Find way to get rid of compiler warnings

[SpenceKonde]

The 1634, 828, and x41 chips give warnings about int-to-pointer cast. I do not know how to make these warnings go away without changing the progmem byte arrays to ints, and thus wasting flash space.

I have not been able to find a compiler flag to turn off the warnings. Some posts discussing this confidently asserted that there was no such flag, and spoke of the thing it was warning about in such terms as if I wished to shake hands with Satan himself, and you should never disable the warning because there's no legitimate reason to do it (clearly said by people who don't write code that has to fit in 1024 instruction words).

However, other posts I have read imply that there's an easy work around that nobody bothered talking about because it's so obvious. I have no idea, and consider this a low priority as it does not impact compilation.

[MCUdude]

There are some other (and minor) warnings as well. When compiling any code for any microcontroller I get these warnings. These are really easy to fix

/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/WInterrupts.c:38:1: warning: 'static' is not at beginning of declaration [-Wold-style-declaration]
 volatile static voidFuncPtr intFunc[NUMBER_EXTERNAL_INTERRUPTS];
 ^

/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/TinySoftwareSPI.cpp:80:6: warning: unused parameter '_data' [-Wunused-parameter]
 byte SoftSPIClass::noTransfer(byte _data){
      ^

/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/TinySoftwareSPI.cpp:211:6: warning: unused parameter 'rate' [-Wunused-parameter]
 void SoftSPIClass::setClockDivider(uint8_t rate)
      ^
/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/WString.cpp: In member function 'int String::lastIndexOf(char, unsigned int) const':
/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/WString.cpp:551:38: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (fromIndex >= len || fromIndex < 0) return -1;
                                      ^
/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/WString.cpp: In member function 'int String::lastIndexOf(const String&, unsigned int) const':
/Users/Hans/Documents/Arduino/hardware/ATTinyCore-master/avr/cores/tiny/WString.cpp:567:63: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
    if (s2.len == 0 || len == 0 || s2.len > len || fromIndex < 0) return -1;
                                                               ^

When it comes to all the warnings for the 1634, 441/841 and 828 I have no idea.. The Arduino team chose the easiest way:

const uint16_t PROGMEM port_to_mode_PGM[] = {
    NOT_A_PORT,
    NOT_A_PORT,
    (uint16_t) &DDRB,
    (uint16_t) &DDRC,
    (uint16_t) &DDRD,
};

[SpenceKonde]

Huh! That's a new warning, then.... I did not see that warning before from static not being first before. That's a fucking dumbass thing to warn about, too!

Interesting about the String warnings, I'll need to look into what the right way to fix that is. I had not seen them - maybe they're only from non-modern tiny's? I don't build for those very often (though they used to build clean, I thought).

The tinysoftspi things are debris that needs to be excised from the core and replaced with #53 - I've almost finished an SPI version of that, and I think a master only wire one will be straightforward.

Yeah - but the way they did it wastes flash space. I refuse to make my core worse in a functional sense just to get rid of warnings.

[bperrybap]

with a cast like this:

  (uint8_t) (uint16_t)(&DDRA),

or this:

  (uint8_t) (int)(&DDRA),

In the larger picture of flash space, when the pin count is small, a ternary is more efficient than having a table lookup from flash on the AVR because the AVR doesn't support direct access to flash which makes flash lookups expensive.

i.e. if the digitalPinToXXX() and portXXXRegister() macros were in the pins_arduino.h header file down in the variant directory for the "board" then the variant pins_arduino.h file could decide whether to use a table in flash or a simple ternary for the operation depending on which was more efficient.

On small pin numbered devices the ternary would be less code and faster lookups which would increase the speed of things like digitalWrite(), particularly when the pin numbers are constants since the ternary will be completely optimized away at compile time and replaced with the final result.

[sleemanj]

if the digitalPinToXXX() and portXXXRegister() macros were in the pins_arduino.h header file dow

This is what I did in my fork for 4/5/9/10/13/x4 and x5...
https://github.com/sleemanj/ATTinyCore/blob/master/avr/variants/tinyX5/pins_arduino.h#L216

increase the speed of things like digitalWrite()

I also optimise pinMode, digitalWrite for compile-time-known situations...
https://github.com/sleemanj/ATTinyCore/blob/master/avr/cores/tiny/Arduino.h#L174