Added multi address slave

[corna]

I've removed the pullups enable in twi.c and I've moved it in Wire.cpp in order to make twi.h/twi.c usable in pure avr-libc projects
I've also added the multi address slave capability; the device can now respond multiple addresses (when configured as slave), and know which one was called thanks to twi_slaveAddress (in twi.c) or TwoWire::slaveAddress (in Wire.cpp). This feature is not supported on uCs without the TWAMR (two wire address mask register), like the ATMega8, and it is disabled with an #ifdef
These boards are:

• Serial Arduino
• Arduino USB
• Arduino Extreme
• Arduino NG (first version)

[corna]

• As reported here, stdbool.h is only supported in latest c++ revision, so I wasn't sure if I could safely add it. Should I include stdbool.h or leave the code as it is?
• compat/twi.c is a typo, I'll fix it later. compat/twi.h simply includes util/twi.h, it was moved nine years ago, I'll add this in the commit message later
• I wasn't sure, therefore I simply followed the original code's style. I'll try
• To make the new version backward compatible, I can replace setAddress with a macro like this #define setAddress(address) setAddressAndMask((address), 0x00)
• Ok, I can define a stub setAddressAndMask that calls setAddress without a mask and print a #warning, in unsupported devices

[matthijskooijman]

As reported here, stdbool.h is only supported in latest c++ revision, so I wasn't sure if I could safely add it. Should I include stdbool.h or leave the code as it is?

According to this, stdbool.h was supported in C (not C++) since C99.

To make the new version backward compatible, I can replace setAddress with a macro like this #define setAddress(address) setAddressAndMask((address), 0x00)

Better not use a macro, but just a static inline function instead (macros get messy quickly, inline function should have the exactly same effect).

Ok, I can define a stub setAddressAndMask that calls setAddress without a mask and print a #warning, in unsupported devices

I'm not sure that a #warning actually triggers when a function is used, or when the function is defiend (e.g. when the preprocessor didnt' remove the #warning). In the latter case, perhaps the "deprecated" or "warning" function attribute may help, see https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html (note that "warning" is only mentioned at the top, but I suspect it works just like "deprecated").

[corna]

I've added the gcc attribute warning that prints a warning only if the function is called somewhere in a microcontroller that doesn't have the TWAMR register. If you don't call it, it doesn't complain.
Last question is: should I remove the double definition for:

void begin(uint8_t);
void begin(int);

void begin(uint8_t, uint8_t);
void begin(int, int);

uint8_t requestFrom(uint8_t, uint8_t);
uint8_t requestFrom(int, int);

uint8_t requestFrom(uint8_t, uint8_t, uint8_t);
uint8_t requestFrom(int, int, int);

The int versions of these functions just call the uint8_t versions casting explicitely the arguments to uint8_t. For example,

uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
{
     return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
}

Is that really necessary? Doesn't the compiler automatically cast them to uint8_t without any complaint or drawback?

[corna]

Also, if you call a function with an argument that exceeds the 8-bit limit, the uint8_t function prints an implicit truncation warning (which is good, the user must know that the function does not accept that argument), while with the overloaded int function doesn't

[corna]

I've committed any requested fix. Can you merge it?

[ffissore]

Sorry for the late reply @corna. After 1.6 release, your PR does not merge any more. Can you update it? We'll make the bot build a test IDE then, so to make others test your patch more easily.

[corna]

Rebased successfully
I've squashed some commits in order to keep the history clean
The latest Arduino IDE doesn't show the unsupported warning anymore, even if i manually create a

#warning Unsupported on this AVR

Is it correct?

[matthijskooijman]

Warnings not being shown is a known issue, see #1728.

[ffissore]

@ArduinoBot build this please

[ArduinoBot]

Build failed.

[corna]

Weird, I've built it successfully on my PC... Do you have the build log?

[ffissore]

An error in the job configuration. Fixed

[ffissore]

@ArduinoBot build this please

[ffissore]

Sorry it looks like I broke our bot

[ffissore]

@ArduinoBot build this please

[ArduinoBot]

Build successful. Please test this code using one of the following:
http://arduino.cc/download.php?f=/javaide/pull_requests/arduino-PR-2403-BUILD-183-linux32.tar.xz
http://arduino.cc/download.php?f=/javaide/pull_requests/arduino-PR-2403-BUILD-183-linux64.tar.xz
http://arduino.cc/download.php?f=/javaide/pull_requests/arduino-PR-2403-BUILD-183-windows.zip
http://arduino.cc/download.php?f=/javaide/pull_requests/arduino-PR-2403-BUILD-183-macosx.zip
http://arduino.cc/download.php?f=/javaide/pull_requests/arduino-PR-2403-BUILD-183-macosx-java-latest.zip

[corna]

I don't have an Arduino at the moment, but I've previously tested it with an ATmega328P. The ATmega had an address mask of 0x08 (8 addresses) and it was able to manage each one independently.
Can someone test it with an Arduino?
Thanks

[ffissore]

I've added a new preference "show all compiler warnings" that turns warnings on
Available as nightly builds in the next few hours

[raphaelcoeffic]

@corna , @ffissore: do you guys still see a possibility to get that merged into mainline? That would be quite useful I think.

[ffissore]

Sorry you've missed the news, but I don't work for arduino any more. See https://groups.google.com/a/arduino.cc/forum/#!msg/developers/YJLX6AZHem4/kpsLef7XBAAJ

[raphaelcoeffic]

@ffissore Thx for the reply & good luck where you are now!

[raphaelcoeffic]

@cmaglie Is there any chance to have this pull request integrated into mainline some time in the future? Thx a lot!

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