rt-thread/libcpu/arm/cortex-r4/stack.c

/*
 * File      : stack.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006, 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://openlab.rt-thread.com/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2008-12-11     XuXinming    first version
 * 2013-05-24     Grissiom     port to RM48x50
 */
#include <rtthread.h>
#include "RM48x50.h"
/**
 * @addtogroup RM48x50
 */
/*@{*/

/**
 * 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)
{
	unsigned long *stk;

	    stk  = (unsigned long*)stack_addr;
	*(  stk) = (unsigned long) tentry;		/* entry point */
	*(--stk) = (unsigned long) texit;		/* lr */
	*(--stk) = 0;							/* r12 */
	*(--stk) = 0;							/* r11 */
	*(--stk) = 0;							/* r10 */
	*(--stk) = 0;							/* r9 */
	*(--stk) = 0;							/* r8 */
	*(--stk) = 0;							/* r7 */
	*(--stk) = 0;							/* r6 */
	*(--stk) = 0;							/* r5 */
	*(--stk) = 0;							/* r4 */
	*(--stk) = 0;							/* r3 */
	*(--stk) = 0;							/* r2 */
	*(--stk) = 0;							/* r1 */
	*(--stk) = (unsigned long)parameter;	/* r0 : argument */

	/* cpsr */
	if ((rt_uint32_t)tentry & 0x01)
		*(--stk) = SVCMODE | 0x20;			/* thumb mode */
	else
		*(--stk) = SVCMODE;					/* arm mode   */

#ifdef __TI_VFP_SUPPORT__
#ifndef RT_VFP_LAZY_STACKING
    {
        #define VFP_DATA_NR 32
        int i;

        for (i = 0; i < VFP_DATA_NR; i++)
        {
            *(--stk) = 0;
        }
        /* FPSCR TODO: do we need to set the values other than 0? */
        *(--stk) = 0;
        /* FPEXC. Enable the FVP if no lazy stacking. */
        *(--stk) = 0x40000000;
    }
#else
        /* FPEXC. Disable the FVP by default. */
        *(--stk) = 0x00000000;
#endif
#endif

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

/*@}*/