update math to add convert int to string

module05/ex02/adc.c

@@ -10,27 +10,13 @@ void adc_init(uint8_t prescaler_value) {
     ADCSRA |= ADC_PRESCALE_SET(prescaler_value);			// Table 24-5 : prescaler ADC
 
 	ADCSRB = ADC_TRIGGER_TIMER_1_COMPARE_B;					// Table 24-6 : ADC Auto Trigger Source
-	ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b1111);	// Table 24-4 : Select ADC channel 0
+	ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b00001111);	// Table 24-4 : Select ADC channel 0
 }
 
 void adc_print_dec(uint16_t value) {
 	char buffer[17] = {0};
-
+	uint16_to_string(value, buffer);
-    // handle zero case
+	uart_printstr(buffer);
-    if (value == 0) {
-        buffer[15] = '0';
-        uart_printstr(&buffer[15]);
-        return;
-    }
-
-	uint8_t pos = 0;
-	while (value) {
-		uint8_t digit = value % 10;
-		buffer[15 - pos] = digit + '0';
-		value /= 10;
-		pos++;
-	}
-	uart_printstr(&buffer[16 - pos]);						// send only from first digit
 }
 
 ISR(ADC_vect) {												// Table 12-6 : interrupt vector for ADC Conversion Complete

module05/ex02/header.h

@@ -25,6 +25,7 @@ extern volatile uint8_t adc_channel;
 void timer_1B_init();
 // math.c
 void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits);
+void uint16_to_string(uint16_t value, char *out);
 // adc.c
 void adc_init(uint8_t prescaler_value);
 uint16_t adc_read(uint8_t channel);

module05/ex02/math.c

@@ -7,3 +7,26 @@ void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits) {				// nu
     }
     out[num_digits] = '\0';
 }
+
+void uint16_to_string(uint16_t value, char buffer[17]) {
+    // handle zero case
+    if (value == 0) {
+        buffer[0] = '0';
+		return;
+    }
+
+	uint8_t size = -1;
+	uint16_t copy = value;
+
+	while (copy) {
+		copy /= 10;
+		size++;
+	}
+
+	while (value) {
+		uint8_t digit = value % 10;
+		buffer[size] = digit + '0';
+		value /= 10;
+		size--;
+	}
+}