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/* ----------------------------------------------------------------------------

 *         ATMEL Microcontroller Software Support

 * ----------------------------------------------------------------------------

 * Copyright (c) 2008, Atmel Corporation

 *

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * - Redistributions of source code must retain the above copyright notice,

 * this list of conditions and the disclaimer below.

 *

 * Atmel's name may not be used to endorse or promote products derived from

 * this software without specific prior written permission.

 *

 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE

 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,

 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,

 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 * ----------------------------------------------------------------------------

 */

//-----------------------------------------------------------------------------

//         Headers

//-----------------------------------------------------------------------------

#include <board.h>

#include "emac.h"

#include <utility/trace.h>

#include <utility/assert.h>

#include <string.h>

//------------------------------------------------------------------------------

//         Definitions

//------------------------------------------------------------------------------

/// The buffer addresses written into the descriptors must be aligned so the

/// last few bits are zero.  These bits have special meaning for the EMAC

/// peripheral and cannot be used as part of the address.

#define EMAC_ADDRESS_MASK   ((unsigned int)0xFFFFFFFC)

#define EMAC_LENGTH_FRAME   ((unsigned int)0x0FFF)    /// Length of frame mask

// receive buffer descriptor bits

#define EMAC_RX_OWNERSHIP_BIT   (1UL <<  0)

#define EMAC_RX_WRAP_BIT        (1UL <<  1)

#define EMAC_RX_SOF_BIT         (1UL << 14)

#define EMAC_RX_EOF_BIT         (1UL << 15)

// Transmit buffer descriptor bits

#define EMAC_TX_LAST_BUFFER_BIT (1UL << 15)

#define EMAC_TX_WRAP_BIT        (1UL << 30)

#define EMAC_TX_USED_BIT        (1UL << 31)

//-----------------------------------------------------------------------------

// Circular buffer management

//-----------------------------------------------------------------------------

// Return count in buffer

#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))

// Return space available, 0..size-1

// We always leave one free char as a completely full buffer

// has head == tail, which is the same as empty

#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))

// Return count up to the end of the buffer.

// Carefully avoid accessing head and tail more than once,

// so they can change underneath us without returning inconsistent results

#define CIRC_CNT_TO_END(head,tail,size) \

   ({int end = (size) - (tail); \

     int n = ((head) + end) & ((size)-1); \

     n < end ? n : end;})

// Return space available up to the end of the buffer

#define CIRC_SPACE_TO_END(head,tail,size) \

   ({int end = (size) - 1 - (head); \

     int n = (end + (tail)) & ((size)-1); \

     n <= end ? n : end+1;})

// Increment head or tail

#define CIRC_INC(headortail,size) \

        headortail++;             \

        if(headortail >= size) {  \

            headortail = 0;       \

        }

#define CIRC_EMPTY(circ)     ((circ)->head == (circ)->tail)

#define CIRC_CLEAR(circ)     ((circ)->head = (circ)->tail = 0)

//------------------------------------------------------------------------------

//      Structures

//------------------------------------------------------------------------------

#ifdef __ICCARM__          // IAR

#pragma pack(4)            // IAR

#define __attribute__(...) // IAR

#endif                     // IAR

/// Describes the type and attribute of Receive Transfer descriptor.

typedef struct _EmacRxTDescriptor {

    unsigned int addr;

    unsigned int status;

} __attribute__((packed, aligned(8))) EmacRxTDescriptor, *PEmacRxTDescriptor;

/// Describes the type and attribute of Transmit Transfer descriptor.

typedef struct _EmacTxTDescriptor {

    unsigned int addr;

    unsigned int status;

} __attribute__((packed, aligned(8))) EmacTxTDescriptor, *PEmacTxTDescriptor;

#ifdef __ICCARM__          // IAR

#pragma pack()             // IAR

#endif                     // IAR

/// Descriptors for RX (required aligned by 8)

typedef struct {

   volatile EmacRxTDescriptor td[RX_BUFFERS];

