From baba1e78c7b8435f9a44de57ae295e505f459e6b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gu=C3=B0ni=20M=C3=A1r=20Gilbert?= <gudni.m.g@gmail.com>
Date: Sat, 15 Apr 2023 18:34:22 +0000
Subject: [PATCH] use uint16_t when writing to Timer/Counter4

Using uint16_t instead of uint32_t reduces code size
and probably is quicker to execute

OCR4C register is 2 bytes on ATmega2560
It's 1 byte on ATmega32u4 and ATmega16u4

Change in memory:
Flash: -80 bytes
SRAM: 0 bytes
---
 Firmware/tone04.c | 49 ++++++++++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/Firmware/tone04.c b/Firmware/tone04.c
index f9a427c32..d9423f383 100644
--- a/Firmware/tone04.c
+++ b/Firmware/tone04.c
@@ -14,24 +14,24 @@
 void timer4_init(void)
 {
 	CRITICAL_SECTION_START;
-	
+
 	SET_OUTPUT(BEEPER);
 	WRITE(BEEPER, LOW);
-	
+
 	SET_OUTPUT(EXTRUDER_0_AUTO_FAN_PIN);
-	
+
 	// Set timer mode 9 (PWM,Phase and Frequency Correct)
 	// Prescaler is CLK/1024
 	// Output compare is disabled on all timer pins
 	// Input capture is disabled
 	// All interrupts are disabled
-	TCCR4A = (1 << WGM40);
-	TCCR4B = (1 << WGM43) | (1 << CS42) | (1 << CS40);
-	OCR4A = 255;
-	OCR4B = 255;
-	OCR4C = 255;
+	TCCR4A = _BV(WGM40);
+	TCCR4B = _BV(WGM43) | _BV(CS42) | _BV(CS40);
+	OCR4A = 255U;
+	OCR4B = 255U;
+	OCR4C = 255U;
 	TIMSK4 = 0;
-	
+
 	CRITICAL_SECTION_END;
 }
 
@@ -41,7 +41,7 @@ void timer4_set_fan0(uint8_t duty)
 	if (duty == 0 || duty == 255)
 	{
 		// We use digital logic if the duty cycle is 0% or 100%
-		TCCR4A &= ~(1 << COM4C1);
+		TCCR4A &= ~_BV(COM4C1);
 		OCR4C = 0;
 		WRITE(EXTRUDER_0_AUTO_FAN_PIN, duty);
 	}
@@ -52,8 +52,8 @@ void timer4_set_fan0(uint8_t duty)
 		// Better be safe than sorry.
 		CRITICAL_SECTION_START;
 		// Enable the PWM output on the fan pin.
-		TCCR4A |= (1 << COM4C1);
-		OCR4C = (((uint32_t)duty) * ((uint32_t)((TIMSK4 & (1 << OCIE4A))?OCR4A:255))) / ((uint32_t)255);
+		TCCR4A |= _BV(COM4C1);
+		OCR4C = (((uint16_t)duty) * ((uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U))) / 255U;
 		CRITICAL_SECTION_END;
 	}
 }
@@ -75,25 +75,26 @@ void tone4(_UNUSED uint8_t _pin, uint16_t frequency)
 {
 	//this ocr and prescalarbits calculation is taken from the Arduino core and simplified for one type of timer only
 	uint8_t prescalarbits = 0b001;
-	uint32_t ocr = F_CPU / frequency / 2 - 1;
-	
-	if (ocr > 0xffff)
-	{
-		ocr = F_CPU / frequency / 2 / 64 - 1;
+	uint32_t pwm_freq = F_CPU / (2 * frequency);
+
+	if (pwm_freq > UINT16_MAX) {
+		pwm_freq /= 64; // Increase prescaler to 64
 		prescalarbits = 0b011;
 	}
-	
+
+	uint16_t ocr = pwm_freq - 1;
+
 	CRITICAL_SECTION_START;
 	// Set calcualted prescaler
 	TCCR4B = (TCCR4B & 0b11111000) | prescalarbits;
 #ifdef EXTRUDER_0_AUTO_FAN_PIN
 	// Scale the fan PWM duty cycle so that it remains constant, but at the tone frequency
-	OCR4C = (((uint32_t)OCR4C) * ocr) / (uint32_t)((TIMSK4 & (1 << OCIE4A))?OCR4A:255);
+	OCR4C = (OCR4C * ocr) / (uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U);
 #endif //EXTRUDER_0_AUTO_FAN_PIN
 	// Set calcualted ocr
 	OCR4A = ocr;
 	// Enable Output compare A interrupt and timer overflow interrupt
-	TIMSK4 |= (1 << OCIE4A) | (1 << TOIE4);
+	TIMSK4 |= _BV(OCIE4A) | _BV(TOIE4);
 	CRITICAL_SECTION_END;
 }
 
@@ -101,14 +102,14 @@ void noTone4(_UNUSED uint8_t _pin)
 {
 	CRITICAL_SECTION_START;
 	// Revert prescaler to CLK/1024
-	TCCR4B = (TCCR4B & 0b11111000) | (1 << CS42) | (1 << CS40);
+	TCCR4B = (TCCR4B & 0b11111000) | _BV(CS42) | _BV(CS40);
 #ifdef EXTRUDER_0_AUTO_FAN_PIN
 	// Scale the fan OCR back to the original value.
-	OCR4C = (((uint32_t)OCR4C) * (uint32_t)255) / (uint32_t)((TIMSK4 & (1 << OCIE4A))?OCR4A:255);
+	OCR4C = (OCR4C * 255U) / (uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U);
 #endif //EXTRUDER_0_AUTO_FAN_PIN
-	OCR4A = 255;
+	OCR4A = 255U;
 	// Disable Output compare A interrupt and timer overflow interrupt
-	TIMSK4 &= ~((1 << OCIE4A) | (1 << TOIE4));
+	TIMSK4 &= ~(_BV(OCIE4A) | _BV(TOIE4));
 	CRITICAL_SECTION_END;
 	// Turn beeper off if it was on when noTone was called
 	WRITE(BEEPER, 0);