2015-08-07 13:30:13 +08:00
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/*
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* File : context_gcc.S
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* This file is part of RT-Thread RTOS
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* COPYRIGHT (C) 2009, RT-Thread Development Team
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rt-thread.org/license/LICENSE
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*
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* Change Logs:
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* Date Author Notes
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* 2009-10-11 Bernard first version
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* 2012-01-01 aozima support context switch load/store FPU register.
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* 2013-06-18 aozima add restore MSP feature.
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* 2013-06-23 aozima support lazy stack optimized.
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*/
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/**
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* @addtogroup cortex-m4
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*/
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/*@{*/
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.cpu cortex-m4
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.syntax unified
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.thumb
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.text
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.equ SCB_VTOR, 0xE000ED08 /* Vector Table Offset Register */
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.equ NVIC_INT_CTRL, 0xE000ED04 /* interrupt control state register */
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.equ NVIC_SYSPRI2, 0xE000ED20 /* system priority register (2) */
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.equ NVIC_PENDSV_PRI, 0x00FF0000 /* PendSV priority value (lowest) */
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.equ NVIC_PENDSVSET, 0x10000000 /* value to trigger PendSV exception */
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/*
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* rt_base_t rt_hw_interrupt_disable();
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*/
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.global rt_hw_interrupt_disable
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.type rt_hw_interrupt_disable, %function
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rt_hw_interrupt_disable:
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MRS r0, PRIMASK
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CPSID I
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BX LR
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/*
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* void rt_hw_interrupt_enable(rt_base_t level);
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*/
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.global rt_hw_interrupt_enable
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.type rt_hw_interrupt_enable, %function
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rt_hw_interrupt_enable:
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MSR PRIMASK, r0
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BX LR
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/*
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* void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
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* r0 --> from
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* r1 --> to
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*/
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.global rt_hw_context_switch_interrupt
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.type rt_hw_context_switch_interrupt, %function
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.global rt_hw_context_switch
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.type rt_hw_context_switch, %function
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rt_hw_context_switch_interrupt:
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rt_hw_context_switch:
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/* set rt_thread_switch_interrupt_flag to 1 */
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LDR r2, =rt_thread_switch_interrupt_flag
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LDR r3, [r2]
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CMP r3, #1
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BEQ _reswitch
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MOV r3, #1
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STR r3, [r2]
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LDR r2, =rt_interrupt_from_thread /* set rt_interrupt_from_thread */
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STR r0, [r2]
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_reswitch:
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LDR r2, =rt_interrupt_to_thread /* set rt_interrupt_to_thread */
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STR r1, [r2]
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LDR r0, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
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LDR r1, =NVIC_PENDSVSET
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STR r1, [r0]
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BX LR
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/* r0 --> switch from thread stack
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* r1 --> switch to thread stack
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* psr, pc, lr, r12, r3, r2, r1, r0 are pushed into [from] stack
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*/
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.global PendSV_Handler
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.type PendSV_Handler, %function
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PendSV_Handler:
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/* disable interrupt to protect context switch */
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MRS r2, PRIMASK
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CPSID I
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/* get rt_thread_switch_interrupt_flag */
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LDR r0, =rt_thread_switch_interrupt_flag
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LDR r1, [r0]
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CBZ r1, pendsv_exit /* pendsv already handled */
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/* clear rt_thread_switch_interrupt_flag to 0 */
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MOV r1, #0x00
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STR r1, [r0]
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LDR r0, =rt_interrupt_from_thread
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LDR r1, [r0]
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CBZ r1, switch_to_thread /* skip register save at the first time */
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MRS r1, psp /* get from thread stack pointer */
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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TST lr, #0x10 /* if(!EXC_RETURN[4]) */
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VSTMDBEQ r1!, {d8 - d15} /* push FPU register s16~s31 */
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#endif
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STMFD r1!, {r4 - r11} /* push r4 - r11 register */
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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MOV r4, #0x00 /* flag = 0 */
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TST lr, #0x10 /* if(!EXC_RETURN[4]) */
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MOVEQ r4, #0x01 /* flag = 1 */
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STMFD r1!, {r4} /* push flag */
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#endif
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LDR r0, [r0]
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STR r1, [r0] /* update from thread stack pointer */
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switch_to_thread:
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LDR r1, =rt_interrupt_to_thread
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LDR r1, [r1]
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LDR r1, [r1] /* load thread stack pointer */
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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LDMFD r1!, {r3} /* pop flag */
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#endif
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LDMFD r1!, {r4 - r11} /* pop r4 - r11 register */
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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CMP r3, #0 /* if(flag_r3 != 0) */
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VLDMIANE r1!, {d8 - d15} /* pop FPU register s16~s31 */
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#endif
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MSR psp, r1 /* update stack pointer */
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pendsv_exit:
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/* restore interrupt */
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MSR PRIMASK, r2
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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ORR lr, lr, #0x10 /* lr |= (1 << 4), clean FPCA. */
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CMP r3, #0 /* if(flag_r3 != 0) */
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BICNE lr, lr, #0x10 /* lr &= ~(1 << 4), set FPCA. */
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#endif
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ORR lr, lr, #0x04
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BX lr
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/*
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* void rt_hw_context_switch_to(rt_uint32 to);
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* r0 --> to
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*/
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.global rt_hw_context_switch_to
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.type rt_hw_context_switch_to, %function
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rt_hw_context_switch_to:
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LDR r1, =rt_interrupt_to_thread
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STR r0, [r1]
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#if defined (__VFP_FP__) && !defined(__SOFTFP__)
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/* CLEAR CONTROL.FPCA */
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MRS r2, CONTROL /* read */
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BIC r2, #0x04 /* modify */
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MSR CONTROL, r2 /* write-back */
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#endif
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/* set from thread to 0 */
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LDR r1, =rt_interrupt_from_thread
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MOV r0, #0x0
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STR r0, [r1]
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/* set interrupt flag to 1 */
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LDR r1, =rt_thread_switch_interrupt_flag
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MOV r0, #1
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STR r0, [r1]
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/* set the PendSV exception priority */
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LDR r0, =NVIC_SYSPRI2
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LDR r1, =NVIC_PENDSV_PRI
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LDR.W r2, [r0,#0x00] /* read */
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ORR r1,r1,r2 /* modify */
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STR r1, [r0] /* write-back */
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LDR r0, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
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LDR r1, =NVIC_PENDSVSET
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STR r1, [r0]
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/* restore MSP */
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LDR r0, =SCB_VTOR
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LDR r0, [r0]
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LDR r0, [r0]
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NOP
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MSR msp, r0
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2017-08-09 09:49:05 +08:00
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/* enable interrupts at processor level */
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CPSIE F
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CPSIE I
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2015-08-07 13:30:13 +08:00
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/* never reach here! */
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/* compatible with old version */
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.global rt_hw_interrupt_thread_switch
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.type rt_hw_interrupt_thread_switch, %function
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rt_hw_interrupt_thread_switch:
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BX lr
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NOP
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.global HardFault_Handler
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.type HardFault_Handler, %function
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HardFault_Handler:
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/* get current context */
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MRS r0, psp /* get fault thread stack pointer */
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PUSH {lr}
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BL rt_hw_hard_fault_exception
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POP {lr}
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ORR lr, lr, #0x04
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BX lr
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