Hi,
> warning 180: using ~ on bit/bool/unsigned char variables
> can give unexpected results due to promotion to int
>
> The corresponding codes are:
> ======================================
> 54 void motor_switch_ori()
> - 55 {
> | 56 mori = ~mori;
> | 57 }
> ======================================
> the asm code generated by sdcc is:
> ======================================
> 467 _motor_switch_ori:
> 468 ; motor_control.c:56: mori = ~mori;
> 469 setb _P1_6
> 470 ret
> ======================================
You want to use "mori = !mori;" (logical NOT) rather than "mori = ~mori;"
(bitwise NEGation), as the latter requires promotion to int (as per the C
standard). You get:
mori == 0 ==> ~mori == ~0 == 0xFFFF != 0 ==> mori = 1
mori == 1 ==> ~mori == ~1 == 0xFFFE != 0 ==> mori = 1
which explains the setb instruction. You have been warned ...
> which is definitely not what I want. What could I do to reverse a bit?
> Or it's a compiler's bug?
It's the standard compliant implementation, no bug here.
Best regards
Raphael
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