ArduinoCore-avr/cores/arduino/HardwareSerial.cpp

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/*
HardwareSerial.cpp - Hardware serial library for Wiring
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Modified 23 November 2006 by David A. Mellis
Modified 28 September 2010 by Mark Sproul
Modified 14 August 2012 by Alarus
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "Arduino.h"
#include "wiring_private.h"
// this next line disables the entire HardwareSerial.cpp,
// this is so I can support Attiny series and any other chip without a uart
#if defined(UBRRH) || defined(UBRR0H) || defined(UBRR1H) || defined(UBRR2H) || defined(UBRR3H)
#include "HardwareSerial.h"
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
// Ensure that the various bit positions we use are available with a 0
// postfix, so we can always use the values for UART0 for all UARTs. The
// alternative, passing the various values for each UART to the
// HardwareSerial constructor also works, but makes the code bigger and
// slower.
#if !defined(TXC0)
#if defined(TXC)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
// On ATmega8, the uart and its bits are not numbered, so there is no TXC0 etc.
#define TXC0 TXC
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
#define RXEN0 RXEN
#define TXEN0 TXEN
#define RXCIE0 RXCIE
#define UDRIE0 UDRIE
#define U2X0 U2X
#define UPE0 UPE
#define UDRE0 UDRE
#elif defined(TXC1)
// Some devices have uart1 but no uart0
#define TXC0 TXC1
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
#define RXEN0 RXEN1
#define TXEN0 TXEN1
#define RXCIE0 RXCIE1
#define UDRIE0 UDRIE1
#define U2X0 U2X1
#define UPE0 UPE1
#define UDRE0 UDRE1
#else
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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#error No UART found in HardwareSerial.cpp
#endif
#endif // !defined TXC0
// Check at compiletime that it is really ok to use the bit positions of
// UART0 for the other UARTs as well, in case these values ever get
// changed for future hardware.
#if defined(TXC1) && (TXC1 != TXC0 || RXEN1 != RXEN0 || RXCIE1 != RXCIE0 || \
UDRIE1 != UDRIE0 || U2X1 != U2X0 || UPE1 != UPE0 || \
UDRE1 != UDRE0)
#error "Not all bit positions for UART1 are the same as for UART0"
#endif
#if defined(TXC2) && (TXC2 != TXC0 || RXEN2 != RXEN0 || RXCIE2 != RXCIE0 || \
UDRIE2 != UDRIE0 || U2X2 != U2X0 || UPE2 != UPE0 || \
UDRE2 != UDRE0)
#error "Not all bit positions for UART2 are the same as for UART0"
#endif
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
#if defined(TXC3) && (TXC3 != TXC0 || RXEN3 != RXEN0 || RXCIE3 != RXCIE0 || \
UDRIE3 != UDRIE0 || U3X3 != U3X0 || UPE3 != UPE0 || \
UDRE3 != UDRE0)
#error "Not all bit positions for UART3 are the same as for UART0"
#endif
inline void store_char(unsigned char c, HardwareSerial *s)
{
int i = (unsigned int)(s->_rx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
// if we should be storing the received character into the location
// just before the tail (meaning that the head would advance to the
// current location of the tail), we're about to overflow the buffer
// and so we don't write the character or advance the head.
if (i != s->_rx_buffer_tail) {
s->_rx_buffer[s->_rx_buffer_head] = c;
s->_rx_buffer_head = i;
}
}
#if !defined(USART0_RX_vect) && defined(USART1_RX_vect)
// do nothing - on the 32u4 the first USART is USART1
#else
#if !defined(USART_RX_vect) && !defined(USART0_RX_vect) && \
!defined(USART_RXC_vect)
#error "Don't know what the Data Received vector is called for the first UART"
#else
void serialEvent() __attribute__((weak));
void serialEvent() {}
#define serialEvent_implemented
#if defined(USART_RX_vect)
ISR(USART_RX_vect)
#elif defined(USART0_RX_vect)
ISR(USART0_RX_vect)
#elif defined(USART_RXC_vect)
ISR(USART_RXC_vect) // ATmega8
#endif
{
#if defined(UDR0)
if (bit_is_clear(UCSR0A, UPE0)) {
unsigned char c = UDR0;
store_char(c, &Serial);
} else {
unsigned char c = UDR0;
};
#elif defined(UDR)
if (bit_is_clear(UCSRA, PE)) {
unsigned char c = UDR;
store_char(c, &Serial);
} else {
unsigned char c = UDR;
};
#else
#error UDR not defined
#endif
}
#endif
#endif
#if defined(USART1_RX_vect)
void serialEvent1() __attribute__((weak));
void serialEvent1() {}
#define serialEvent1_implemented
ISR(USART1_RX_vect)
{
if (bit_is_clear(UCSR1A, UPE1)) {
