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In dicformat deconstruct MODE 2 sectors so if they have correct ECC, correct/empty EDC, those fields are not stored in the image.

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This commit is contained in:
Natalia Portillo
2018-08-02 23:25:20 +01:00
parent 076297bbbd
commit 04c1b358aa
3 changed files with 84 additions and 24 deletions
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56
DiscImageChef.DiscImages/DiscImageChef/CdEcc.cs
View File

@@ -41,9 +41,12 @@ namespace DiscImageChef.DiscImages
byte[] eccBTable;
byte[] eccFTable;
uint[] edcTable;
bool initedEdc;
void EccInit()
{
if(initedEdc) return;
eccFTable = new byte[256];
eccBTable = new byte[256];
edcTable = new uint[256];
@@ -57,30 +60,22 @@ namespace DiscImageChef.DiscImages
for(j = 0; j < 8; j++) edc = (edc >> 1) ^ ((edc & 1) > 0 ? 0xD8018001 : 0);
edcTable[i] = edc;
}
initedEdc = true;
}
bool SuffixIsCorrect(byte[] sector)
{
if(!initedEdc) EccInit();
if(sector[0x814] != 0x00 || // reserved (8 bytes)
sector[0x815] != 0x00 || sector[0x816] != 0x00 || sector[0x817] != 0x00 || sector[0x818] != 0x00 ||
sector[0x819] != 0x00 || sector[0x81A] != 0x00 || sector[0x81B] != 0x00) return false;
byte[] address = new byte[4];
byte[] data = new byte[2060];
byte[] data2 = new byte[2232];
byte[] eccP = new byte[172];
byte[] eccQ = new byte[104];
Array.Copy(sector, 0x0C, address, 0, 4);
Array.Copy(sector, 0x10, data, 0, 2060);
Array.Copy(sector, 0x10, data2, 0, 2232);
Array.Copy(sector, 0x81C, eccP, 0, 172);
Array.Copy(sector, 0x8C8, eccQ, 0, 104);
bool correctEccP = CheckEcc(ref address, ref data, 86, 24, 2, 86, ref eccP);
bool correctEccP = CheckEcc(sector, sector, 86, 24, 2, 86, sector, 0xC, 0x10, 0x81C);
if(!correctEccP) return false;
bool correctEccQ = CheckEcc(ref address, ref data2, 52, 43, 86, 88, ref eccQ);
bool correctEccQ = CheckEcc(sector, sector, 52, 43, 86, 88, sector, 0xC, 0x10, 0x81C + 0xAC);
if(!correctEccQ) return false;
uint storedEdc = BitConverter.ToUInt32(sector, 0x810);
@@ -93,8 +88,31 @@ namespace DiscImageChef.DiscImages
return calculatedEdc == storedEdc;
}
bool CheckEcc(ref byte[] address, ref byte[] data, uint majorCount, uint minorCount, uint majorMult,
uint minorInc, ref byte[] ecc)
bool SuffixIsCorrectMode2(byte[] sector)
{
if(!initedEdc) EccInit();
byte[] zeroaddress = new byte[4];
bool correctEccP = CheckEcc(zeroaddress, sector, 86, 24, 2, 86, sector, 0, 0x10, 0x81C);
if(!correctEccP) return false;
bool correctEccQ = CheckEcc(zeroaddress, sector, 52, 43, 86, 88, sector, 0, 0x10, 0x81C + 0xAC);
if(!correctEccQ) return false;
uint storedEdc = BitConverter.ToUInt32(sector, 0x818);
uint edc = 0;
int size = 0x808;
int pos = 0x10;
for(; size > 0; size--) edc = (edc >> 8) ^ edcTable[(edc ^ sector[pos++]) & 0xFF];
uint calculatedEdc = edc;
return calculatedEdc == storedEdc;
}
bool CheckEcc(byte[] address, byte[] data, uint majorCount, uint minorCount, uint majorMult,
uint minorInc,
byte[] ecc, int addressOffset, int dataOffset, int eccOffset)
{
uint size = majorCount * minorCount;
uint major;
@@ -106,7 +124,7 @@ namespace DiscImageChef.DiscImages
uint minor;
for(minor = 0; minor < minorCount; minor++)
{
byte temp = idx < 4 ? address[idx] : data[idx - 4];
byte temp = idx < 4 ? address[idx + addressOffset] : data[idx + dataOffset - 4];
idx += minorInc;
if(idx >= size) idx -= size;
eccA ^= temp;
@@ -115,7 +133,7 @@ namespace DiscImageChef.DiscImages
}
eccA = eccBTable[eccFTable[eccA] ^ eccB];
if(ecc[major] != eccA || ecc[major + majorCount] != (eccA ^ eccB)) return false;
if(ecc[major + eccOffset] != eccA || ecc[major + majorCount + eccOffset] != (eccA ^ eccB)) return false;
}
return true;
@@ -217,6 +235,7 @@ namespace DiscImageChef.DiscImages
TrackType type)
{
byte[] computedEdc;
if(!initedEdc) EccInit();
switch(type)
{
@@ -281,6 +300,7 @@ namespace DiscImageChef.DiscImages
uint ComputeEdc(uint edc, byte[] src, int size, int srcOffset = 0)
{
if(!initedEdc) EccInit();
int pos = srcOffset;
for(; size > 0; size--) edc = (edc >> 8) ^ edcTable[(edc ^ src[pos++]) & 0xFF];

