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/*** Marlin 3D Printer Firmware* Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]** Based on Sprinter and grbl.* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm** This program is free software: you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation, either version 3 of the License, or* (at your option) any later version.** This program is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with this program. If not, see <http://www.gnu.org/licenses/>.**//*** MarlinSerial.cpp - Hardware serial library for Wiring* Copyright (c) 2006 Nicholas Zambetti. All right reserved.** Modified 23 November 2006 by David A. Mellis* Modified 28 September 2010 by Mark Sproul* Modified 14 February 2016 by Andreas Hardtung (added tx buffer)* Modified 01 October 2017 by Eduardo José Tagle (added XON/XOFF)* Modified 10 June 2018 by Eduardo José Tagle (See #10991)*/// Disable HardwareSerial.cpp to support chips without a UART (Attiny, etc.)#include "MarlinConfig.h"#if USE_MARLINSERIAL && (defined(UBRRH) || defined(UBRR0H) || defined(UBRR1H) || defined(UBRR2H) || defined(UBRR3H))#include "MarlinSerial.h"#include "Marlin.h"struct ring_buffer_r {unsigned char buffer[RX_BUFFER_SIZE];volatile ring_buffer_pos_t head, tail;};#if TX_BUFFER_SIZE > 0struct ring_buffer_t {unsigned char buffer[TX_BUFFER_SIZE];volatile uint8_t head, tail;};#endif#if UART_PRESENT(SERIAL_PORT)ring_buffer_r rx_buffer = { { 0 }, 0, 0 };#if TX_BUFFER_SIZE > 0ring_buffer_t tx_buffer = { { 0 }, 0, 0 };#endifstatic bool _written;#endif#if ENABLED(SERIAL_XON_XOFF)constexpr uint8_t XON_XOFF_CHAR_SENT = 0x80, // XON / XOFF Character was sentXON_XOFF_CHAR_MASK = 0x1F; // XON / XOFF character to send// XON / XOFF character definitionsconstexpr uint8_t XON_CHAR = 17, XOFF_CHAR = 19;uint8_t xon_xoff_state = XON_XOFF_CHAR_SENT | XON_CHAR;#endif#if ENABLED(SERIAL_STATS_DROPPED_RX)uint8_t rx_dropped_bytes = 0;#endif#if ENABLED(SERIAL_STATS_RX_BUFFER_OVERRUNS)uint8_t rx_buffer_overruns = 0;#endif#if ENABLED(SERIAL_STATS_RX_FRAMING_ERRORS)uint8_t rx_framing_errors = 0;#endif#if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)ring_buffer_pos_t rx_max_enqueued = 0;#endif// A SW memory barrier, to ensure GCC does not overoptimize loops#define sw_barrier() asm volatile("": : :"memory");#if ENABLED(EMERGENCY_PARSER)#include "emergency_parser.h"#endif// "Atomically" read the RX head index value without disabling interrupts:// This MUST be called with RX interrupts enabled, and CAN'T be called// from the RX ISR itself!FORCE_INLINE ring_buffer_pos_t atomic_read_rx_head() {#if RX_BUFFER_SIZE > 256// Keep reading until 2 consecutive reads return the same value,// meaning there was no update in-between caused by an interrupt.// This works because serial RX interrupts happen at a slower rate// than successive reads of a variable, so 2 consecutive reads with// the same value means no interrupt updated it.ring_buffer_pos_t vold, vnew = rx_buffer.head;sw_barrier();do {vold = vnew;vnew = rx_buffer.head;sw_barrier();} while (vold != vnew);return vnew;#else// With an 8bit index, reads are always atomic. No need for special handlingreturn rx_buffer.head;#endif}#if RX_BUFFER_SIZE > 256static volatile bool rx_tail_value_not_stable = false;static volatile uint16_t rx_tail_value_backup = 0;#endif// Set RX tail index, taking into account the RX ISR could interrupt// the write to this variable in the middle - So a backup strategy// is used to ensure reads of the correct values.