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/*
* Copyright (c) 2006-2018, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2009-10-11 Bernard first version
* 2012-01-01 aozima support context switch load/store FPU register.
* 2013-06-18 aozima add restore MSP feature.
* 2013-06-23 aozima support lazy stack optimized.
* 2018-07-24 aozima enhancement hard fault exception handler.
*/
/**
* @addtogroup cortex-m4
*/
/*@{*/
#include <rtconfig.h>
.cpu cortex-m4
.syntax unified
.thumb
.text
.equ SCB_VTOR, 0xE000ED08 /* Vector Table Offset Register */
.equ NVIC_INT_CTRL, 0xE000ED04 /* interrupt control state register */
.equ NVIC_SYSPRI2, 0xE000ED20 /* system priority register (2) */
.equ NVIC_PENDSV_PRI, 0xFFFF0000 /* PendSV and SysTick priority value (lowest) */
.equ NVIC_PENDSVSET, 0x10000000 /* value to trigger PendSV exception */
/*
* 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, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
LDR r1, =NVIC_PENDSVSET
STR r1, [r0]
BX LR
/* r0 --> switch from thread stack
* r1 --> switch 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, #0x00
STR r1, [r0]
LDR r0, =rt_interrupt_from_thread
LDR r1, [r0]
CBZ r1, switch_to_thread /* skip register save at the first time */
MRS r1, psp /* get from thread stack pointer */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
TST lr, #0x10 /* if(!EXC_RETURN[4]) */
IT EQ
VSTMDBEQ r1!, {d8 - d15} /* push FPU register s16~s31 */
#endif
STMFD r1!, {r4 - r11} /* push r4 - r11 register */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
MOV r4, #0x00 /* flag = 0 */
TST lr, #0x10 /* if(!EXC_RETURN[4]) */
IT EQ
MOVEQ r4, #0x01 /* flag = 1 */
STMFD r1!, {r4} /* push flag */
#endif
LDR r0, [r0]
STR r1, [r0] /* update from thread stack pointer */
switch_to_thread:
LDR r1, =rt_interrupt_to_thread
LDR r1, [r1]
LDR r1, [r1] /* load thread stack pointer */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
LDMFD r1!, {r3} /* pop flag */
#endif
LDMFD r1!, {r4 - r11} /* pop r4 - r11 register */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
CMP r3, #0 /* if(flag_r3 != 0) */
IT NE
VLDMIANE r1!, {d8 - d15} /* pop FPU register s16~s31 */
#endif
MSR psp, r1 /* update stack pointer */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
ORR lr, lr, #0x10 /* lr |= (1 << 4), clean FPCA. */
CMP r3, #0 /* if(flag_r3 != 0) */
IT NE
BICNE lr, lr, #0x10 /* lr &= ~(1 << 4), set FPCA. */
#endif
#if defined (RT_USING_MEM_PROTECTION)
PUSH {r0-r3, r12, lr}
LDR r1, =rt_current_thread
LDR r0, [r1]
BL rt_hw_mpu_table_switch
POP {r0-r3, r12, lr}
#endif
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]
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
/* CLEAR CONTROL.FPCA */
MRS r2, CONTROL /* read */
BIC r2, #0x04 /* modify */
MSR CONTROL, r2 /* write-back */
#endif
/* set from thread to 0 */
LDR r1, =rt_interrupt_from_thread
MOV r0, #0x0
STR r0, [r1]
/* set interrupt flag to 1 */
LDR r1, =rt_thread_switch_interrupt_flag
MOV r0, #1
STR r0, [r1]
/* set the PendSV and SysTick exception priority */
LDR r0, =NVIC_SYSPRI2
LDR r1, =NVIC_PENDSV_PRI
LDR.W r2, [r0,#0x00] /* read */
ORR r1,r1,r2 /* modify */
STR r1, [r0] /* write-back */
LDR r0, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
LDR r1, =NVIC_PENDSVSET
STR r1, [r0]
/* restore MSP */
LDR r0, =SCB_VTOR
LDR r0, [r0]
LDR r0, [r0]
NOP
MSR msp, r0
/* enable interrupts at processor level */
CPSIE F
CPSIE I
/* ensure PendSV exception taken place before subsequent operation */
DSB
ISB
/* 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, msp /* get fault context from handler. */
TST lr, #0x04 /* if(!EXC_RETURN[2]) */
BEQ _get_sp_done
MRS r0, psp /* get fault context from thread. */
_get_sp_done:
STMFD r0!, {r4 - r11} /* push r4 - r11 register */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
STMFD r0!, {lr} /* push dummy for flag */
#endif
STMFD r0!, {lr} /* push exec_return register */
TST lr, #0x04 /* if(!EXC_RETURN[2]) */
BEQ _update_msp
MSR psp, r0 /* update stack pointer to PSP. */
B _update_done
_update_msp:
MSR msp, r0 /* update stack pointer to MSP. */
_update_done:
PUSH {LR}
BL rt_hw_hard_fault_exception
POP {LR}
ORR lr, lr, #0x04
BX lr
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