ref: a10d303e7c2d5f961c6b7ad5421cef5daf307fea
dir: /demos/stm32f429_disco/startup.S/
/******************************************************************************
* author: Freddie Chopin, http://www.freddiechopin.info/
* file: startup.S
* last change: 2012-03-18
*
* chip: ARMv7-M(E) (Cortex-M3 / Cortex-M4)
* compiler: arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.6.2
* 20110921 (release) [ARM/embedded-4_6-branch revision 182083]
*
* description:
* ARMv7-M(E) (Cortex-M3 / Cortex-M4) assembly startup code
******************************************************************************/
#define PRIMASK_MASK_EXCEPTIONS_bit 0
#define PRIMASK_MASK_EXCEPTIONS (1 << PRIMASK_MASK_EXCEPTIONS_bit)
#define FAULTMASK_MASK_EXCEPTIONS_bit 0
#define FAULTMASK_MASK_EXCEPTIONS (1 << FAULTMASK_MASK_EXCEPTIONS_bit)
#define CONTROL_THREAD_UNPRIVILEGED_bit 0
#define CONTROL_ALTERNATE_STACK_bit 1
#define CONTROL_THREAD_UNPRIVILEGED (1 << CONTROL_THREAD_UNPRIVILEGED_bit)
#define CONTROL_ALTERNATE_STACK (1 << CONTROL_ALTERNATE_STACK_bit)
/*
+=============================================================================+
| ARMv7-M(E) (Cortex-M3 / Cortex-M4) startup code
+=============================================================================+
*/
.text
.balign 2
.syntax unified
.thumb
.thumb_func
.global Reset_Handler
Reset_Handler:
/*
+-----------------------------------------------------------------------------+
| Initialize the process stack pointer
+-----------------------------------------------------------------------------+
*/
ldr r0, =__process_stack_end
msr PSP, r0
/*
+-----------------------------------------------------------------------------+
| Thread mode uses process stack (PSP) and is privileged
+-----------------------------------------------------------------------------+
*/
movs r0, #CONTROL_ALTERNATE_STACK
msr CONTROL, r0
isb
/*
+-----------------------------------------------------------------------------+
| Branch to low_level_init_0() function (.data and .bss are not initialized!)
+-----------------------------------------------------------------------------+
*/
ldr r0, =low_level_init_0
blx r0
/*
+-----------------------------------------------------------------------------+
| Initialize .data section
+-----------------------------------------------------------------------------+
*/
ldr r1, =__data_init_start
ldr r2, =__data_start
ldr r3, =__data_end
1: cmp r2, r3
ittt lo
ldrlo r0, [r1], #4
strlo r0, [r2], #4
blo 1b
/*
+-----------------------------------------------------------------------------+
| Zero-init .bss section
+-----------------------------------------------------------------------------+
*/
movs r0, #0
ldr r1, =__bss_start
ldr r2, =__bss_end
1: cmp r1, r2
itt lo
strlo r0, [r1], #4
blo 1b
/*
+-----------------------------------------------------------------------------+
| Call C++ constructors for global and static objects
+-----------------------------------------------------------------------------+
*/
#ifdef __USES_CXX
ldr r0, =__libc_init_array
blx r0
#endif
/*
+-----------------------------------------------------------------------------+
| Branch to low_level_init_1() function
+-----------------------------------------------------------------------------+
*/
ldr r0, =low_level_init_1
blx r0
/*
+-----------------------------------------------------------------------------+
| Branch to main() with link
+-----------------------------------------------------------------------------+
*/
ldr r0, =main
blx r0
/*
+-----------------------------------------------------------------------------+
| Call C++ destructors for global and static objects
+-----------------------------------------------------------------------------+
*/
#ifdef __USES_CXX
ldr r0, =__libc_fini_array
blx r0
#endif
/*
+-----------------------------------------------------------------------------+
| On return - loop till the end of the world
+-----------------------------------------------------------------------------+
*/
b .
/*
+=============================================================================+
| __default_low_level_init() - replacement for undefined low_level_init_0()
| and/or low_level_init_1(). This function just returns.
+=============================================================================+
*/
.text
.balign 2
.syntax unified
.thumb
.thumb_func
.global __default_low_level_init
__default_low_level_init:
bx lr
/*
+=============================================================================+
| assign undefined low_level_init_0() and/or low_level_init_1() to
| __default_low_level_init()
+=============================================================================+
*/
.weak low_level_init_0
.global low_level_init_0
.set low_level_init_0, __default_low_level_init
.weak low_level_init_1
.global low_level_init_1
.set low_level_init_1, __default_low_level_init
/******************************************************************************
* END OF FILE
******************************************************************************/