unsigned char c = UDR1;
store_char(c, &Serial1);
} else {
unsigned char c = UDR1;
};
}
#endif
#if defined(USART2_RX_vect) && defined(UDR2)
void serialEvent2() __attribute__((weak));
void serialEvent2() {}
#define serialEvent2_implemented
ISR(USART2_RX_vect)
{
if (bit_is_clear(UCSR2A, UPE2)) {
unsigned char c = UDR2;
store_char(c, &Serial2);
} else {
unsigned char c = UDR2;
};
}
#endif
#if defined(USART3_RX_vect) && defined(UDR3)
void serialEvent3() __attribute__((weak));
void serialEvent3() {}
#define serialEvent3_implemented
ISR(USART3_RX_vect)
{
if (bit_is_clear(UCSR3A, UPE3)) {
unsigned char c = UDR3;
store_char(c, &Serial3);
} else {
unsigned char c = UDR3;
};
}
#endif
void serialEventRun(void)
{
#ifdef serialEvent_implemented
if (Serial.available()) serialEvent();
#endif
#ifdef serialEvent1_implemented
if (Serial1.available()) serialEvent1();
#endif
#ifdef serialEvent2_implemented
if (Serial2.available()) serialEvent2();
#endif
#ifdef serialEvent3_implemented
if (Serial3.available()) serialEvent3();
#endif
}
#if !defined(USART0_UDRE_vect) && defined(USART1_UDRE_vect)
// do nothing - on the 32u4 the first USART is USART1
#else
#if !defined(UART0_UDRE_vect) && !defined(UART_UDRE_vect) && !defined(USART0_UDRE_vect) && !defined(USART_UDRE_vect)
#error "Don't know what the Data Register Empty vector is called for the first UART"
#else
#if defined(UART0_UDRE_vect)
ISR(UART0_UDRE_vect)
#elif defined(UART_UDRE_vect)
ISR(UART_UDRE_vect)
#elif defined(USART0_UDRE_vect)
ISR(USART0_UDRE_vect)
#elif defined(USART_UDRE_vect)
ISR(USART_UDRE_vect)
#endif
{
if (Serial._tx_buffer_head == Serial._tx_buffer_tail) {
// Buffer empty, so disable interrupts
#if defined(UCSR0B)
cbi(UCSR0B, UDRIE0);
#else
cbi(UCSRB, UDRIE);
#endif
}
else {
// There is more data in the output buffer. Send the next byte
unsigned char c = Serial._tx_buffer[Serial._tx_buffer_tail];
Serial._tx_buffer_tail = (Serial._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
#if defined(UDR0)
UDR0 = c;
#elif defined(UDR)
UDR = c;
#else
#error UDR not defined
#endif
}
}
#endif
#endif
#ifdef USART1_UDRE_vect
ISR(USART1_UDRE_vect)
{
if (Serial1._tx_buffer_head == Serial1._tx_buffer_tail) {
// Buffer empty, so disable interrupts
cbi(UCSR1B, UDRIE1);
}
else {
// There is more data in the output buffer. Send the next byte
unsigned char c = Serial1._tx_buffer[Serial1._tx_buffer_tail];
Serial1._tx_buffer_tail = (Serial1._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
UDR1 = c;
}
}
#endif
#ifdef USART2_UDRE_vect
ISR(USART2_UDRE_vect)
{
if (Serial2._tx_buffer_head == Serial2._tx_buffer_tail) {
// Buffer empty, so disable interrupts
cbi(UCSR2B, UDRIE2);
}
else {
// There is more data in the output buffer. Send the next byte
unsigned char c = Serial2._tx_buffer[Serial2._tx_buffer_tail];
Serial2._tx_buffer_tail = (Serial2._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
UDR2 = c;
}
}
#endif
#ifdef USART3_UDRE_vect
ISR(USART3_UDRE_vect)
{
if (Serial3._tx_buffer_head == Serial3._tx_buffer_tail) {
// Buffer empty, so disable interrupts
cbi(UCSR3B, UDRIE3);
}
else {
// There is more data in the output buffer. Send the next byte
unsigned char c = Serial3._tx_buffer[Serial3._tx_buffer_tail];
Serial3._tx_buffer_tail = (Serial3._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
UDR3 = c;
}
}
#endif
// Constructors ////////////////////////////////////////////////////////////////
HardwareSerial::HardwareSerial(
volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
volatile uint8_t *ucsrc, volatile uint8_t *udr)
{
_tx_buffer_head = _tx_buffer_tail = 0;
_rx_buffer_head = _rx_buffer_tail = 0;
_ubrrh = ubrrh;
_ubrrl = ubrrl;
_ucsra = ucsra;
_ucsrb = ucsrb;
_ucsrc = ucsrc;
_udr = udr;
}
// Public Methods //////////////////////////////////////////////////////////////
void HardwareSerial::begin(unsigned long baud, byte config)
{
// Try u2x mode first
uint16_t baud_setting = (F_CPU / 4 / baud - 1) / 2;
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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*_ucsra = 1 << U2X0;
// hardcoded exception for 57600 for compatibility with the bootloader
// shipped with the Duemilanove and previous boards and the firmware
// on the 8U2 on the Uno and Mega 2560. Also, The baud_setting cannot
// be > 4095, so switch back to non-u2x mode if the baud rate is too
// low.
if (((F_CPU == 16000000UL) && (baud == 57600)) || (baud_setting >4095))
{
*_ucsra = 0;
baud_setting = (F_CPU / 8 / baud - 1) / 2;
}
// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)
*_ubrrh = baud_setting >> 8;
*_ubrrl = baud_setting;
//set the data bits, parity, and stop bits
#if defined(__AVR_ATmega8__)
config |= 0x80; // select UCSRC register (shared with UBRRH)
#endif
*_ucsrc = config;
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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sbi(*_ucsrb, RXEN0);
sbi(*_ucsrb, TXEN0);
sbi(*_ucsrb, RXCIE0);
cbi(*_ucsrb, UDRIE0);
}
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void HardwareSerial::end()
{
// wait for transmission of outgoing data
while (_tx_buffer_head != _tx_buffer_tail)
;
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
2013-04-18 05:17:47 -07:00
cbi(*_ucsrb, RXEN0);
cbi(*_ucsrb, TXEN0);
cbi(*_ucsrb, RXCIE0);
cbi(*_ucsrb, UDRIE0);
// clear any received data
_rx_buffer_head = _rx_buffer_tail;
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}
int HardwareSerial::available(void)
{
return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail) % SERIAL_BUFFER_SIZE;
}
int HardwareSerial::peek(void)
{
if (_rx_buffer_head == _rx_buffer_tail) {
return -1;
} else {
return _rx_buffer[_rx_buffer_tail];
}
}
int HardwareSerial::read(void)
{
// if the head isn't ahead of the tail, we don't have any characters
if (_rx_buffer_head == _rx_buffer_tail) {
return -1;
} else {
unsigned char c = _rx_buffer[_rx_buffer_tail];
_rx_buffer_tail = (unsigned int)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
return c;
}
}
void HardwareSerial::flush()
{
// UDR is kept full while the buffer is not empty, so TXC triggers when EMPTY && SENT
while (transmitting && ! (*_ucsra & _BV(TXC0)));
transmitting = false;
}
size_t HardwareSerial::write(uint8_t c)
{
int i = (_tx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
// If the output buffer is full, there's nothing for it other than to
// wait for the interrupt handler to empty it a bit
// ???: return 0 here instead?
while (i == _tx_buffer_tail)
;
_tx_buffer[_tx_buffer_head] = c;
_tx_buffer_head = i;
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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sbi(*_ucsrb, UDRIE0);
// clear the TXC bit -- "can be cleared by writing a one to its bit location"
transmitting = true;
sbi(*_ucsra, TXC0);
return 1;
}
// Preinstantiate Objects //////////////////////////////////////////////////////
#if defined(UBRRH) && defined(UBRRL)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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HardwareSerial Serial(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR);
#elif defined(UBRR0H) && defined(UBRR0L)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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HardwareSerial Serial(&UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UCSR0C, &UDR0);
#elif defined(USBCON)
// do nothing - Serial object and buffers are initialized in CDC code
#else
#error no serial port defined (port 0)
#endif
#if defined(UBRR1H)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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HardwareSerial Serial1(&UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1);
#endif
#if defined(UBRR2H)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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HardwareSerial Serial2(&UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2);
#endif
#if defined(UBRR3H)
Use constants for register bit positions in HardwareSerial Previously, the constants to use for the bit positions of the various UARTs were passed to the HardwareSerial constructor. However, this meant that whenever these values were used, the had to be indirectly loaded, resulting in extra code overhead. Additionally, since there is no instruction to shift a value by a variable amount, the 1 << x expressions (inside _BV and sbi() / cbi()) would be compiled as a loop instead of being evaluated at compiletime. Now, the HardwareSerial class always uses the constants for the bit positions of UART 0 (and some code is present to make sure these constants exist, even for targets that only have a single unnumbered UART or start at UART1). This was already done for the TXC0 constant, for some reason. For the actual register addresses, this approach does not work, since these are of course different between the different UARTs on a single chip. Of course, always using the UART 0 constants is only correct when the constants are actually identical for the different UARTs. It has been verified that this is currently the case for all targets supported by avr-gcc 4.7.2, and the code contains compile-time checks to verify this for the current target, in case a new target is added for which this does not hold. This verification was done using: for i in TXC RXEN TXEN RXCIE UDRIE U2X UPE; do echo $i; grep --no-filename -r "#define $i[0-9]\? " /usr/lib/avr/include/avr/io* | sed "s/#define $i[0-9]\?\s*\(\S\)\+\s*\(\/\*.*\*\/\)\?$/\1/" | sort | uniq ; done This command shows that the above constants are identical for all uarts on all platforms, except for TXC, which is sometimes 6 and sometimes 0. Further investigation shows that it is always 6, except in io90scr100.h, but that file defines TXC0 with value 6 for the UART and uses TXC with value 0 for some USB-related register. This commit reduces program size on the uno by around 120 bytes.
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HardwareSerial Serial3(&UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3);
#endif
#endif // whole file