImage* diskImage);
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inline const DiskImage* GetDiskImage() const { return diskImage; }
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void Eject();
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void Reset();
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inline unsigned Track() const { return headTrackPos; }
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inline unsigned SectorPos() const { return headBitOffset >> 3; }
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inline unsigned GetHeadBitOffset() const { return headBitOffset; }
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inline bool IsMotorOn() const { return motor; }
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inline bool IsLEDOn() const { return LED; }
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inline unsigned char GetLastHeadDirection() const { return lastHeadDirection; } // For simulated head movement sounds
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private:
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inline float GenerateRandomFluxReversalTime(float min, float max) { return ((max - min) * ((float)rand() / RAND_MAX)) + min; } // Inputs in micro seconds
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inline void ResetEncoderDecoder(float min, float max)
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{
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UE7Counter = CLOCK_SEL_AB; // A and B inputs of UE7 come from the VIA's CLOCK SEL A/B outputs (ie PB5/6)
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UF4Counter = 0;
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randomFluxReversalTime = GenerateRandomFluxReversalTime(min, max);
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}
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inline void UpdateHeadSectorPosition()
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{
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// Disk spins at 300rpm = 5rps so to calculate how many 16Mhz cycles one rotation takes;-
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// 16000000 / 5 = 3200000;
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static const float CYCLES_16Mhz_PER_ROTATION = 3200000.0f;
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bitsInTrack = diskImage->BitsInTrack(headTrackPos);
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headBitOffset %= bitsInTrack;
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cyclesPerBit = CYCLES_16Mhz_PER_ROTATION / (float)bitsInTrack;
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}
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inline void MoveHead(unsigned char headDirection)
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{
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if (lastHeadDirection != headDirection)
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{
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if (((lastHeadDirection - 1) & 3) == headDirection)
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{
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if (headTrackPos > 0) headTrackPos--;
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// else head bang
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}
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else if (((lastHeadDirection + 1) & 3) == headDirection)
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{
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if (headTrackPos < HALF_TRACK_COUNT - 1) headTrackPos++;
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}
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lastHeadDirection = headDirection;
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UpdateHeadSectorPosition();
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}
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}
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void DumpTrack(unsigned track); // Used for debugging disk images.
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u32 AdvanceSectorPositionR(int& byte_offset); // No reason why I seperate these into individual read and write versions. I was just trying to get the bit stream to line up when rewriting over existing data.
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u32 AdvanceSectorPositionW(int& byte_offset);
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bool GetNextBit();
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void SetNextBit(bool value);
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DiskImage* diskImage;
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// When swapping disks some code waits for the write protect signal to go high which will happen if a human ejects a disk.
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// Emulate this by asserting the write protect signal for a few cycles before inserting the new disk image.
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u32 newDiskImageQueuedCylesRemaining;
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// CA1 (input)
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// - !BYTE SYNC
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// CA2 (output)
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// - BYTE SYNC enable
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// CB1 (NC)
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// - check pulled H/L
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// CB2 (output)
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// - R/!W
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m6522* m_pVIA;
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float cyclesForBit;
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u32 readShiftRegister;
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unsigned headTrackPos;
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u32 headBitOffset;
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float randomFluxReversalTime;
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int UE7Counter;
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int UF4Counter;
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int UE3Counter;
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int CLOCK_SEL_AB;
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bool SO;
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unsigned char lastHeadDirection;
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u32 bitsInTrack;
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float cyclesPerBit;
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bool motor;
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bool LED;
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u8 writeShiftRegister;
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};
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#endif
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