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Commit Graph

80 Commits

Author SHA1 Message Date
Matt Robinson
cd9657ffd0 Clean up unused var from HardwareSerial_private.h 2014-01-28 20:39:15 +00:00
Matthijs Kooijman
9ad14b2f0c In HardwareSerial::write, bypass the queue when it's empty
This helps improve the effective datarate on high (>500kbit/s) bitrates,
by skipping the interrupt and associated overhead. At 1 Mbit/s the
implementation previously got up to about 600-700 kbit/s, but now it
actually gets up to the 1Mbit/s (values are rough estimates, though).
2014-01-22 12:06:02 +01:00
Cristian Maglie
275c0a02b1 Inlined HardwareSerial calls to RX ISR.
Moreover, declaring pointers-to-registers as const and using initializer
list in class constructor allows the compiler to further improve inlining
performance.

This change recovers about 50 bytes of program space on single-UART devices.

See #1711
2014-01-22 11:19:35 +01:00
Matthijs Kooijman
0e97bcb2df Put each HardwareSerial instance in its own .cpp file
By putting the ISRs and HardwareSerial instance for each instance in a
separate compilation unit, the compile will only consider them for
linking when the instance is actually used. The ISR is always referenced
by the compiler runtime and the Serialx_available() function is always
referenced by SerialEventRun(), but both references are weak and thus do
not cause the compilation to be included in the link by themselves.

The effect of this is that when multiple HardwareSerial ports are
available, but not all are used, buffers are only allocated and ISRs are
only included for the serial ports that are used. On the mega, this
lowers memory usage from 653 bytes to just 182 when only using the first
serial port.

On boards with just a single port, there is no change, since the code
and memory was already left out when no serial port was used at all.

This fixes #1425 and fixes #1259.
2014-01-22 09:39:19 +01:00
Matthijs Kooijman
8e43c1a0cd Centrally decide which hardware UARTS are available
Before, this decision was made in few different places, based on
sometimes different register defines.

Now, HardwareSerial.h decides wich UARTS are available, defines
USE_HWSERIALn macros and HardwareSerial.cpp simply checks these macros
(together with some #ifs to decide which registers to use for UART 0).
For consistency, USBAPI.h also defines a HAVE_CDCSERIAL macro when
applicable.

For supported targets, this should change any behaviour. For unsupported
targets, the error messages might subtly change because some checks are
moved or changed.

Additionally, this moves the USBAPI.h include form HardareSerial.h into
Arduino.h and raises an error when both CDC serial and UART0 are
available (previously this would silently use UART0 instead of CDC, but
there is not currently any Atmel chip available for which this would
occur).
2014-01-22 09:38:34 +01:00
Matthijs Kooijman
0be4e8cd3c Disable the UDRE interrupt sooner in HardwareSerial
Before, the interrupt was disabled when it was triggered and it turned
out there was no data to send. However, the interrupt can be disabled
already when the last byte is written to the UART, since write() will
always re-enable the interrupt when it adds new data to the buffer.

Closes: #1008
2014-01-22 09:38:25 +01:00
Matthijs Kooijman
ccd8880a37 Fix lockup when writing to HardwareSerial with interrupts disabled
When interrupts are disabled, writing to HardwareSerial could cause a
lockup. When the tx buffer is full, a busy-wait loop is used to wait for
the interrupt handler to free up a byte in the buffer. However, when
interrupts are disabled, this will of course never happen and the
Arduino will lock up. This often caused lockups when doing (big) debug
printing from an interrupt handler.

Additionally, calling flush() with interrupts disabled while
transmission was in progress would also cause a lockup.

When interrupts are disabled, the code now actively checks the UDRE
(UART Data Register Empty) and calls the interrupt handler to free up
room if the bit is set.

This can lead to delays in interrupt handlers when the serial buffer is
full, but a delay is of course always preferred to a lockup.

Closes: #672
References: #1147
2014-01-22 09:38:16 +01:00
Matthijs Kooijman
4fb15f29ed Fix HardwareSerial::flush() when interrupts are kept disabled for a while
It turns out there is an additional corner case. The analysis in the
previous commit wrt to flush() assumes that the data register is always
kept filled by the interrupt handler, so the TXC bit won't get set until
all the queued bytes have been transmitted. But, when interrupts are
disabled for a longer period (for example when an interrupt handler for
another device is running for longer than 1-2 byte times), it could
happen that the UART stops transmitting while there are still more bytes
queued (but these are in the buffer, not in the UDR register, so the
UART can't know about them).

