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標題: 發(fā)一個winarm編譯器的lpc2000啟動文件 [打印本頁]

作者: machunshui 時間: 2009-7-13 14:48
標題: 發(fā)一個winarm編譯器的lpc2000啟動文件
發(fā)一個winarm編譯器的lpc2000啟動文件,感覺寫的非常清晰.

   .global main                   // int main(void)

      .global _etext                // -> .data initial values in ROM
      .global _data                // -> .data area in RAM
      .global _edata                // end of .data area
      .global __bss_start          // -> .bss area in RAM
      .global __bss_end__          // end of .bss area
      .global _stack                // top of stack

// Stack Sizes
      .set  UND_STACK_SIZE, 0x00000004
      .set  ABT_STACK_SIZE, 0x00000004
      .set  FIQ_STACK_SIZE, 0x00000004
      .set  IRQ_STACK_SIZE, 0X00000080
      .set  SVC_STACK_SIZE, 0x00000004

// Standard definitions of Mode bits and Interrupt (I & F) flags in PSRs
      .set  MODE_USR, 0x10          // User Mode
      .set  MODE_FIQ, 0x11          // FIQ Mode
      .set  MODE_IRQ, 0x12          // IRQ Mode
      .set  MODE_SVC, 0x13          // Supervisor Mode
      .set  MODE_ABT, 0x17          // Abort Mode
      .set  MODE_UND, 0x1B          // Undefined Mode
      .set  MODE_SYS, 0x1F          // System Mode

      .equ  I_BIT, 0x80             // when I bit is set, IRQ is disabled
      .equ  F_BIT, 0x40             // when F bit is set, FIQ is disabled

      .text
      .code 32
      .align 2

      .global _boot
      .func _boot
_boot:

// Runtime Interrupt Vectors
// -------------------------
Vectors:
      b    _start                   // reset - _start
      ldr pc,_undf                // undefined - _undf
      ldr pc,_swi                // SWI - _swi
      ldr pc,_pabt                // program abort - _pabt
      ldr pc,_dabt                // data abort - _dabt
      nop                            // reserved
      ldr pc,[pc,#-0xFF0]          // IRQ - read the VIC
      ldr pc,_fiq                // FIQ - _fiq

#if 0
// Use this group for production
_undf:  .word _reset                   // undefined - _reset
_swi: .word _reset                   // SWI - _reset
_pabt:  .word _reset                   // program abort - _reset
_dabt:  .word _reset                   // data abort - _reset
_irq: .word _reset                   // IRQ - _reset
_fiq: .word _reset                   // FIQ - _reset

#else
// Use this group for development
_undf:  .word __undf                   // undefined
_swi: .word __swi                   // SWI
_pabt:  .word __pabt                   // program abort
_dabt:  .word __dabt                   // data abort
_irq: .word __irq                   // IRQ
_fiq: .word __fiq                   // FIQ

__undf: b    .                      // undefined
__swi:  b    .                      // SWI
__pabt: b    .                      // program abort
__dabt: b    .                      // data abort
__irq:  b    .                      // IRQ
__fiq:  b    .                      // FIQ
#endif
      .size _boot, . - _boot
      .endfunc

// Setup the operating mode & stack.
// ---------------------------------
      .global _start, start, _mainCRTStartup
      .func _start

_start:
start:
_mainCRTStartup:

// Initialize Interrupt System
// - Set stack location for each mode
// - Leave in System Mode with Interrupts Disabled
// -----------------------------------------------
      ldr r0,=_stack
      msr CPSR_c,#MODE_UND|I_BIT|F_BIT // Undefined Instruction Mode
      mov sp,r0
      sub r0,r0,#UND_STACK_SIZE
      msr CPSR_c,#MODE_ABT|I_BIT|F_BIT // Abort Mode
      mov sp,r0
      sub r0,r0,#ABT_STACK_SIZE
      msr CPSR_c,#MODE_FIQ|I_BIT|F_BIT // FIQ Mode
      mov sp,r0
      sub r0,r0,#FIQ_STACK_SIZE
      msr CPSR_c,#MODE_IRQ|I_BIT|F_BIT // IRQ Mode
      mov sp,r0
      sub r0,r0,#IRQ_STACK_SIZE
      msr CPSR_c,#MODE_SVC|I_BIT|F_BIT // Supervisor Mode
      mov sp,r0
      sub r0,r0,#SVC_STACK_SIZE
      msr CPSR_c,#MODE_SYS|I_BIT|F_BIT // System Mode
      mov sp,r0

// Copy initialized data to its execution address in RAM
// -----------------------------------------------------
#ifdef ROM_RUN
      ldr r1,=_etext             // -> ROM data start
      ldr r2,=_data                // -> data start
      ldr r3,=_edata             // -> end of data
1:    cmp r2,r3                   // check if data to move
      ldrlo r0,[r1],#4             // copy it
      strlo r0,[r2],#4
      blo 1b                      // loop until done
#endif
// Clear .bss
// ----------
      mov r0,#0                   // get a zero
      ldr r1,=__bss_start          // -> bss start
      ldr r2,=__bss_end__          // -> bss end
2:    cmp r1,r2                   // check if data to clear
      strlo r0,[r1],#4             // clear 4 bytes
      blo 2b                      // loop until done

// Call main program: main(0)
// --------------------------
      mov r0,#0                   // no arguments (argc = 0)
      mov r1,r0
      mov r2,r0
      mov fp,r0                   // null frame pointer
      mov r7,r0                   // null frame pointer for thumb
      ldr r10,=main
      mov lr,pc
      bx r10                      // enter main()

      .size _start, . - _start
      .endfunc

      .global _reset, reset, exit, abort
      .func _reset
_reset:
reset:
exit:
abort:
#if 0
// Disable interrupts, then force a hardware reset by driving P23 low
// -------------------------------------------------------------------
      mrs r0,cpsr                // get PSR
      orr r0,r0,#I_BIT|F_BIT       // disable IRQ and FIQ
      msr cpsr,r0                // set up status register

      ldr r1,=(PS_BASE)          // PS Base Address
      ldr r0,=(PS_PIO)             // PIO Module
      str r0,[r1,#PS_PCER_OFF]    // enable its clock
      ldr r1,=(PIO_BASE)          // PIO Base Address
      ldr r0,=(1<<23)             // P23
      str r0,[r1,#PIO_PER_OFF]    // make sure pin is contolled by PIO
      str r0,[r1,#PIO_CODR_OFF]    // set the pin low
      str r0,[r1,#PIO_OER_OFF]    // make it an output
#endif
      b    .                      // loop until reset

      .size _reset, . - _reset
      .endfunc

      .end

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