/*
 * Copyright (c) 2020, Shenzhen Academy of Aerospace Technology
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2020-10-16     Dystopia     the first version
 */

#include <rtthread.h>

/**
 * 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_uint32_t *stk;
    int window_index;
    int register_index;

    stack_addr += sizeof(rt_uint32_t);
    stack_addr  = (rt_uint8_t *)RT_ALIGN_DOWN((rt_uint32_t)stack_addr, 8);
    stk      = (rt_uint32_t *)stack_addr;

    stk -= 24;
    stk -= 8;

    for (register_index = 0; register_index != 8; register_index++)
        stk[register_index] = 0xdeadbeef;

    for (window_index = 0; window_index != 8; window_index++)
    {
        stk -= 16;
        for (register_index = 0; register_index != 16; register_index++)
            stk[register_index] = 0xdeadbeef;
        if (window_index == 0)
        {
            stk[8] = (rt_uint32_t)parameter;
            stk[15] = (rt_uint32_t)texit - 8;
        }
    }

    stk -= 34;
    for (register_index = 0; register_index != 34; register_index++)
        stk[register_index] = 0;

    stk -= 4;
    stk[0] = (rt_uint32_t)tentry; //pc
    stk[1] = (rt_uint32_t)tentry + 4; //npc
    stk[2] = 0x10C7; //psr
    stk[3] = 0x2; //wim

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