Cleanup and reset ramp direction after a short delay

This also refactors the fixed level table which is now a list of indexes
in the normal ramping table. This saves some memory because we have less
computations later.

Also ramping_up is now just signed ramp_direction.

We also consistently ramp into the direction of the initial brightness
(more or less, you'll see).

README.md

@@ -37,7 +37,9 @@ The default is: no strobe, ramping UI, no mode memory, do not freeze on ramp end
 
 ### Ramping UI
 
-Turn the light on and it will start ramping up and down. Short tap the switch to freeze the current brightness. Tap again to resume ramping.
+Turn the light on and it will start ramping up and down. Short tap the switch to freeze the current brightness. Tap again to resume ramping. The direction of ramping will be reset after one second in fixed state.
+
+The default is to ramp down from the current level, except if set to "start on high". Or in other words: It will ramp into the direction of the initial brightness. This also means that it will ramp up if "start on high" is not set because it is already at the floor (and vice versa if "start on high" is set).
 
 Tap three times to go into turbo mode. There is no timer, so make sure to monitor the temperature. Tap again to go back to ramping.
 

rampinglight.c

@@ -46,8 +46,8 @@
 #define TURBO_PWM 255
 #define BEACON_PWM 5
 
-#define FIXED_SIZE sizeof(fixed_values)
-#define FIXED_VALUES 1,35,118,255
+#define FIXED_VALUES_MAP 0,21,42,63  // Index in ramp_values
+#define FIXED_STEPS sizeof(fixed_values_map)
 
 #define CBD_BYTES 8
 #define CBD_PATTERN 0xAA
@@ -109,7 +109,7 @@ typedef union {
 
 // Lookup tables in flash
 const uint8_t __flash ramp_values[] = { RAMP_VALUES };
-const uint8_t __flash fixed_values[] = { FIXED_VALUES };
+const uint8_t __flash fixed_values_map[] = { FIXED_VALUES_MAP };
 const uint8_t __flash voltage_table[] = { 0, BAT_25P, BAT_50P, BAT_75P };
 
 // Variables that are not initialized and survive a restart for a short time
@@ -117,7 +117,7 @@ uint8_t cold_boot_detect[CBD_BYTES] __attribute__((section(".noinit")));
 register enum State state           asm("r2");
 register uint8_t output             asm("r3");
 register uint8_t fast_presses       asm("r4");
-register uint8_t ramping_up         asm("r5");
+register int8_t ramp_direction      asm("r5");
 
 // Variables that will be initialized on start
 register Options options            asm("r6");
@@ -178,14 +178,11 @@ static void set_pwm(const uint8_t pwm) {
 /**
  * Set output to a level as defined in the ramp table.
  *
- * @param level Index in ramp_values or fixed_values depending on fixed_mode
+ * @param level Index in ramp_values or fixed_values_map depending on fixed_mode
  */
 void set_level(const uint8_t level) {
-  if (options.fixed_mode) {
-    set_pwm(fixed_values[options.start_high ? FIXED_SIZE - level - 1 : level]);
-  } else {
-    set_pwm(ramp_values[level]);
-  }
+  const uint8_t lvl = options.fixed_mode ? fixed_values_map[level] : level;
+  set_pwm(ramp_values[options.start_high ? RAMP_SIZE - lvl - 1 : lvl]);
   enable_output();
 }
 
@@ -381,16 +378,12 @@ int main(void) {
     state = kDefault;
 #endif  // ifdef OVERTURE
     fast_presses = 0;
-    ramping_up = 1;
+    ramp_direction = -1;
 
     if (options.mode_memory && output_eeprom != 0xFF) {
       output = output_eeprom;
     } else {
-      if (!options.fixed_mode && options.start_high) {
-        output = RAMP_SIZE - 1;
-      } else {
-        output = 0;
-      }
+      output = 0;
     }
   } else {  // User has tapped the power button
     delay_10ms(4);  // Simple button debounce
@@ -435,7 +428,7 @@ int main(void) {
             break;
 
           case kFixed:
-            output = (output + 1) % FIXED_SIZE;
+            output = (output + 1) % FIXED_STEPS;
             save_output();
             break;
 
@@ -464,11 +457,13 @@ int main(void) {
         continue;  // Skip main loop cycle and continue with correct mode
 
       case kRamping:
-        ramping_up =
-            (ramping_up && output < RAMP_SIZE - 1) ||
-            (!ramping_up && output == 0);
+        if (output == RAMP_SIZE - 1) {
+          ramp_direction = -1;
+        } else if (output == 0) {
+          ramp_direction = 1;
+        }
 
-        output += ramping_up ? 1 : -1;
+        output += ramp_direction;
         set_level(output);
 
         if (output == RAMP_SIZE - 1 || output == 0) {
@@ -488,6 +483,7 @@ int main(void) {
       case kFrozen:
         set_level(output);
         delay_s();
+        ramp_direction = -1;
         break;
 
       case kTurbo: