rt-thread/bsp/tm4c129x/libraries/driverlib/interrupt.c

//*****************************************************************************
//
// interrupt.c - Driver for the NVIC Interrupt Controller.
//
// Copyright (c) 2005-2020 Texas Instruments Incorporated.  All rights reserved.
// Software License Agreement
//
//   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 following disclaimer.
//
//   Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the
//   distribution.
//
//   Neither the name of Texas Instruments Incorporated nor the names of
//   its contributors may be used to endorse or promote products derived
//   from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS 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.
//
// This is part of revision 2.2.0.295 of the Tiva Peripheral Driver Library.
//
//*****************************************************************************

//*****************************************************************************
//
//! \addtogroup interrupt_api
//! @{
//
//*****************************************************************************

#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_ints.h"
#include "inc/hw_nvic.h"
#include "inc/hw_types.h"
#include "driverlib/cpu.h"
#include "driverlib/debug.h"
#include "driverlib/interrupt.h"

//*****************************************************************************
//
// This is a mapping between priority grouping encodings and the number of
// preemption priority bits.
//
//*****************************************************************************
static const uint32_t g_pui32Priority[] =
{
    NVIC_APINT_PRIGROUP_0_8, NVIC_APINT_PRIGROUP_1_7, NVIC_APINT_PRIGROUP_2_6,
    NVIC_APINT_PRIGROUP_3_5, NVIC_APINT_PRIGROUP_4_4, NVIC_APINT_PRIGROUP_5_3,
    NVIC_APINT_PRIGROUP_6_2, NVIC_APINT_PRIGROUP_7_1
};

//*****************************************************************************
//
// This is a mapping between interrupt number and the register that contains
// the priority encoding for that interrupt.
//
//*****************************************************************************
static const uint32_t g_pui32Regs[] =
{
    0, NVIC_SYS_PRI1, NVIC_SYS_PRI2, NVIC_SYS_PRI3, NVIC_PRI0, NVIC_PRI1,
    NVIC_PRI2, NVIC_PRI3, NVIC_PRI4, NVIC_PRI5, NVIC_PRI6, NVIC_PRI7,
    NVIC_PRI8, NVIC_PRI9, NVIC_PRI10, NVIC_PRI11, NVIC_PRI12, NVIC_PRI13,
    NVIC_PRI14, NVIC_PRI15, NVIC_PRI16, NVIC_PRI17, NVIC_PRI18, NVIC_PRI19,
    NVIC_PRI20, NVIC_PRI21, NVIC_PRI22, NVIC_PRI23, NVIC_PRI24, NVIC_PRI25,
    NVIC_PRI26, NVIC_PRI27, NVIC_PRI28, NVIC_PRI29, NVIC_PRI30, NVIC_PRI31,
    NVIC_PRI32, NVIC_PRI33, NVIC_PRI34
};

//*****************************************************************************
//
// This is a mapping between interrupt number (for the peripheral interrupts
// only) and the register that contains the interrupt enable for that
// interrupt.
//
//*****************************************************************************
static const uint32_t g_pui32EnRegs[] =
{
    NVIC_EN0, NVIC_EN1, NVIC_EN2, NVIC_EN3, NVIC_EN4
};

//*****************************************************************************
//
// This is a mapping between interrupt number (for the peripheral interrupts
// only) and the register that contains the interrupt disable for that
// interrupt.
//
//*****************************************************************************
static const uint32_t g_pui32Dii16Regs[] =
{
    NVIC_DIS0, NVIC_DIS1, NVIC_DIS2, NVIC_DIS3, NVIC_DIS4
};

//*****************************************************************************
//
// This is a mapping between interrupt number (for the peripheral interrupts
// only) and the register that contains the interrupt pend for that interrupt.
//
//*****************************************************************************
static const uint32_t g_pui32PendRegs[] =
{
    NVIC_PEND0, NVIC_PEND1, NVIC_PEND2, NVIC_PEND3, NVIC_PEND4
};

