commit d244ca

2026-03-29 14:10:12 Bob Green: -/-

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`programming/handling interrupts.md` ..
@@ 17,3 17,63 @@
	}
	```
	gcc knows that functions declared using either of the above methods should end with the `rte` rather than `rts` instruction.
+
+	## Example
+	```c
+	#include <stdio.h>
+	#include <machine.h>
+
+	#define LEDS1 0xa0
+	#define LEDS2 0x50
+
+	static unsigned int ticks = 0;
+
+	void twiddle_thumbs(void);
+
+	void ISR isr(void) {
+	ticks++;
+
+	*pit_tsr = 1;
+	}
+
+	void scan() {
+	static int lednum = 2;
+	static int delta = 1;
+
+	clear_led(lednum);
+
+	lednum += delta;
+	if ((lednum < 2) \|\| (lednum > 7)) {
+	delta = -delta;
+	lednum += delta;
+	lednum += delta;
+	}
+
+	set_led(lednum);
+	}
+
+	int main(void) {
+	unsigned char ivr = *pit_tivr;
+
+	int loop = 0;
+
+	printf("Press any key...\n");
+
+	_pit_set_counter(1000);
+	*pit_tsr = 1;
+
+	set_isr_vector(ivr, isr);
+
+	while (!_char_available()) {
+	printf("%08x\r", ticks);
+
+	loop++;
+	if (loop == 100) {
+	scan();
+	loop = 0;
+	}
+	}
+
+	_getchar();
+	}
+	```