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How many instruction cycles?

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I am trying to work out how many instruction cycles a subroutine takes.
It has a lot of loops and goes back and foward and would drive me insane couning each cycle.

Is there an easy way to work out how many insctuction cycles a routine takes?
Like a program for example?

Can you do it in MPLAB?
as in paste a section of code in, get it to run it, and it counts each cycle?
 
For example.

The routine below.
I know I can follow the routine through, and count each cycle, but is there and easier way to calculate it?

Code:
DELAY_Xms
        MOVLW   0xCE
        MOVWF   0x20
        MOVLW   0x08
        MOVWF   0x21
        MOVLW   0x01
        MOVWF   0x22
        Call    DELAY
        RETURN

DELAY
        DECFSZ  0x20, f
        GOTO    $+2
        DECFSZ  0x21, f
        GOTO    $+2
        DECFSZ  0x22, f
        GOTO    DELAY
        RETURN
 

Pommie

Well-Known Member
Most Helpful Member
Use the simulator and stopwatch in MPLAB. Place a breakpoint on the first and last lines. Hit F9 and zero the stopwatch at the first breakpoint. Hit F9 again and see how many cycles it takes.

Mike.
 

Pommie

Well-Known Member
Most Helpful Member
That error is normally because you put the breakpoint on a line with no instruction or you have inserted lines in your code and not reassembled. Try reassembling and running again.

Mike.
 

Mike - K8LH

Well-Known Member
Here's a more general purpose fixed delay subsystem you might like to simulate Jake.

Regards, Mike

Code:
delayhi equ     0x20

;******************************************************************
;  K8LH DelayCy() subsystem macro generates four instructions     *
;******************************************************************
        radix   dec
clock   equ     4               ; 4, 8, 12, 16, 20 (MHz), etc.
usecs   equ     clock/4         ; cycles/microsecond multiplier
msecs   equ     clock/4*1000    ; cycles/millisecond multiplier

DelayCy macro   delay           ; 11..327690 cycle range
        movlw   high((delay-11)/5)+1
        movwf   delayhi
        movlw   low ((delay-11)/5)
        call    uDelay-((delay-11)%5)
        endm

;******************************************************************
;  example code for simulation testing                            *
;******************************************************************
        org     0x000
        radix   dec
SimTest
        DelayCy(12*msecs)       ; <- put simulator PC here
        goto    $               ; <- put simulator break point here

;******************************************************************
;  K8LH DelayCy() subsystem 16-bit uDelay(11..327690 cycle) sub-  *
;  routine uses Mike Bond's 4-word 5-cycle 16-bit timing loop     *
;                                                                 *
;  9 words, 1 RAM variable, 14-bit core                           *
;******************************************************************
        nop                     ; entry for (delay-11)%5 == 4     |B0
        nop                     ; entry for (delay-11)%5 == 3     |B0
        nop                     ; entry for (delay-11)%5 == 2     |B0
        nop                     ; entry for (delay-11)%5 == 1     |B0
uDelay  addlw   -1              ; subtract 5 cycle loop time      |B0
        skpc                    ; borrow? no, skip, else          |B0
        decfsz  delayhi,F       ; done?  yes, skip, else          |B0
        goto    uDelay          ; do another loop                 |B0
        return                  ;                                 |B0
;******************************************************************
 
Last edited:

spindrah

New Member
set up a timer, clear it just befor you do what you want to test, then read it after return and display it.
 
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