   EMAC_RxCallback rxCb; /// Callback function to be invoked once a frame has been received

   unsigned short idx;

} RxTd;

/// Descriptors for TX (required aligned by 8)

typedef struct {

   volatile EmacTxTDescriptor td[TX_BUFFERS];

   EMAC_TxCallback txCb[TX_BUFFERS];    /// Callback function to be invoked once TD has been processed

   EMAC_WakeupCallback wakeupCb;        /// Callback function to be invoked once several TD have been released

   unsigned short wakeupThreshold; /// Number of free TD before wakeupCb is invoked

   unsigned short head;            /// Circular buffer head pointer incremented by the upper layer (buffer to be sent)

   unsigned short tail;            /// Circular buffer head pointer incremented by the IT handler (buffer sent)

} TxTd;

//------------------------------------------------------------------------------

//         Internal variables

//------------------------------------------------------------------------------

// Receive Transfer Descriptor buffer

#ifdef __ICCARM__          // IAR

#pragma data_alignment=8   // IAR

#endif                     // IAR

static volatile RxTd rxTd;

// Transmit Transfer Descriptor buffer

#ifdef __ICCARM__          // IAR

#pragma data_alignment=8   // IAR

#endif                     // IAR

static volatile TxTd txTd;

/// Send Buffer

// Section 3.6 of AMBA 2.0 spec states that burst should not cross 1K Boundaries.

// Receive buffer manager writes are burst of 2 words => 3 lsb bits of the address shall be set to 0

#ifdef __ICCARM__          // IAR

#pragma data_alignment=8   // IAR

#endif                     // IAR

static volatile unsigned char pTxBuffer[TX_BUFFERS * EMAC_TX_UNITSIZE] __attribute__((aligned(8)));

#ifdef __ICCARM__          // IAR

#pragma data_alignment=8   // IAR

#endif                     // IAR

/// Receive Buffer

static volatile unsigned char pRxBuffer[RX_BUFFERS * EMAC_RX_UNITSIZE] __attribute__((aligned(8)));

/// Statistics

static volatile EmacStats EmacStatistics;

//-----------------------------------------------------------------------------

//         Internal functions

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

/// Wait PHY operation complete.

/// Return 1 if the operation completed successfully.

/// May be need to re-implemented to reduce CPU load.

/// \param retry: the retry times, 0 to wait forever until complete.

//-----------------------------------------------------------------------------

static unsigned char EMAC_WaitPhy( unsigned int retry )

{

    unsigned int retry_count = 0;

    while((AT91C_BASE_EMAC->EMAC_NSR & AT91C_EMAC_IDLE) == 0) {

        // Dead LOOP!

        if (retry == 0) {

            continue;

        }

        // Timeout check

        retry_count++;

        if(retry_count >= retry) {

            trace_LOG(trace_ERROR, "E: Wait PHY time out\n\r");

            return 0;

        }

    }

    return 1;

}

//-----------------------------------------------------------------------------

//         Exported functions

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

//          PHY management functions

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

/// Set MDC clock according to current board clock. Per 802.3, MDC should be

/// less then 2.5MHz.

/// Return 1 if successfully, 0 if MDC clock not found.

//-----------------------------------------------------------------------------

unsigned char EMAC_SetMdcClock( unsigned int mck )

{

    int clock_dividor;

    if (mck <= 20000000) {

        clock_dividor = AT91C_EMAC_CLK_HCLK_8;          /// MDC clock = MCK/8

    }

    else if (mck <= 40000000) {

        clock_dividor = AT91C_EMAC_CLK_HCLK_16;         /// MDC clock = MCK/16

    }

    else if (mck <= 80000000) {

        clock_dividor = AT91C_EMAC_CLK_HCLK_32;         /// MDC clock = MCK/32

    }

    else if (mck <= 160000000) {

        clock_dividor = AT91C_EMAC_CLK_HCLK_64;         /// MDC clock = MCK/64

    }

    else {

        trace_LOG(trace_ERROR, "E: No valid MDC clock.\n\r");

        return 0;

