What's the interrupt latency and/or overhead when using DT-Ints?

[Ioannis]

Finally I did the test on a 16F887 at 8MHz, and came up with a 49 usec to enter ISR and around 45 to exit.



The code I used is this:

wsave   var byte $70 system
wsave1   var byte $A0 system
wsave2   var byte $120 system
wsave3   var byte $1A0 system


INCLUDE "DT_INTS-14.bas"
INCLUDE "ReEnterPBP.bas"

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR0_INT,  _TimezUp,   PBP,  yes
    endm
    INT_CREATE              ; Creates the interrupt processor
ENDASM

TRISB = %00000000           ' PortB.0 and PortB.1 are outputs.

@ INT_ENABLE  TMR0_INT      ; Enable INT0 interrupts

Main:
    portB.4 = !portb.4        ' Toggle PortB.1 as fast as we can
Goto Main

TimezUp:
    ' Create a short pulse on PortB.0
    portb.5 = 1
    PAUSEUS 15
    portB.5 = 0
@ INT_RETURN

It seems that comparing to 25K20, the 887 executes less instructions...? Is it possible?

Ioannis