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Avoid out-of-bounds video access #332

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Merged
merged 1 commit into from
May 31, 2025
Merged

Avoid out-of-bounds video access #332

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26 changes: 26 additions & 0 deletions defines.h
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,32 @@ namespace VCC
};


//
// bounds checking on existing array
// NOTE: only for video surface, out-of-bounds wraps
//
template <class T, size_t Size>
struct VideoArray
{
VideoArray(T* p) : data(p) {}

T& operator[](size_t index)
{
assert(index < Size);
return data[index % Size];
}

const T& operator[](size_t index) const
{
assert(index < Size);
return data[index % Size];
}

private:
T* data;
};


//
// protect T by verifying surrounding bytes
//
Expand Down
36 changes: 19 additions & 17 deletions tcc1014graphics.c
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Expand Up @@ -30,12 +30,14 @@ This file is part of VCC (Virtual Color Computer).
#include <stdio.h>
#include <commctrl.h> // Windows common controls

using Surface32 = VCC::VideoArray<unsigned int, 640 * 480>;

void SetupDisplay(void); //This routine gets called every time a software video register get updated.
void MakeRGBPalette (void);
void MakeCMPpalette(void);
bool DDFailedCheck(HRESULT hr, char *szMessage);
char *DDErrorString(HRESULT hr);
void RenderPMODE4NTSC(unsigned int* surfaceDest, int XpitchDest, const unsigned char* cocoSrc, char scanLines);
void RenderPMODE4NTSC(Surface32 surface32, size_t surfaceDest, int XpitchDest, const unsigned char* cocoSrc, char scanLines);

//extern STRConfig CurrentConfig;
static unsigned char ColorValues[4]={0,85,170,255};
Expand Down Expand Up @@ -6364,7 +6366,7 @@ void UpdateScreen32(SystemState *USState32)
char Pix = 0, Bit = 0, Sphase = 0;
static char Carry1 = 0, Carry2 = 0;
static char Pcolor = 0;
unsigned int *szSurface32 = USState32->PTRsurface32;
Surface32 szSurface32(USState32->PTRsurface32);
unsigned short y = USState32->LineCounter;
long Xpitch = USState32->SurfacePitch;
Carry1 = 1;
Expand Down Expand Up @@ -8280,10 +8282,10 @@ case 192+2: //Bpp=0 Sr=2
// byte pointer to ram
unsigned char* cocoRam = (unsigned char*)WideBuffer;
// destination screen (less 2 pixels for bleed)
unsigned int* surfaceDest = szSurface32 + (((y + VertCenter) * 2) * Xpitch) + HorzCenter - 2;
size_t surfaceDest = (((y + VertCenter) * 2) * Xpitch) + HorzCenter - 2;
// source coco screens
unsigned char* cocoSrc = cocoRam + (VidMask & (Start + (unsigned char)Hoffset));
RenderPMODE4NTSC(surfaceDest, Xpitch, cocoSrc, USState32->ScanLines);
RenderPMODE4NTSC(szSurface32, surfaceDest, Xpitch, cocoSrc, USState32->ScanLines);
}
else
for (HorzBeam=0;HorzBeam<BytesperRow;HorzBeam+=2) //1bbp Stretch=2
Expand Down Expand Up @@ -10115,27 +10117,27 @@ unsigned char SetColorInvert(unsigned char Tmp)
*/

// Render even/odd 2x2 ntsc pixels
void RenderNTSCPixel2x2(unsigned int* surfaceDest, int XpitchDest, char colorIndex, char scanLines)
void RenderNTSCPixel2x2(Surface32 surface32, size_t surfaceDest, int XpitchDest, char colorIndex, char scanLines)
{
colorIndex <<= 1;
unsigned int colorEven = ArtifactsNTSC[ColorInvert][ArtifactsNTSCIndex[colorIndex]];
unsigned int colorOdd = ArtifactsNTSC[ColorInvert][ArtifactsNTSCIndex[colorIndex + 1]];
// render even pixel
*surfaceDest = colorEven;
*(surfaceDest + 1) = colorEven;
if (!scanLines) *(surfaceDest + XpitchDest) = colorEven;
if (!scanLines) *(surfaceDest + XpitchDest + 1) = colorEven;
surface32[surfaceDest] = colorEven;
surface32[surfaceDest + 1] = colorEven;
if (!scanLines) surface32[surfaceDest + XpitchDest] = colorEven;
if (!scanLines) surface32[surfaceDest + XpitchDest + 1] = colorEven;
surfaceDest += 2;
// render odd pixel
*surfaceDest = colorOdd;
*(surfaceDest + 1) = colorOdd;
surface32[surfaceDest] = colorOdd;
surface32[surfaceDest + 1] = colorOdd;
if (scanLines) return;
*(surfaceDest + XpitchDest) = colorOdd;
*(surfaceDest + XpitchDest + 1) = colorOdd;
surface32[surfaceDest + XpitchDest] = colorOdd;
surface32[surfaceDest + XpitchDest + 1] = colorOdd;
}

// Render one raster line to surface 1bbp Stretch=2
void RenderPMODE4NTSC(unsigned int* surfaceDest, int XpitchDest, const unsigned char* cocoSrc, char scanLines)
void RenderPMODE4NTSC(Surface32 surface32, size_t surfaceDest, int XpitchDest, const unsigned char* cocoSrc, char scanLines)
{
const char cocoBorderPixel = 3; // white

Expand All @@ -10153,15 +10155,15 @@ void RenderPMODE4NTSC(unsigned int* surfaceDest, int XpitchDest, const unsigned
// roll in next pixel
bitPattern = ((bitPattern << 2) + nextCocoPixel) & 0x3F;
cocoByte <<= 2;
RenderNTSCPixel2x2(surfaceDest, XpitchDest, bitPattern, scanLines);
RenderNTSCPixel2x2(surface32, surfaceDest, XpitchDest, bitPattern, scanLines);
surfaceDest += 4;
}
}

// end of line pixels (ntsc bleed with border)
bitPattern = ((bitPattern << 2) + cocoBorderPixel) & 0x3F;
RenderNTSCPixel2x2(surfaceDest, XpitchDest, bitPattern, scanLines);
RenderNTSCPixel2x2(surface32, surfaceDest, XpitchDest, bitPattern, scanLines);
surfaceDest += 4;
bitPattern = ((bitPattern << 2) + cocoBorderPixel) & 0x3F;
RenderNTSCPixel2x2(surfaceDest, XpitchDest, bitPattern, scanLines);
RenderNTSCPixel2x2(surface32, surfaceDest, XpitchDest, bitPattern, scanLines);
}