⚡️ Use fast types where it helps

Marlin/src/HAL/AVR/HAL_SPI.cpp

@@ -198,7 +198,7 @@ void spiBegin() {
     // output pin high - like sending 0xFF
     WRITE(SD_MOSI_PIN, HIGH);
 
-    for (uint8_t i = 0; i < 8; ++i) {
+    for (uint_fast8_t i = 0; i < 8; ++i) {
       WRITE(SD_SCK_PIN, HIGH);
 
       nop; // adjust so SCK is nice
@@ -225,7 +225,7 @@ void spiBegin() {
   void spiSend(uint8_t data) {
     // no interrupts during byte send - about 8µs
     cli();
-    for (uint8_t i = 0; i < 8; ++i) {
+    for (uint_fast8_t i = 0; i < 8; ++i) {
       WRITE(SD_SCK_PIN, LOW);
       WRITE(SD_MOSI_PIN, data & 0x80);
       data <<= 1;

Marlin/src/HAL/AVR/fast_pwm.cpp

@@ -132,7 +132,7 @@ void MarlinHAL::set_pwm_frequency(const pin_t pin, const uint16_t f_desired) {
 
     DEBUG_ECHOLNPGM("f=", f);
     DEBUG_ECHOLNPGM("(prescaler loop)");
-    for (uint8_t i = 0; i < COUNT(prescaler); ++i) {          // Loop through all prescaler values
+    for (uint_fast8_t i = 0; i < COUNT(prescaler); ++i) {          // Loop through all prescaler values
       const uint32_t p = prescaler[i];                        // Extend to 32 bits for calculations
       DEBUG_ECHOLNPGM("prescaler[", i, "]=", p);
       uint16_t res_fast_temp, res_pc_temp;
@@ -232,7 +232,7 @@ void MarlinHAL::init_pwm_timers() {
     #endif
   };
 
-  for (uint8_t i = 0; i < COUNT(pwm_pin); ++i)
+  for (uint_fast8_t i = 0; i < COUNT(pwm_pin); ++i)
     set_pwm_frequency(pwm_pin[i], 1000);
 }
 

Marlin/src/HAL/AVR/pinsDebug.h

@@ -77,12 +77,12 @@
 
 void PRINT_ARRAY_NAME(uint8_t x) {
   PGM_P const name_mem_pointer = (PGM_P)pgm_read_ptr(&pin_array[x].name);
-  for (uint8_t y = 0; y < MAX_NAME_LENGTH; ++y) {
+  for (uint_fast8_t y = 0; y < MAX_NAME_LENGTH; ++y) {
     char temp_char = pgm_read_byte(name_mem_pointer + y);
     if (temp_char != 0)
       SERIAL_CHAR(temp_char);
     else {
-      for (uint8_t i = 0; i < MAX_NAME_LENGTH - y; ++i) SERIAL_CHAR(' ');
+      for (uint_fast8_t i = 0; i < MAX_NAME_LENGTH - y; ++i) SERIAL_CHAR(' ');
       break;
     }
   }

Marlin/src/HAL/AVR/u8g_com_HAL_AVR_sw_spi.cpp

@@ -88,7 +88,7 @@ void u8g_spiSend_sw_AVR_mode_0(uint8_t val) {
   volatile uint8_t *outData = u8g_outData,
                    *outClock = u8g_outClock;
   U8G_ATOMIC_START();
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     if (val & 0x80)
       *outData |= bitData;
     else
@@ -108,7 +108,7 @@ void u8g_spiSend_sw_AVR_mode_3(uint8_t val) {
   volatile uint8_t *outData = u8g_outData,
                    *outClock = u8g_outClock;
   U8G_ATOMIC_START();
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     *outClock &= bitNotClock;
     if (val & 0x80)
       *outData |= bitData;

