udma.c

lm3s下lwip的udp

//!
//! This function is used to set the parameters for a uDMA transfer.  These are
//! typically parameters that are changed often.  The function
//! uDMAChannelControlSet() MUST be called at least once for this channel prior
//! to calling this function.
//!
//! The \e ulChannel parameter is one of the choices documented in the
//! uDMAChannelEnable() function.  It should be the logical OR of the channel
//! with either \b UDMA_PRI_SELECT or \b UDMA_ALT_SELECT to choose whether the
//! primary or alternate data structure is used.
//!
//! The \e ulMode parameter should be one of the following values:
//!
//! - \b UDMA_MODE_STOP stops the uDMA transfer.  The controller sets the mode
//!   to this value at the end of a transfer.
//! - \b UDMA_MODE_BASIC to perform a basic transfer based on request.
//! - \b UDMA_MODE_AUTO to perform a transfer that will always complete once
//!   started even if request is removed.
//! - \b UDMA_MODE_PINGPONG to set up a transfer that switches between the
//!   primary and alternate control structures for the channel.  This allows
//!   use of ping-pong buffering for uDMA transfers.
//! - \b UDMA_MODE_MEM_SCATTER_GATHER to set up a memory scatter-gather
//!   transfer.
//! - \b UDMA_MODE_PER_SCATTER_GATHER to set up a peripheral scatter-gather
//!   transfer.
//!
//! The \e pvSrcAddr and \e pvDstAddr parameters are pointers to the first
//! location of the data to be transferred.  These addresses should be aligned
//! according to the item size.  The compiler will take care of this if the
//! pointers are pointing to storage of the appropriate data type.
//!
//! The \e ulTransferSize parameter is the number of data items, not the number
//! of bytes.
//!
//! The two scatter/gather modes, memory and peripheral, are actually different
//! depending on whether the primary or alternate control structure is
//! selected.  This function will look for the \b UDMA_PRI_SELECT and
//! \b UDMA_ALT_SELECT flag along with the channel number and will set the
//! scatter/gather mode as appropriate for the primary or alternate control
//! structure.
//!
//! The channel must also be enabled using uDMAChannelEnable() after calling
//! this function.  The transfer will not begin until the channel has been set
//! up and enabled.  Note that the channel is automatically disabled after the
//! transfer is completed, meaning that uDMAChannelEnable() must be called
//! again after setting up the next transfer.
//!
//! \note Great care must be taken to not modify a channel control stucture
//! that is in use or else the results will be unpredictable, including the
//! possibility of undesired data transfers to or from memory or peripherals.
//! For BASIC and AUTO modes, it is safe to make changes when the channel is
//! disabled, or the uDMAChannelModeGet() returns \b UDMA_MODE_STOP.  For
//! PINGPONG or one of the SCATTER_GATHER modes, it is safe to modify the
//! primary or alternate control structure only when the other is being used.
//! The uDMAChannelModeGet() function will return \b UDMA_MODE_STOP when a
//! channel control structure is inactive and safe to modify.
//!
//! \return None.
//
//*****************************************************************************
void
uDMAChannelTransferSet(unsigned long ulChannel, unsigned long ulMode,
                       void *pvSrcAddr, void *pvDstAddr,
                       unsigned long ulTransferSize)
{
    tDMAControlTable *pControlTable;
    unsigned long ulControl;
    unsigned long ulSize;
    unsigned long ulInc;

    //
    // Check the arguments.
    //
    ASSERT(ulChannel < 64);
    ASSERT(HWREG(UDMA_CTLBASE) != 0);
    ASSERT(ulMode <= UDMA_MODE_PER_SCATTER_GATHER);
    ASSERT((unsigned long)pvSrcAddr >= 0x20000000);
    ASSERT((unsigned long)pvDstAddr >= 0x20000000);
    ASSERT((ulTransferSize != 0) && (ulTransferSize <= 1024));

    //
    // Get the base address of the control table.
    //
    pControlTable = (tDMAControlTable *)HWREG(UDMA_CTLBASE);

    //
    // Get the current control word value and mask off the mode and size
    // fields.
    //
    ulControl = (pControlTable[ulChannel].ulControl &
                 ~(UDMA_CHCTL_XFERSIZE_M | UDMA_CHCTL_XFERMODE_M));