In this case, the TXC bit would get set, but the transmission is not
complete yet. We can easily detect this case by looking at the head and
tail pointers, but it seems easier to instead look at the UDRIE bit
(the TX interrupt is enabled if and only if there are bytes in the
queue). To fix this corner case, this commit:
 - Checks the UDRIE bit and only if it is unset, looks at the TXC bit.
 - Moves the clearing of TXC from write() to the tx interrupt handler.
   This (still) causes the TXC bit to be cleared whenever a byte is
   queued when the buffer is empty (in this case the tx interrupt will
   trigger directly after write() is called). It also causes the TXC bit
   to be cleared whenever transmission is resumed after it halted
   because interrupts have been disabled for too long.

As a side effect, another race condition is prevented. This could occur
at very high bitrates, where the transmission would be completed before
the code got time to clear the TXC0 register, making the clear happen
_after_ the transmission was already complete. With the new code, the
clearing of TXC happens directly after writing to the UDR register,
while interrupts are disabled, and we can be certain the data
transmission needs more time than one instruction to complete. This
fixes #1463 and replaces #1456.
2014-01-22 09:38:04 +01:00
Matthijs Kooijman
3d346518e0 Improve HardwareSerial::flush()
The flush() method blocks until all characters in the serial buffer have
been written to the uart _and_ transmitted. This is checked by waiting
until the "TXC" (TX Complete) bit is set by the UART, signalling
completion. This bit is cleared by write() when adding a new byte to the
buffer and set by the hardware after tranmission ends, so it is always
guaranteed to be zero from the moment the first byte in a sequence is
queued until the moment the last byte is transmitted, and it is one from
the moment the last byte in the buffer is transmitted until the first
byte in the next sequence is queued.

However, the TXC bit is also zero from initialization to the moment the
first byte ever is queued (and then continues to be zero until the first
sequence of bytes completes transmission). Unfortunately we cannot
manually set the TXC bit during initialization, we can only clear it. To
make sure that flush() would not (indefinitely) block when it is called
_before_ anything was written to the serial device, the "transmitting"
variable was introduced.

This variable suggests that it is only true when something is
transmitting, which isn't currently the case (it remains true after
transmission is complete until flush() is called, for example).
Furthermore, there is no need to keep the status of transmission, the
only thing needed is to remember if anything has ever been written, so
the corner case described above can be detected.

This commit improves the code by:
 - Renaming the "transmitting" variable to _written (making it more
   clear and following the leading underscore naming convention).
 - Not resetting the value of _written at the end of flush(), there is
   no point to this.
 - Only checking the "_written" value once in flush(), since it can
   never be toggled off anyway.
 - Initializing the value of _written in both versions of _begin (though
   it probably gets initialized to 0 by default anyway, better to be
   explicit).
2014-01-22 09:37:54 +01:00
Matthijs Kooijman
722675bd1f Use bit_is_clear in HardwareSerial::flush()
This is slightly more clear than the previous explicit comparison.
2014-01-22 09:37:44 +01:00
Matthijs Kooijman
03fac844a8 Move interrupt handlers into HardwareSerial class
The actual interrupt vectors are of course defined as before, but they
let new methods in the HardwareSerial class do the actual work. This
greatly reduces code duplication and prepares for one of my next commits
which requires the tx interrupt handler to be called from another
context as well.

The actual content of the interrupts handlers was pretty much identical,
so that remains unchanged (except that store_char was now only needed
once, so it was inlined).

Now all access to the buffers are inside the HardwareSerial class, the
buffer variables can be made private.

One would expect a program size reduction from this change (at least
with multiple UARTs), but due to the fact that the interrupt handlers
now only have indirect access to a few registers (which previously were
just hardcoded in the handlers) and because there is some extra function
call overhead, the code size on the uno actually increases by around
70 bytes. On the mega, which has four UARTs, the code size decreases by
around 70 bytes.
2014-01-16 16:59:06 +01:00
Matthijs Kooijman
e40cf5b7b8 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.
2014-01-16 16:36:06 +01:00
Matthijs Kooijman
6ac8185c08 Define a _NOP() macro
Recent avr-libc releases define one, but this allows using it also on
older avr-libc releases.
2014-01-16 16:29:41 +01:00
Matthijs Kooijman
6cce4787bf Simplify HardwareSerial::begin()
This simplifies the baud rate calculation, removing the need for a goto
and shortening the code a bit. Other than that, this code should not use
any different settings than before.

