Subversion Repositories openrisc

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

 * Copyright (c) 2009 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. *

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

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

 *                           Preprocessor Definitions

 *                           ------------------------

 * APP_ENTRY_POINT

 *

 *   Defines the application entry point function, if undefined this setting

 *   defaults to "main".

 *

 * USE_PROCESS_STACK

 *

 *   If defined, thread mode will be configured to use the process stack if

 *   the size of the process stack is greater than zero bytes in length.

 *

 * INITIALIZE_STACK

 *

 *   If defined, the contents of the stack will be initialized to a the

 *   value 0xCC.

 *

 * FULL_LIBRARY

 *

 *  If defined then

 *    - argc, argv are setup by the debug_getargs.

 *    - the exit symbol is defined and executes on return from main.

 *    - the exit symbol calls destructors, atexit functions and then debug_exit.

 *

 *  If not defined then

 *    - argc and argv are zero.

 *    - no exit symbol, code loops on return from main.

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

#ifndef APP_ENTRY_POINT

#define APP_ENTRY_POINT main

#endif

#ifndef ARGSSPACE

#define ARGSSPACE 128

#endif

  .global _start

  .syntax unified

  .extern APP_ENTRY_POINT

#ifdef FULL_LIBRARY

  .global exit

#endif

  .section .init, "ax"

  .code 16

  .align 2

  .thumb_func

_start:

#ifdef __RAM_BUILD

  ldr r1, =__stack_end__

  mov sp, r1

#endif

#ifdef INITIALIZE_STACK

  mov r2, #0xCC

  ldr r0, =__stack_start__

#ifndef __RAM_BUILD

  mov r1, sp

#endif

  bl memory_set

#endif

#ifdef USE_PROCESS_STACK

  /* Set up process stack if size > 0 */

  ldr r1, =__stack_process_end__

  ldr r0, =__stack_process_start__

  subs r2, r1, r0

  beq 1f

  msr psp, r1

  mov r2, #2

  msr control, r2

#ifdef INITIALIZE_STACK

  mov r2, #0xCC

  bl memory_set

#endif

1:

#endif

  /* Copy initialised memory sections into RAM (if necessary). */

  ldr r0, =__data_load_start__

  ldr r1, =__data_start__

  ldr r2, =__data_end__

  bl memory_copy

  ldr r0, =__text_load_start__

  ldr r1, =__text_start__

  ldr r2, =__text_end__

  bl memory_copy

  ldr r0, =__fast_load_start__

  ldr r1, =__fast_start__

  ldr r2, =__fast_end__

  bl memory_copy

  ldr r0, =__ctors_load_start__

  ldr r1, =__ctors_start__

  ldr r2, =__ctors_end__

  bl memory_copy

  ldr r0, =__dtors_load_start__

  ldr r1, =__dtors_start__

  ldr r2, =__dtors_end__

  bl memory_copy

  ldr r0, =__rodata_load_start__

  ldr r1, =__rodata_start__

  ldr r2, =__rodata_end__

  bl memory_copy

  /* Zero the bss. */

  ldr r0, =__bss_start__

  ldr r1, =__bss_end__

  mov r2, #0

  bl memory_set

  /* Initialise the heap */

  ldr r0, = __heap_start__

  ldr r1, = __heap_end__

  sub r1, r1, r0

  mov r2, #0

  str r2, [r0]

  add r0, r0, #4

  str r1, [r0]

  /* Call constructors */

  ldr r0, =__ctors_start__

  ldr r1, =__ctors_end__

ctor_loop:

  cmp r0, r1

  beq ctor_end

  ldr r2, [r0]

  add r0, #4

  push {r0-r1}

  blx r2

  pop {r0-r1}

  b ctor_loop

ctor_end:

  /* Setup initial call frame */

  mov r0, #0

  mov lr, r0

  mov r12, sp

start:

  /* Jump to application entry point */

#ifdef FULL_LIBRARY

  mov r0, #ARGSSPACE

  ldr r1, =args

  ldr r2, =debug_getargs

  blx r2

  ldr r1, =args

#else

  mov r0, #0

  mov r1, #0

#endif

  ldr r2, =APP_ENTRY_POINT

  blx r2

#ifdef FULL_LIBRARY

  .thumb_func

exit:

  mov r5, r0 // save the exit parameter/return result

  /* Call destructors */

  ldr r0, =__dtors_start__

  ldr r1, =__dtors_end__

dtor_loop:

  cmp r0, r1

  beq dtor_end

  ldr r2, [r0]

  add r0, #4

  push {r0-r1}

  blx r2

  pop {r0-r1}

  b dtor_loop

dtor_end:

  /* Call atexit functions */

  ldr r2, =_execute_at_exit_fns

  blx r2

  /* Call debug_exit with return result/exit parameter */

  mov r0, r5

  ldr r2, =debug_exit

  blx r2

#endif

  /* Returned from application entry point, loop forever. */

exit_loop:

  b exit_loop

memory_copy:

  cmp r0, r1

  beq 2f

  subs r2, r2, r1

  beq 2f

1:

  ldrb r3, [r0]

  add r0, r0, #1

  strb r3, [r1]

  add r1, r1, #1

  subs r2, r2, #1

  bne 1b

2:

  bx lr

memory_set:

  cmp r0, r1

  beq 1f

  strb r2, [r0]

  add r0, r0, #1

  b memory_set

1:

  bx lr

#ifdef FULL_LIBRARY

  .bss

args:

  .space ARGSSPACE

#endif