//*****************************************************************************
//
// This is a mapping between interrupt number (for the peripheral interrupts
// only) and the register that contains the interrupt unpend for that
// interrupt.
//
//*****************************************************************************
static const uint32_t g_pui32UnpendRegs[] =
{
    NVIC_UNPEND0, NVIC_UNPEND1, NVIC_UNPEND2, NVIC_UNPEND3, NVIC_UNPEND4
};

//*****************************************************************************
//
//! \internal
//! The default interrupt handler.
//!
//! This is the default interrupt handler for all interrupts.  It simply loops
//! forever so that the system state is preserved for observation by a
//! debugger.  Since interrupts must be disabled before unregistering the
//! corresponding handler, this should never be called during normal operation.
//!
//! \return None.
//
//*****************************************************************************
static void
_IntDefaultHandler(void)
{
    //
    // Go into an infinite loop.
    //
    while(1)
    {
    }
}

//*****************************************************************************
//
// The processor vector table.
//
// This contains a list of the handlers for the various interrupt sources in
// the system.  The layout of this list is defined by the hardware; assertion
// of an interrupt causes the processor to start executing directly at the
// address given in the corresponding location in this list.
//
//*****************************************************************************
//
// Set the size of the vector table to the largest number of interrupts of
// any device
//
#undef NUM_INTERRUPTS
#define NUM_INTERRUPTS                          155
#if defined(ewarm)
#pragma data_alignment=1024
static __no_init void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void) @ "VTABLE";
#elif defined(sourcerygxx)
static __attribute__((section(".cs3.region-head.ram")))
void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void) __attribute__ ((aligned(1024)));
#elif defined(ccs) || defined(DOXYGEN)
#pragma DATA_ALIGN(g_pfnRAMVectors, 1024)
#pragma DATA_SECTION(g_pfnRAMVectors, ".vtable")
void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void);
#else
static __attribute__((section("vtable")))
void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void) __attribute__((aligned(1024)));
#endif

//*****************************************************************************
//
//! Enables the processor interrupt.
//!
//! This function allows the processor to respond to interrupts.  This function
//! does not affect the set of interrupts enabled in the interrupt controller;
//! it just gates the single interrupt from the controller to the processor.
//!
//! \b Example: Enable interrupts to the processor.
//!
//! \verbatim
//! //
//! // Enable interrupts to the processor.
//! //
//! IntMasterEnable();
//!
//! \endverbatim
//!
//! \return Returns \b true if interrupts were disabled when the function was
//! called or \b false if they were initially enabled.
//
//*****************************************************************************
bool
IntMasterEnable(void)
{
    //
    // Enable processor interrupts.
    //
    return(CPUcpsie());
}

//*****************************************************************************
//
//! Disables the processor interrupt.
//!
//! This function prevents the processor from receiving interrupts.  This
//! function does not affect the set of interrupts enabled in the interrupt
//! controller; it just gates the single interrupt from the controller to the
//! processor.
//!
//! \note Previously, this function had no return value.  As such, it was
//! possible to include <tt>interrupt.h</tt> and call this function without
//! having included <tt>hw_types.h</tt>.  Now that the return is a
//! <tt>bool</tt>, a compiler error occurs in this case.  The solution
//! is to include <tt>hw_types.h</tt> before including <tt>interrupt.h</tt>.
//!
//! \b Example: Disable interrupts to the processor.
//!
//! \verbatim
//! //
//! // Disable interrupts to the processor.
//! //
//! IntMasterDisable();
//!
//! \endverbatim
//!
//! \return Returns \b true if interrupts were already disabled when the
//! function was called or \b false if they were initially enabled.
//
//*****************************************************************************
bool
IntMasterDisable(void)
{
    //
    // Disable processor interrupts.
    //
    return(CPUcpsid());
}

