BYTE MSDReadHandler(void)
{
static BYTE MSDReadState = MSD_READ10_WAIT;
switch(MSDReadState)
{
case MSD_READ10_WAIT:
LBA.v[3]=gblCBW.CBWCB[2];
LBA.v[2]=gblCBW.CBWCB[3];
LBA.v[1]=gblCBW.CBWCB[4];
LBA.v[0]=gblCBW.CBWCB[5];
TransferLength.v[1]=gblCBW.CBWCB[7];
TransferLength.v[0]=gblCBW.CBWCB[8];
msd_csw.bCSWStatus=0x0;
msd_csw.dCSWDataResidue=0x0;
MSDReadState = MSD_READ10_BLOCK;
//Fall through to MSD_READ_BLOCK
case MSD_READ10_BLOCK:
if(TransferLength.Val == 0)
{
MSDReadState = MSD_READ10_WAIT;
break;
}
TransferLength.Val--; // we have read 1 LBA
MSDReadState = MSD_READ10_SECTOR;
//Fall through to MSD_READ10_SECTOR
case MSD_READ10_SECTOR:
//if the old data isn't completely sent yet
if(USBHandleBusy(USBMSDInHandle) != 0)
{
break;
}
if(LUNSectorRead(LBA.Val, (BYTE*)&msd_buffer[0]) != TRUE)
{
msd_csw.bCSWStatus=0x01; // Error 0x01 Refer page#18
// of BOT specifications
/* Don't read any more data*/
msd_csw.dCSWDataResidue=0x0;
MSD_State = MSD_DATA_IN;
break;
}
LBA.Val++;
msd_csw.bCSWStatus=0x00; // success
msd_csw.dCSWDataResidue=BLOCKLEN_512;//in order to send the
//512 bytes of data read
ptrNextData=(BYTE *)&msd_buffer[0];
MSDReadState = MSD_READ10_TX_SECTOR;
//Fall through to MSD_READ10_TX_SECTOR
case MSD_READ10_TX_SECTOR:
if(msd_csw.dCSWDataResidue == 0)
{
MSDReadState = MSD_READ10_BLOCK;
break;
}
MSDReadState = MSD_READ10_TX_PACKET;
//Fall through to MSD_READ10_TX_PACKET
case MSD_READ10_TX_PACKET:
if ((msd_csw.bCSWStatus==0x00)&&(msd_csw.dCSWDataResidue>=MSD_IN_EP_SIZE))
{
/* Write next chunk of data to EP Buffer and send */
if(USBHandleBusy(USBMSDInHandle))
{
break;
}
USBMSDInHandle = USBTxOnePacket(MSD_DATA_IN_EP,ptrNextData,MSD_IN_EP_SIZE);
MSDReadState = MSD_READ10_TX_SECTOR;
gblCBW.dCBWDataTransferLength-= MSD_IN_EP_SIZE;
msd_csw.dCSWDataResidue-=MSD_IN_EP_SIZE;
ptrNextData+=MSD_IN_EP_SIZE;
}
break;
}
return MSDReadState;
}
BYTE MSDReadHandler(void)
{
switch(MSDReadState)
{
case MSD_READ10_WAIT:
LBA.v[3]=gblCBW.CBWCB[2];
LBA.v[2]=gblCBW.CBWCB[3];
LBA.v[1]=gblCBW.CBWCB[4];
LBA.v[0]=gblCBW.CBWCB[5];
TransferLength.v[1]=gblCBW.CBWCB[7];
TransferLength.v[0]=gblCBW.CBWCB[8];
//Assume success initially, msd_csw.bCSWStatus will get set to 0x01
//or 0x02 later if an error is detected during the actual read sequence.
msd_csw.bCSWStatus=0x0;
msd_csw.dCSWDataResidue=0x0;
MSDReadState = MSD_READ10_BLOCK;
//Fall through to MSD_READ_BLOCK
case MSD_READ10_BLOCK:
if(TransferLength.Val == 0)
{
MSDReadState = MSD_READ10_WAIT;
break;
}
TransferLength.Val--; // we have read 1 LBA
MSDReadState = MSD_READ10_SECTOR;
//Fall through to MSD_READ10_SECTOR
case MSD_READ10_SECTOR:
//if the old data isn't completely sent yet
if(USBHandleBusy(USBMSDInHandle) != 0)
{
break;
}
//Try to read a sector worth of data from the media, but check for
//possible errors.
if(LUNSectorRead(LBA.Val, (BYTE*)&msd_buffer[0]) != TRUE)
{
if(MSDRetryAttempt < MSD_FAILED_READ_MAX_ATTEMPTS)
{
MSDRetryAttempt++;
break;
}
else
{
//Too many consecutive failed reads have occurred. Need to
//give up and abandon the sector read attempt; something must
//be wrong and we don't want to get stuck in an infinite loop.
//Need to indicate to the host that a device error occurred.
//However, we can't send the CSW immediately, since the host
//still expects to receive sector read data on the IN endpoint
//first. Therefore, we still send dummy bytes, before
//we send the CSW with the failed status in it.
msd_csw.bCSWStatus=0x01; // Error 0x01 Refer page#18
// of BOT specifications
//Set error status sense keys, so the host can check them later
//to determine how to proceed.
gblSenseData[LUN_INDEX].SenseKey=S_MEDIUM_ERROR;
gblSenseData[LUN_INDEX].ASC=ASC_NO_ADDITIONAL_SENSE_INFORMATION;
gblSenseData[LUN_INDEX].ASCQ=ASCQ_NO_ADDITIONAL_SENSE_INFORMATION;
}
}//else we successfully read a sector worth of data from our media
LBA.Val++;
msd_csw.dCSWDataResidue=BLOCKLEN_512;//in order to send the
//512 bytes of data read
ptrNextData=(BYTE *)&msd_buffer[0];
MSDReadState = MSD_READ10_TX_SECTOR;
//Fall through to MSD_READ10_TX_SECTOR
case MSD_READ10_TX_SECTOR:
if(msd_csw.dCSWDataResidue == 0)
{
MSDReadState = MSD_READ10_BLOCK;
break;
}
MSDReadState = MSD_READ10_TX_PACKET;
//Fall through to MSD_READ10_TX_PACKET
case MSD_READ10_TX_PACKET:
/* Write next chunk of data to EP Buffer and send */
//Make sure the endpoint is available before using it.
if(USBHandleBusy(USBMSDInHandle))
{
break;
}
//Prepare the USB module to send an IN transaction worth of data to the host.
USBMSDInHandle = USBTxOnePacket(MSD_DATA_IN_EP,ptrNextData,MSD_IN_EP_SIZE);
MSDReadState = MSD_READ10_TX_SECTOR;
gblCBW.dCBWDataTransferLength-= MSD_IN_EP_SIZE;
msd_csw.dCSWDataResidue-=MSD_IN_EP_SIZE;
ptrNextData+=MSD_IN_EP_SIZE;
break;
default:
//Illegal condition, should never occur. In the event that it ever
//did occur anyway, try to notify the host of the error.
msd_csw.bCSWStatus=0x02; //indicate "Phase Error"
//Advance state machine
MSDReadState = MSD_READ10_WAIT;
}
return MSDReadState;
}