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Some video-related comment clean up & simplified VideoGetVblBar()

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This commit is contained in:
tomcw 2016-12-11 15:02:12 +00:00
parent b8b90a6bd9
commit 3e0d399665
3 changed files with 16 additions and 38 deletions
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9
source/Memory.cpp
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@ -1506,18 +1506,21 @@ void MemReset()
BYTE MemReadFloatingBus(const ULONG uExecutedCycles)
{
#if 0
// TC (11/12/2016) This comment is out of date.
// - TODO: Check "Rainbow" Bug #254, then remove this comment
// NTSC: It is tempting to replace with
// return NTSC_VideoGetScannerAddress( );
// But that breaks "Rainbow" Bug #254 if NTSC_VideoGetScannerAddress() is not correct.
// This is out of sync with VideoGetScannerAddress() due to two reasons:
// This is out of sync with VideoGetScannerAddress() due to this reason:
// a) returning a cached copy of g_aHorzClockMemAddress
// Fixed by calling: updateVideoScannerAddressTXT or updateVideoScannerAddressHGR()
// b) A bug? in APPLE_IIE_HORZ_CLOCK_OFFSET[0][8] containing the incorrect value of 0x006F
uint16_t addr1 = NTSC_VideoGetScannerAddress();
uint16_t addr2 = VideoGetScannerAddress(NULL, uExecutedCycles);
_ASSERT(addr1 == addr2);
#endif
return mem[ VideoGetScannerAddress(NULL, uExecutedCycles) ];
// return mem[ VideoGetScannerAddress(NULL, uExecutedCycles) ]; // NG: ANSI STORY (End Credits) - repro by running from "Turn the disk over"
return mem[ NTSC_VideoGetScannerAddress() ]; // OK: This does the 2-cycle adjust for ANSI STORY (End Credits)
}
//===========================================================================

2
source/NTSC.cpp
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@ -287,7 +287,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
static unsigned APPLE_IIE_HORZ_CLOCK_OFFSET[5][VIDEO_SCANNER_MAX_HORZ] =
{
{0x0068,0x0068,0x0069,0x006A,0x006B,0x006C,0x006D,0x006E,0x006F, // bug? 0x106F - see comment in Memory.cpp, MemReadFloatingBus(const ULONG)
{0x0068,0x0068,0x0069,0x006A,0x006B,0x006C,0x006D,0x006E,0x006F,
0x0070,0x0071,0x0072,0x0073,0x0074,0x0075,0x0076,0x0077,
0x0078,0x0079,0x007A,0x007B,0x007C,0x007D,0x007E,0x007F,
0x0000,0x0001,0x0002,0x0003,0x0004,0x0005,0x0006,0x0007,

43
source/Video.cpp
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@ -227,6 +227,7 @@ int const kPALVSyncLine = 264; // line when VSync starts (PAL)
int const kVLine0State = 0x100; // V[543210CBA] = 100000000
int const kVPresetLine = 256; // line when V state presets
int const kVSyncLines = 4; // lines per VSync duration
int const kVDisplayableScanLines = 192; // max displayable scanlines
static COLORREF customcolors[256]; // MONOCHROME is last custom color
@ -884,10 +885,6 @@ BYTE VideoCheckMode (WORD, WORD address, BYTE, BYTE, ULONG uExecutedCycles)
BYTE VideoCheckVbl ( ULONG uExecutedCycles )
{
bool bVblBar = VideoGetVblBar(uExecutedCycles);
// NTSC: It is tempting to replace with
// bool bVblBar = !NTSC_VideoIsVbl();
// But during full-speed, the NTSC video-scanner is not updated, so video-dependent Apple II code can hang
BYTE r = KeybGetKeycode();
return (r & ~0x80) | (bVblBar ? 0x80 : 0);
}
@ -1549,40 +1546,18 @@ WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles)
//===========================================================================
// Derived from VideoGetScannerAddress()
bool VideoGetVblBar(const DWORD uExecutedCycles)
{
// get video scanner position
//
int nCycles = CpuGetCyclesThisVideoFrame(uExecutedCycles);
// get video scanner position
int nCycles = CpuGetCyclesThisVideoFrame(uExecutedCycles);
// calculate video parameters according to display standard
//
int nScanLines = bVideoScannerNTSC ? kNTSCScanLines : kPALScanLines;
int nScanCycles = nScanLines * kHClocks;
nCycles %= nScanCycles;
// calculate video parameters according to display standard
const int kScanLines = bVideoScannerNTSC ? kNTSCScanLines : kPALScanLines;
const int kScanCycles = kScanLines * kHClocks;
nCycles %= kScanCycles;
// calculate vertical scanning state
//
int nVLine = nCycles / kHClocks; // which vertical scanning line
int nVState = kVLine0State + nVLine; // V state bits
if ((nVLine >= kVPresetLine)) // check for previous vertical state preset
{
nVState -= nScanLines; // compensate for preset
}
int v_3 = (nVState >> 6) & 1;
int v_4 = (nVState >> 7) & 1;
// update VBL' state
//
if (v_4 & v_3) // VBL?
{
return false; // Y: VBL' is false
}
else
{
return true; // N: VBL' is true
}
// VBL'
return nCycles < kVDisplayableScanLines * kHClocks;
}
//===========================================================================