Marlin/src/HAL/DUE/dogm/u8g_com_HAL_DUE_sw_spi_shared.cpp

@@ -81,7 +81,7 @@ Pio *SCK_pPio, *MOSI_pPio;
 uint32_t SCK_dwMask, MOSI_dwMask;
 
 void u8g_spiSend_sw_DUE_mode_0(uint8_t val) { // 3MHz
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     if (val & 0x80)
       MOSI_pPio->PIO_SODR = MOSI_dwMask;
     else
@@ -95,7 +95,7 @@ void u8g_spiSend_sw_DUE_mode_0(uint8_t val) { // 3MHz
 }
 
 void u8g_spiSend_sw_DUE_mode_3(uint8_t val) { // 3.5MHz
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     SCK_pPio->PIO_CODR = SCK_dwMask;
     DELAY_NS(50);
     if (val & 0x80)

Marlin/src/HAL/DUE/fastio/G2_PWM.h

@@ -63,7 +63,7 @@ extern PWM_map ISR_table[NUM_PWMS];
 extern uint32_t motor_current_setting[3];
 
 #define IR_BIT(p) (WITHIN(p, 0, 3) ? (p) : (p) + 4)
-#define COPY_ACTIVE_TABLE() do{ for (uint8_t i = 0; i < 6; ++i) work_table[i] = active_table[i]; }while(0)
+#define COPY_ACTIVE_TABLE() do{ for (uint_fast8_t i = 0; i < 6; ++i) work_table[i] = active_table[i]; }while(0)
 
 #define PWM_MR0 19999         // base repetition rate minus one count - 20mS
 #define PWM_PR 24             // prescaler value - prescaler divide by 24 + 1  -  1 MHz output

Marlin/src/HAL/DUE/usb/usb_task.c

@@ -245,7 +245,7 @@ bool usb_task_extra_string(void) {
     return false;
   }
 
-  for (uint8_t i = 0; i < str_lgt; i++)
+  for (uint_fast8_t i = 0; i < str_lgt; i++)
     extra_strings_desc.string[i] = cpu_to_le16((le16_t)str[i]);
 
   extra_strings_desc.header.bLength = 2 + str_lgt * 2;

Marlin/src/HAL/ESP32/i2s.cpp

@@ -356,7 +356,7 @@ void i2s_push_sample() {
   // Every 4µs (when space in DMA buffer) toggle each expander PWM output using
   // the current duty cycle/frequency so they sync with any steps (once
   // through the DMA/FIFO buffers).  PWM signal inversion handled by other functions
-  for (uint8_t p = 0; p < MAX_EXPANDER_BITS; ++p) {
+  for (uint_fast8_t p = 0; p < MAX_EXPANDER_BITS; ++p) {
     if (hal.pwm_pin_data[p].pwm_duty_ticks > 0) { // pin has active pwm?
       if (hal.pwm_pin_data[p].pwm_tick_count == 0) {
         if (TEST32(i2s_port_data, p)) {  // hi->lo

Marlin/src/HAL/LPC1768/main.cpp

@@ -68,7 +68,7 @@ void MarlinHAL::init() {
     #endif
 
     // Flash status LED 3 times to indicate Marlin has started booting
-    for (uint8_t i = 0; i < 6; ++i) {
+    for (uint_fast8_t i = 0; i < 6; ++i) {
       TOGGLE(LED_PIN);
       delay(100);
     }

Marlin/src/HAL/LPC1768/tft/tft_spi.cpp

@@ -74,7 +74,7 @@ uint32_t TFT_SPI::ReadID(uint16_t Reg) {
     WRITE(TFT_CS_PIN, LOW);
     WriteReg(Reg);
 
-    for (uint8_t i = 0; i < 4; ++i) {
+    for (uint_fast8_t i = 0; i < 4; ++i) {
       SPIx.read((uint8_t*)&d, 1);
       data = (data << 8) | d;
     }

Marlin/src/HAL/LPC1768/tft/xpt2046.cpp

@@ -121,7 +121,7 @@ extern uint8_t spiTransfer(uint8_t b);
 uint16_t XPT2046::SoftwareIO(uint16_t data) {
   uint16_t result = 0;
 
