[其他] Cortex-M3 ARM代码编译，链接与启动过程深度分析

    Total RO  Size (Code + RO Data)                12008 (  11.73kB)

    Total RW  Size (RW Data + ZI Data)              2664 (   2.60kB)

    Total ROM Size (Code + RO Data + RW Data)      12068 (  11.79kB)

 

.global  g_pfnVectors

.global  Default_Handler

 

/* start address for the initialization values of the .data section. 

defined in linker script */

.word  _sidata

/* start address for the .data section. defined in linker script */  

.word  _sdata

/* end address for the .data section. defined in linker script */

.word  _edata

/* start address for the .bss section. defined in linker script */

.word  _sbss

/* end address for the .bss section. defined in linker script */

.word  _ebss

/* stack used for SystemInit_ExtMemCtl; always internal RAM used */

 

/**

 * [url=home.php?mod=space&uid=247401]@brief[/url]  This is the code that gets called when the processor first

 *          starts execution following a reset event. Only the absolutely

 *          necessary set is performed, after which the application

 *          supplied main() routine is called. 

 * @param  None

 * @retval : None

*/

 

    .section  .text.Reset_Handler

  .weak  Reset_Handler

  .type  Reset_Handler, %function

Reset_Handler:  

 

/* Copy the data segment initializers from flash to SRAM */  

  movs  r1, #0

  b  LoopCopyDataInit

 

CopyDataInit:

  ldr  r3, =_sidata

  ldr  r3, [r3, r1]

  str  r3, [r0, r1]

  adds  r1, r1, #4

    

LoopCopyDataInit:

  ldr  r0, =_sdata

  ldr  r3, =_edata

  adds  r2, r0, r1

  cmp  r2, r3

  bcc  CopyDataInit

  ldr  r2, =_sbss

  b  LoopFillZerobss

/* Zero fill the bss segment. */  

FillZerobss:

  movs  r3, #0

  str  r3, [r2], #4

    

LoopFillZerobss:

  ldr  r3, = _ebss

  cmp  r2, r3

  bcc  FillZerobss

 

/* Call the clock system intitialization function.*/

  bl  SystemInit   

/* Call static constructors */

/*    bl __libc_init_array    */

/* Call the application's entry point.'*/

  bl  main

  bx  lr    

.size  Reset_Handler, .-Reset_Handler

 

 

/* Define output sections */

SECTIONS

{

  /* The startup code goes first into FLASH */

  /* isr_vector启动代码中断服务向量表区域从所谓的零地址0x0800 0000开始*/

  .isr_vector :

  {

    . = ALIGN(4);

    KEEP(*(.isr_vector)) /* Startup code */

    . = ALIGN(4);

  } >FLASH

......

......

}

 

/* Define output sections */

SECTIONS

{

......

......

  /* The program code and other data goes into FLASH */

  .text :

  {

    . = ALIGN(4);

    *(.text)           /* .text sections (code) */

    *(.text*)          /* .text* sections (code) */

    *(.rodata)         /* .rodata sections (constants, strings, etc.) */

    *(.rodata*)        /* .rodata* sections (constants, strings, etc.) */

    *(.glue_7)         /* glue arm to thumb code */

    *(.glue_7t)        /* glue thumb to arm code */

        *(.eh_frame)

 

    KEEP (*(.init))

    KEEP (*(.fini))

 

    . = ALIGN(4);

    _etext = .;        /* define a global symbols at end of code */

  } >FLASH

......

......

}

 

/* Define output sections */

SECTIONS

{

......

......

/* used by the startup to initialize data */

  _sidata = .;

 

  /* Initialized data sections goes into RAM, load LMA copy after code */

  .data : AT ( _sidata )

  {

    . = ALIGN(4);

    _sdata = .;        /* create a global symbol at data start */

    *(.data)           /* .data sections */

    *(.data*)          /* .data* sections */

 

    . = ALIGN(4);

    _edata = .;        /* define a global symbol at data end */

  } >RAM

 

  /* Uninitialized data section */

  . = ALIGN(4);

  .bss :

  {

    /* This is used by the startup in order to initialize the .bss secion */

    _sbss = .;         /* define a global symbol at bss start */

    __bss_start__ = _sbss;

    *(.bss)

    *(.bss*)

    *(COMMON)

 

    . = ALIGN(4);

    _ebss = .;         /* define a global symbol at bss end */

    __bss_end__ = _ebss;

  } >RAM

 

  PROVIDE ( end = _ebss );

  PROVIDE ( _end = _ebss );

......

......

}