//*****************************************************************************
//
//! Registers a function to be called when an interrupt occurs.
//!
//! \param ui32Interrupt specifies the interrupt in question.
//! \param pfnHandler is a pointer to the function to be called.
//!
//! This function is used to specify the handler function to be called when the
//! given interrupt is asserted to the processor.  The \e ui32Interrupt
//! parameter must be one of the valid \b INT_* values listed in Peripheral
//! Driver Library User's Guide and defined in the inc/hw_ints.h header file.
//! When the interrupt occurs, if it is enabled (via IntEnable()), the handler
//! function is called in interrupt context.  Because the handler function can
//! preempt other code, care must be taken to protect memory or peripherals
//! that are accessed by the handler and other non-handler code.
//!
//! \note The use of this function (directly or indirectly via a peripheral
//! driver interrupt register function) moves the interrupt vector table from
//! flash to SRAM.  Therefore, care must be taken when linking the application
//! to ensure that the SRAM vector table is located at the beginning of SRAM;
//! otherwise the NVIC does not look in the correct portion of memory for the
//! vector table (it requires the vector table be on a 1 kB memory alignment).
//! Normally, the SRAM vector table is so placed via the use of linker scripts.
//! See the discussion of compile-time versus run-time interrupt handler
//! registration in the introduction to this chapter.
//!
//! \b Example: Set the UART 0 interrupt handler.
//!
//! \verbatim
//!
//! //
//! // UART 0 interrupt handler.
//! //
//! void
//! UART0Handler(void)
//! {
//!     //
//!     // Handle interrupt.
//!     //
//! }
//!
//! //
//! // Set the UART 0 interrupt handler.
//! //
//! IntRegister(INT_UART0, UART0Handler);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntRegister(uint32_t ui32Interrupt, void (*pfnHandler)(void))
{
    uint32_t ui32Idx, ui32Value;

    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Make sure that the RAM vector table is correctly aligned.
    //
    ASSERT(((uint32_t)g_pfnRAMVectors & 0x000003ff) == 0);

    //
    // See if the RAM vector table has been initialized.
    //
    if(HWREG(NVIC_VTABLE) != (uint32_t)g_pfnRAMVectors)
    {
        //
        // Copy the vector table from the beginning of FLASH to the RAM vector
        // table.
        //
        ui32Value = HWREG(NVIC_VTABLE);
        for(ui32Idx = 0; ui32Idx < NUM_INTERRUPTS; ui32Idx++)
        {
            g_pfnRAMVectors[ui32Idx] = (void (*)(void))HWREG((ui32Idx * 4) +
                                                             ui32Value);
        }

        //
        // Point the NVIC at the RAM vector table.
        //
        HWREG(NVIC_VTABLE) = (uint32_t)g_pfnRAMVectors;
    }

    //
    // Save the interrupt handler.
    //
    g_pfnRAMVectors[ui32Interrupt] = pfnHandler;
}

//*****************************************************************************
//
//! Unregisters the function to be called when an interrupt occurs.
//!
//! \param ui32Interrupt specifies the interrupt in question.
//!
//! This function is used to indicate that no handler is called when the
//! given interrupt is asserted to the processor.  The \e ui32Interrupt
//! parameter must be one of the valid \b INT_* values listed in Peripheral
//! Driver Library User's Guide and defined in the inc/hw_ints.h header file.
//! The interrupt source is automatically disabled (via IntDisable()) if
//! necessary.
//!
//! \sa IntRegister() for important information about registering interrupt
//! handlers.
//!
//! \b Example: Reset the UART 0 interrupt handler to the default handler.
//!
//! \verbatim
//! //
//! // Reset the UART 0 interrupt handler to the default handler.
//! //
//! IntUnregister(INT_UART0);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntUnregister(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Reset the interrupt handler.
    //
    g_pfnRAMVectors[ui32Interrupt] = _IntDefaultHandler;
}

//*****************************************************************************
//
//! Sets the priority grouping of the interrupt controller.
//!
//! \param ui32Bits specifies the number of bits of preemptable priority.
//!
//! This function specifies the split between preemptable priority levels and
//! sub-priority levels in the interrupt priority specification.  The range of
//! the grouping values are dependent upon the hardware implementation; on
//! the Tiva C and E Series family, three bits are available for hardware
//! interrupt prioritization and therefore priority grouping values of three
//! through seven have the same effect.
//!
//! \b Example: Set the priority grouping for the interrupt controller.
//!
//! \verbatim
//! //
//! // Set the priority grouping for the interrupt controller to 2 bits.
//! //
//! IntPriorityGroupingSet(2);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntPriorityGroupingSet(uint32_t ui32Bits)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Bits < NUM_PRIORITY);

