/*
*********************************************************************************************************
*                                               uC/OS-II
*                                         The Real-Time Kernel
*
*                        (c) Copyright 1992-1999, Jean J. Labrosse, Weston, FL
*                                          All Rights Reserved
*
*                                       80x86/80x88 Specific code
*                                 LARGE MEMORY MODEL WITH FLOATING-POINT
*                                          Borland C/C++ V4.51
*
*
* File         : OS_CPU_C.C
* By           : Jean J. Labrosse
* Port Version : V1.00
*********************************************************************************************************
*/

#define  OS_CPU_GLOBALS
#include "includes.h"

/*
*********************************************************************************************************
*                                             LOCAL CONSTANTS
*
* Note(s) : 1) OS_NTASKS_FP  establishes the number of tasks capable of supporting floating-point.  One
*              task is removed for the idle task because it doesn't do floating-point at all.
*           2) OS_FP_STORAGE_SIZE  currently allocates 128 bytes of storage even though the 80486 
*              (or Pentium processors) only require 108 bytes to save the FPU context.  I decided to
*              allocate 128 bytes for future expansion.  Also, I used INT32U to ensure that storage is 
*              located on a 32-bit boundary.
*********************************************************************************************************
*/

#define  OS_NTASKS_FP         (OS_MAX_TASKS + OS_N_SYS_TASKS - 1)
#define  OS_FP_STORAGE_SIZE   (32 * sizeof(INT32U))

/*
*********************************************************************************************************
*                                             LOCAL VARIABLES
*********************************************************************************************************
*/

static  OS_MEM  *OSFPPartPtr;          /* Pointer to memory partion holding FPU storage areas          */

static  INT32U   OSFPPart[OS_NTASKS_FP][OS_FP_STORAGE_SIZE];

/*$PAGE*/
/*
*********************************************************************************************************
*                                        INITIALIZE A TASK'S STACK
*
* Description: This function is called by either OSTaskCreate() or OSTaskCreateExt() to initialize the
*              stack frame of the task being created.  This function is highly processor specific.
*
* Arguments  : task          is a pointer to the task code
*
*              pdata         is a pointer to a user supplied data area that will be passed to the task
*                            when the task first executes.
*
*              ptos          is a pointer to the top of stack.  It is assumed that 'ptos' points to
*                            a 'free' entry on the task stack.  If OS_STK_GROWTH is set to 1 then 
*                            'ptos' will contain the HIGHEST valid address of the stack.  Similarly, if
*                            OS_STK_GROWTH is set to 0, the 'ptos' will contains the LOWEST valid address
*                            of the stack.
*
*              opt           specifies options that can be used to alter the behavior of OSTaskStkInit().
*                            (see uCOS_II.H for OS_TASK_OPT_???).
*
* Returns    : Always returns the location of the new top-of-stack' once the processor registers have
*              been placed on the stack in the proper order.
*
* Note(s)    : Interrupts are enabled when your task starts executing. You can change this by setting the
*              PSW to 0x0002 instead.  In this case, interrupts would be disabled upon task startup.  The
*              application code would be responsible for enabling interrupts at the beginning of the task
*              code.  You will need to modify OSTaskIdle() and OSTaskStat() so that they enable 
*              interrupts.  Failure to do this will make your system crash!
*********************************************************************************************************
*/

OS_STK *OSTaskStkInit (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT16U opt)
{
    INT16U *stk;


    opt    = opt;                           /* 'opt' is not used, prevent warning                      */
    stk    = (INT16U *)ptos;                /* Load stack pointer                                      */
    *stk-- = (INT16U)FP_SEG(pdata);         /* Simulate call to function with argument                 */
    *stk-- = (INT16U)FP_OFF(pdata);         
    *stk-- = (INT16U)FP_SEG(task);
    *stk-- = (INT16U)FP_OFF(task);
    *stk-- = (INT16U)0x0202;                /* SW = Interrupts enabled                                 */
    *stk-- = (INT16U)FP_SEG(task);          /* Put pointer to task   on top of stack                   */
    *stk-- = (INT16U)FP_OFF(task);
    *stk-- = (INT16U)0xAAAA;                /* AX = 0xAAAA                                             */
    *stk-- = (INT16U)0xCCCC;                /* CX = 0xCCCC                                             */
    *stk-- = (INT16U)0xDDDD;                /* DX = 0xDDDD                                             */
    *stk-- = (INT16U)0xBBBB;                /* BX = 0xBBBB                                             */
    *stk-- = (INT16U)0x0000;                /* SP = 0x0000                                             */
    *stk-- = (INT16U)0x1111;                /* BP = 0x1111                                             */
    *stk-- = (INT16U)0x2222;                /* SI = 0x2222                                             */
    *stk-- = (INT16U)0x3333;                /* DI = 0x3333                                             */
    *stk-- = (INT16U)0x4444;                /* ES = 0x4444                                             */
    *stk   = _DS;                           /* DS = Current value of DS                                */
    return ((OS_STK *)stk);
}

/*$PAGE*/
#if OS_CPU_HOOKS_EN
/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                            (BEGINNING)
*
* Description: This function is called by OSInit() at the beginning of OSInit().
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
#if OS_VERSION > 203
void OSInitHookBegin (void)
{
}
#endif


/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                               (END)
*                                        INITIALIZE FP SUPPORT
*
* Description: This function is called to initialize the memory partition needed to support context
*              switching the Floating-Point registers.  This function is called by OSInit() at the end of 
*              OSInit().
*
* Arguments  : none
*
* Returns    : none
*
* Note(s)    : 1) Tasks that are to use FP support MUST be created with OSTaskCreateExt().
*              2) For the 80486 processor, 108 bytes are required to save the FPU context.  I decided to
*                 allocate 128 bytes (i.e. 32 * INT32U) for future expansion.  Also, I used INT32U to 
*                 ensure that storage is located on a 32-bit boundary.
*              3) I decided to 'change' the 'Options' attribute for the statistic task in case you
*                 use OSTaskStatHook() and need to perform floating-point operations in this function.
*                 This only applies if OSTaskStat() was created with OSTaskCreateExt().
*********************************************************************************************************
*/

#if OS_VERSION > 203
void OSInitHookEnd (void)
{
    INT8U    err;
#if OS_TASK_STAT_EN
    OS_TCB  *ptcb;
    void    *pblk;
#endif
    
    
    OSFPPartPtr = OSMemCreate(&OSFPPart[0][0], OS_NTASKS_FP, OS_FP_STORAGE_SIZE, &err);
    
#if OS_TASK_STAT_EN && OS_TASK_CREATE_EXT_EN       /* CHANGE 'OPTIONS' for OSTaskStat()                */