    //
    // Adjust the mode if the alt control structure is selected.
    //
    if(ulChannel & UDMA_ALT_SELECT)
    {
        if((ulMode == UDMA_MODE_MEM_SCATTER_GATHER) ||
           (ulMode == UDMA_MODE_PER_SCATTER_GATHER))
        {
            ulMode |= UDMA_MODE_ALT_SELECT;
        }
    }

    //
    // Set the transfer size and mode in the control word (but dont write the
    // control word yet as it could kick off a transfer).
    //
    ulControl |= ulMode | ((ulTransferSize - 1) << 4);

    //
    // Get the data item size from the control word (set previously).
    //
    ulSize = (ulControl & UDMA_CHCTL_DSTSIZE_M) >> 28;

    //
    // Convert the transfer size to be in units of bytes.  Shift (multiply) to
    // get the value in bytes, based on the data item size.
    //
    ulTransferSize = ulTransferSize << ulSize;

    //
    // Get the address increment value for the source, from the control word.
    //
    ulInc = (ulControl & UDMA_CHCTL_SRCINC_M);

    //
    // Compute the ending source address of the transfer.  If the source
    // increment is set to none, then the ending address is the same as the
    // beginning.
    //
    if(ulInc != UDMA_SRC_INC_NONE)
    {
        pvSrcAddr = (void *)((unsigned long)pvSrcAddr + ulTransferSize - 1);
    }

    //
    // Load the source ending address into the control block.
    //
    pControlTable[ulChannel].pvSrcEndAddr = pvSrcAddr;

    //
    // Get the address increment value for the destination, from the control
    // word.
    //
    ulInc = (ulControl & UDMA_CHCTL_DSTINC_M);

    //
    // Compute the ending destination address of the transfer.  If the
    // destination increment is set to none, then the ending address is the
    // same as the beginning.
    //
    if(ulInc != UDMA_DST_INC_NONE)
    {
        pvDstAddr = (void *)((unsigned long)pvDstAddr + ulTransferSize - 1);
    }

    //
    // Load the destination ending address into the control block.
    //
    pControlTable[ulChannel].pvDstEndAddr = pvDstAddr;

    //
    // Write the new control word value.
    //
    pControlTable[ulChannel].ulControl = ulControl;
}

//*****************************************************************************
//
//! Gets the current transfer size for a uDMA channel.
//!
//! \param ulChannel is the logical or of the uDMA channel number with either
//! \b UDMA_PRI_SELECT or \b UDMA_ALT_SELECT.
//!
//! This function is used to get the uDMA transfer size for a channel.  The
//! transfer size is the number of items to transfer, where the size of an item
//! might be 8, 16, or 32 bits.  If a partial transfer has already occurred,
//! then the number of remaining items will be returned.  If the transfer is
//! complete, then 0 will be returned.
//!
//! The \e ulChannel parameter is one of the choices documented in the
//! uDMAChannelEnable() function.  It should be the logical OR of the channel
//! with either \b UDMA_PRI_SELECT or \b UDMA_ALT_SELECT to choose whether
//! the primary or alternate data structure is used.
//!
//! \return Returns the number of items remaining to transfer.
//
//*****************************************************************************
unsigned long
uDMAChannelSizeGet(unsigned long ulChannel)
{
    tDMAControlTable *pControlTable;
    unsigned long ulControl;

    //
    // Check the arguments.
    //
    ASSERT(ulChannel < 64);
    ASSERT(HWREG(UDMA_CTLBASE) != 0);

    //
    // Get the base address of the control table.
    //
    pControlTable = (tDMAControlTable *)HWREG(UDMA_CTLBASE);

    //
    // Get the current control word value and mask off all but the size field.
    //
    ulControl = pControlTable[ulChannel].ulControl & UDMA_CHCTL_XFERSIZE_M;

    //
    // Shift the size field and add one, then return to user.
    //
    return((ulControl >> 4) + 1);
}