    }

    AT91C_BASE_EMAC->EMAC_NCFGR = (AT91C_BASE_EMAC->EMAC_NCFGR & (~AT91C_EMAC_CLK))

                                 | clock_dividor;

    return 1;

}

//-----------------------------------------------------------------------------

/// Enable MDI with PHY

//-----------------------------------------------------------------------------

void EMAC_EnableMdio( void )

{

    AT91C_BASE_EMAC->EMAC_NCR |= AT91C_EMAC_MPE;

}

//-----------------------------------------------------------------------------

/// Enable MDI with PHY

//-----------------------------------------------------------------------------

void EMAC_DisableMdio( void )

{

    AT91C_BASE_EMAC->EMAC_NCR &= ~AT91C_EMAC_MPE;

}

//-----------------------------------------------------------------------------

/// Enable MII mode for EMAC, called once after autonegotiate

//-----------------------------------------------------------------------------

void EMAC_EnableMII( void )

{

    AT91C_BASE_EMAC->EMAC_USRIO = AT91C_EMAC_CLKEN;

}

//-----------------------------------------------------------------------------

/// Enable RMII mode for EMAC, called once after autonegotiate

//-----------------------------------------------------------------------------

void EMAC_EnableRMII( void )

{

    AT91C_BASE_EMAC->EMAC_USRIO = AT91C_EMAC_CLKEN | AT91C_EMAC_RMII;

}

//-----------------------------------------------------------------------------

/// Read PHY register.

/// Return 1 if successfully, 0 if timeout.

/// \param PhyAddress PHY Address

/// \param Address Register Address

/// \param pValue Pointer to a 32 bit location to store read data

/// \param retry The retry times, 0 to wait forever until complete.

//-----------------------------------------------------------------------------

unsigned char EMAC_ReadPhy(unsigned char PhyAddress,

                           unsigned char Address,

                           unsigned int *pValue,

                           unsigned int retry)

{

    AT91C_BASE_EMAC->EMAC_MAN = (AT91C_EMAC_SOF & (0x01 << 30))

                              | (AT91C_EMAC_CODE & (2 << 16))

                              | (AT91C_EMAC_RW & (2 << 28))

                              | (AT91C_EMAC_PHYA & ((PhyAddress & 0x1f) << 23))

                              | (AT91C_EMAC_REGA & (Address << 18));

    if ( EMAC_WaitPhy(retry) == 0 ) {

        trace_LOG(trace_ERROR, "TimeOut EMAC_ReadPhy\n\r");

        return 0;

    }

    *pValue = ( AT91C_BASE_EMAC->EMAC_MAN & 0x0000ffff );

    return 1;

}

//-----------------------------------------------------------------------------

/// Write PHY register

/// Return 1 if successfully, 0 if timeout.

/// \param PhyAddress PHY Address

/// \param Address Register Address

/// \param Value Data to write ( Actually 16 bit data )

/// \param retry The retry times, 0 to wait forever until complete.

//-----------------------------------------------------------------------------

unsigned char EMAC_WritePhy(unsigned char PhyAddress,

                            unsigned char Address,

                            unsigned int  Value,

                            unsigned int  retry)

{

    AT91C_BASE_EMAC->EMAC_MAN = (AT91C_EMAC_SOF & (0x01 << 30))

                              | (AT91C_EMAC_CODE & (2 << 16))

                              | (AT91C_EMAC_RW & (1 << 28))

                              | (AT91C_EMAC_PHYA & ((PhyAddress & 0x1f) << 23))

                              | (AT91C_EMAC_REGA & (Address << 18))

                              | (AT91C_EMAC_DATA & Value) ;

    if ( EMAC_WaitPhy(retry) == 0 ) {

        trace_LOG(trace_ERROR, "TimeOut EMAC_WritePhy\n\r");

        return 0;