// -Must NOT be called from the RX ISR -FORCE_INLINE void atomic_set_rx_tail(ring_buffer_pos_t value) {#if RX_BUFFER_SIZE > 256// Store the new value in the backuprx_tail_value_backup = value;sw_barrier();// Flag we are about to change the true valuerx_tail_value_not_stable = true;sw_barrier();// Store the new valuerx_buffer.tail = value;sw_barrier();// Signal the new value is completely stored into the valuerx_tail_value_not_stable = false;sw_barrier();#elserx_buffer.tail = value;#endif}// Get the RX tail index, taking into account the read could be// interrupting in the middle of the update of that index value// -Called from the RX ISR -FORCE_INLINE ring_buffer_pos_t atomic_read_rx_tail() {#if RX_BUFFER_SIZE > 256// If the true index is being modified, return the backup valueif (rx_tail_value_not_stable) return rx_tail_value_backup;#endif// The true index is stable, return itreturn rx_buffer.tail;}// (called with RX interrupts disabled)FORCE_INLINE void store_rxd_char() {// Get the tail - Nothing can alter its value while this ISR is executing, but there's// a chance that this ISR interrupted the main process while it was updating the index.// The backup mechanism ensures the correct value is always returned.const ring_buffer_pos_t t = atomic_read_rx_tail();// Get the head pointer - This ISR is the only one that modifies its value, so it's safe to read herering_buffer_pos_t h = rx_buffer.head;// Get the next elementring_buffer_pos_t i = (ring_buffer_pos_t)(h + 1) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);// This must read the M_UCSRxA register before reading the received byte to detect error causes#if ENABLED(SERIAL_STATS_DROPPED_RX)if (TEST(M_UCSRxA, M_DORx) && !++rx_dropped_bytes) --rx_dropped_bytes;#endif#if ENABLED(SERIAL_STATS_RX_BUFFER_OVERRUNS)if (TEST(M_UCSRxA, M_DORx) && !++rx_buffer_overruns) --rx_buffer_overruns;#endif#if ENABLED(SERIAL_STATS_RX_FRAMING_ERRORS)if (TEST(M_UCSRxA, M_FEx) && !++rx_framing_errors) --rx_framing_errors;#endif// Read the character from the USARTuint8_t c = M_UDRx;#if ENABLED(EMERGENCY_PARSER)emergency_parser.update(c);#endif// If the character is to be stored at the index just before the tail// (such that the head would advance to the current tail), the RX FIFO is// full, so don't write the character or advance the head.if (i != t) {rx_buffer.buffer[h] = c;h = i;}#if ENABLED(SERIAL_STATS_DROPPED_RX)else if (!++rx_dropped_bytes) --rx_dropped_bytes;#endif#if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)// Calculate count of bytes stored into the RX bufferconst ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(h - t) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);// Keep track of the maximum count of enqueued bytesNOLESS(rx_max_enqueued, rx_count);#endif#if ENABLED(SERIAL_XON_XOFF)// If the last char that was sent was an XONif ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XON_CHAR) {// Bytes stored into the RX bufferconst ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(h - t) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);// If over 12.5% of RX buffer capacity, send XOFF before running out of// RX buffer space .. 325 bytes @ 250kbits/s needed to let the host react// and stop sending bytes. This translates to 13mS propagation time.if (rx_count >= (RX_BUFFER_SIZE) / 8) {// At this point, definitely no TX interrupt was executing, since the TX ISR can't be preempted.// Don't enable the TX interrupt here as a means to trigger the XOFF char, because if it happens// to be in the middle of trying to disable the RX interrupt in the main program, eventually the// enabling of the TX interrupt could be undone. The ONLY reliable thing this can do to ensure// the sending of the XOFF char is to send it HERE AND NOW.// About to send the XOFF charxon_xoff_state = XOFF_CHAR | XON_XOFF_CHAR_SENT;// Wait until the TX register becomes empty and send it - Here there could be a problem// - While waiting for the TX register to empty, the RX register could receive a new// character. This must also handle that situation!while (!TEST(M_UCSRxA, M_UDREx)) {if (TEST(M_UCSRxA,M_RXCx)) {// A char arrived while waiting for the TX buffer to be empty - Receive and process it!i = (ring_buffer_pos_t)(h + 1) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);// Read the character from the USARTc = M_UDRx;#if ENABLED(EMERGENCY_PARSER)emergency_parser.update(c);#endif// If the character is to be stored at the index just before the tail// (such that the head would advance to the current tail), the FIFO is// full, so don't write the character or advance the head.if (i != t) {rx_buffer.buffer[h] = c;h = i;}#if ENABLED(SERIAL_STATS_DROPPED_RX)else if (!