Make read bulk fan speed read correctly from the array

This avoids the problem where the current index has outdated data.
It does however mean the first piece of stored data is empty, but it is
a worthwile tradeoff.

prosjekt.X/command-handler.c

@@ -1,4 +1,5 @@
 #include "command-handler.h"
+#include "fan_speeeed.h"
 
 // Initialize empty, global command context
 volatile command_context_t context = {UNKNOWN_COMMAND, SRC_NONE, FAN_NONE,
@@ -235,18 +236,32 @@ uint8_t route_command(int pos) {
         break;
     case READ_FAN_SPEED:
         if (context.fan == FAN1) {
-            return fan1_history[0];
+            return fan1_history[fan1_history_index];
         } else if (context.fan == FAN2) {
-            return fan2_history[0];
+            return fan2_history[fan2_history_index];
         } else {
             return 0;
         }
         break;        
     case READ_BULK_FAN_SPEED:
         if (context.fan == FAN1) {
-            return fan1_history[pos];
+            // Validate that pos is valid, if not return 0
+            if (pos >= 512) { return 0; }
+            
+            // Calculate the index position
+            int16_t index = fan1_history_index - pos;
+            if (index < 0) { index = 511-pos; }
+            
+            return fan1_history[index];
         } else if (context.fan == FAN2) {
-            return fan2_history[pos];
+            // Validate that pos is valid, if not return 0
+            if (pos >= 512) { return 0; }
+            
+            // Calculate the index position
+            int16_t index = fan2_history_index - pos;
+            if (index < 0) { index = 511-pos; }
+            
+            return fan2_history[index];
         } else {
             return 0;
         }

prosjekt.X/command-handler.h

@@ -66,6 +66,9 @@ typedef struct {
 // Fan history variables
 extern volatile uint16_t fan1_history[512];
 extern volatile uint16_t fan2_history[512];
+// Fan history index variable
+volatile uint16_t fan1_history_index = 0;
+volatile uint16_t fan2_history_index = 0;
 
 // Config
 extern volatile config_t config;

prosjekt.X/fan_speeeed.c

@@ -98,8 +98,25 @@ ISR(AC1_AC_vect){ // AC1 vec flag
 // TIMER INTERUPT
 ISR (TCA0_OVF_vect) {
     cli();
-    RPM_calculation(fan1_edge_counter,timer_period_ms);
-    RPM_calculation(fan2_edge_counter,timer_period_ms);
+    
+    // Increment the index, or reset if it is at the top
+    if (fan1_history_index < 512) {
+        fan1_history_index++;
+    } else {
+        fan1_history_index = 0;
+    }
+    
+    if (fan2_history_index < 512) {
+        fan2_history_index++;
+    } else {
+        fan2_history_index = 0;
+    }
+    
+    // Calculate the fanspeed
+    fan1_history[fan1_history_index] = RPM_calculation(fan1_edge_counter,timer_period_ms);
+    fan2_history[fan2_history_index] = RPM_calculation(fan2_edge_counter,timer_period_ms);
+        
+    // Reset the edge counter
     fan1_edge_counter = 0;
     fan2_edge_counter = 0;
     TCA0.SINGLE.INTFLAGS = TCA_SINGLE_OVF_bm ;

prosjekt.X/fan_speeeed.h

@@ -29,6 +29,12 @@ extern "C" {
      * and inspiration form practice 6 for TCA0 setup
      */
     
+// Fan history variables
+extern volatile uint16_t fan1_history[512];
+extern volatile uint16_t fan2_history[512];
+// Fan history index variable
+volatile uint16_t fan1_history_index = 0;
+volatile uint16_t fan2_history_index = 0;
     
     // INITALICE TIMER COUNTER
     void init_TCA0();