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Hello everybody!
If you please could help with this problem. I am writing a timer32 interrupt handler and try to use inline assembly.
I wrote the simplest code, which triggers a port pin high and then low at the minimal possible time interval. One instruction turns it on, the next one - off. The code is very simple.
The problem is when I used a debugger (msp432 launchpad), I saw that the compiler actually had changed my code!!! I saw that it stored the values to registers, different from what I wrote AND the worst thing was, the compiler thought that writing #1 to the port ( STRB r1, [r0] ) was totally redundant, since the next instruction writes a zero there, so the compiler simply dumped that instruction. So it changes my assembly code! Could please anyone tell me how to force the compiler to stop playing a smart ass and to implement my inline assembly code exactly the way it is written and do all the instructions I write? Thank you!!!
void T32_INT1_IRQHandler(void){ __asm{ MOV R0, #0x40004c03 //DIO port address MOV r1, #1 MOV r2, #0 STRB r1, [r0] //Port pin High STRB r2, [r0] //Port pin Low } }
Hello Pete! I have thought about it also, alas, to no avail. The instruction was still missing. But the funny thing was that when I finally wrote the code in pure asm and the instruction was finally implemented, there was no visible difference in pin jerking speed, whether the on and off instructions went in a row, or had a MOV in between! Perhaps the internal guts of the MSP432 are wired in such a way that it can move some number to a register while storing another number somewhere else? Or perhaps my oscilloscope bullsh*ts.