    //
    // Set the priority grouping.
    //
    HWREG(NVIC_APINT) = NVIC_APINT_VECTKEY | g_pui32Priority[ui32Bits];
}

//*****************************************************************************
//
//! Gets the priority grouping of the interrupt controller.
//!
//! This function returns the split between preemptable priority levels and
//! sub-priority levels in the interrupt priority specification.
//!
//! \b Example: Get the priority grouping for the interrupt controller.
//!
//! \verbatim
//! //
//! // Get the priority grouping for the interrupt controller.
//! //
//! IntPriorityGroupingGet();
//!
//! \endverbatim
//!
//! \return The number of bits of preemptable priority.
//
//*****************************************************************************
uint32_t
IntPriorityGroupingGet(void)
{
    uint32_t ui32Loop, ui32Value;

    //
    // Read the priority grouping.
    //
    ui32Value = HWREG(NVIC_APINT) & NVIC_APINT_PRIGROUP_M;

    //
    // Loop through the priority grouping values.
    //
    for(ui32Loop = 0; ui32Loop < NUM_PRIORITY; ui32Loop++)
    {
        //
        // Stop looping if this value matches.
        //
        if(ui32Value == g_pui32Priority[ui32Loop])
        {
            break;
        }
    }

    //
    // Return the number of priority bits.
    //
    return(ui32Loop);
}

//*****************************************************************************
//
//! Sets the priority of an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt in question.
//! \param ui8Priority specifies the priority of the interrupt.
//!
//! This function is used to set the priority of an interrupt.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file.  The \e ui8Priority parameter specifies the interrupts
//! hardware priority level of the interrupt in the interrupt controller.
//! When multiple interrupts are asserted simultaneously, the ones with the
//! highest priority are processed before the lower priority interrupts.
//! Smaller numbers correspond to higher interrupt priorities; priority 0 is
//! the highest interrupt priority.
//!
//! \note The hardware priority mechanism only looks at the upper 3 bits of the
//! priority level, so any prioritization must be performed in those bits.  The
//! remaining bits can be used to sub-prioritize the interrupt sources, and may
//! be used by the hardware priority mechanism on a future part.  This
//! arrangement allows priorities to migrate to different NVIC implementations
//! without changing the gross prioritization of the interrupts.
//!
//! \b Example: Set priorities for UART 0 and USB interrupts.
//!
//! \verbatim
//! //
//! // Set the UART 0 interrupt priority to the lowest priority.
//! //
//! IntPrioritySet(INT_UART0, 0xE0);
//!
//! //
//! // Set the USB 0 interrupt priority to the highest priority.
//! //
//! IntPrioritySet(INT_USB0, 0);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntPrioritySet(uint32_t ui32Interrupt, uint8_t ui8Priority)
{
    uint32_t ui32Temp;

    //
    // Check the arguments.
    //
    ASSERT((ui32Interrupt >= 4) && (ui32Interrupt < NUM_INTERRUPTS));

    //
    // Set the interrupt priority.
    //
    ui32Temp = HWREG(g_pui32Regs[ui32Interrupt >> 2]);
    ui32Temp &= ~(0xFF << (8 * (ui32Interrupt & 3)));
    ui32Temp |= ui8Priority << (8 * (ui32Interrupt & 3));
    HWREG(g_pui32Regs[ui32Interrupt >> 2]) = ui32Temp;
}

