xpacket_fifo_v1_00_b.c

来自「适合KS8695X」· C语言 代码 · 共 449 行 · 第 1/2 页

* words such that if the byte count specified is incorrect, but is still
* possible based on the number of words in the FIFO, up to 3 garbage bytes
* may be present at the end of the buffer.
* <br><br>
* This function assumes that if the device consuming data from the FIFO is
* a byte device, the order of the bytes to be consumed is from the most
* significant byte to the least significant byte of a 32 bit word removed
* from the FIFO.
*
******************************************************************************/
XStatus
XPacketFifoV100b_Read(XPacketFifoV100b * InstancePtr,
		      u8 * BufferPtr, u32 ByteCount)
{
	u32 FifoCount;
	u32 WordCount;
	u32 ExtraByteCount;
	u32 *WordBuffer = (u32 *) BufferPtr;

	/* assert to verify valid input arguments including 32 bit alignment of
	 * the buffer pointer
	 */
	XASSERT_NONVOID(InstancePtr != NULL);
	XASSERT_NONVOID(BufferPtr != NULL);
	XASSERT_NONVOID(((u32) BufferPtr &
			 (XPF_FIFO_WIDTH_BYTE_COUNT - 1)) == 0);
	XASSERT_NONVOID(ByteCount != 0);
	XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

	/* get the count of how many 32 bit words are in the FIFO, if there aren't
	 * enought words to satisfy the request, return an error
	 */

	FifoCount = XIo_In32(InstancePtr->RegBaseAddress +
			     XPF_COUNT_STATUS_REG_OFFSET) & XPF_COUNT_MASK;

	if ((FifoCount * XPF_FIFO_WIDTH_BYTE_COUNT) < ByteCount) {
		return XST_PFIFO_LACK_OF_DATA;
	}

	/* calculate the number of words to read from the FIFO before the word
	 * containing the extra bytes, and calculate the number of extra bytes
	 * the extra bytes are defined as those at the end of the buffer when
	 * the buffer does not end on a 32 bit boundary
	 */
	WordCount = ByteCount / XPF_FIFO_WIDTH_BYTE_COUNT;
	ExtraByteCount = ByteCount % XPF_FIFO_WIDTH_BYTE_COUNT;

	/* Read the 32 bit words from the FIFO for all the buffer except the
	 * last word which contains the extra bytes, the following code assumes
	 * that the buffer is 32 bit aligned, otherwise an alignment exception could
	 * be generated
	 */
	for (FifoCount = 0; FifoCount < WordCount; FifoCount++) {
		WordBuffer[FifoCount] = XIo_In32(InstancePtr->DataBaseAddress);
	}

	/* if there are extra bytes to handle, read the last word from the FIFO
	 * and insert the extra bytes into the buffer
	 */
	if (ExtraByteCount > 0) {
		u32 LastWord;
		u8 *ExtraBytesBuffer = (u8 *) (WordBuffer + WordCount);

		/* get the last word from the FIFO for the extra bytes */

		LastWord = XIo_In32(InstancePtr->DataBaseAddress);

		/* one extra byte in the last word, put the byte into the next location
		 * of the buffer, bytes in a word of the FIFO are ordered from most
		 * significant byte to least
		 */
		if (ExtraByteCount == 1) {
			ExtraBytesBuffer[0] = (u8) (LastWord >> 24);
		}

		/* two extra bytes in the last word, put each byte into the next two
		 * locations of the buffer
		 */
		else if (ExtraByteCount == 2) {
			ExtraBytesBuffer[0] = (u8) (LastWord >> 24);
			ExtraBytesBuffer[1] = (u8) (LastWord >> 16);
		}
		/* three extra bytes in the last word, put each byte into the next three
		 * locations of the buffer
		 */
		else if (ExtraByteCount == 3) {
			ExtraBytesBuffer[0] = (u8) (LastWord >> 24);
			ExtraBytesBuffer[1] = (u8) (LastWord >> 16);
			ExtraBytesBuffer[2] = (u8) (LastWord >> 8);
		}
	}
	return XST_SUCCESS;
}