    }

    return 1;

}

//-----------------------------------------------------------------------------

/// Setup the EMAC for the link : speed 100M/10M and Full/Half duplex

/// \param speed        Link speed, 0 for 10M, 1 for 100M

/// \param fullduplex   1 for Full Duplex mode

//-----------------------------------------------------------------------------

void EMAC_SetLinkSpeed(unsigned char speed, unsigned char fullduplex)

{

    unsigned int ncfgr;

    ncfgr = AT91C_BASE_EMAC->EMAC_NCFGR;

    ncfgr &= ~(AT91C_EMAC_SPD | AT91C_EMAC_FD);

    if (speed) {

        ncfgr |= AT91C_EMAC_SPD;

    }

    if (fullduplex) {

        ncfgr |= AT91C_EMAC_FD;

    }

    AT91C_BASE_EMAC->EMAC_NCFGR = ncfgr;

}

//-----------------------------------------------------------------------------

//          EMAC functions

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

/// EMAC Interrupt handler

//-----------------------------------------------------------------------------

void EMAC_Handler(void)

{

    volatile EmacTxTDescriptor *pTxTd;

    volatile EMAC_TxCallback   *pTxCb;

    unsigned int isr;

    unsigned int rsr;

    unsigned int tsr;

    unsigned int rxStatusFlag;

    unsigned int txStatusFlag;

    //trace_LOG(trace_DEBUG, "EMAC_Handler\n\r");

    isr = AT91C_BASE_EMAC->EMAC_ISR & AT91C_BASE_EMAC->EMAC_IMR;

    rsr = AT91C_BASE_EMAC->EMAC_RSR;

    tsr = AT91C_BASE_EMAC->EMAC_TSR;

    // RX packet

    if ((isr & AT91C_EMAC_RCOMP) || (rsr & AT91C_EMAC_REC)) {

        rxStatusFlag = AT91C_EMAC_REC;

        // Frame received

        EmacStatistics.rx_packets++;

        // Check OVR

        if (rsr & AT91C_EMAC_OVR) {

            rxStatusFlag |= AT91C_EMAC_OVR;

            EmacStatistics.rx_ovrs++;

        }

        // Check BNA

        if (rsr & AT91C_EMAC_BNA) {

            rxStatusFlag |= AT91C_EMAC_BNA;

            EmacStatistics.rx_bnas++;

        }

        // Clear status

        AT91C_BASE_EMAC->EMAC_RSR |= rxStatusFlag;

        // Invoke callbacks

        if (rxTd.rxCb) {

            rxTd.rxCb(rxStatusFlag);

        }

    }

    // TX packet

    if ((isr & AT91C_EMAC_TCOMP) || (tsr & AT91C_EMAC_COMP)) {

        txStatusFlag = AT91C_EMAC_COMP;

        EmacStatistics.tx_comp ++;

        // A frame transmitted

        // Check RLE

        if (tsr & AT91C_EMAC_RLES) {

            txStatusFlag |= AT91C_EMAC_RLES;

            EmacStatistics.tx_errors++;

        }

        // Check COL

        if (tsr & AT91C_EMAC_COL) {

            txStatusFlag |= AT91C_EMAC_COL;

            EmacStatistics.collisions++;

        }

        // Check BEX

        if (tsr & AT91C_EMAC_BEX) {

            txStatusFlag |= AT91C_EMAC_BEX;

            EmacStatistics.tx_exausts++;

        }

        // Check UND

        if (tsr & AT91C_EMAC_UND) {

            txStatusFlag |= AT91C_EMAC_UND;

            EmacStatistics.tx_underruns++;

        }

        // Clear status

        AT91C_BASE_EMAC->EMAC_TSR |= txStatusFlag;

        // Sanity check: Tx buffers have to be scheduled

        ASSERT(!CIRC_EMPTY(&txTd),

            "-F- EMAC Tx interrupt received meanwhile no TX buffers has been scheduled\n\r");

