changes.txt

一个基于AVR 单片机的操作系统,有组于了解操作系统在单片机上运行的内幕.

5/19/2005 New Release AvrX 2.6.f for WinAvr 3.4+

1. Got rid of all inp() outb() stuff and went to direct assignment.
   this should work for IAR as well.

2. Updated makefiles for dwarf-2 & cof/extended cof debug support.  THe AvrX
   source will never be part of the debug module, unfortunately.

4. Add AvrX synchronized FIFO facility

5. Write C serial i/o that is pretty generic using fifo's

9/16/2002 New release AvrX 2.6.e
1. Touched headers and source files to allow compilation under both
   GCC 3.02 and 3.2 (Added SFR_IO_ADDR() macro for all I/O addresses)

   IAR stuff most certainly broken now, particularly for interrupt vectors.
   GCC changed how vectors are specified with 3.0 and the IAR support was
   written based upon 2.97 support.

2. Touched all C files (samples and tests) to
      #define _SFR_ASM_COMPAT 1
   which is a hack to make all the old outp, inp stuff work.  For new
   3.2 code, use direct I/O.  I.e. char temp = SREG or PORTA |= 0x01

6/04/2002 New release AvrX 2.6.d
1. New tasking code for zippier performance
    - Moved kernel data into a struct and accessed them via a pointer.
      this actually saved cycles and words when more than two accesses
      were needed.  This affected "avrx.inc", tasking, semaphores,
      single step, priority, terminate and probably other files.

    - Re-arranged _Prolog() to exit early if entering from the IDLE
      task.  I.e. no context is saved or restored for IDLE.
      NB: It is no longer possible to do work during IDLE.  If
      you need a background IDLE task, create a new task with a low
      priority.  With the changes, the round trip from IDLE for a timer
      handler interrupt is ~140 cycles vs ~240 prior to the changes.  This
      won't allow faster interrupts since the round trip when interrupting
      a task is no faster, but it will reduce system load overall.

    - Modified _QueuePid slightly to return status.  Used this
      status to optimize AvrXIntSetSemaphore() so the context switch
      is skipped if the top of the run queue (self) hasn't changed.

2. Added terminate function to monitor.
    - Now you can k[oooo] a task.  Then you can p[oooo] to re-initialize
      it and then r[oooo] to start it running again.  Whoohoo.

3. Updated all regression tests and verified they worked
    - TestCase3 was checking little-endien (pre IAR rework) so
      I removed the macro.

4. Updated "serialio.s" to include the file "avrx-signal.h" which is
   needed with the #define SIG_UART_DATA when using 3.02 or earlier versions
   of gcc-avr.  The GCC file "sig-avr.h" would work fine as well.

5/31/2002 update for mega128 support in GCC
1. mostly minor changes to re-name stuff to conform to new register and
   bit names in the iom128.h file.  Files touched:

   samples/hardware.h - Check for m128 and use alternate bit names
   samples/*.c      - included new header for serialio routines.
   avrx/serialio.h  - new header with function prototypes
   avrx/serialio.s  - lots of #ifdef for changing bit names
   avrx/monitor.s   - bug fixes in address handling when modifying memory
   avrx/avrx_eeprom.s - bug fix where small chips won't compile (used EEARH)
   avrx/avrx_generatesinglestepinterrupt.s
                    - redefined bit name when using '128

6/8/2001 avrx 2.6
1. Updated source code with aliases for all registers (avrxctoasm.h) to
allow assembling under either avr-gcc or IAR C compilers.

2. I replaced avrx macros "AVRX_TASK" and "AVRX_TASKDEF" with New macros:
	AVRX_IAR_TASKDEF
	AVRX_GCC_TASKDEF
	AVRX_IAR_TASK
	AVRX_GCC_TASK
see the header file "avrx.h" for all the gory details.

3. Added several new header files to implement the interrupt table function
of GCC in the IAR environment (DON'T USE THE IAR INTERRUPT CONSTRUCTS!)
	avrx-io.h
	avrx-signal.h
	avrio.h (actually this is a pre-release IAR file...)
	avrx_iar_intvect.s

4. changed the way "Epilog()" works to work around optimization issues
in IAR C compiler.

5. Updated samples and test cases to build under either compiler

6. Updated Makefile to reflect the differing needs of GCC and IAR

7. Look for more release notes on the avrx web site on how to deal with IAR.  It
is not as simple as GCC..

2/28/01 avrx 2.5b

1. Updated kernel and debugger to work with 2.97 and later
version of avr-gcc.  This change reflects the new calling
conventions: p1 = R24, p2 = R22, etc.

2. The 01/18 version of the compiler has subtle bugs with -O3
optimization.  Build samples and test code -Os or -O2

7-4-00	avrx 2.5a

1. Modified AvrXWaitSemaphore and AvrXSetSemaphore (and varients)
to vastly speed up the trivial case of no tasks waiting, or
the semaphore already set.  Previously a half-context switch
was made upon entry and exit of each routine.  In AvrX 2.3 this
was relatively inexpensive and preserved all registers used in
the call.  In 2.5 all registers are switched (to allow C to be
used everywhere) and it became expensive.  Since GCC does not
expect R17-R31 to be preserved (except R29:28) across calls I
was able to move the half context switch to the precise point
where a context switch would be needed (e.g. when a task needs
to block, or when un-blocking another task).  Now, when using
Semaphores as a mutual exlusion flag (e.g. resource access like
EEPromRead/Write) the normal case will be very cheap: just grab
and release the flag.  The only time any real work is done is
when two tasks attempt to access the resource at the same time.

A side effect of the change, implied above, is that registers
R22-27, 30 & 31 are not preserved across calls.  This doesn't
affect GCC, but will cause problems for assembly code that used
to count on all registers being preserved.

2. Added a series of macros to simplify the C code of an AvrX
task.  From the header file "AvrX.H"  Updated the sample code
with the macros.

AVRX_TASK(start, stacksz, priority)
	Declare task data structures and forward reference to task
AVRX_TASKDEF(start, stacksz, priority)
	Declare task data structure and the top level C
	declaration (AVRX_TASK + C function declaration)
AVRX_SIGINT(vector)
	Declare the top level C declaration for an
	interrupt handler
AVRX_EXTERNTASK(start)
	Declare external task data structures
PID(start)
	Return the pointer to the task PID
TCB(start)
	Return the pointer to the task TCB

6-20-00 avrx 2.5

1. Initial release of AvrX rewritten for the avr-gcc compiler.
All pointers changed to 'near' (16 bits) and all interfaces
modified to be native GCC.  Also, the context switch was modified
to swap the entire context since C can and does use all registers.

Although the stack usage rises a lot, compared to AvrX 2.3, overall
the speed of execution is very similar.  The former took 211 cycles
to process a timer tick with an active timer in the queue.  The
new version takes 239 cycles, about 10% slower.  The bulk of the
cycles are in the context switch from user code to kernel and back
(~160).

2. Included test cases to exercise basic AvrX functionality.  Test
cases cover semaphores, basic tasking, message queues and timer queues.

3. Included sample code illustrating how to write an interrupt handler,
extend the message model to include data and how to use timers.

4. Extended the AvrX model with a special version of a timer element
that queues itself onto a message queue when expired.  This allows a
task to wait upon a message queue for multiple events including timers.