//*****************************************************************************
//
//! Writes a block of data to the transmit buffer and queues it for
//! transmission to the USB controller.
//!
//! \param psBuffer points to the pointer instance into which data is to be
//! written.
//! \param pucData points to the first byte of data which is to be written.
//! \param ulLength is the number of bytes of data to write to the buffer.
//!
//! This function copies the supplied data into the transmit buffer. The
//! transmit buffer data will be packetized according to the constraints
//! imposed by the lower layer in use and sent to the USB controller as soon as
//! possible. Once a packet is transmitted and acknowledged, a
//! \b USB_EVENT_TX_COMPLETE event will be sent to the application callback
//! indicating the number of bytes that have been sent from the buffer.
//!
//! Attempts to send more data than there is space for in the transmit buffer
//! will result in fewer bytes than expected being written. The value returned
//! by the function indicates the actual number of bytes copied to the buffer.
//!
//! \return Returns the number of bytes actually written.
//
//*****************************************************************************
unsigned long
USBBufferWrite(const tUSBBuffer *psBuffer, const unsigned char *pucData,
unsigned long ulLength)
{
unsigned long ulSpace;
tUSBBufferVars *psVars;
//
// Check parameter validity.
//
ASSERT(psBuffer && pucData);
ASSERT(psBuffer->bTransmitBuffer == true);
//
// Get our workspace variables.
//
psVars = psBuffer->pvWorkspace;
//
// How much space is left in the buffer?
//
ulSpace = USBRingBufFree(&psVars->sRingBuf);
//
// How many bytes will we write?
//
ulLength = (ulLength > ulSpace) ? ulSpace : ulLength;
//
// Write the data to the buffer.
//
if(ulLength)
{
USBRingBufWrite(&psVars->sRingBuf, pucData, ulLength);
}
//
// Try to transmit the next packet to the host.
//
ScheduleNextTransmission(psBuffer);
//
// Tell the caller how many bytes we wrote to the buffer.
//
return(ulLength);
}
//*****************************************************************************
//
//! Writes a block of data to the transmit buffer and queues it for
//! transmission to the USB controller.
//!
//! \param psBuffer points to the pointer instance into which data is to be
//! written.
//! \param pui8Data points to the first byte of data which is to be written.
//! \param ui32Length is the number of bytes of data to write to the buffer.
//!
//! This function copies the supplied data into the transmit buffer. The
//! transmit buffer data will be packetized according to the constraints
//! imposed by the lower layer in use and sent to the USB controller as soon as
//! possible. Once a packet is transmitted and acknowledged, a
//! \b USB_EVENT_TX_COMPLETE event will be sent to the application callback
//! indicating the number of bytes that have been sent from the buffer.
//!
//! Attempts to send more data than there is space for in the transmit buffer
//! will result in fewer bytes than expected being written. The value returned
//! by the function indicates the actual number of bytes copied to the buffer.
//!
//! \return Returns the number of bytes actually written.
//
//*****************************************************************************
uint32_t
USBBufferWrite(const tUSBBuffer *psBuffer, const uint8_t *pui8Data,
uint32_t ui32Length)
{
uint32_t ui32Space;
tUSBBufferVars *psPrivate;
//
// Check parameter validity.
//
ASSERT(psBuffer && pui8Data);
ASSERT(psBuffer->bTransmitBuffer == true);
//
// Create a writable pointer to the private data.
//
psPrivate = &((tUSBBuffer *)psBuffer)->sPrivateData;
//
// How much space is left in the buffer?
//
ui32Space = USBRingBufFree(&psPrivate->sRingBuf);
//
// How many bytes will we write?
//
ui32Length = (ui32Length > ui32Space) ? ui32Space : ui32Length;
//
// Write the data to the buffer.
//
if(ui32Length)
{
USBRingBufWrite(&psPrivate->sRingBuf, pui8Data, ui32Length);
}
//
// Try to transmit the next packet to the host.
//
ScheduleNextTransmission((tUSBBuffer *)psBuffer);
//
// Tell the caller how many bytes we wrote to the buffer.
//
return(ui32Length);
}
//*****************************************************************************
//
// Handles USB_EVENT_RX_AVAILABLE for a receive buffer.
//
// \param psBuffer points to the buffer which is receiving the event.
// \param ulSize is the size reported in the event.
// \param pucData is the pointer provided in the event.
