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/*
* Copyright (c) 2006-2021, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2010-11-13 weety first version
*/
#define CONFIG_STACKSIZE 512
#define S_FRAME_SIZE 68
#define S_PC 64
#define S_LR 60
#define S_SP 56
#define S_IP 52
#define S_FP 48
#define S_R10 44
#define S_R9 40
#define S_R8 36
#define S_R7 32
#define S_R6 28
#define S_R5 24
#define S_R4 20
#define S_R3 16
#define S_R2 12
#define S_R1 8
#define S_R0 4
#define S_CPSR 0
.equ I_BIT, 0x80 @ when I bit is set, IRQ is disabled
.equ F_BIT, 0x40 @ when F bit is set, FIQ is disabled
.equ USERMODE, 0x10
.equ FIQMODE, 0x11
.equ IRQMODE, 0x12
.equ SVCMODE, 0x13
.equ ABORTMODE, 0x17
.equ UNDEFMODE, 0x1b
.equ MODEMASK, 0x1f
.equ NOINT, 0xc0
.equ RAM_BASE, 0x00000000 /*Start address of RAM */
.equ ROM_BASE, 0x80000000 /*Start address of Flash */
.equ EINT_ENABLE0, 0x01c48018
.equ EINT_ENABLE1, 0x01c4801c
/*
*************************************************************************
*
* Jump vector table
*
*************************************************************************
*/
.section .init, "ax"
.code 32
.globl _start
_start:
b reset
ldr pc, _vector_undef
ldr pc, _vector_swi
ldr pc, _vector_pabt
ldr pc, _vector_dabt
ldr pc, _vector_resv
ldr pc, _vector_irq
ldr pc, _vector_fiq
_vector_undef: .word vector_undef
_vector_swi: .word vector_swi
_vector_pabt: .word vector_pabt
_vector_dabt: .word vector_dabt
_vector_resv: .word vector_resv
_vector_irq: .word vector_irq
_vector_fiq: .word vector_fiq
.balignl 16,0xdeadbeef
/*
*************************************************************************
*
* Startup Code (reset vector)
* relocate armboot to ram
* setup stack
* jump to second stage
*
*************************************************************************
*/
_TEXT_BASE:
.word TEXT_BASE
/*
* rtthread kernel start and end
* which are defined in linker script
*/
.globl _rtthread_start
_rtthread_start:
.word _start
.globl _rtthread_end
_rtthread_end:
.word _end
/*
* rtthread bss start and end which are defined in linker script
*/
.globl _bss_start
_bss_start:
.word __bss_start
.globl _bss_end
_bss_end:
.word __bss_end
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
.word _irq_stack_start + 1024
.globl FIQ_STACK_START
FIQ_STACK_START:
.word _fiq_stack_start + 1024
.globl UNDEFINED_STACK_START
UNDEFINED_STACK_START:
.word _undefined_stack_start + CONFIG_STACKSIZE
.globl ABORT_STACK_START
ABORT_STACK_START:
.word _abort_stack_start + CONFIG_STACKSIZE
.globl _STACK_START
_STACK_START:
.word _svc_stack_start + 1024
/* ----------------------------------entry------------------------------*/
reset:
/* set the cpu to SVC32 mode */
mrs r0,cpsr
bic r0,r0,#MODEMASK
orr r0,r0,#SVCMODE
msr cpsr,r0
/* mask all IRQs by clearing all bits in the INTMRs */
mov r1, $0
ldr r0, =EINT_ENABLE0
str r1, [r0]
ldr r0, =EINT_ENABLE1
str r1, [r0]
#if 0
/* set interrupt vector */
ldr r0, _TEXT_BASE
mov r1, #0x00
add r2, r0, #0x40 /* size, 32bytes */
copy_loop:
ldmia r0!, {r3-r10} /* copy from source address [r0] */
stmia r1!, {r3-r10} /* copy to target address [r1] */
cmp r0, r2 /* until source end addreee [r2] */
ble copy_loop
#endif
/* setup stack */
bl stack_setup
/* clear .bss */
mov r0,#0 /* get a zero */
ldr r1,=__bss_start /* bss start */
ldr r2,=__bss_end /* bss end */
bss_loop:
cmp r1,r2 /* check if data to clear */
strlo r0,[r1],#4 /* clear 4 bytes */
blo bss_loop /* loop until done */
