/*
 * File      : cpuport.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2009 - 2011, RT-Thread Development Team
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rt-thread.org/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2011-02-23     Bernard      the first version
 */

#include <rtthread.h>

extern volatile rt_uint8_t rt_interrupt_nest;

/* switch flag on interrupt and thread pointer to save switch record */
rt_uint32_t rt_interrupt_from_thread;
rt_uint32_t rt_interrupt_to_thread;
rt_uint8_t rt_thread_switch_interrput_flag;

/**
 * This function will initialize hardware interrupt
 */
void rt_hw_interrupt_init(void)
{
    /* init interrupt nest, and context in thread sp */
    rt_interrupt_nest = 0;
    rt_interrupt_from_thread = 0;
    rt_interrupt_to_thread = 0;
    rt_thread_switch_interrput_flag = 0;
}

/**
 * This function will initialize thread stack
 *
 * @param tentry the entry of thread
 * @param parameter the parameter of entry
 * @param stack_addr the beginning stack address
 * @param texit the function will be called when thread exit
 *
 * @return stack address
 */
rt_uint8_t *rt_hw_stack_init(void *tentry, void *parameter, rt_uint8_t *stack_addr, void *texit)
{
    rt_uint16_t  *pstk16;
    rt_uint16_t   flag;

    flag       = 0x0040;
    pstk16     = (rt_uint16_t *)stack_addr;
    pstk16--;

    /* Simulate ISR entry */
    *pstk16--  = (flag&0x00FF)                                  /* ... The lowest byte of the FLAG register     */
               | (((rt_uint32_t)tentry>>8)&0x00000F00)          /* ... The highest nibble of the PC register    */
               | ((flag<<4)&0xF000);                            /* ... The highest nibble of the FLAG register  */
    *pstk16--  = (((rt_uint32_t)tentry)&0x0000FFFF);            /* ... The lowest bytes of the PC register      */
    
    /* Save registers onto stack frame */
    *pstk16--  = (rt_uint16_t)0xFBFB;                           /* ... FB register                              */
    *pstk16--  = (rt_uint16_t)0x3B3B;                           /* ... SB register                              */
    *pstk16--  = (rt_uint16_t)0xA1A1;                           /* ... A1 register                              */
    *pstk16--  = (rt_uint16_t)0xA0A0;                           /* ... A0 register                              */
    *pstk16--  = (rt_uint16_t)0x3333;                           /* ... R3 register                              */
    *pstk16--  = (rt_uint32_t)parameter >> 16L;                 /* ... Pass argument in R2 register             */
    *pstk16--  = (rt_uint32_t)parameter & 0x0000FFFFL;          /* ... Pass argument in R1 register             */
    *pstk16    = (rt_uint16_t)0x0000;                           /* ... R0 register                              */

    /* return task's current stack address */
    return (rt_uint8_t *)pstk16;
}

void rt_hw_context_switch(rt_uint32_t from, rt_uint32_t to)
{
    rt_interrupt_from_thread = from;
    rt_interrupt_to_thread = to;
    asm("INT #0");    
}

void rt_hw_context_switch_interrupt(rt_uint32_t from, rt_uint32_t to)
{
    if (rt_thread_switch_interrput_flag != 1)
    {
        rt_thread_switch_interrput_flag = 1;
        rt_interrupt_from_thread = from;        
    }
    rt_interrupt_to_thread = to;  
}