++rx_dropped_bytes) --rx_dropped_bytes;#endif}sw_barrier();}M_UDRx = XOFF_CHAR;// Clear the TXC bit -- "can be cleared by writing a one to its bit// location". This makes sure flush() won't return until the bytes// actually got writtenSBI(M_UCSRxA, M_TXCx);// At this point there could be a race condition between the write() function// and this sending of the XOFF char. This interrupt could happen between the// wait to be empty TX buffer loop and the actual write of the character. Since// the TX buffer is full because it's sending the XOFF char, the only way to be// sure the write() function will succeed is to wait for the XOFF char to be// completely sent. Since an extra character could be received during the wait// it must also be handled!while (!TEST(M_UCSRxA, M_UDREx)) {if (TEST(M_UCSRxA,M_RXCx)) {// A char arrived while waiting for the TX buffer to be empty - Receive and process it!i = (ring_buffer_pos_t)(h + 1) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);// Read the character from the USARTc = M_UDRx;#if ENABLED(EMERGENCY_PARSER)emergency_parser.update(c);#endif// If the character is to be stored at the index just before the tail// (such that the head would advance to the current tail), the FIFO is// full, so don't write the character or advance the head.if (i != t) {rx_buffer.buffer[h] = c;h = i;}#if ENABLED(SERIAL_STATS_DROPPED_RX)else if (!++rx_dropped_bytes) --rx_dropped_bytes;#endif}sw_barrier();}// At this point everything is ready. The write() function won't// have any issues writing to the UART TX register if it needs to!}}#endif // SERIAL_XON_XOFF// Store the new head value - The main loop will retry until the value is stablerx_buffer.head = h;}#if TX_BUFFER_SIZE > 0// (called with TX irqs disabled)FORCE_INLINE void _tx_udr_empty_irq(void) {// Read positionsuint8_t t = tx_buffer.tail;const uint8_t h = tx_buffer.head;#if ENABLED(SERIAL_XON_XOFF)// If an XON char is pending to be sent, do it nowif (xon_xoff_state == XON_CHAR) {// Send the characterM_UDRx = XON_CHAR;// clear the TXC bit -- "can be cleared by writing a one to its bit// location". This makes sure flush() won't return until the bytes// actually got writtenSBI(M_UCSRxA, M_TXCx);// Remember we sent it.xon_xoff_state = XON_CHAR | XON_XOFF_CHAR_SENT;// If nothing else to transmit, just disable TX interrupts.if (h == t) CBI(M_UCSRxB, M_UDRIEx); // (Non-atomic, could be reenabled by the main program, but eventually this will succeed)return;}#endif// If nothing to transmit, just disable TX interrupts. This could// happen as the result of the non atomicity of the disabling of RX// interrupts that could end reenabling TX interrupts as a side effect.if (h == t) {CBI(M_UCSRxB, M_UDRIEx); // (Non-atomic, could be reenabled by the main program, but eventually this will succeed)return;}// There is something to TX, Send the next byteconst uint8_t c = tx_buffer.buffer[t];t = (t + 1) & (TX_BUFFER_SIZE - 1);M_UDRx = c;tx_buffer.tail = t;// Clear the TXC bit (by writing a one to its bit location).// Ensures flush() won't return until the bytes are actually written/SBI(M_UCSRxA, M_TXCx);// Disable interrupts if there is nothing to transmit following this byteif (h == t) CBI(M_UCSRxB, M_UDRIEx); // (Non-atomic, could be reenabled by the main program, but eventually this will succeed)}#ifdef M_USARTx_UDRE_vectISR(M_USARTx_UDRE_vect) { _tx_udr_empty_irq(); }#endif#endif // TX_BUFFER_SIZE#ifdef M_USARTx_RX_vectISR(M_USARTx_RX_vect) { store_rxd_char(); }#endif// Public Methodsvoid MarlinSerial::begin(const long baud) {uint16_t baud_setting;bool useU2X = true;#if F_CPU == 16000000UL && SERIAL_PORT == 0// Hard-coded exception for compatibility with the bootloader shipped// with the Duemilanove and previous boards, and the firmware on the// 8U2 on the Uno and Mega 2560.if (baud == 57600) useU2X = false;#endifif (useU2X) {M_UCSRxA = _BV(M_U2Xx);baud_setting = (F_CPU / 4 / baud - 1) / 2;}else {M_UCSRxA = 0;baud_setting = (F_CPU / 8 / baud - 1) / 2;}// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)M_UBRRxH = baud_setting >> 8;M_UBRRxL = baud_setting;SBI(M_UCSRxB, M_RXENx);SBI(M_UCSRxB, M_TXENx);SBI(M_UCSRxB, M_RXCIEx);#if TX_BUFFER_SIZE > 0CBI(M_UCSRxB, M_UDRIEx);#endif_written = false;}void MarlinSerial::end() {CBI(M_UCSRxB, M_RXENx);CBI(M_UCSRxB, M_TXENx);CBI(M_UCSRxB, M_RXCIEx);CBI(M_UCSRxB, M_UDRIEx);}int MarlinSerial::peek(void) {const ring_buffer_pos_t h = atomic_read_rx_head(), t = rx_buffer.tail;return h == t ? -1 : rx_buffer.buffer[t];}int MarlinSerial::read(void) {const ring_buffer_pos_t h = atomic_read_rx_head();// Read the tail. Main thread owns it, so it is safe to directly read itring_buffer_pos_t t = rx_buffer.tail;// If nothing to read, return nowif (h == t) return -1;// Get the next charconst int v = rx_buffer.buffer[t];t = (ring_buffer_pos_t)(t + 1) & (RX_BUFFER_SIZE - 1);// Advance tail - Making sure the RX ISR will always get an stable value, even// if it interrupts the writing of the value of that variable in the middle.atomic_set_rx_tail(t);#if ENABLED(SERIAL_XON_XOFF)// If the XOFF char was sent, or about to be sent...if ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XOFF_CHAR) {// Get count of bytes in the RX bufferconst ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(h - t) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);if (rx_count < (RX_BUFFER_SIZE) / 10) {#if TX_BUFFER_SIZE > 0// Signal we want an XON character to be sent.xon_xoff_state = XON_CHAR;// Enable TX ISR. Non atomic, but it will eventually enable themSBI(M_UCSRxB, M_UDRIEx);#else// If not using TX interrupts, we must send the XON char nowxon_xoff_state = XON_CHAR | XON_XOFF_CHAR_SENT;while (!TEST(M_UCSRxA, M_UDREx)) sw_barrier();M_UDRx = XON_CHAR;#endif}}#endifreturn v;}ring_buffer_pos_t MarlinSerial::available(void) {const ring_buffer_pos_t h = atomic_read_rx_head(), t = rx_buffer.tail;return (ring_buffer_pos_t)(RX_BUFFER_SIZE + h - t) & (RX_BUFFER_SIZE - 1);}void MarlinSerial::flush(void) {// Set the tail to the head:// - Read the RX head index in a safe way. (See atomic_read_rx_head.)// - Set the tail, making sure the RX ISR will always get a stable value, even// if it interrupts the writing of the value of that variable in the middle.atomic_set_rx_tail(atomic_read_rx_head());#if ENABLED(SERIAL_XON_XOFF)// If the XOFF char was sent, or about to be sent...if ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XOFF_CHAR) {#if TX_BUFFER_SIZE > 0// Signal we want an XON character to be sent.xon_xoff_state = XON_CHAR;// Enable TX ISR. Non atomic, but it will eventually enable it.SBI(M_UCSRxB, M_UDRIEx);#else// If not using TX interrupts, we must send the XON char nowxon_xoff_state = XON_CHAR | XON_XOFF_CHAR_SENT;while (!TEST(M_UCSRxA, M_UDREx)) sw_barrier();M_UDRx = XON_CHAR;#endif}#endif}#if TX_BUFFER_SIZE > 0void MarlinSerial::write(const uint8_t c) {_written = true;// If the TX interrupts are disabled and the data register// is empty, just write the byte to the data register and// be done. This shortcut helps significantly improve the// effective datarate at high (>500kbit/s) bitrates, where// interrupt overhead becomes a slowdown.// Yes, there is a race condition between the sending of the// XOFF char at the RX ISR, but it is properly handled thereif (!TEST(M_UCSRxB, M_UDRIEx) && TEST(M_UCSRxA, M_UDREx)) {M_UDRx = c;// clear the TXC bit -- "can be cleared by writing a one to its bit// location". This makes sure flush() won't return until the bytes// actually got writtenSBI(M_UCSRxA, M_TXCx);return;}const uint8_t i = (tx_buffer.head + 1) & (TX_BUFFER_SIZE - 1);// If global interrupts are disabled (as the result of being called from an ISR)...if (!ISRS_ENABLED()) {// Make room by polling if it is possible to transmit, and do so!while (i == tx_buffer.tail) {// If we can transmit another byte, do it.if (TEST(M_UCSRxA, M_UDREx)) _tx_udr_empty_irq();// Make sure compiler rereads tx_buffer.tailsw_barrier();}}else {// Interrupts are enabled, just wait until there is spacewhile (i == tx_buffer.tail) { sw_barrier(); }}// Store new char. head is always safe to movetx_buffer.buffer[tx_buffer.head] = c;tx_buffer.head = i;// Enable TX ISR - Non atomic, but it will eventually enable TX ISRSBI(M_UCSRxB, M_UDRIEx);}void MarlinSerial::flushTX(void) {// No bytes written, no need to flush. This special case is needed since there's// no way to force the TXC (transmit complete) bit to 1 during initialization.if (!