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#include <stdint.h>
#include <string.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "software_pwm.h"
#include "pins.h"
static struct pwm_event {
//ENTIRE port
//(ex if pin 3, 2, 4 are on and we want 6, this should be 0b01011100)
uint8_t port;
uint8_t time;
struct pwm_event **map_ptr;
} events[SOFTPWM_PIN_COUNT];
static struct pwm_event *pin_event_map[SOFTPWM_PIN_COUNT];
void init_softpwm() {
SOFTPWM_DDR = 0xff;
for(size_t event_i = 0; event_i < SOFTPWM_PIN_COUNT; event_i++) {
pin_event_map[event_i] = &events[event_i];
events[event_i].map_ptr = &pin_event_map[event_i];
events[event_i].time = event_i + 1;
events[event_i].port = (1 << (event_i + 1)) - 1;
}
//use external 10mhz clock (we just have one laying around)
//then prescale by 1024. Check at different freqs for brightness
TCCR0A = 0b00000010;
TIMSK0 = 0b00000011;
OCR0A = events[0].time;
TIFR0 = 0b00000010; //interupts enabled!
sei();
}
static void event_move(struct pwm_event *dest, struct pwm_event *src) {
*dest = *src;
*(dest->map_ptr) = src;
}
/**
* okay, let me explain. This is really weird and gross, I know.
* I did it when I was *very* low on sleep.
* Why did I do it like this? Well, I was worried about accuracy;
* for some stupid reason I thought I really needed the actual pwm ISR to be as fast
* as possible. I don't feel like redoing this in a simpler fasion,
* so while this code *is* embaracing, I'll get around to it later.
**/
void softpwm_set(uint8_t pin, uint8_t value) {
struct pwm_event *event_to_shift;
struct pwm_event modified_event_cpy = *pin_event_map[pin];
modified_event_cpy.time = value;
if(value < modified_event_cpy.time) {
for(event_to_shift = pin_event_map[pin - 1];
(event_to_shift >= events)
|| (modified_event_cpy.time < event_to_shift[-1].time);
event_to_shift = &event_to_shift[-1])
{
event_to_shift->port |= (1 << pin);
event_move(&event_to_shift[1], event_to_shift);
}
event_move(&event_to_shift[1], &modified_event_cpy);
return;
}
if(value > modified_event_cpy.time) {
for(event_to_shift = pin_event_map[pin + 1];
(event_to_shift < &events[SOFTPWM_PIN_COUNT])
|| (modified_event_cpy.time > event_to_shift[1].time);
event_to_shift = &event_to_shift[1])
{
event_to_shift->port &= ~(1 << pin);
event_move(&event_to_shift[-1], event_to_shift);
}
}
event_move(&event_to_shift[-1], &modified_event_cpy);
}
ISR(TIMER0_OVF_vect) {
SOFTPWM_PORT = 0;
PORTA ^= 1;
}
//ISR for pwm timer. Need to look at assembly output to ensure proper optimization
//(would it be faster to have two different arrays vs a struct? idk if the offset is computed compile or runtime)
ISR(TIMER0_COMP_vect) {
static uint8_t eventcount = 0;
//eventcount = (eventcount <= SOFTPWM_PIN_COUNT) ? eventcount + 1 : 0;
SOFTPWM_PORT = events[eventcount].port;
eventcount = (eventcount + 1) % 8;
OCR0A = events[eventcount].time;
PORTA ^= 2;
}
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