/*****************************************************************************/
/*
*
* Write data into a packet FIFO. The packet FIFO is currently 32 bits wide
* such that an input buffer which is a series of bytes must be written into the
* FIFO a word at a time. If the buffer is not a multiple of 32 bit words, it is
* necessary for this function to format the remaining bytes into a single 32
* bit word to be inserted into the FIFO. This is necessary to avoid any
* accesses past the end of the buffer.
*
* @param InstancePtr contains a pointer to the FIFO to operate on.
* @param BufferPtr points to the memory buffer that data is to be read from
*        and written into the FIFO. Since this buffer is a byte buffer, the data
*        is assumed to be endian independent. This buffer must be 32 bit aligned
*        or an alignment exception could be generated.
* @param ByteCount contains the number of bytes to read from the buffer and to
*        write to the FIFO.
*
* @return
*
* XST_SUCCESS is returned if the operation succeeded.  If there is not enough
* room in the FIFO to hold the specified bytes, XST_PFIFO_NO_ROOM is
* returned.
*
* @note
*
* This function assumes that if the device inserting data into the FIFO is
* a byte device, the order of the bytes in each 32 bit word is from the most
* significant byte to the least significant byte.
*
******************************************************************************/
XStatus
XPacketFifoV100b_Write(XPacketFifoV100b * InstancePtr,
		       u8 * BufferPtr, u32 ByteCount)
{
	u32 FifoCount;
	u32 WordCount;
	u32 ExtraByteCount;
	u32 *WordBuffer = (u32 *) BufferPtr;

	/* assert to verify valid input arguments including 32 bit alignment of
	 * the buffer pointer
	 */
	XASSERT_NONVOID(InstancePtr != NULL);
	XASSERT_NONVOID(BufferPtr != NULL);
	XASSERT_NONVOID(((u32) BufferPtr &
			 (XPF_FIFO_WIDTH_BYTE_COUNT - 1)) == 0);
	XASSERT_NONVOID(ByteCount != 0);
	XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

	/* get the count of how many words may be inserted into the FIFO */

	FifoCount = XIo_In32(InstancePtr->RegBaseAddress +
			     XPF_COUNT_STATUS_REG_OFFSET) & XPF_COUNT_MASK;

	/* Calculate the number of 32 bit words required to insert the specified
	 * number of bytes in the FIFO and determine the number of extra bytes
	 * if the buffer length is not a multiple of 32 bit words
	 */

	WordCount = ByteCount / XPF_FIFO_WIDTH_BYTE_COUNT;
	ExtraByteCount = ByteCount % XPF_FIFO_WIDTH_BYTE_COUNT;

	/* take into account the extra bytes in the total word count */

	if (ExtraByteCount > 0) {
		WordCount++;
	}

	/* if there's not enough room in the FIFO to hold the specified
	 * number of bytes, then indicate an error,
	 */
	if (FifoCount < WordCount) {
		return XST_PFIFO_NO_ROOM;
	}

	/* readjust the word count to not take into account the extra bytes */

	if (ExtraByteCount > 0) {
		WordCount--;
	}

	/* Write all the bytes of the buffer which can be written as 32 bit
	 * words into the FIFO, waiting to handle the extra bytes seperately
	 */
	for (FifoCount = 0; FifoCount < WordCount; FifoCount++) {
		XIo_Out32(InstancePtr->DataBaseAddress, WordBuffer[FifoCount]);
	}

	/* if there are extra bytes to handle, extract them from the buffer
	 * and create a 32 bit word and write it to the FIFO
	 */
	if (ExtraByteCount > 0) {
		u32 LastWord = 0;
		u8 *ExtraBytesBuffer = (u8 *) (WordBuffer + WordCount);

		/* one extra byte in the buffer, put the byte into the last word
		 * to be inserted into the FIFO, perform this processing inline rather
		 * than in a loop to help performance
		 */
		if (ExtraByteCount == 1) {
			LastWord = ExtraBytesBuffer[0] << 24;
		}

		/* two extra bytes in the buffer, put each byte into the last word
		 * to be inserted into the FIFO
		 */
		else if (ExtraByteCount == 2) {
			LastWord = ExtraBytesBuffer[0] << 24 |
			    ExtraBytesBuffer[1] << 16;
		}

		/* three extra bytes in the buffer, put each byte into the last word
		 * to be inserted into the FIFO
		 */
		else if (ExtraByteCount == 3) {
			LastWord = ExtraBytesBuffer[0] << 24 |
			    ExtraBytesBuffer[1] << 16 |
			    ExtraBytesBuffer[2] << 8;
		}

		/* write the last 32 bit word to the FIFO and return with no errors */

		XIo_Out32(InstancePtr->DataBaseAddress, LastWord);
	}

	return XST_SUCCESS;
}