//*****************************************************************************
//
//! Gets the priority of an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt in question.
//!
//! This function gets the priority of an interrupt.  The \e ui32Interrupt
//! parameter must be one of the valid \b INT_* values listed in Peripheral
//! Driver Library User's Guide and defined in the inc/hw_ints.h header file.
//! See IntPrioritySet() for a full definition of the priority value.
//!
//! \b Example: Get the current UART 0 interrupt priority.
//!
//! \verbatim
//! //
//! // Get the current UART 0 interrupt priority.
//! //
//! IntPriorityGet(INT_UART0);
//!
//! \endverbatim
//!
//! \return Returns the interrupt priority for the given interrupt.
//
//*****************************************************************************
int32_t
IntPriorityGet(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT((ui32Interrupt >= 4) && (ui32Interrupt < NUM_INTERRUPTS));

    //
    // Return the interrupt priority.
    //
    return((HWREG(g_pui32Regs[ui32Interrupt >> 2]) >>
            (8 * (ui32Interrupt & 3))) & 0xFF);
}

//*****************************************************************************
//
//! Enables an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt to be enabled.
//!
//! The specified interrupt is enabled in the interrupt controller.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file. Other enables for the interrupt (such as at the peripheral
//! level) are unaffected by this function.
//!
//! \b Example: Enable the UART 0 interrupt.
//!
//! \verbatim
//! //
//! // Enable the UART 0 interrupt in the interrupt controller.
//! //
//! IntEnable(INT_UART0);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntEnable(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to enable.
    //
    if(ui32Interrupt == FAULT_MPU)
    {
        //
        // Enable the MemManage interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_MEM;
    }
    else if(ui32Interrupt == FAULT_BUS)
    {
        //
        // Enable the bus fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_BUS;
    }
    else if(ui32Interrupt == FAULT_USAGE)
    {
        //
        // Enable the usage fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_USAGE;
    }
    else if(ui32Interrupt == FAULT_SYSTICK)
    {
        //
        // Enable the System Tick interrupt.
        //
        HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
    }
    else if(ui32Interrupt >= 16)
    {
        //
        // Enable the general interrupt.
        //
        HWREG(g_pui32EnRegs[(ui32Interrupt - 16) / 32]) =
            1 << ((ui32Interrupt - 16) & 31);
    }
}

//*****************************************************************************
//
//! Disables an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt to be disabled.
//!
//! The specified interrupt is disabled in the interrupt controller.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file.  Other enables for the interrupt (such as at the peripheral
//! level) are unaffected by this function.
//!
//! \b Example: Disable the UART 0 interrupt.
//!
//! \verbatim
//! //
//! // Disable the UART 0 interrupt in the interrupt controller.
//! //
//! IntDisable(INT_UART0);
//!
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntDisable(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to disable.
    //
    if(ui32Interrupt == FAULT_MPU)
    {
        //
        // Disable the MemManage interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_MEM);
    }
    else if(ui32Interrupt == FAULT_BUS)
    {
        //
        // Disable the bus fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_BUS);
    }
    else if(ui32Interrupt == FAULT_USAGE)
    {
        //
        // Disable the usage fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_USAGE);
    }
    else if(ui32Interrupt == FAULT_SYSTICK)
    {
        //
        // Disable the System Tick interrupt.
        //
        HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);
    }
    else if(ui32Interrupt >= 16)
    {
        //
        // Disable the general interrupt.
        //
        HWREG(g_pui32Dii16Regs[(ui32Interrupt - 16) / 32]) =
            1 << ((ui32Interrupt - 16) & 31);
    }
}

//*****************************************************************************
//
//! Returns if a peripheral interrupt is enabled.
//!
//! \param ui32Interrupt specifies the interrupt to check.
//!
//! This function checks if the specified interrupt is enabled in the interrupt
//! controller.  The \e ui32Interrupt parameter must be one of the valid
//! \b INT_* values listed in Peripheral Driver Library User's Guide and
//! defined in the inc/hw_ints.h header file.
//!
//! \b Example: Disable the UART 0 interrupt if it is enabled.
//!
//! \verbatim
//! //
//! // Disable the UART 0 interrupt if it is enabled.
//! //
//! if(IntIsEnabled(INT_UART0))
//! {
//!     IntDisable(INT_UART0);
//! }
//! \endverbatim
//!
//! \return A non-zero value if the interrupt is enabled.
//
//*****************************************************************************
uint32_t
IntIsEnabled(uint32_t ui32Interrupt)
{
    uint32_t ui32Ret;