//*****************************************************************************
//
//! Gets the transfer mode for a uDMA channel.
//!
//! \param ulChannel is the logical or of the uDMA channel number with either
//! \b UDMA_PRI_SELECT or \b UDMA_ALT_SELECT.
//!
//! This function is used to get the transfer mode for the uDMA channel.  It
//! can be used to query the status of a transfer on a channel.  When the
//! transfer is complete the mode will be \b UDMA_MODE_STOP.
//!
//! The \e ulChannel parameter is one of the choices documented in the
//! uDMAChannelEnable() function.  It should be the logical OR of the channel
//! with either \b UDMA_PRI_SELECT or \b UDMA_ALT_SELECT to choose whether the
//! primary or alternate data structure is used.
//!
//! \return Returns the transfer mode of the specified channel and control
//! structure, which will be one of the following values: \b UDMA_MODE_STOP,
//! \b UDMA_MODE_BASIC, \b UDMA_MODE_AUTO, \b UDMA_MODE_PINGPONG,
//! \b UDMA_MODE_MEM_SCATTER_GATHER, or \b UDMA_MODE_PER_SCATTER_GATHER.
//
//*****************************************************************************
unsigned long
uDMAChannelModeGet(unsigned long ulChannel)
{
    tDMAControlTable *pControlTable;
    unsigned long ulControl;

    //
    // Check the arguments.
    //
    ASSERT(ulChannel < 64);
    ASSERT(HWREG(UDMA_CTLBASE) != 0);

    //
    // Get the base address of the control table.
    //
    pControlTable = (tDMAControlTable *)HWREG(UDMA_CTLBASE);

    //
    // Get the current control word value and mask off all but the mode field.
    //
    ulControl = pControlTable[ulChannel].ulControl & UDMA_CHCTL_XFERMODE_M;

    //
    // Check if scatter/gather mode, and if so, mask off the alt bit.
    //
    if(((ulControl & ~UDMA_MODE_ALT_SELECT) == UDMA_MODE_MEM_SCATTER_GATHER) ||
       ((ulControl & ~UDMA_MODE_ALT_SELECT) == UDMA_MODE_PER_SCATTER_GATHER))
    {
        ulControl &= ~UDMA_MODE_ALT_SELECT;
    }

    //
    // Return the mode to the caller.
    //
    return(ulControl);
}

//*****************************************************************************
//
//! Registers an interrupt handler for the uDMA controller.
//!
//! \param ulIntChannel identifies which uDMA interrupt is to be registered.
//! \param pfnHandler is a pointer to the function to be called when the
//! interrupt is activated.
//!
//! This sets and enables the handler to be called when the uDMA controller
//! generates an interrupt.  The \e ulIntChannel parameter should be one of the
//! following:
//!
//! - \b UDMA_INT_SW to register an interrupt handler to process interrupts
//!   from the uDMA software channel (UDMA_CHANNEL_SW)
//! - \b UDMA_INT_ERR to register an interrupt handler to process uDMA error
//!   interrupts
//!
//! \sa IntRegister() for important information about registering interrupt
//! handlers.
//!
//! \note The interrupt handler for uDMA is for transfer completion when the
//! channel UDMA_CHANNEL_SW is used, and for error interrupts.  The
//! interrupts for each peripheral channel are handled through the individual
//! peripheral interrupt handlers.
//!
//! \return None.
//
//*****************************************************************************
void
uDMAIntRegister(unsigned long ulIntChannel, void (*pfnHandler)(void))
{
    //
    // Check the arguments.
    //
    ASSERT(pfnHandler);
    ASSERT((ulIntChannel == UDMA_INT_SW) || (ulIntChannel == UDMA_INT_ERR));

    //
    // Register the interrupt handler.
    //
    IntRegister(ulIntChannel, pfnHandler);

    //
    // Enable the memory management fault.
    //
    IntEnable(ulIntChannel);
}

//*****************************************************************************
//
//! Unregisters an interrupt handler for the uDMA controller.
//!
//! \param ulIntChannel identifies which uDMA interrupt to unregister.
//!
//! This function will disable and clear the handler to be called for the
//! specified uDMA interrupt.  The \e ulIntChannel parameter should be one of
//! \b UDMA_INT_SW or \b UDMA_INT_ERR as documented for the function
//! uDMAIntRegister().
//!
//! \sa IntRegister() for important information about registering interrupt
//! handlers.
//!
//! \return None.
//
//*****************************************************************************
void
uDMAIntUnregister(unsigned long ulIntChannel)
{
    //
    // Disable the interrupt.
    //
    IntDisable(ulIntChannel);

    //
    // Unregister the interrupt handler.
    //
    IntUnregister(ulIntChannel);
}

//*****************************************************************************
//
// Close the Doxygen group.
//! @}
//
//*****************************************************************************