-  for (uint8_t j = 0x80; j; j >>= 1) {
+  for (uint_fast8_t j = 0x80; j; j >>= 1) {
     WRITE(TOUCH_SCK_PIN, LOW);
     WRITE(TOUCH_MOSI_PIN, data & j ? HIGH : LOW);
     if (READ(TOUCH_MISO_PIN)) result |= j;

Marlin/src/HAL/LPC1768/u8g/u8g_com_HAL_LPC1768_sw_spi.cpp

@@ -75,7 +75,7 @@
 
 uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck_pin, const pin_t miso_pin, const pin_t mosi_pin ) {
 
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     if (spi_speed == 0) {
       LPC176x::gpio_set(mosi_pin, !!(b & 0x80));
       LPC176x::gpio_set(sck_pin, HIGH);
@@ -85,16 +85,16 @@ uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck
     }
     else {
       const uint8_t state = (b & 0x80) ? HIGH : LOW;
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         LPC176x::gpio_set(mosi_pin, state);
 
-      for (uint8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
+      for (uint_fast8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
         LPC176x::gpio_set(sck_pin, HIGH);
 
       b <<= 1;
       if (miso_pin >= 0 && LPC176x::gpio_get(miso_pin)) b |= 1;
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         LPC176x::gpio_set(sck_pin, LOW);
     }
   }
@@ -104,7 +104,7 @@ uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck
 
 uint8_t swSpiTransfer_mode_3(uint8_t b, const uint8_t spi_speed, const pin_t sck_pin, const pin_t miso_pin, const pin_t mosi_pin ) {
 
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     const uint8_t state = (b & 0x80) ? HIGH : LOW;
     if (spi_speed == 0) {
       LPC176x::gpio_set(sck_pin, LOW);
@@ -113,13 +113,13 @@ uint8_t swSpiTransfer_mode_3(uint8_t b, const uint8_t spi_speed, const pin_t sck
       LPC176x::gpio_set(sck_pin, HIGH);
     }
     else {
-      for (uint8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
+      for (uint_fast8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
         LPC176x::gpio_set(sck_pin, LOW);
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         LPC176x::gpio_set(mosi_pin, state);
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         LPC176x::gpio_set(sck_pin, HIGH);
     }
     b <<= 1;

Marlin/src/HAL/NATIVE_SIM/u8g/u8g_com_st7920_sw_spi.cpp

@@ -70,7 +70,7 @@ static pin_t SCK_pin_ST7920_HAL, MOSI_pin_ST7920_HAL_HAL;
 static uint8_t SPI_speed = 0;
 
 static uint8_t swSpiTransfer(uint8_t b, const uint8_t spi_speed, const pin_t sck_pin, const pin_t miso_pin, const pin_t mosi_pin) {
-  for (uint8_t i = 0; i < 8; i++) {
+  for (uint_fast8_t i = 0; i < 8; i++) {
     WRITE_PIN(mosi_pin, !!(b & 0x80));
     DELAY_CYCLES(SPI_SPEED);
     WRITE_PIN(sck_pin, HIGH);

Marlin/src/HAL/NATIVE_SIM/u8g/u8g_com_sw_spi.cpp

@@ -70,7 +70,7 @@
 #endif
 
 uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck_pin, const pin_t miso_pin, const pin_t mosi_pin ) {
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     if (spi_speed == 0) {
       WRITE_PIN(mosi_pin, !!(b & 0x80));
       WRITE_PIN(sck_pin, HIGH);
@@ -80,16 +80,16 @@ uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck
     }
     else {
       const uint8_t state = (b & 0x80) ? HIGH : LOW;
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         WRITE_PIN(mosi_pin, state);
 