    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Initialize the return value.
    //
    ui32Ret = 0;

    //
    // Determine the interrupt to disable.
    //
    if(ui32Interrupt == FAULT_MPU)
    {
        //
        // Check the MemManage interrupt.
        //
        ui32Ret = HWREG(NVIC_SYS_HND_CTRL) & NVIC_SYS_HND_CTRL_MEM;
    }
    else if(ui32Interrupt == FAULT_BUS)
    {
        //
        // Check the bus fault interrupt.
        //
        ui32Ret = HWREG(NVIC_SYS_HND_CTRL) & NVIC_SYS_HND_CTRL_BUS;
    }
    else if(ui32Interrupt == FAULT_USAGE)
    {
        //
        // Check the usage fault interrupt.
        //
        ui32Ret = HWREG(NVIC_SYS_HND_CTRL) & NVIC_SYS_HND_CTRL_USAGE;
    }
    else if(ui32Interrupt == FAULT_SYSTICK)
    {
        //
        // Check the System Tick interrupt.
        //
        ui32Ret = HWREG(NVIC_ST_CTRL) & NVIC_ST_CTRL_INTEN;
    }
    else if(ui32Interrupt >= 16)
    {
        //
        // Check the general interrupt.
        //
        ui32Ret = HWREG(g_pui32EnRegs[(ui32Interrupt - 16) / 32]) &
                  (1 << ((ui32Interrupt - 16) & 31));
    }
    return(ui32Ret);
}

//*****************************************************************************
//
//! Pends an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt to be pended.
//!
//! The specified interrupt is pended in the interrupt controller.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file.  Pending an interrupt causes the interrupt controller to
//! execute the corresponding interrupt handler at the next available time,
//! based on the current interrupt state priorities.  For example, if called by
//! a higher priority interrupt handler, the specified interrupt handler is not
//! called until after the current interrupt handler has completed execution.
//! The interrupt must have been enabled for it to be called.
//!
//! \b Example: Pend a UART 0 interrupt.
//!
//! \verbatim
//! //
//! // Pend a UART 0 interrupt.
//! //
//! IntPendSet(INT_UART0);
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntPendSet(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to pend.
    //
    if(ui32Interrupt == FAULT_NMI)
    {
        //
        // Pend the NMI interrupt.
        //
        HWREG(NVIC_INT_CTRL) |= NVIC_INT_CTRL_NMI_SET;
    }
    else if(ui32Interrupt == FAULT_PENDSV)
    {
        //
        // Pend the PendSV interrupt.
        //
        HWREG(NVIC_INT_CTRL) |= NVIC_INT_CTRL_PEND_SV;
    }
    else if(ui32Interrupt == FAULT_SYSTICK)
    {
        //
        // Pend the SysTick interrupt.
        //
        HWREG(NVIC_INT_CTRL) |= NVIC_INT_CTRL_PENDSTSET;
    }
    else if(ui32Interrupt >= 16)
    {
        //
        // Pend the general interrupt.
        //
        HWREG(g_pui32PendRegs[(ui32Interrupt - 16) / 32]) =
            1 << ((ui32Interrupt - 16) & 31);
    }
}

