关于MSP432的FPU的问题

/*
 * -------------------------------------------
 *    MSP432 DriverLib - v01_04_00_18 
 * -------------------------------------------
 *
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 * Copyright (c) 2015, Texas Instruments Incorporated
 * All rights reserved.
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 *
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 *    notice, this list of conditions and the following disclaimer.
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 *
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 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
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 * --/COPYRIGHT--*/
/*******************************************************************************
 * MSP432 FPU - Simple FPU Operation
 *
 * Description: In this barebone example, the FPU is enabled and the
 * effectiveness of the FPU with respect to floating point math is examined
 * versus having the FPU disabled. A perpetual while loop is set up that
 * continuously does floating point calculation. When the push button
 * attached to P6.7 is pressed, the FPU is enabled/disabled. This shows
 * the user the power consumption differences when having the FPU enabled
 * versus having the FPU disabled. Less cycle counts mean the user can enter a
 * low power mode quicker.
 *
 *                MSP432P401
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST               |
 *            |                  |
 *            |            P1.1  |<--Toggle Switch
 *            |                  |
 *            |                  |
 *
 * Author: Timothy Logan
 ******************************************************************************/
/* DriverLib Includes */
#include "driverlib.h"

/* Standard Includes */
#include <stdint.h>

#include <stdbool.h>
#include <math.h>

/* Statics */
static volatile bool flipFlop;

int main(void)
{
    volatile float fCalculate;
    uint32_t ii;
    flipFlop = false;

    MAP_WDT_A_holdTimer();

    /* Configuring P1.1 as an input and enabling interrupts */
    MAP_GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P1, GPIO_PIN1);
    MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, GPIO_PIN1);
    MAP_GPIO_enableInterrupt(GPIO_PORT_P1, GPIO_PIN1);
    MAP_Interrupt_enableInterrupt(INT_PORT1);
    MAP_Interrupt_enableMaster();

    while(1)
    {
        for(ii=0;ii<20;ii++)
        {
            fCalculate = (sin(50.5) * (12.2f / 50.1f) * 10.22f / 3) * ii;
        }
    }
}

/* GPIO ISR */
void gpio_isr(void)
{
    uint32_t status;

    status = MAP_GPIO_getEnabledInterruptStatus(GPIO_PORT_P1);
    MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, status);

    /* Toggling the output on the LED */
    if(status & GPIO_PIN1)
    {
        if(flipFlop)
        {
            MAP_FPU_disableModule();
            flipFlop = false;
        }
        else
        {
            MAP_FPU_enableModule();
            flipFlop = true;
        }
    }

}