_written) return;// If global interrupts are disabled (as the result of being called from an ISR)...if (!ISRS_ENABLED()) {// Wait until everything was transmitted - We must do polling, as interrupts are disabledwhile (tx_buffer.head != tx_buffer.tail || !TEST(M_UCSRxA, M_TXCx)) {// If there is more space, send an extra characterif (TEST(M_UCSRxA, M_UDREx))_tx_udr_empty_irq();sw_barrier();}}else {// Wait until everything was transmittedwhile (tx_buffer.head != tx_buffer.tail || !TEST(M_UCSRxA, M_TXCx)) sw_barrier();}// At this point nothing is queued anymore (DRIE is disabled) and// the hardware finished transmission (TXC is set).}#else // TX_BUFFER_SIZE == 0void MarlinSerial::write(const uint8_t c) {_written = true;while (!TEST(M_UCSRxA, M_UDREx)) sw_barrier();M_UDRx = c;}void MarlinSerial::flushTX(void) {// No bytes written, no need to flush. This special case is needed since there's// no way to force the TXC (transmit complete) bit to 1 during initialization.if (!_written) return;// Wait until everything was transmittedwhile (!TEST(M_UCSRxA, M_TXCx)) sw_barrier();// At this point nothing is queued anymore (DRIE is disabled) and// the hardware finished transmission (TXC is set).}#endif // TX_BUFFER_SIZE == 0/*** Imports from print.h*/void MarlinSerial::print(char c, int base) {print((long)c, base);}void MarlinSerial::print(unsigned char b, int base) {print((unsigned long)b, base);}void MarlinSerial::print(int n, int base) {print((long)n, base);}void MarlinSerial::print(unsigned int n, int base) {print((unsigned long)n, base);}void MarlinSerial::print(long n, int base) {if (base == 0) write(n);else if (base == 10) {if (n < 0) { print('-'); n = -n; }printNumber(n, 10);}elseprintNumber(n, base);}void MarlinSerial::print(unsigned long n, int base) {if (base == 0) write(n);else printNumber(n, base);}void MarlinSerial::print(double n, int digits) {printFloat(n, digits);}void MarlinSerial::println(void) {print('\r');print('\n');}void MarlinSerial::println(const String& s) {print(s);println();}void MarlinSerial::println(const char c[]) {print(c);println();}void MarlinSerial::println(char c, int base) {print(c, base);println();}void MarlinSerial::println(unsigned char b, int base) {print(b, base);println();}void MarlinSerial::println(int n, int base) {print(n, base);println();}void MarlinSerial::println(unsigned int n, int base) {print(n, base);println();}void MarlinSerial::println(long n, int base) {print(n, base);println();}void MarlinSerial::println(unsigned long n, int base) {print(n, base);println();}void MarlinSerial::println(double n, int digits) {print(n, digits);println();}// Private Methodsvoid MarlinSerial::printNumber(unsigned long n, uint8_t base) {if (n) {unsigned char buf[8 * sizeof(long)]; // Enough space for base 2int8_t i = 0;while (n) {buf[i++] = n % base;n /= base;}while (i--)print((char)(buf[i] + (buf[i] < 10 ? '0' : 'A' - 10)));}elseprint('0');}void MarlinSerial::printFloat(double number, uint8_t digits) {// Handle negative numbersif (number < 0.0) {print('-');number = -number;}// Round correctly so that print(1.999, 2) prints as "2.00"double rounding = 0.5;for (uint8_t i = 0; i < digits; ++i)rounding *= 0.1;number += rounding;// Extract the integer part of the number and print itunsigned long int_part = (unsigned long)number;double remainder = number - (double)int_part;print(int_part);// Print the decimal point, but only if there are digits beyondif (digits) {print('.');// Extract digits from the remainder one at a timewhile (digits--) {remainder *= 10.0;int toPrint = int(remainder);print(toPrint);remainder -= toPrint;}}}// PreinstantiateMarlinSerial customizedSerial;#endif // USE_MARLINSERIAL && (UBRRH || UBRR0H || UBRR1H || UBRR2H || UBRR3H)// For AT90USB targets use the UART for BT interfacing#if !USE_MARLINSERIAL && ENABLED(BLUETOOTH)HardwareSerial bluetoothSerial;#endif