        // Check the buffers

        while (CIRC_CNT(txTd.head, txTd.tail, TX_BUFFERS)) {

            pTxTd = txTd.td + txTd.tail;

            pTxCb = txTd.txCb + txTd.tail;

            // Exit if buffer has not been sent yet

            if ((pTxTd->status & EMAC_TX_USED_BIT) == 0) {

                break;

            }

            // Notify upper layer that packet has been sent

            if (*pTxCb) {

                (*pTxCb)(txStatusFlag);

            }

            CIRC_INC( txTd.tail, TX_BUFFERS );

        }

        // If a wakeup has been scheduled, notify upper layer that it can send

        // other packets, send will be successfull.

        if( (CIRC_SPACE(txTd.head, txTd.tail, TX_BUFFERS) >= txTd.wakeupThreshold)

         &&  txTd.wakeupCb) {

            txTd.wakeupCb();

        }

    }

}

//-----------------------------------------------------------------------------

/// Initialize the EMAC with the emac controller address

/// \param id     HW ID for power management

/// \param pTxWakeUpfct Thresold TX Wakeup Callback

/// \param pRxfct       RX Wakeup Callback

/// \param pMacAddress  Mac Address

/// \param enableCAF    enable AT91C_EMAC_CAF if needed by application

/// \param enableNBC    AT91C_EMAC_NBC if needed by application

//-----------------------------------------------------------------------------

void EMAC_Init( unsigned char id, const unsigned char *pMacAddress,

                unsigned char enableCAF, unsigned char enableNBC )

{

    int Index;

    unsigned int Address;

    // Check parameters

    ASSERT(RX_BUFFERS * EMAC_RX_UNITSIZE > EMAC_FRAME_LENTGH_MAX,

           "E: RX buffers too small\n\r");

    trace_LOG(trace_DEBUG, "EMAC_Init\n\r");

    // Power ON

    AT91C_BASE_PMC->PMC_PCER = 1 << id;

    // Disable TX & RX and more

    AT91C_BASE_EMAC->EMAC_NCR = 0;

    // disable

    AT91C_BASE_EMAC->EMAC_IDR = ~0;

    rxTd.idx = 0;

    CIRC_CLEAR(&txTd);

    // Setup the RX descriptors.

    for(Index = 0; Index < RX_BUFFERS; Index++) {

        Address = (unsigned int)(&(pRxBuffer[Index * EMAC_RX_UNITSIZE]));

        // Remove EMAC_RX_OWNERSHIP_BIT and EMAC_RX_WRAP_BIT

        rxTd.td[Index].addr = Address & EMAC_ADDRESS_MASK;

        rxTd.td[Index].status = 0;

    }

    rxTd.td[RX_BUFFERS - 1].addr |= EMAC_RX_WRAP_BIT;

    // Setup the TX descriptors.

    for(Index = 0; Index < TX_BUFFERS; Index++) {

        Address = (unsigned int)(&(pTxBuffer[Index * EMAC_TX_UNITSIZE]));

        txTd.td[Index].addr = Address;

        txTd.td[Index].status = EMAC_TX_USED_BIT;

    }

    txTd.td[TX_BUFFERS - 1].status = EMAC_TX_USED_BIT | EMAC_TX_WRAP_BIT;

    // Set the MAC address

    if( pMacAddress != (unsigned char *)0 ) {

        AT91C_BASE_EMAC->EMAC_SA1L = ( ((unsigned int)pMacAddress[3] << 24)

                                     | ((unsigned int)pMacAddress[2] << 16)

                                     | ((unsigned int)pMacAddress[1] << 8 )

                                     |                pMacAddress[0] );

        AT91C_BASE_EMAC->EMAC_SA1H = ( ((unsigned int)pMacAddress[5] << 8 )

                                     |                pMacAddress[4] );

    }

    // Now setup the descriptors

    // Receive Buffer Queue Pointer Register

    AT91C_BASE_EMAC->EMAC_RBQP = (unsigned int) (rxTd.td);

    // Transmit Buffer Queue Pointer Register

    AT91C_BASE_EMAC->EMAC_TBQP = (unsigned int) (txTd.td);

    AT91C_BASE_EMAC->EMAC_NCR = AT91C_EMAC_CLRSTAT;

    // Clear all status bits in the receive status register.

