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/*****************************************************************************

 * Copyright (c) 2001, 2002 Rowley Associates Limited.                       *

 *                                                                           *

 * This file may be distributed under the terms of the License Agreement     *

 * provided with this software.                                              *

 *                                                                           *

 * THIS FILE IS PROVIDED AS IS WITH NO WARRANTY OF ANY KIND, INCLUDING THE   *

 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. *

 *****************************************************************************/

  .section .init, "ax"

  .code 32

  .align 0

  .weak _start

  .global __start

  .global __gccmain

  .extern main

  .extern exit

/*****************************************************************************

 * Function    : _start                                                      *

 * Description : Main entry point and startup code for C system.             *

 *****************************************************************************/

_start:

__start:

  mrs r0, cpsr

  bic r0, r0, #0x1F

  /* Setup stacks */

  orr r1, r0, #0x1B /* Undefined mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_und_end__

  orr r1, r0, #0x17 /* Abort mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_abt_end__

  orr r1, r0, #0x12 /* IRQ mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_irq_end__

  orr r1, r0, #0x11 /* FIQ mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_fiq_end__

  orr r1, r0, #0x13 /* Supervisor mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_svc_end__

#ifdef SUPERVISOR_START

  /* Start application in supervisor mode */

  ldr r1, =__stack_end__ /* Setup user/system mode stack */

  mov r2, sp

  stmfd r2!, {r1}

  ldmfd r2, {sp}^

#else

  /* Start application in system mode */

  orr r1, r0, #0x1F /* System mode */

  msr cpsr_cxsf, r1

  ldr sp, =__stack_end__

#endif

  /* Copy from initialised data section to data section (if necessary). */

  ldr r0, =__data_load_start__

  ldr r1, =__data_start__

  cmp r0, r1

  beq copy_data_end

  ldr r2, =__data_end__

  subs r2, r2, r1

  beq copy_data_end

copy_data_loop:

  ldrb r3, [r0], #+1

  strb r3, [r1], #+1

  subs r2, r2, #1

  bne copy_data_loop

copy_data_end:

  /* Copy from initialised text section to text section (if necessary). */

  ldr r0, =__text_load_start__

  ldr r1, =__text_start__

  cmp r0, r1

  beq copy_text_end

  ldr r2, =__text_end__

  subs r2, r2, r1

  beq copy_text_end

copy_text_loop:

  ldrb r3, [r0], #+1

  strb r3, [r1], #+1

  subs r2, r2, #1

  bne copy_text_loop

copy_text_end:

  /* Copy from initialised fast_text section to fast_text section (if necessary). */

  ldr r0, =__fast_load_start__

  ldr r1, =__fast_start__

  cmp r0, r1

  beq copy_fast_end

  ldr r2, =__fast_end__

  subs r2, r2, r1

  beq copy_fast_end

copy_fast_loop:

  ldrb r3, [r0], #+1

  strb r3, [r1], #+1

  subs r2, r2, #1

  bne copy_fast_loop

copy_fast_end:

  /* Zero the bss. */

  ldr r0, =__bss_start__

  ldr r1, =__bss_end__

  mov r2, #0

zero_bss_loop:

  cmp r0, r1

  beq zero_bss_end

  strb r2, [r0], #+1

  b zero_bss_loop

zero_bss_end:

#ifdef CHECK

  /* Check data */

  ldr r0, =__data_load_start__

  ldr r1, =__data_start__

  cmp r0, r1

  beq check_data_end

  ldr r2, =__data_end__

  subs r2, r2, r1

  beq check_data_end

check_data_loop:

  ldrb r3, [r0], #+1

  ldrb r4, [r1], #+1

  cmp r3, r4

  bne data_error_loop

  subs r2, r2, #1

  bne check_data_loop

check_data_end:

  /* Check text */

  ldr r0, =__text_load_start__

  ldr r1, =__text_start__

  cmp r0, r1

  beq check_text_end

  ldr r2, =__text_end__

  subs r2, r2, r1

  beq check_text_end

check_text_loop:

  ldrb r3, [r0], #+1

  ldrb r4, [r1], #+1

  cmp r3, r4

  bne text_error_loop

  subs r2, r2, #1

  bne check_text_loop

check_text_end:

  /* Check fast */

  ldr r0, =__fast_load_start__

  ldr r1, =__fast_start__

  cmp r0, r1

  beq check_fast_end

  ldr r2, =__fast_end__

  subs r2, r2, r1

  beq check_fast_end

check_fast_loop:

  ldrb r3, [r0], #+1

  ldrb r4, [r1], #+1

  cmp r3, r4

  bne fast_error_loop

  subs r2, r2, #1

  bne check_fast_loop

check_fast_end:

  /* Check bss */

  ldr r0, =__bss_start__

  ldr r1, =__bss_end__

  mov r2, #0

check_bss_loop:

  cmp r0, r1

  beq check_bss_end

  ldrb r2, [r0], #+1

  cmp r2, #0

  bne bss_error_loop

  b check_bss_loop

check_bss_end:

#endif

  /* Initialise the heap */

  ldr r0, = __heap_start__

  ldr r1, = __heap_end__

  sub r1, r1, r0     /* r1 = r1-r0 */

  mov r2, #0

  str r2, [r0], #+4 /* *r0++ = 0 */

  str r1, [r0]      /* *r0 = __heap_end__ - __heap_start__ */

  /* Call constructors */

  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

  mov pc, r2

  ldmfd sp!, {r0-r1}

  b ctor_loop

ctor_end:

  /* Setup initial call frame */

  mov lr, #4

  mov r12, sp

  stmfd sp!, {r11-r12, lr-pc}

  sub r11, r12, #0x00000004

start:

  /* Jump to main entry point */

  mov r0, #0

  mov r1, #0

  ldr r2, =main

  mov lr, pc

#ifdef __ARM_ARCH_3__

  mov pc, r2

#else

  bx r2

#endif

  /* Call destructors */

  ldr r0, =__dtors_start__

  ldr r1, =__dtors_end__

dtor_loop:

  cmp r0, r1

  beq dtor_end

  ldr r2, [r0], #+4

  stmfd sp!, {r0-r1}

  mov lr, pc

  mov pc, r2

  ldmfd sp!, {r0-r1}

  b dtor_loop

dtor_end:

  /* Return from main, loop forever. */

exit_loop:

  b exit_loop

#ifdef CHECK

data_error_loop:

  b data_error_loop

text_error_loop:

  b text_error_loop

fast_error_loop:

  b fast_error_loop

bss_error_loop:

  b bss_error_loop

#endif