5
DiscImageChef.DiscImages/DiscImageChef/Enums.cs
View File

@@ -253,7 +253,10 @@ namespace DiscImageChef.DiscImages
enum CdFixFlags : uint
{
NotDumped = 0x10000000,
Correct = 0x20000000
Correct = 0x20000000,
Mode2Form1Ok = 0x30000000,
Mode2Form2Ok = 0x40000000,
Mode2Form2NoCrc = 0x50000000
}
}
}

41
DiscImageChef.DiscImages/DiscImageChef/Write.cs
View File

@@ -1249,8 +1249,46 @@ namespace DiscImageChef.DiscImages
if(mode2Subheaders == null) mode2Subheaders = new byte[imageInfo.Sectors * 8];
bool correctEcc = SuffixIsCorrectMode2(data);
bool correctEdc = false;
if(correctEcc)
{
uint computedEdc = ComputeEdc(0, data, 0x808, 0x10);
uint edc = BitConverter.ToUInt32(data, 0x818);
correctEdc = computedEdc == edc;
}
else
{
uint computedEdc = ComputeEdc(0, data, 0x91C, 0x10);
uint edc = BitConverter.ToUInt32(data, 0x92C);
correctEdc = computedEdc == edc;
}
if(correctEcc && correctEdc)
{
sector = new byte[2048];
if(sectorSuffixDdt == null) sectorSuffixDdt = new uint[imageInfo.Sectors];
sectorSuffixDdt[sectorAddress] = (uint)CdFixFlags.Mode2Form1Ok;
Array.Copy(data, 24, sector, 0, 2048);
}
else if(correctEdc)
{
sector = new byte[2324];
if(sectorSuffixDdt == null) sectorSuffixDdt = new uint[imageInfo.Sectors];
sectorSuffixDdt[sectorAddress] = (uint)CdFixFlags.Mode2Form2Ok;
Array.Copy(data, 24, sector, 0, 2324);
}
else if(BitConverter.ToUInt32(data, 0x92C) == 0)
{
sector = new byte[2324];
if(sectorSuffixDdt == null) sectorSuffixDdt = new uint[imageInfo.Sectors];
sectorSuffixDdt[sectorAddress] = (uint)CdFixFlags.Mode2Form2NoCrc;
Array.Copy(data, 24, sector, 0, 2324);
}
else Array.Copy(data, 24, sector, 0, 2328);
Array.Copy(data, 16, mode2Subheaders, (int)sectorAddress * 8, 8);
Array.Copy(data, 24, sector, 0, 2328);
return WriteSector(sector, sectorAddress);
}
@@ -2454,7 +2492,6 @@ namespace DiscImageChef.DiscImages
blockStream = null;
}
if(sectorSubchannel != null)
{
idxEntry = new IndexEntry