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AppleWin
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WOZ: Change track head movement positioning to work on bit (not nibble) offset. (#1022)

This commit is contained in:
tomcw 2022-08-21 11:48:42 +01:00
parent 74a664840f
commit 5888a2b4a6
1 changed files with 17 additions and 9 deletions
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26
source/Disk.cpp
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@ -301,8 +301,15 @@ void Disk2InterfaceCard::ReadTrack(const int drive, ULONG uExecutedCycles)
UpdateBitStreamPosition(*pFloppy, bitCellDelta);
}
const UINT32 currentPosition = pFloppy->m_byte;
const UINT32 currentTrackLength = pFloppy->m_nibbles;
if (ImageIsWOZ(pFloppy->m_imagehandle) && (pFloppy->m_bitCount == 0))
{
// WOZ: m_bitCount only ever 0 on initial power on
pFloppy->m_bitOffset = 0;
pFloppy->m_bitCount = 8;
}
const UINT32 currentBitPosition = pFloppy->m_bitOffset;
const UINT32 currentBitTrackLength = pFloppy->m_bitCount;
ImageReadTrack(
pFloppy->m_imagehandle,
@ -312,7 +319,7 @@ void Disk2InterfaceCard::ReadTrack(const int drive, ULONG uExecutedCycles)
&pFloppy->m_bitCount,
m_enhanceDisk);
if (!ImageIsWOZ(pFloppy->m_imagehandle) || (currentTrackLength == 0))
if (!ImageIsWOZ(pFloppy->m_imagehandle))
{
pFloppy->m_byte = 0;
}
@ -325,14 +332,15 @@ void Disk2InterfaceCard::ReadTrack(const int drive, ULONG uExecutedCycles)
pFloppy->m_bitCount = 8;
}
pFloppy->m_byte = (currentPosition * pFloppy->m_nibbles) / currentTrackLength; // Ref: WOZ-1.01
pFloppy->m_byte += 1; // Round-up for sensitive cross-track sync check (GH#1022)
pFloppy->m_bitOffset = (currentBitPosition * pFloppy->m_bitCount) / currentBitTrackLength; // Ref: WOZ-1.01
pFloppy->m_bitOffset += 7; // Round-up for sensitive cross-track sync check (GH#1022)
if (pFloppy->m_byte >= (pFloppy->m_nibbles-1)) // Last nibble may not be complete, so advance by 1 nibble
pFloppy->m_byte = 0;
if (pFloppy->m_bitOffset >= pFloppy->m_bitCount)
pFloppy->m_bitOffset = 0;
pFloppy->m_byte = pFloppy->m_bitOffset / 8;
pFloppy->m_bitMask = 1 << (7 - (pFloppy->m_bitOffset % 8));
pFloppy->m_bitOffset = pFloppy->m_byte*8;
pFloppy->m_bitMask = 1 << 7;
pFloppy->m_extraCycles = 0.0;
pDrive->m_headWindow = 0;
}