    AT91C_BASE_EMAC->EMAC_RSR = (AT91C_EMAC_OVR | AT91C_EMAC_REC | AT91C_EMAC_BNA);

    // Clear all status bits in the transmit status register

    AT91C_BASE_EMAC->EMAC_TSR = ( AT91C_EMAC_UBR | AT91C_EMAC_COL | AT91C_EMAC_RLES

                                | AT91C_EMAC_BEX | AT91C_EMAC_COMP

                                | AT91C_EMAC_UND );

    // Clear interrupts

    AT91C_BASE_EMAC->EMAC_ISR;

    // Enable the copy of data into the buffers

    // ignore broadcasts, and don't copy FCS.

    AT91C_BASE_EMAC->EMAC_NCFGR |= (AT91C_EMAC_DRFCS | AT91C_EMAC_PAE);

    if( enableCAF == EMAC_CAF_ENABLE ) {

        AT91C_BASE_EMAC->EMAC_NCFGR |= AT91C_EMAC_CAF;

    }

    if( enableNBC == EMAC_NBC_ENABLE ) {

        AT91C_BASE_EMAC->EMAC_NCFGR |= AT91C_EMAC_NBC;

    }

    // Enable Rx and Tx, plus the stats register.

    AT91C_BASE_EMAC->EMAC_NCR |= (AT91C_EMAC_TE | AT91C_EMAC_RE | AT91C_EMAC_WESTAT);

    // Setup the interrupts for TX (and errors)

    AT91C_BASE_EMAC->EMAC_IER = AT91C_EMAC_RXUBR

                              | AT91C_EMAC_TUNDR

                              | AT91C_EMAC_RLEX

                              | AT91C_EMAC_TXERR

                              | AT91C_EMAC_TCOMP

                              | AT91C_EMAC_ROVR

                              | AT91C_EMAC_HRESP;

}

//-----------------------------------------------------------------------------

/// Get the statstic information & reset it

/// \param pStats   Pointer to EmacStats structure to copy the informations

/// \param reset    Reset the statistics after copy it

//-----------------------------------------------------------------------------

void EMAC_GetStatistics(EmacStats *pStats, unsigned char reset)

{

    unsigned int ncrBackup = 0;

    trace_LOG(trace_DEBUG, "EMAC_GetStatistics\n\r");

    // Sanity check

    if (pStats == (EmacStats *) 0) {

        return;

    }

    ncrBackup = AT91C_BASE_EMAC->EMAC_NCR & (AT91C_EMAC_TE | AT91C_EMAC_RE);

    // Disable TX/RX

    AT91C_BASE_EMAC->EMAC_NCR = ncrBackup & ~(AT91C_EMAC_TE | AT91C_EMAC_RE);

    // Copy the informations

    memcpy(pStats, (void*)&EmacStatistics, sizeof(EmacStats));

    // Reset the statistics

    if (reset) {

        memset((void*)&EmacStatistics, 0x00, sizeof(EmacStats));

        AT91C_BASE_EMAC->EMAC_NCR = ncrBackup | AT91C_EMAC_CLRSTAT;

    }

    // restore NCR

    AT91C_BASE_EMAC->EMAC_NCR = ncrBackup;

}

//-----------------------------------------------------------------------------

/// Send a packet with EMAC.

/// If the packet size is larger than transfer buffer size error returned.