//
// This function is responsible for reading data from the lower layer into
// the buffer or, if we had previously passed a section of the buffer to the
// lower layer for it to write into directly, updating the buffer write pointer
// to add the new data to the buffer.
//
// If the pointer provided is NULL, we call the low level pfnTransfer function
// to get the new data. If the pointer is not NULL and not within the existing
// ring buffer, we copy the data directly from the pointer to the buffer and
// return the number of bytes read.
//
// \return Returns the number of bytes read from the lower layer.
//
//*****************************************************************************
static unsigned long
HandleRxAvailable(tUSBBuffer *psBuffer, unsigned long ulSize,
unsigned char *pucData)
{
tUSBBufferVars *psVars;
unsigned long ulAvail, ulRead, ulPacket, ulRetCount;
//
// Get a pointer to our workspace variables.
//
psVars = psBuffer->pvWorkspace;
//
// Has the data already been read into memory?
//
if(pucData)
{
//
// Yes - is it already in our ring buffer?
//
if((pucData >= psBuffer->pcBuffer) &&
(pucData < psBuffer->pcBuffer + psBuffer->ulBufferSize))
{
//
// The data is already in our ring buffer so merely update the
// write pointer to add the new data.
//
USBRingBufAdvanceWrite(&psVars->sRingBuf, ulSize);
//
// In this case, we pass back 0 to indicate that the lower layer
// doesn't need to make any buffer pointer updates.
//
ulRetCount = 0;
}
else
{
//
// The data is not within our buffer so we need to copy it into
// the buffer.
//
// How much space does the buffer have available?
//
ulAvail = USBRingBufFree(&psVars->sRingBuf);
//
// How much should we copy?
//
ulRead = (ulAvail < ulSize) ? ulAvail : ulSize;
//
// Copy the data into the buffer.
//
USBRingBufWrite(&psVars->sRingBuf, pucData, ulRead);
//
// We need to return the number of bytes we read in this case
// since the buffer supplied to us was owned by the lower layer and
// it may need to update its read pointer.
//
ulRetCount = ulRead;
}
}
else
{
//
// We were passed a NULL pointer so the low level driver has not read
// the data into memory yet. We need to call the transfer function to
// get the packet.
//
// How big is the packet that we need to receive?
//
ulPacket = psBuffer->pfnAvailable(psBuffer->pvHandle);
//
// How much contiguous space do we have in the buffer?
//
ulAvail = USBRingBufContigFree(&psVars->sRingBuf);
//
// Get as much of the packet as we can in the available space.
//
ulRead = psBuffer->pfnTransfer(psBuffer->pvHandle,
(psVars->sRingBuf.pucBuf +
psVars->sRingBuf.ulWriteIndex),
ulAvail, true);
//
// Advance the ring buffer write pointer to add our new data.
//
if(ulRead)
{
USBRingBufAdvanceWrite(&psVars->sRingBuf, ulRead);
}
//
// Did we get the whole packet?
//
if(ulRead < ulPacket)
{
//
// No - how much space do we have in the buffer?
//
ulAvail = USBRingBufContigFree(&psVars->sRingBuf);
//
// If there is any space left, read as much of the remainder of
// the packet as we can.
//
if(ulAvail)
{
ulPacket =
psBuffer->pfnTransfer(psBuffer->pvHandle,
(psVars->sRingBuf.pucBuf +
psVars->sRingBuf.ulWriteIndex),
ulAvail, true);
//
// Update the write pointer after we read more data into the
// buffer.
//
if(ulPacket)
{
USBRingBufAdvanceWrite(&psVars->sRingBuf, ulPacket);
}
}
}
//
// We need to return 0 in this case to indicate that the lower layer
// need not perform any buffer maintenance as a result of the callback.
//
ulRetCount = 0;
}
//
// How much data do we have in the buffer?
//
ulAvail = USBRingBufUsed(&psVars->sRingBuf);
//
// Pass the event on to the client with the current read pointer and
// available data size. The client is expected to understand the ring
// structure and be able to deal with wrap if it wants to read the data
// directly from the buffer.
//
ulRead = psBuffer->pfnCallback(psBuffer->pvCBData,
USB_EVENT_RX_AVAILABLE,
ulAvail,
(psVars->sRingBuf.pucBuf +
psVars->sRingBuf.ulReadIndex));
//
// If the client read anything from the buffer, update the read pointer.
//
USBRingBufAdvanceRead(&psVars->sRingBuf, ulRead);
//
// Return the correct value to the low level driver.
//
return(ulRetCount);
}