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rt-thread-official/libcpu/arm/lpc24xx/start_gcc.S

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/*
* File : start.S
* This file is part of RT-Thread RTOS
* COPYRIGHT (C) 2006, RT-Thread Development Team
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://openlab.rt-thread.com/license/LICENSE
*
* Change Logs:
* Date Author Notes
* 2008-12-11 XuXinming first version
* 2011-03-17 Bernard update to 0.4.x
*/
#define WDMOD (0xE0000000 + 0x00)
#define VICIntEnClr (0xFFFFF000 + 0x014)
#define VICVectAddr (0xFFFFF000 + 0xF00)
#define VICIntSelect (0xFFFFF000 + 0x00C)
#define PLLCFG (0xE01FC000 + 0x084)
#define PLLCON (0xE01FC000 + 0x080)
#define PLLFEED (0xE01FC000 + 0x08C)
#define PLLSTAT (0xE01FC000 + 0x088)
#define CCLKCFG (0xE01FC000 + 0x104)
#define MEMMAP (0xE01FC000 + 0x040)
#define SCS (0xE01FC000 + 0x1A0)
#define CLKSRCSEL (0xE01FC000 + 0x10C)
#define MAMCR (0xE01FC000 + 0x000)
#define MAMTIM (0xE01FC000 + 0x004)
/* stack memory */
.section .bss.noinit
.equ IRQ_STACK_SIZE, 0x00000200
.equ FIQ_STACK_SIZE, 0x00000100
.equ UDF_STACK_SIZE, 0x00000004
.equ ABT_STACK_SIZE, 0x00000004
.equ SVC_STACK_SIZE, 0x00000200
.space IRQ_STACK_SIZE
IRQ_STACK:
.space FIQ_STACK_SIZE
FIQ_STACK:
.space UDF_STACK_SIZE
UDF_STACK:
.space ABT_STACK_SIZE
ABT_STACK:
.space SVC_STACK_SIZE
SVC_STACK:
.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
/*
* 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
.text
.code 32
/* the system entry */
reset:
/* enter svc mode */
msr cpsr_c, #SVCMODE|NOINT
/*watch dog disable */
ldr r0,=WDMOD
ldr r1,=0x0
str r1,[r0]
/* all interrupt disable */
ldr r0,=VICIntEnClr
ldr r1,=0xffffffff
str r1,[r0]
ldr r1, =VICVectAddr
ldr r0, =0x00
str r0, [r1]
ldr r1, =VICIntSelect
ldr r0, =0x00
str r0, [r1]
/* setup stack */
bl stack_setup
/* copy .data to SRAM */
ldr r1, =_sidata /* .data start in image */
ldr r2, =_edata /* .data end in image */
ldr r3, =_sdata /* sram data start */
data_loop:
ldr r0, [r1, #0]
str r0, [r3]
add r1, r1, #4
add r3, r3, #4
cmp r3, r2 /* check if data to clear */
blo data_loop /* loop until done */
/* 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
.equ USERMODE, 0x10
.equ FIQMODE, 0x11
.equ IRQMODE, 0x12
.equ SVCMODE, 0x13
.equ ABORTMODE, 0x17
.equ UNDEFMODE, 0x1b
.equ MODEMASK, 0x1f
.equ NOINT, 0xc0
/* exception handlers */
vector_undef: bl rt_hw_trap_udef
vector_swi: bl rt_hw_trap_swi
vector_pabt: bl rt_hw_trap_pabt
vector_dabt: bl rt_hw_trap_dabt
vector_resv: 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 _interrupt_thread_switch and don't return
*/
ldr r0, =rt_thread_switch_interrupt_flag
ldr r1, [r0]
cmp r1, #1
beq _interrupt_thread_switch
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
_interrupt_thread_switch:
mov r1, #0 /* clear rt_thread_switch_interrupt_flag */
str r1, [r0]
ldmfd sp!, {r0-r12,lr} /* reload saved registers */
stmfd sp!, {r0-r3} /* save r0-r3 */
mov r1, sp
add sp, sp, #16 /* restore sp */
sub r2, lr, #4 /* save old task's pc to r2 */
mrs r3, spsr /* disable interrupt */
orr r0, r3, #NOINT
msr spsr_c, r0
ldr r0, =.+8 /* switch to interrupted task's stack */
movs pc, r0
stmfd sp!, {r2} /* push old task's pc */
stmfd sp!, {r4-r12,lr} /* push old task's lr,r12-r4 */
mov r4, r1 /* Special optimised code below */
mov r5, r3
ldmfd r4!, {r0-r3}
stmfd sp!, {r0-r3} /* push old task's r3-r0 */
stmfd sp!, {r5} /* push old task's psr */
mrs r4, spsr
stmfd sp!, {r4} /* push old task's spsr */
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 spsr */
msr SPSR_cxsf, r4
ldmfd sp!, {r4} /* pop new task's psr */
msr CPSR_cxsf, r4
ldmfd sp!, {r0-r12,lr,pc} /* pop new task's r0-r12,lr & pc */
stack_setup:
mrs r0, cpsr
bic r0, r0, #MODEMASK
orr r1, r0, #UNDEFMODE|NOINT
msr cpsr_cxsf, r1 /* undef mode */
ldr sp, =UDF_STACK
orr r1,r0,#ABORTMODE|NOINT
msr cpsr_cxsf,r1 /* abort mode */
ldr sp, =ABT_STACK
orr r1,r0,#IRQMODE|NOINT
msr cpsr_cxsf,r1 /* IRQ mode */
ldr sp, =IRQ_STACK
orr r1,r0,#FIQMODE|NOINT
msr cpsr_cxsf,r1 /* FIQ mode */
ldr sp, =FIQ_STACK
bic r0,r0,#MODEMASK
orr r1,r0,#SVCMODE|NOINT
msr cpsr_cxsf,r1 /* SVC mode */
ldr sp, =SVC_STACK
/* USER mode is not initialized. */
mov pc,lr /* The LR register may be not valid for the mode changes.*/
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