please dont rip this site

PIC 18C Microcontoller Program Flow Method

Co-routines/tasks Allows all cocalls

Bob Ammerman [rammerman at prodigy.net] of RAm Systems says

The PIC18Cxx2 chips contain quite a few nice new features. One of the neatest is programmable access to the stack. This feature allows many powerful tricks.

Notes:

  1. this code has _NOT_ been tested!
  2. all multi-byte values are little-endian
  3. I assume the code space never exceeds 16 bits worth (which it never will on the 242, 252, 442 or 452 chips). 
 Co-routines/tasks version 2
   Allows cocalls from subroutines.
   Works by allocating parts of the stack space to each coroutine/task.

Note: limits the available stack depth for each task. There is no checking
if one task overruns anothers stack!

 CBLOCK
   TASKX_SP ; STKPTR for task X
   TASKY_SP ; STKPTR for task Y
 ENDC

initialize:
  ; initialize values for all but the first task
   movlw 16  ; start tasky's stack at level 16
   movwf TASKY_SP,A
   movwf STKPTR,A
   movlw low(tasky)
   movwf TOSL,A
   movlw high(tasky)
   movwf TOSH,A

   clrf  STKPTR,A ; back to first task's stack area

   ...fall thru into first task...
taskx:
   .
   .
   .
   rcall x_cocall_y
   .
   .
   rcall x_cocall_y
   .
   bra  taskx

x_cocall_y:
   movff STKPTR,TASKX_SP
   movff TASKY_SP,STKPTR
   return

tasky:
   .
   .
   .
   rcall y_cocall_x
   .
   .
   rcall y_cocall_x
   .
   bra  tasky

y_cocall_x:
   movff STKPTR,TASKY_SP
   movff TASKX_SP,STKPTR
   return
file: /Techref/microchip/18c/multitask-coop2-ba.htm, 1KB, , updated: 2000/10/12 12:14, local time: 2025/7/23 18:05,
TOP NEW HELP FIND: 
216.73.216.8,10-1-101-55:LOG IN
 ©2025 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://www.piclist.com/Techref/microchip/18c/multitask-coop2-ba.htm"> PIC 18C Microcontoller Program Flow Method for Co-routines/tasks Allows all cocalls</A>
After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?
  PICList 2025 contributors:
o List host: MIT, Site host massmind.org, Top posters @none found
- Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.
 

Welcome to www.piclist.com!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .