readme.txt

关于ucos 在avr128 中应用用icc编译

03-Jan-01  
David Poole 
[e-mail]

0. Paranoia.

I'm providing this chunk of code in the hopes that it will be useful to other
folks as they come up to speed on using uCOS-II.  An embedded system is an
unforgiving learning environment so I created these functions to allow me to
work the kinks out of our product under Linux.

Any possible usefulness of this code is purely coincidental.  If it breaks,
don't act too surprised.


1. Introduction.

See linuxucos.c for descriptions of uCOS-II functions that are currently
implemented.  There are currently only 14 of the many uCOS-II functions
implemented.  


2. History

13-Dec-01  Initial "release" as 'fakeucos'
01-Jan-01  Added support for OSFlagAccept(), OSFlagCreate(), OSFlagPend()
           and OSFlagPost().  Renamed to 'linuxucos'


3. Integration with uCOS-II.

None of the actual uCOS-II source code is compiled.  linuxucos replaces the
functions of uCOS-II with its own built on SysV IPC and POSIX threads
mechanisms.

Normally porting uCOS-II to a new product (not platform) requires hits to 
os_cfg.h.  The only thing required in os_cfg.h is 

#define OS_TICKS_PER_SEC        1000    /* Set the number of ticks in one second                        */

as linuxucos uses a 1ms tick on Linux.  (See OSTimeGet().)

No changes are required to os_cpu.h as only the typedef's are used.

Please note that I've tried very hard to maintain the functional similarity
between linuxucos and uCOS-II.  To the best I could, the functions will
behave the same under Linux as under uCOS-II.  I've had to sacrifice some
performance under Linux (polling on semaphores, for example) to maintain 
the functional similarity.

    - polling on SysV semaphores (OSMutex???())
    - polling on SysV message queues (OSQ???())
    - each OSFlagPost() wakes up *all* sleeping threads; it is the sleeping
      threads' responsiblity to verify its flags (in uCOS-II, the caller
      verifies the flags before waking the sleeping threads)


4. Changes.

Changes to uCOS-II core code:

ucos_ii.h
  The return type of the task function ptr passed to OSTaskCreate() and 
  OSTaskCreateExt() is different between POSIX threads and uCOS-II 
  (void *) vs (void).  A new #def THREAD is used to switch between the
  two definitions.  FAKE_UCOS must be defined before includes.h is 
  included to use the new pthreads return type.  All tasks that are
  to be portable between Linux and uCOS-II must have return type THREAD.


  In source file linuxucos.c:

    #include "includes.h"

    THREAD task1( void *arg )
    {
        while( 1 ) {
            // do things
        }
    }

    int main( void )
    {
        ...
        os_err = OSTaskCreate( task1, (void *)1, task1_stack, TASK1_PRIO );
        ...
    }

  In the Makefile:

    linuxucos : linuxucos.c
            $(CC) $(CFLAGS) -DLINUX_UCOS $< -o $@ -lpthread