/*
 * File      : context.S
 * 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://www.rt-thread.org/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2006-03-13     Bernard      first version
 */

#define NOINT			0xc0

/*
 * rt_base_t rt_hw_interrupt_disable()/*
 */
.globl rt_hw_interrupt_disable
rt_hw_interrupt_disable:
	mrs r0, cpsr
	orr r1, r0, #NOINT
	msr cpsr_c, r1
	mov pc, lr

/*
 * void rt_hw_interrupt_enable(rt_base_t level)/*
 */
.globl rt_hw_interrupt_enable
rt_hw_interrupt_enable:
	msr cpsr, r0
	mov pc, lr

/*
 * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to)/*
 * r0 --> from
 * r1 --> to
 */
.globl rt_hw_context_switch
rt_hw_context_switch:
	stmfd	sp!, {lr}			/* push pc (lr should be pushed in place of PC) */
	stmfd	sp!, {r0-r12, lr}	/* push lr & register file */

	mrs		r4, cpsr
	stmfd	sp!, {r4}			/* push cpsr */
	mrs		r4, spsr
	stmfd	sp!, {r4}			/* push spsr */

	str		sp, [r0]			/* store sp in preempted tasks TCB */
	ldr		sp, [r1]			/* get new task stack pointer */

	ldmfd	sp!, {r4}			/* pop new task spsr */
	msr		spsr_cxsf, r4
	ldmfd	sp!, {r4}			/* pop new task cpsr */
	msr		cpsr_cxsf, r4

	ldmfd	sp!, {r0-r12, lr, pc}	/* pop new task r0-r12, lr & pc */

/*
 * void rt_hw_context_switch_to(rt_uint32 to)/*
 * r0 --> to
 */
.globl rt_hw_context_switch_to
rt_hw_context_switch_to:
	ldr		sp, [r0]			/* get new task stack pointer */

	ldmfd	sp!, {r4}			/* pop new task spsr */
	msr		spsr_cxsf, r4
	ldmfd	sp!, {r4}			/* pop new task cpsr */
	msr		cpsr_cxsf, r4

	ldmfd	sp!, {r0-r12, lr, pc}	/* pop new task r0-r12, lr & pc */

/*
 * void rt_hw_context_switch_interrupt(rt_uint32 from, rt_uint32 to)/*
 */
.globl rt_thread_switch_interrupt_flag
.globl rt_interrupt_from_thread
.globl rt_interrupt_to_thread
.globl rt_hw_context_switch_interrupt
rt_hw_context_switch_interrupt:
	ldr		r2, =rt_thread_switch_interrupt_flag
	ldr		r3, [r2]
	cmp		r3, #1
	beq		_reswitch
	mov		r3, #1							/* set rt_thread_switch_interrupt_flag to 1 */
	str		r3, [r2]
	ldr		r2, =rt_interrupt_from_thread	/* set rt_interrupt_from_thread */
	str		r0, [r2]
_reswitch:
	ldr		r2, =rt_interrupt_to_thread		/* set rt_interrupt_to_thread */
	str		r1, [r2]
	mov		pc, lr