Subversion Repositories mips32r1

#include <stdlib.h>

#include "drivers/lcd.h"

#include "drivers/led.h"

#include "os/lock.h"

static int lock;

void LED_showTID(int tid);

void LED_hideTID(int tid);

void delay(void);

/* Each thread will enter at main */

int main(void)

{

        int tid = 0;

        char val = 0;

        /* Load unique thread ID which is stored in register k1 */

        asm (

                "addu %[tid], $27, $0\n\t"

                : [tid] "=r"(tid)

                :

                :

        );

        /* Allow a single thread to set up the LCD screen and LEDs*/

        if (tid == 1) {

                LED_write(0);

                LCD_clear();

                LCD_setPos(0);

                LCD_printString("Thread: 12345678");

                LCD_setPos(16);

                LCD_printString("Work:");

        }

        /* Loop a critical section in which work is performed */

        while (1) {

                Lock(&lock, NULL, NULL);

                LED_showTID(tid);

                LCD_setPos(23 + (uint8_t)tid);

                LCD_printByte(val);

                val++;

                LED_hideTID(tid);

                Unlock(&lock);

                delay();

        }

        return 0;

}

/* delay:

 *   Create a software delay. Use this to increase or decrease

 *   the probability that the thread holds the lock when the

 *   scheduler swaps it out.

 */

void delay(void)

{

        /* A higher value of 'c' makes it less likely that

         * a lock will be held, but also lowers throughput. */

        volatile unsigned int c = 16;  // 0, 2, 8, 14, 16, 18, 500, 507

        while (c != 0) {

                c--;

        }

}

/* check_violation:

 *   Checks to see if more than one LED is lit, meaning that more

 *   than one is in the critical section. If this is true, the

 *   Error LED is lit.

 */

void check_violation(uint8_t led)

{

        int i;

        int found_high = 0;

        for (i=0; i<8; i++) {

                found_high += (led & 0x1);

                if (found_high > 1) {

                        LED_write(LED_read() | LED_ERROR);

                        break;

                }

                led >>= 1;

        }

}

/* LED_showTID:

 *   Shows the thread ID (1->8) as a single lit LED (0->7).

 */

void LED_showTID(int tid)

{

        uint32_t led;

        led = LED_read();

        led |= (0x80 >> (tid - 1));

        LED_write(led);

        check_violation(led);

}

/* LED_hideTID:

 *   Turns off the LED (0->7) corresponding to the thread ID (1->8).

 */

void LED_hideTID(int tid)

{

        uint32_t led;

        led = LED_read();

        led &= ~(0x80 >> (tid - 1));

        LED_write(led);

}