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