rt-thread-official/libcpu/arm/cortex-m3/context_gcc.S

200 lines
5.5 KiB
ArmAsm

/***************************************************************************//**
* @file context_gcc.S
* @brief Context switch functions
* COPYRIGHT (C) 2011, RT-Thread Development Team
* @author Bernard, onelife
* @version 0.4 beta
*******************************************************************************
* @section License
* 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
*******************************************************************************
* @section Change Logs
* Date Author Notes
* 2009-10-11 Bernard first version
* 2010-12-29 onelife Modify for EFM32
* 2011-06-17 onelife Merge all of the assembly source code into
* context_gcc.S
* 2011-07-12 onelife Add interrupt context check function
******************************************************************************/
/***************************************************************************//**
* @addtogroup cortex-m3
* @{
******************************************************************************/
.cpu cortex-m3
.fpu softvfp
.syntax unified
.thumb
.text
.equ ICSR, 0xE000ED04 /* interrupt control state register */
.equ PENDSVSET_BIT, 0x10000000 /* value to trigger PendSV exception */
.equ SHPR3, 0xE000ED20 /* system priority register (3) */
.equ PENDSV_PRI_LOWEST, 0x00FF0000 /* PendSV priority value (lowest) */
/*
* rt_base_t rt_hw_interrupt_disable();
*/
.global rt_hw_interrupt_disable
.type rt_hw_interrupt_disable, %function
rt_hw_interrupt_disable:
MRS R0, PRIMASK
CPSID I
BX LR
/*
* void rt_hw_interrupt_enable(rt_base_t level);
*/
.global rt_hw_interrupt_enable
.type rt_hw_interrupt_enable, %function
rt_hw_interrupt_enable:
MSR PRIMASK, R0
BX LR
/*
* void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
* R0 --> from
* R1 --> to
*/
.global rt_hw_context_switch_interrupt
.type rt_hw_context_switch_interrupt, %function
.global rt_hw_context_switch
.type rt_hw_context_switch, %function
rt_hw_context_switch_interrupt:
rt_hw_context_switch:
/* set rt_thread_switch_interrupt_flag to 1 */
LDR R2, =rt_thread_switch_interrupt_flag
LDR R3, [R2]
CMP R3, #1
BEQ _reswitch
MOV R3, #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]
LDR R0, =ICSR /* trigger the PendSV exception (causes context switch) */
LDR R1, =PENDSVSET_BIT
STR R1, [R0]
BX LR
/* R0 --> swith from thread stack
* R1 --> swith to thread stack
* psr, pc, LR, R12, R3, R2, R1, R0 are pushed into [from] stack
*/
.global PendSV_Handler
.type PendSV_Handler, %function
PendSV_Handler:
/* disable interrupt to protect context switch */
MRS R2, PRIMASK
CPSID I
/* get rt_thread_switch_interrupt_flag */
LDR R0, =rt_thread_switch_interrupt_flag
LDR R1, [R0]
CBZ R1, pendsv_exit /* pendsv aLReady handled */
/* clear rt_thread_switch_interrupt_flag to 0 */
MOV R1, #0
STR R1, [R0]
LDR R0, =rt_interrupt_from_thread
LDR R1, [R0]
CBZ R1, swtich_to_thread /* skip register save at the first time */
MRS R1, PSP /* get from thread stack pointer */
STMFD R1!, {R4 - R11} /* push R4 - R11 register */
LDR R0, [R0]
STR R1, [R0] /* update from thread stack pointer */
swtich_to_thread:
LDR R1, =rt_interrupt_to_thread
LDR R1, [R1]
LDR R1, [R1] /* load thread stack pointer */
LDMFD R1!, {R4 - R11} /* pop R4 - R11 register */
MSR PSP, R1 /* update stack pointer */
pendsv_exit:
/* restore interrupt */
MSR PRIMASK, R2
ORR LR, LR, #0x04
BX LR
/*
* void rt_hw_context_switch_to(rt_uint32 to);
* R0 --> to
*/
.global rt_hw_context_switch_to
.type rt_hw_context_switch_to, %function
rt_hw_context_switch_to:
LDR R1, =rt_interrupt_to_thread
STR R0, [R1]
/* set from thread to 0 */
LDR R1, =rt_interrupt_from_thread
MOV R0, #0
STR R0, [R1]
/* set interrupt flag to 1 */
LDR R1, =rt_thread_switch_interrupt_flag
MOV R0, #1
STR R0, [R1]
/* set the PendSV exception priority */
LDR R0, =SHPR3
LDR R1, =PENDSV_PRI_LOWEST
LDR.W R2, [R0,#0] /* read */
ORR R1, R1, R2 /* modify */
STR R1, [R0] /* write-back */
LDR R0, =ICSR /* trigger the PendSV exception (causes context switch) */
LDR R1, =PENDSVSET_BIT
STR R1, [R0]
CPSIE I /* enable interrupts at processor level */
/* never reach here! */
/* compatible with old version */
.global rt_hw_interrupt_thread_switch
.type rt_hw_interrupt_thread_switch, %function
rt_hw_interrupt_thread_switch:
BX LR
NOP
.global HardFault_Handler
.type HardFault_Handler, %function
HardFault_Handler:
/* get current context */
MRS R0, PSP /* get fault thread stack pointer */
PUSH {LR}
BL rt_hw_hard_fault_exception
POP {LR}
ORR LR, LR, #0x04
BX LR
/*
* rt_uint32_t rt_hw_interrupt_check(void);
* R0 --> state
*/
.global rt_hw_interrupt_check
.type rt_hw_interrupt_check, %function
rt_hw_interrupt_check:
MRS R0, IPSR
BX LR
/***************************************************************************//**
* @}
******************************************************************************/