Hello all!
I'm writing to a chip with a cortex m-4 in it and the compiler creates a weird assembly:
I'm trying to develop an I2C driver so i have a made some unions to allow easy access to registers, it all worked fine until today - today things got quite phishy!
take a look:
compiler option:
here is the code for the union of "reg":
typedef union { uint32_t value; struct { unsigned dummy1 :1 unsigned dummy2 :1 . . . unsigned dummy32 :1 }fields; } IC_INTR_MASK; /******************************/ //module typedef typedef struct _MODULE_S { IC_INTR_STAT IC_INTR_STAT; } I2CInitDef;
As you can see the compiler creates the assembly with a "!"(write back to the register) - so after I write 0x00 to "reg->IC_INTR_MASK.value" the pointer of "reg" is no longer point to the right address!
I can tell I'm using this method to write hardware registers all over my code and it always works fine! what do you thing might be the problem here?
I just saw that after the first write into "reg" its address changes, and that means that every other writes into "reg" are in 0x30 offset from its actual start address.
I used the IDE watch to verify it... and then I looked at the assembly to see what is the difference between this write to other writes I do in my code...