context_rvds.S

;/*
; * File      : context_rvds.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
; * 2009-01-20     Bernard      first version
; */

NOINT	EQU		0xc0	; disable interrupt in psr

	AREA |.text|, CODE, READONLY, ALIGN=2
	ARM
	REQUIRE8
	PRESERVE8

;/*
; * rt_base_t rt_hw_interrupt_disable();
; */
rt_hw_interrupt_disable	PROC
	EXPORT rt_hw_interrupt_disable
	MRS r0, cpsr
	ORR r1, r0, #NOINT
	MSR cpsr_c, r1
	BX	lr
	ENDP

;/*
; * void rt_hw_interrupt_enable(rt_base_t level);
; */
rt_hw_interrupt_enable	PROC
	EXPORT rt_hw_interrupt_enable
	MSR cpsr_c, r0
	BX	lr
	ENDP

;/*
; * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
; * r0 --> from
; * r1 --> to
; */
rt_hw_context_switch	PROC
	EXPORT 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
	TST     lr, #0x01
	BEQ     _ARM_MODE
	ORR     r4, r4, #0x20       ; it's thumb code

_ARM_MODE
	STMFD	sp!, {r4}			; push cpsr

	STR	    sp, [r0]			; store sp in preempted tasks TCB
	LDR	    sp, [r1]			; get new task stack pointer

	LDMFD	sp!, {r4}			; pop new task cpsr to spsr
	MSR     spsr_cxsf, r4
	BIC     r4, r4, #0x20       ; must be ARM mode
	MSR	    cpsr_cxsf, r4

	LDMFD	sp!, {r0-r12, lr, pc}^	; pop new task r0-r12, lr & pc, copy spsr to cpsr
	ENDP

;/*
; * void rt_hw_context_switch_to(rt_uint32 to);
; * r0 --> to
; */
rt_hw_context_switch_to	PROC
	EXPORT rt_hw_context_switch_to
	LDR	sp, [r0]				; get new task stack pointer

	LDMFD	sp!, {r4}			; pop new task cpsr to spsr
	MSR	    spsr_cxsf, r4
	BIC     r4, r4, #0x20       ; must be ARM mode
	MSR	    cpsr_cxsf, r4

	LDMFD	sp!, {r0-r12, lr, pc}^	; pop new task r0-r12, lr & pc, copy spsr to cpsr
	ENDP

;/*
; * void rt_hw_context_switch_interrupt(rt_uint32 from, rt_uint32 to);
; */
	IMPORT rt_thread_switch_interrupt_flag
	IMPORT rt_interrupt_from_thread
	IMPORT rt_interrupt_to_thread

rt_hw_context_switch_interrupt	PROC
	EXPORT 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]
	BX	lr
	ENDP

	END