EDIT: Solved: Managed to find WInterrupts.c in C:\Users<USERNAME>\AppData\Roaming\Arduino15\packages\arduino\hardware\sam\1.6.4\cores\arduino
not sure if this is common but that's where is located in my installation, I can't remember if I did something strange when installing or if I had to add DUE at a later time than when I initially installed it.
antodom:
Hi all,I have made a small improvement to WInterrupts.c which allows a faster interrupt dispatching associated to generic I/O pins. That is, the callbacks we set with function attachInterrupt().
Basically I have modified the code of the interrupt handler functions PIOA_Handler(), PIOB_Handler(), PIOC_Handler() and PIOD_handler() in the original WInterrupts.c. The improvement consists mainly in taking advantage of ATSAM3XE assembler instruction CLZ. With this instruction it is possible to calculate the number of leading zeros in a 32 bit value in just one machine instruction. CLZ is available in C/C++ using CMSIS function __CLZ().
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@antodom & all
I'm drawing a blank here - I can't find the WInterrupts.c in my installation containing PIOA_Handler, PIOB_Handler, etc, just the one for AVR based boards. I searched the arduino installation folder and that's the only one I have. Any help locating it would be greatly appreciated, I have IDE v1.6.5
By the way, the __CLZ solution is brilliant, looks to be about 4 times faster than the for() loop.
Thanks in advance