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52 lines
1.2 KiB
C

#include "tm4c.h" // the same as "lm4f120h5qr.h" in the video
#include "delay.h"
#define LED_RED (1U << 1)
#define LED_BLUE (1U << 2)
#define LED_GREEN (1U << 3)
unsigned fact(unsigned n); // prototype
int main(void) {
unsigned volatile x;
x = fact(0U);
x = 2U + 3U*fact(1U);
(void)fact(5U);
SYSCTL_GPIOHBCTL_R |= (1U << 5); /* enable AHB for GPIOF */
SYSCTL_RCGCGPIO_R |= (1U << 5); /* enable clock for GPIOF */
GPIO_PORTF_AHB_DIR_R |= (LED_RED | LED_BLUE | LED_GREEN);
GPIO_PORTF_AHB_DEN_R |= (LED_RED | LED_BLUE | LED_GREEN);
/* start with turning all LEDs off (note the use of array []) */
GPIO_PORTF_AHB_DATA_BITS_R[LED_RED | LED_BLUE | LED_GREEN] = 0;
GPIO_PORTF_AHB_DATA_BITS_R[LED_BLUE] = LED_BLUE;
while (1) {
GPIO_PORTF_AHB_DATA_BITS_R[LED_RED] = LED_RED;
delay(1000000);
GPIO_PORTF_AHB_DATA_BITS_R[LED_RED] = 0;
delay(500000);
}
//return 0; // unreachable code
}
unsigned fact(unsigned n) {
// factorial function definition (recursive):
// 0! = 1
// n! = n*(n-1)! for n > 0
if (n == 0U) {
return 1U;
}
else {
return n * fact(n - 1U);
}
}