-      for (uint8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
+      for (uint_fast8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
         WRITE_PIN(sck_pin, HIGH);
 
       b <<= 1;
       if (miso_pin >= 0 && READ_PIN(miso_pin)) b |= 1;
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         WRITE_PIN(sck_pin, LOW);
     }
   }
@@ -99,7 +99,7 @@ uint8_t swSpiTransfer_mode_0(uint8_t b, const uint8_t spi_speed, const pin_t sck
 
 uint8_t swSpiTransfer_mode_3(uint8_t b, const uint8_t spi_speed, const pin_t sck_pin, const pin_t miso_pin, const pin_t mosi_pin ) {
 
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     const uint8_t state = (b & 0x80) ? HIGH : LOW;
     if (spi_speed == 0) {
       WRITE_PIN(sck_pin, LOW);
@@ -108,13 +108,13 @@ uint8_t swSpiTransfer_mode_3(uint8_t b, const uint8_t spi_speed, const pin_t sck
       WRITE_PIN(sck_pin, HIGH);
     }
     else {
-      for (uint8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
+      for (uint_fast8_t j = 0; j < spi_speed + (miso_pin >= 0 ? 0 : 1); ++j)
         WRITE_PIN(sck_pin, LOW);
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         WRITE_PIN(mosi_pin, state);
 
-      for (uint8_t j = 0; j < spi_speed; ++j)
+      for (uint_fast8_t j = 0; j < spi_speed; ++j)
         WRITE_PIN(sck_pin, HIGH);
     }
     b <<= 1;

Marlin/src/HAL/SAMD51/HAL.cpp

@@ -650,10 +650,10 @@ void MarlinHAL::adc_init() {
   #if ADC_IS_REQUIRED
     memset(adc_results, 0xFF, sizeof(adc_results));                         // Fill result with invalid values
 
-    for (uint8_t pi = 0; pi < COUNT(adc_pins); ++pi)
+    for (uint_fast8_t pi = 0; pi < COUNT(adc_pins); ++pi)
       pinPeripheral(adc_pins[pi], PIO_ANALOG);
 
-    for (uint8_t ai = FIRST_ADC; ai <= LAST_ADC; ++ai) {
+    for (uint_fast8_t ai = FIRST_ADC; ai <= LAST_ADC; ++ai) {
       Adc* adc = ((Adc*[])ADC_INSTS)[ai];
 
       // ADC clock setup
@@ -685,7 +685,7 @@ void MarlinHAL::adc_init() {
 
 void MarlinHAL::adc_start(const pin_t pin) {
   #if ADC_IS_REQUIRED
-    for (uint8_t pi = 0; pi < COUNT(adc_pins); ++pi)
+    for (uint_fast8_t pi = 0; pi < COUNT(adc_pins); ++pi)
       if (pin == adc_pins[pi]) { adc_result = adc_results[pi]; return; }
   #endif
 

Marlin/src/HAL/STM32/HAL_SPI.cpp

@@ -84,7 +84,7 @@ static SPISettings spiConfig;
   void spiBeginTransaction(uint32_t spiClock, uint8_t bitOrder, uint8_t dataMode) { /* do nothing */ }
 
   uint8_t HAL_SPI_STM32_SpiTransfer_Mode_3(uint8_t b) { // using Mode 3
-    for (uint8_t bits = 8; bits--;) {
+    for (uint_fast8_t bits = 8; bits--;) {
       WRITE(SD_SCK_PIN, LOW);
       WRITE(SD_MOSI_PIN, b & 0x80);
 

Marlin/src/HAL/STM32/fastio.cpp

@@ -29,7 +29,7 @@
 GPIO_TypeDef* FastIOPortMap[LastPort + 1] = { 0 };
 
 void FastIO_init() {
-  for (uint8_t i = 0; i < NUM_DIGITAL_PINS; ++i)
+  for (uint_fast8_t i = 0; i < NUM_DIGITAL_PINS; ++i)
     FastIOPortMap[STM_PORT(digitalPin[i])] = get_GPIO_Port(STM_PORT(digitalPin[i]));
 }
 

