From e811d778ea51ac1e25588a9cc957fca4f532ea5a Mon Sep 17 00:00:00 2001
From: Brett Weiland <brett_weiland@bpcspace.com>
Date: Fri, 27 Oct 2023 07:10:26 -0500
Subject: init

---
 software_pwm_old.cb | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 software_pwm_old.cb

(limited to 'software_pwm_old.cb')

diff --git a/software_pwm_old.cb b/software_pwm_old.cb
new file mode 100644
index 0000000..db609af
--- /dev/null
+++ b/software_pwm_old.cb
@@ -0,0 +1,96 @@
+#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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