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rt-thread-official/libcpu/arm/cortex-m4/context_rvds.S

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ArmAsm
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;/*
;* Copyright (c) 2006-2018, RT-Thread Development Team
;*
;* SPDX-License-Identifier: Apache-2.0
;*
; * Change Logs:
; * Date Author Notes
; * 2009-01-17 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.
; * 2024-08-13 Evlers allows rewrite to interrupt enable/disable api to support independent interrupts management
; */
;/**
; * @addtogroup cortex-m4
; */
;/*@{*/
SCB_VTOR EQU 0xE000ED08 ; Vector Table Offset Register
NVIC_INT_CTRL EQU 0xE000ED04 ; interrupt control state register
NVIC_SYSPRI2 EQU 0xE000ED20 ; system priority register (2)
NVIC_PENDSV_PRI EQU 0xFFFF0000 ; PendSV and SysTick priority value (lowest)
NVIC_PENDSVSET EQU 0x10000000 ; value to trigger PendSV exception
AREA |.text|, CODE, READONLY, ALIGN=2
THUMB
REQUIRE8
PRESERVE8
IMPORT rt_thread_switch_interrupt_flag
IMPORT rt_interrupt_from_thread
IMPORT rt_interrupt_to_thread
;/*
; * rt_base_t rt_hw_interrupt_disable();
; */
rt_hw_interrupt_disable PROC
EXPORT rt_hw_interrupt_disable [WEAK]
MRS r0, PRIMASK
CPSID I
BX LR
ENDP
;/*
; * void rt_hw_interrupt_enable(rt_base_t level);
; */
rt_hw_interrupt_enable PROC
EXPORT rt_hw_interrupt_enable [WEAK]
MSR PRIMASK, r0
BX LR
ENDP
;/*
; * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
; * r0 --> from
; * r1 --> to
; */
rt_hw_context_switch_interrupt
EXPORT rt_hw_context_switch_interrupt
rt_hw_context_switch PROC
EXPORT 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
ENDP
; r0 --> switch from thread stack
; r1 --> switch to thread stack
; psr, pc, lr, r12, r3, r2, r1, r0 are pushed into [from] stack
PendSV_Handler PROC
EXPORT 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 {FPU} != "SoftVFP"
TST lr, #0x10 ; if(!EXC_RETURN[4])
VSTMFDEQ r1!, {d8 - d15} ; push FPU register s16~s31
ENDIF
STMFD r1!, {r4 - r11} ; push r4 - r11 register
IF {FPU} != "SoftVFP"
MOV r4, #0x00 ; flag = 0
TST lr, #0x10 ; if(!EXC_RETURN[4])
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 {FPU} != "SoftVFP"
LDMFD r1!, {r3} ; pop flag
ENDIF
LDMFD r1!, {r4 - r11} ; pop r4 - r11 register
IF {FPU} != "SoftVFP"
CMP r3, #0 ; if(flag_r3 != 0)
VLDMFDNE r1!, {d8 - d15} ; pop FPU register s16~s31
ENDIF
MSR psp, r1 ; update stack pointer
IF {FPU} != "SoftVFP"
ORR lr, lr, #0x10 ; lr |= (1 << 4), clean FPCA.
CMP r3, #0 ; if(flag_r3 != 0)
BICNE lr, lr, #0x10 ; lr &= ~(1 << 4), set FPCA.
ENDIF
pendsv_exit
; restore interrupt
MSR PRIMASK, r2
ORR lr, lr, #0x04
BX lr
ENDP
;/*
; * void rt_hw_context_switch_to(rt_uint32 to);
; * r0 --> to
; * this fucntion is used to perform the first thread switch
; */
rt_hw_context_switch_to PROC
EXPORT rt_hw_context_switch_to
; set to thread
LDR r1, =rt_interrupt_to_thread
STR r0, [r1]
IF {FPU} != "SoftVFP"
; 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
; trigger the PendSV exception (causes context switch)
LDR r0, =NVIC_INT_CTRL
LDR r1, =NVIC_PENDSVSET
STR r1, [r0]
; restore MSP
LDR r0, =SCB_VTOR
LDR r0, [r0]
LDR r0, [r0]
MSR msp, r0
; enable interrupts at processor level
CPSIE F
CPSIE I
; clear the BASEPRI register to disable masking priority
MOV r0, #0x00
MSR BASEPRI, r0
; ensure PendSV exception taken place before subsequent operation
DSB
ISB
; never reach here!
ENDP
; compatible with old version
rt_hw_interrupt_thread_switch PROC
EXPORT rt_hw_interrupt_thread_switch
BX lr
ENDP
IMPORT rt_hw_hard_fault_exception
EXPORT HardFault_Handler
HardFault_Handler PROC
; get current context
TST lr, #0x04 ; if(!EXC_RETURN[2])
ITE EQ
MRSEQ r0, msp ; [2]=0 ==> Z=1, get fault context from handler.
MRSNE r0, psp ; [2]=1 ==> Z=0, get fault context from thread.
STMFD r0!, {r4 - r11} ; push r4 - r11 register
IF {FPU} != "SoftVFP"
STMFD r0!, {lr} ; push dummy for flag
ENDIF
STMFD r0!, {lr} ; push exec_return register
TST lr, #0x04 ; if(!EXC_RETURN[2])
ITE EQ
MSREQ msp, r0 ; [2]=0 ==> Z=1, update stack pointer to MSP.
MSRNE psp, r0 ; [2]=1 ==> Z=0, update stack pointer to PSP.
PUSH {lr}
BL rt_hw_hard_fault_exception
POP {lr}
ORR lr, lr, #0x04
BX lr
ENDP
ALIGN 4
END
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