Mike Harrison wrote:
> 365: irrxsum1+=irbyte1;
> 115 087A MOVF 0x7a, W
> 116 00C3 MOVWF 0x43
> 117 0843 MOVF 0x43, W
> 118 07F4 ADDWF 0x74, F
>
> Should be 2 instructions
>
> 366: ircnt1=0;
> 119 1003 BCF 0x3, 0
> 11A 3000 MOVLW 0
> 11B 1803 BTFSC 0x3, 0
> 11C 3001 MOVLW 0x1
> 11D 00FB MOVWF 0x7b
>
> This is especially bizarre - should be 1 CLRF instruction
>
> 349: irtmr1+=bittime2; // bittime2 is a constant
> 0DF 300E MOVLW 0xe
> 0E0 00C3 MOVWF 0x43
> 0E1 0843 MOVF 0x43, W
> 0E2 07F5 ADDWF 0x75, F
>
> Should be 2 instructions
>
>
> 350: ircnt1++;
> 0E3 3001 MOVLW 0x1
> 0E4 00C3 MOVWF 0x43
> 0E5 0843 MOVF 0x43, W
> 0E6 07FB ADDWF 0x7b, F
>
> Should be 1 INCF instruction
>
> 322: irin=PORTA;
> 090 0805 MOVF 0x5, W
> 091 00C3 MOVWF 0x43
> 092 0843 MOVF 0x43, W
> 093 00FC MOVWF 0x7c
>
> Why is it storing in two places?
It's obviously using location 43h as a sort of working register. This is
probably due to generating code to handle wide integers run in the single
byte case, and would hopefully dissappear with the optimizer. If you care
about efficiency, then either use the optimizer or write it in assembly. It
seems you're getting exactly what you paid for.
The second case looks like it didn't check for the special case of 0 and is
doing some extra instructions to deal with signed/unsigned issues. Did you
define all the variables unsigned that didn't really need to be signed?
You've got to do your part too, especially when the optimizer is turned off.
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