• State Not Answered
  • Locked Locked
  • Replies 5 replies
  • Subscribers 21 subscribers
  • Views 1368 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
Related
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

DJNZ instruction running simulator of DScope doesn't work properly

Lloyd Frei

Observing action single stepping through below code segment reveals that DJNZ instruction in
div_loop doesn't decrement R6. On first loop execution it adds 16. The next loop through decrements.
Susequent loopings causes it to have an add other times a decrement. Running version 2.30 of uVision.

Code

div_OK: MOV R1,xh
MOV R0,xl
MOV R2,#00
MOV R3,#00
mov xh,#00
mov xl,#00
MOV R6,#16

div_loop: clr c
mov a,R0
rlc a
mov R0,a
mov a,R1
rlc a
mov a,xl
rlc a
mov xl,a
mov a,xh
rlc a
mov xh,a
lcall sub16
mov c,ov
cpl c
jnc div_1
mov xh,zh
mov xl,zl
div_1: mov a,r2
rlc a
mov r2,a
mov a,r3
rlc a
mov r3,a
djnz R6,div_loop
mov z3,r3
mov z2,r2
mov z1,xh
mov z0,xl
mov r4,xh
mov r5,xl
clr OV
ret


sub16: mov a,xl
clr c
subb a,yl
mov zl,a
mov a,xh
subb a,yh
mov zh,a
mov ov,c
ret

Parents Reply Children