The uC/OS-II port for Keil C V6.20, V6.21 or higher
               By John X. Liu, China, (johnxliu@163.com)


1. About this port.
      This package contains the files of porting uC/OS-II to Keil C 
      environment,  including  the  necessary head files and source 
      files and an example to show how to use this port.

2. Files list.
      This package  only  included  the  files specific to port for 
      Keil C, and  assumed that you have all the other uC/OS source 
      files.

      Porting files:
          OS_CPU.H    Defines the data types and some macros needed 
                      by uC/OS.  Also  defines some macros to work-
                      around  the problem that some keil c keywords 
                      were used  as identifiers  in uC/OS-II source 
                      files.

          OS_KC51.H   Declaring the uC/OS functions with 'reentrant' 
                      suffix, so that they are reentrant functions.

          OS_KCDEF.H  Reconvert Keil's keywords to make them available.

          INCLUDES.H  Puts all needed header files included together 
                      so that in c source files less header files are 
                      needed to be included.

          OS_CPU_C.C  The c part of porting source files.

          OS_CPU_A.ASM  The assembling language part.

      Example files:
          OS_CFG.H    The configuaration file, specific to every 
                      application, used to define what features of 
                      the os are needed to be included 

          EX1L.C      The example file which can be found in EX1_IX86L 
                      directory originally, ported to keil c environment.

          PC.H        The PC-emulating head file, ported from \SOFTWARE\PC

          PC.C        The PC-emulating source file, implemented some PC
                      functions by emulating. ported from \SOFTWARE\PC

          PC51EMU.DLL   The debug dll of Keil UV2 degugger environment. 
                        To be used to emulate the behavior of a PC display.

          EX1KC51.UV2   The example's project file.

          EX1KC51.OPT   Option file of the project.

      Document: 
          Readme.Txt   This file.

3. About the porting files.
      The required functions have been implemented according to the 
      description in the book 'μC/OS, The Real-Time Kernel'. Mainly 
      the work of porting is arround how to save the statues of CPU
      and restore later. The status includes the registers ACC, B,
      PSW, DPTR, IE, R0-R7, SP, and the hardware stack resides in 
      8051 strach RAM. This work is fulfiled by c code in OS_CPU_C.C 
      and some assembly code in OS_CPU_A.ASM.

      Due to Keil C's specific grammer, function declared by default 
      is non-reentrant. If you want a function to be reentrantable, 
      you must add a 'reentrant' after the declaration, like this:
         func() reentrant
         {
           .
           .
           .
         }
      So it is unfortunately necessary for every keil c user to modify
      the declaration of every funtions to make them work as expected in 
      Keil C environment. In this port the os_kcdef.h declares all uC/OS
      functions reentrant. But you still need do lots of thing. You must 
      modify the uC/OS function declarations in both header files and 
      source files to make them conform to the ones in os_kcdef.h.

4. The example.
      In the directory \SOFTWARE\UCOS-II\EX1_IX86L there is an example 
      of Borland C porting running under MS-DOS. I found that it is a 
      nice illustration of uC/OS multi-tasking feature, so I adopted it
      to show the porting in keil c environment. Of course, 8051 chip is 
      quite different from PC platform. So I wrote a Keil C UV2 debugger
      simulator DLL to display the result. It maps the XDATA:0-0x1000 as 
      PC's display buffer at B800:0 and displays the characters and 
      attributes whatever writen to there as same as PC does.
      To see the result of the example, you should copy the PC51Emu.DLL
      to the Keil's C51\Bin directory and add a '-dPC51Emu' at the 
      paramters editbox of dialog DLL in debug panel of the project's 
      options.

5. Compiling and running the example files.
      First, Unzip the files in this package to a directory,  
      i.e. \SOFTWARE\uCOS-II\I8051\Keil, make the directory current.
      then copy all uC/OS files in the directory \SOFTWARE\uCOS-II\SOURCE 
      to the current directory, edit the function declarations in UCOS_II.H, 
      OS_*.C to make them same with the ones in OS_KCDEF.H.

      Second, Run Keil's UV2 IDE, open the project file "Ex1KC51.UV2", 
      click compile or build, let KC compile all the source files, and 
      build the target Ex1Kc51. If any error occurs, correct it. Mostly
      circumstance it is due to incorrect modifing of uC/OS source code.
      It is simple to find the mismatches out and correct them.

      Third, start debugging, and check the peripheral menu, you will 
      see a menu item 'Virtual screen' added there. Click the menu item, 
      a PC-liked virtual screen window will display. Run the example in 
      full speed, you will see all the output of the example shown on 
      virtual screen.

      You may run the original example in \SOFTWARE\uCOS-II\EX1_I86L, 
      to compare the outcome with the one shown in virtual screen.

6. Adapting this port in your application.
      1) Copy the files you need from the directory of this example 
         to the directory of your project.
      2) Read and edit the OS_CPU.H and select a critical method 
         best fit to you.
      3) Read and edit the OS_CFG.H and decide what system services
         you need in your project.
      4) Write the interrupt service routines as described in 
         OS_CPU_C.C. If you like you may reimplement the OSTickISR.
      5) At least in your first task you must write code to initialize 
         the timer that uC/OS uses. If you change the timer rate, you 
         must change the OS_TICKS_PER_SEC to the right value.

7.Limitation.
      This port has some limitations. Listed as below.
      1) Only large mode is supported.
      2) Does not support register banking for interrupt service routine.
      3) Does not support RET_PSTK or RET_XSTK, saving return address 
         in reentrant stack
      4) Does not support multiple data pointer accessing.