Code was suggested by Rob Tillaart on github.

Closes: #1262
2014-01-16 16:04:33 +01:00
Matthijs Kooijman
db5da3691e Remove unused variable 2014-01-16 13:52:40 +01:00
Cristian Maglie
1fab8c85e6 Slightly reduce code utilization by inlining HardwareSerail begin(baud) and operator bool() 2014-01-16 13:50:59 +01:00
Matthijs Kooijman
f35ec75dce Remove duplicate code from HardwareSerial::begin() methods.
There are two begin methods, one which accepts just a baud rate and
uses the default bit settings and one which accepts both a baudrate and
a bit config. Previously, both of these contained a complete
implementation, but now the former just calls the latter, explicitely
passing the default 8N1 configuration.

Technically, this causes a small change: Before the UCSRC register was
untouched when calling begin(baud), now it is explicitely initialized
with 8N1. However, since this is the default configuration for at least
the Uno and the Mega (didn't check any others), probably for all avrs,
this shouldn't effectively change anything. Given that the Arduino
documentation also documents this as the default when none is passed,
explicitly setting it is probably a good idea in any case.
2014-01-16 13:20:11 +01:00
Matthijs Kooijman
dde1a7541f Make some operators in IPAddress const
These functions do not modify the IPAddress object, but were not marked
as const. This meant that you could not do:

void set_ip(const IPAddress& ip) {
	uint32_t copy = ip;
}

Since calling operator uint32_t() on ip would discard the constness of
the reference.
2014-01-15 16:20:48 +01:00
Federico Fissore
dfe77f388d Removed = char from #define. See https://github.com/arduino/Arduino/issues/1792#issuecomment-31650586 2014-01-06 18:20:37 +01:00
Federico Fissore
9fce7f1839 Added new EULER constant. Fixes #1792 2014-01-06 09:48:34 +01:00
Cristian Maglie
673847c8b6 Improved portability of String class (maniacbug) 2014-01-01 17:22:40 +01:00
Cristian Maglie
ffddfc81f6 Merge branch 'cast' of github.com:Lauszus/Arduino into Lauszus-cast
Conflicts:
	hardware/arduino/avr/cores/arduino/Print.cpp
2013-12-31 20:11:08 +01:00
Matthijs Kooijman
98777e816f Use PGM_P instead of prog_char
On later versions of avr-libc, prog_char is deprecated. In 0acebeeff4
the one occurence of prog_char was replaced by "char PROGMEM", which is
not entirely correct (PROGMEM is supposed to be an attribute on a
variable, not on a type, even though this is how things work in older
libc versions). However, in 1130fede3a a few new occurences of
prog_char are introduced, which break compilation on newer libc versions
again.

This commit changes all these pointer types to use the PGM_P macro from
<avr/pgmspace.h>. This macro is just "const char *" in newer libc
versions and "const prog_char *" in older versions, so it should always
work.

References #795
2013-12-31 20:01:40 +01:00
Kristian Lauszus
5d361f5f47 Use reinterpret_cast to cast __FlashStringHelper to const char* 2013-12-27 20:01:03 +01:00
Matthijs Kooijman
2ea12d0220 Remove unneeded casts in Print::write(const String&)
Now that Print::write(const char*) is also available, these casts are no
longer needed.
2013-12-24 13:22:43 +01:00
Matthijs Kooijman
f304abe35f Add uint8_t* versions of methods in Stream
The new functions just call their char* equivalents, but this allows
reading bytes into a buffer of uint8_t as well as chars.
2013-12-24 13:22:42 +01:00
Matthijs Kooijman
250386802f Add Print::write(const char *, size_t)
The new function just calls Print::write(const uint8_t *, size_t), but
this allows writing out a buffer of chars (without having to learn about
casts).
2013-12-24 13:22:42 +01:00
Federico Fissore
88a2ca18fd Print.print optimization. Closes #1760 2013-12-23 11:50:39 +01:00
Cristian Maglie
8f1e3fd703 Using NOT_AN_INTERRUPT defined constant 2013-10-31 12:44:24 +01:00
Cristian Maglie
dc86455097 Merge branch 'master' into ide-1.5.x 2013-09-30 16:25:10 +02:00
Cristian Maglie
d4fe0a13b6 Merge branch 'ide-1.5.x' into dev-ide-1.5.x-discovery
Conflicts:
	build/shared/revisions.txt
2013-09-10 12:10:57 +02:00
Cristian Maglie
cd7196c592 Fixed HardwareSerial bug introduced in 1.5.3.
Fixes #1568
2013-09-09 13:09:27 +02:00
Federico Fissore
effb59da4b Merge remote-tracking branch 'arduino/ide-1.5.x' into dev-ide-1.5.x-discovery 2013-09-06 12:59:24 +02:00
Cristian Maglie
c86eed942d Fixed String class regression after f80c6c5f35
This should make explicit String-from-integer constructor working again:

   int a = 10;
   String(a, 4);
2013-09-03 18:40:30 +02:00
Cristian Maglie
ea8c14421a Merge branch 'ide-1.5.x' into dev-ide-1.5.x-discovery
Conflicts:
	app/src/processing/app/Preferences.java
	app/src/processing/app/debug/Uploader.java
2013-08-23 15:59:24 +02:00
Cristian Maglie
fc338b461f Merged robot core 2013-08-22 16:29:49 +02:00
Cristian Maglie
00210189fe Removed unused flags from String (free 1 byte of SRAM) 2013-08-20 15:15:47 +02:00
Cristian Maglie
ab82b1a405 Merge branch 'master' into ide-1.5.x 2013-07-31 17:33:55 +02:00
Cristian Maglie
0b632dba47 Merge branch 'ide-1.5.x' into dev-ide-1.5.x-discovery
Conflicts:
	hardware/arduino/avr/cores/arduino/USBCore.cpp
2013-07-30 10:45:44 +02:00
Cristian Maglie
d3be60ead6 Applied USB CDC updates to robot's core. 2013-07-30 10:39:41 +02:00
Cristian Maglie
8c1ce45531 Move buffers into USB CDC (look #947 and #1369 for reference) 2013-07-27 12:06:42 +02:00
Cristian Maglie
4055ac13f3 Applied HardwareSerial updates to robot's core. 2013-07-26 13:50:34 +02:00
Cristian Maglie
ae4427f2ea Fixed compile problem for Leonardo after 0bd6a2d20f 2013-07-26 12:50:17 +02:00
Matthijs Kooijman
f50372a2a6 Make private members of HardwareSerial protected
This allows users to create subclasses.

Closes: #947
2013-07-26 12:41:35 +02:00
Matthijs Kooijman
0bd6a2d20f Move buffers into HardwareSerial
This removes the need for doing an extra pointer dereference on every
access to the buffers, shrinking the code by around 100 bytes.

The members for these buffers must be public for now, since the
interrupt handlers also need to access them. These can later be made
private again.

Furthermore, the struct ring_buffer was removed. This allows the all
head and tail pointers to be put into the HardwareSerial struct before
the actual buffers, so the pointers all end up in the first 32 bytes of
the struct that can be accessed using a single instruction (ldd).

References: #947
2013-07-26 12:39:56 +02:00
Matthijs Kooijman
e0a9a7676b Use uint8_t for HardwareSerial ringbuffer pointers
Since the buffers aren't bigger than 64 bytes, these values can be
smaller. This saves a few bytes of ram, but also saves around 50 bytes
of program space, since the values can now be loaded using a single
instruction.

To prevent problems when people manually increase the buffer size, a
compile-time check is added.

Closes: #1078
2013-07-26 12:18:56 +02:00
Angus Gratton
1a99be33a3 Remove hardcoded product names (all provided for in boards.txt) 2013-07-17 14:38:05 +02:00
Angus Gratton
6abdeecbf5 Fix whitespace (tabify), oops 2013-07-17 14:37:49 +02:00
Angus Gratton
15e73e8daa Allow USB product and manufacturer strings to be supplied in boards.txt 2013-07-17 14:37:29 +02:00
Cristian Maglie
34885b019b Refactored YunClient and YunServer classes.
Added YunClient.connect() methods.
2013-07-04 17:15:52 +02:00