/* call C++ constructors of global objects */
ldr r0, =__ctors_start__
ldr r1, =__ctors_end__
ctor_loop:
cmp r0, r1
beq ctor_end
ldr r2, [r0], #4
stmfd sp!, {r0-r1}
mov lr, pc
bx r2
ldmfd sp!, {r0-r1}
b ctor_loop
ctor_end:
/* start RT-Thread Kernel */
ldr pc, _rtthread_startup
_rtthread_startup:
.word rtthread_startup
#if defined (__FLASH_BUILD__)
_load_address:
.word ROM_BASE + _TEXT_BASE
#else
_load_address:
.word RAM_BASE + _TEXT_BASE
#endif
/*
*************************************************************************
*
* Interrupt handling
*
*************************************************************************
*/
.macro push_exp_reg
sub sp, sp, #S_FRAME_SIZE @/* Sizeof(struct rt_hw_stack) */
stmib sp, {r0 - r12} @/* Calling r0-r12 */
mov r0, sp
mrs r6, spsr @/* Save CPSR */
str lr, [r0, #S_PC] @/* Push PC */
str r6, [r0, #S_CPSR] @/* Push CPSR */
@ switch to SVC mode with no interrupt
msr cpsr_c, #I_BIT|F_BIT|SVCMODE
str sp, [r0, #S_SP] @/* Save calling SP */
str lr, [r0, #S_LR] @/* Save calling PC */
.endm
/* exception handlers */
.align 5
vector_undef:
push_exp_reg
bl rt_hw_trap_udef
.align 5
vector_swi:
push_exp_reg
bl rt_hw_trap_swi
.align 5
vector_pabt:
push_exp_reg
bl rt_hw_trap_pabt
.align 5
vector_dabt:
push_exp_reg
bl rt_hw_trap_dabt
.align 5
vector_resv:
push_exp_reg
bl rt_hw_trap_resv
.globl rt_interrupt_enter
.globl rt_interrupt_leave
.globl rt_thread_switch_interrupt_flag
.globl rt_interrupt_from_thread
.globl rt_interrupt_to_thread
vector_irq:
stmfd sp!, {r0-r12,lr}
bl rt_interrupt_enter
bl rt_hw_trap_irq
bl rt_interrupt_leave
@ if rt_thread_switch_interrupt_flag set, jump to
@ rt_hw_context_switch_interrupt_do and don't return
ldr r0, =rt_thread_switch_interrupt_flag
ldr r1, [r0]
cmp r1, #1
beq rt_hw_context_switch_interrupt_do
ldmfd sp!, {r0-r12,lr}
subs pc, lr, #4
.align 5
vector_fiq:
stmfd sp!,{r0-r7,lr}
bl rt_hw_trap_fiq
ldmfd sp!,{r0-r7,lr}
subs pc,lr,#4
rt_hw_context_switch_interrupt_do:
mov r1, #0 @ clear flag
str r1, [r0]
ldmfd sp!, {r0-r12,lr}@ reload saved registers
stmfd sp, {r0-r2} @ save r0-r2
mrs r0, spsr @ get cpsr of interrupt thread
sub r1, sp, #4*3
sub r2, lr, #4 @ save old task's pc to r2
@ switch to SVC mode with no interrupt
msr cpsr_c, #I_BIT|F_BIT|SVCMODE
stmfd sp!, {r2} @ push old task's pc
stmfd sp!, {r3-r12,lr}@ push old task's lr,r12-r4
ldmfd r1, {r1-r3} @ restore r0-r2 of the interrupt thread
stmfd sp!, {r1-r3} @ push old task's r0-r2
stmfd sp!, {r0} @ push old task's cpsr
ldr r4, =rt_interrupt_from_thread
ldr r5, [r4]
str sp, [r5] @ store sp in preempted tasks's TCB
ldr r6, =rt_interrupt_to_thread
ldr r6, [r6]
ldr sp, [r6] @ get new task's stack pointer
ldmfd sp!, {r4} @ pop new task's cpsr to spsr
msr spsr_cxsf, r4
ldmfd sp!, {r0-r12,lr,pc}^ @ pop new task's r0-r12,lr & pc, copy spsr to cpsr
stack_setup:
mrs r0, cpsr
bic r0, r0, #MODEMASK
orr r1, r0, #UNDEFMODE|NOINT
msr cpsr_cxsf, r1 /* undef mode */
ldr sp, UNDEFINED_STACK_START
orr r1,r0,#ABORTMODE|NOINT
msr cpsr_cxsf,r1 /* abort mode */
ldr sp, ABORT_STACK_START
orr r1,r0,#IRQMODE|NOINT
msr cpsr_cxsf,r1 /* IRQ mode */
ldr sp, IRQ_STACK_START
orr r1,r0,#FIQMODE|NOINT
msr cpsr_cxsf,r1 /* FIQ mode */
ldr sp, FIQ_STACK_START
bic r0,r0,#MODEMASK
orr r1,r0,#SVCMODE|NOINT
msr cpsr_cxsf,r1 /* SVC mode */
ldr sp, _STACK_START
/* USER mode is not initialized. */
bx lr /* The LR register may be not valid for the mode changes.*/
/*/*}*/
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