/// \param buffer   The buffer to be send

/// \param size     The size of buffer to be send

/// \param fEMAC_TxCallback Threshold Wakeup callback

/// \param fWakeUpCb   TX Wakeup

/// \return         OK, Busy or invalid packet

//-----------------------------------------------------------------------------

unsigned char EMAC_Send(void *pBuffer,

                        unsigned int size,

                        EMAC_TxCallback fEMAC_TxCallback)

{

    volatile EmacTxTDescriptor *pTxTd;

    volatile EMAC_TxCallback   *pTxCb;

    //trace_LOG(trace_DEBUG, "EMAC_Send\n\r");

    // Check parameter

    if (size > EMAC_TX_UNITSIZE) {

        trace_LOG(trace_ERROR, "-E- EMAC driver does not split send packets.");

        trace_LOG(trace_ERROR, " It can send %d bytes max in one packet (%u bytes requested)\n\r",

            EMAC_TX_UNITSIZE, size);

        return EMAC_TX_INVALID_PACKET;

    }

    // If no free TxTd, buffer can't be sent, schedule the wakeup callback

    if( CIRC_SPACE(txTd.head, txTd.tail, TX_BUFFERS) == 0) {

        return EMAC_TX_BUFFER_BUSY;

    }

    // Pointers to the current TxTd

    pTxTd = txTd.td + txTd.head;

    pTxCb = txTd.txCb + txTd.head;

    // Sanity check

    ASSERT((pTxTd->status & EMAC_TX_USED_BIT) != 0,

        "-F- Buffer is still under EMAC control\n\r");

    // Setup/Copy data to transmition buffer

    if (pBuffer && size) {

        // Driver manage the ring buffer

        memcpy((void *)pTxTd->addr, pBuffer, size);

    }

    // Tx Callback

    *pTxCb = fEMAC_TxCallback;

    // Update TD status

    // The buffer size defined is length of ethernet frame

    // so it's always the last buffer of the frame.

    if (txTd.head == TX_BUFFERS-1) {

        pTxTd->status =

            (size & EMAC_LENGTH_FRAME) | EMAC_TX_LAST_BUFFER_BIT | EMAC_TX_WRAP_BIT;

    }

    else {

        pTxTd->status = (size & EMAC_LENGTH_FRAME) | EMAC_TX_LAST_BUFFER_BIT;

    }

    CIRC_INC(txTd.head, TX_BUFFERS)

    // Tx packets count

    EmacStatistics.tx_packets++;

    // Now start to transmit if it is not already done

    AT91C_BASE_EMAC->EMAC_NCR |= AT91C_EMAC_TSTART;

    return EMAC_TX_OK;

}

//-----------------------------------------------------------------------------

/// Receive a packet with EMAC

/// If not enough buffer for the packet, the remaining data is lost but right

/// frame length is returned.

/// \param pFrame           Buffer to store the frame

/// \param frameSize        Size of the frame

/// \param pRcvSize         Received size

/// \return                 OK, no data, or frame too small

//-----------------------------------------------------------------------------

unsigned char EMAC_Poll(unsigned char *pFrame,

                        unsigned int frameSize,

                        unsigned int *pRcvSize)

{

    unsigned short bufferLength;

    unsigned int   tmpFrameSize=0;

    unsigned char  *pTmpFrame=0;

    unsigned int   tmpIdx = rxTd.idx;

    volatile EmacRxTDescriptor *pRxTd = rxTd.td + rxTd.idx;

    ASSERT(pFrame, "F: EMAC_Poll\n\r");

    char isFrame = 0;

    // Set the default return value

    *pRcvSize = 0;

    // Process received RxTd

    while ((pRxTd->addr & EMAC_RX_OWNERSHIP_BIT) == EMAC_RX_OWNERSHIP_BIT) {

        // A start of frame has been received, discard previous fragments

        if ((pRxTd->status & EMAC_RX_SOF_BIT) == EMAC_RX_SOF_BIT) {

            // Skip previous fragment

            while (tmpIdx != rxTd.idx) {