Marlin/src/HAL/STM32/tft/gt911.cpp

@@ -90,7 +90,7 @@ bool SW_IIC::read_ack() {
 }
 
 void SW_IIC::send_byte(uint8_t txd) {
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     write_sda(txd & 0x80); // write data bit
     txd <<= 1;
     iic_delay(1);
@@ -107,7 +107,7 @@ uint8_t SW_IIC::read_byte(bool ack) {
   uint8_t data = 0;
 
   set_sda_in();
-  for (uint8_t i = 0; i < 8; ++i) {
+  for (uint_fast8_t i = 0; i < 8; ++i) {
     write_scl(HIGH); // SCL = 1
     iic_delay(1);
     data <<= 1;
@@ -128,12 +128,12 @@ SW_IIC GT911::sw_iic = SW_IIC(GT911_SW_I2C_SDA_PIN, GT911_SW_I2C_SCL_PIN);
 void GT911::write_reg(uint16_t reg, uint8_t reg_len, uint8_t* w_data, uint8_t w_len) {
   sw_iic.start();
   sw_iic.send_byte(gt911_slave_address);  // Set IIC Slave address
-  for (uint8_t i = 0; i < reg_len; ++i) {  // Set reg address
+  for (uint_fast8_t i = 0; i < reg_len; ++i) {  // Set reg address
     uint8_t r = (reg >> (8 * (reg_len - 1 - i))) & 0xFF;
     sw_iic.send_byte(r);
   }
 
-  for (uint8_t i = 0; i < w_len; ++i) {  // Write data to reg
+  for (uint_fast8_t i = 0; i < w_len; ++i) {  // Write data to reg
     sw_iic.send_byte(w_data[i]);
   }
   sw_iic.stop();
@@ -142,15 +142,15 @@ void GT911::write_reg(uint16_t reg, uint8_t reg_len, uint8_t* w_data, uint8_t w_
 void GT911::read_reg(uint16_t reg, uint8_t reg_len, uint8_t* r_data, uint8_t r_len) {
   sw_iic.start();
   sw_iic.send_byte(gt911_slave_address);  // Set IIC Slave address
-  for (uint8_t i = 0; i < reg_len; ++i) {  // Set reg address
+  for (uint_fast8_t i = 0; i < reg_len; ++i) {  // Set reg address
     uint8_t r = (reg >> (8 * (reg_len - 1 - i))) & 0xFF;
     sw_iic.send_byte(r);
   }
 
   sw_iic.start();
   sw_iic.send_byte(gt911_slave_address + 1);  // Set read mode
 
-  for (uint8_t i = 0; i < r_len; ++i)
+  for (uint_fast8_t i = 0; i < r_len; ++i)
     r_data[i] = sw_iic.read_byte(1);  // Read data from reg
 
   sw_iic.stop();

Marlin/src/HAL/STM32/tft/xpt2046.cpp

@@ -153,7 +153,7 @@ uint16_t XPT2046::HardwareIO(uint16_t data) {
 uint16_t XPT2046::SoftwareIO(uint16_t data) {
   uint16_t result = 0;
 
-  for (uint8_t j = 0x80; j > 0; j >>= 1) {
+  for (uint_fast8_t j = 0x80; j > 0; j >>= 1) {
     WRITE(TOUCH_SCK_PIN, LOW);
     __DSB();
     WRITE(TOUCH_MOSI_PIN, data & j ? HIGH : LOW);

Marlin/src/HAL/STM32/timers.cpp

@@ -316,8 +316,8 @@ static constexpr struct { TimerPurpose p; int t; } timers_in_use[] = {
 };
 
 static constexpr bool verify_no_timer_conflicts() {
-  for (uint8_t i = 0; i < COUNT(timers_in_use); ++i)
-    for (uint8_t j = i + 1; j < COUNT(timers_in_use); ++j)
+  for (uint_fast8_t i = 0; i < COUNT(timers_in_use); ++i)
+    for (uint_fast8_t j = i + 1; j < COUNT(timers_in_use); ++j)
       if (timers_in_use[i].t == timers_in_use[j].t) return false;
   return true;
 }