PIC Math - the need for speed

[Darrel Taylor]

Apparently, your Scope works Really Well.

I ran the numbers again for a 16F877 this time, and the results are rather surprising.

Start:                     ' Cycles   uS@20mhz
    PORTD.0 = 1            '    1         .2
    Delay = Value /*$004D  '  243       48.6
    PORTD.0 = 0            '    1         .2
    PauseUs 700            ' 3502      700.4
Goto Start                 '    4         .8
                             -----     -----
           '    Loop Total   3751      750.2
           ' Without Pause    249

                            ' Cycles   uS@20mhz
Dummy1 = OldPulseTime >> 2  '  37        7.4
Delay = Dummy1 >> 2         '  37        7.4
Delay = Delay + Dummy1      '   6        1.2
                             -----     -----
              '      Total     80       16.0

                            ' Cycles   uS@20mhz
Dummy1 = OldPulseTime >> 1  '   5        1.0
Dummy1 = Dummy1 >> 1        '   3         .6
Delay = Dummy1 >> 1         '   5        1.0 
Delay = Delay >> 1          '   3         .6
Delay = Delay + Dummy1      '   6        1.2
                             -----     -----
              '      Total     22        4.2

I really didn't expect that much difference between the same code compiled for the 2 different chips.

Way to go Ingvar.