//*****************************************************************************
//
//! Un-pends an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt to be un-pended.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file.
//!
//! The specified interrupt is un-pended in the interrupt controller.  This
//! causes any previously generated interrupts that have not been handled
//! yet (due to higher priority interrupts or the interrupt not having been
//! enabled yet) to be discarded.
//!
//! \b Example: Un-pend a UART 0 interrupt.
//!
//! \verbatim
//! //
//! // Un-pend a UART 0 interrupt.
//! //
//! IntPendClear(INT_UART0);
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntPendClear(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ui32Interrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to unpend.
    //
    if(ui32Interrupt == FAULT_PENDSV)
    {
        //
        // Unpend the PendSV interrupt.
        //
        HWREG(NVIC_INT_CTRL) |= NVIC_INT_CTRL_UNPEND_SV;
    }
    else if(ui32Interrupt == FAULT_SYSTICK)
    {
        //
        // Unpend the SysTick interrupt.
        //
        HWREG(NVIC_INT_CTRL) |= NVIC_INT_CTRL_PENDSTCLR;
    }
    else if(ui32Interrupt >= 16)
    {
        //
        // Unpend the general interrupt.
        //
        HWREG(g_pui32UnpendRegs[(ui32Interrupt - 16) / 32]) =
            1 << ((ui32Interrupt - 16) & 31);
    }
}

//*****************************************************************************
//
//! Sets the priority masking level
//!
//! \param ui32PriorityMask is the priority level that is masked.
//!
//! This function sets the interrupt priority masking level so that all
//! interrupts at the specified or lesser priority level are masked.  Masking
//! interrupts can be used to globally disable a set of interrupts with
//! priority below a predetermined threshold.  A value of 0 disables priority
//! masking.
//!
//! Smaller numbers correspond to higher interrupt priorities.  So for example
//! a priority level mask of 4 allows interrupts of priority level 0-3,
//! and interrupts with a numerical priority of 4 and greater are blocked.
//!
//! \note The hardware priority mechanism only looks at the upper 3 bits of the
//! priority level, so any prioritization must be performed in those bits.
//!
//! \b Example: Mask of interrupt priorities greater than or equal to 0x80.
//!
//! \verbatim
//! //
//! // Mask of interrupt priorities greater than or equal to 0x80.
//! //
//! IntPriorityMaskSet(0x80);
//! \endverbatim
//!
//! \return None.
//
//*****************************************************************************
void
IntPriorityMaskSet(uint32_t ui32PriorityMask)
{
    //
    // Set the priority mask.
    //
    CPUbasepriSet(ui32PriorityMask);
}

//*****************************************************************************
//
//! Gets the priority masking level
//!
//! This function gets the current setting of the interrupt priority masking
//! level.  The value returned is the priority level such that all interrupts
//! of that and lesser priority are masked.  A value of 0 means that priority
//! masking is disabled.
//!
//! Smaller numbers correspond to higher interrupt priorities.  So for example
//! a priority level mask of 4 allows interrupts of priority level 0-3,
//! and interrupts with a numerical priority of 4 and greater are blocked.
//!
//! The hardware priority mechanism only looks at the upper 3 bits of the
//! priority level, so any prioritization must be performed in those bits.
//!
//! \b Example: Get the current interrupt priority mask.
//!
//! \verbatim
//! //
//! // Get the current interrupt priority mask.
//! //
//! IntPriorityMaskGet();
//! \endverbatim
//!
//! \return Returns the value of the interrupt priority level mask.
//
//*****************************************************************************
uint32_t
IntPriorityMaskGet(void)
{
    //
    // Return the current priority mask.
    //
    return(CPUbasepriGet());
}

//*****************************************************************************
//
//! Triggers an interrupt.
//!
//! \param ui32Interrupt specifies the interrupt to be triggered.
//!
//! This function performs a software trigger of an interrupt.  The
//! \e ui32Interrupt parameter must be one of the valid \b INT_* values listed
//! in Peripheral Driver Library User's Guide and defined in the inc/hw_ints.h
//! header file.  The interrupt controller behaves as if the corresponding
//! interrupt line was asserted, and the interrupt is handled in the same
//! manner (meaning that it must be enabled in order to be processed, and the
//! processing is based on its priority with respect to other unhandled
//! interrupts).
//!
//! \return None.
//
//*****************************************************************************
void
IntTrigger(uint32_t ui32Interrupt)
{
    //
    // Check the arguments.
    //
    ASSERT((ui32Interrupt >= 16) && (ui32Interrupt < NUM_INTERRUPTS));

    //
    // Trigger this interrupt.
    //
    HWREG(NVIC_SW_TRIG) = ui32Interrupt - 16;
}

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