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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file GCC/ARMCMx/crt0_v6m.s
* @brief Generic ARMv6-M (Cortex-M0/M1) startup file for ChibiOS/RT.
*
* @addtogroup ARMCMx_CORE
* @{
*/
#if !defined(__DOXYGEN__)
.set CONTROL_MODE_PRIVILEGED, 0
.set CONTROL_MODE_UNPRIVILEGED, 1
.set CONTROL_USE_MSP, 0
.set CONTROL_USE_PSP, 2
.text
.balign 2
.syntax unified
.thumb
/*
* Reset handler.
*/
.thumb_func
.global ResetHandler
.weak ResetHandler
ResetHandler:
/*
* Interrupts are globally masked initially.
*/
cpsid i
/*
* Stack pointers initialization.
*/
ldr r0, =__ram_end__
ldr r1, =__main_stack_size__
subs r0, r0, r1
/*
* Note that r0 is the main stack low boundary address and process
* stack initial top address.
*/
msr PSP, r0
/*
* Early initialization phase, it is empty by default.
*/
bl __early_init
/*
* Data initialization.
* NOTE: It assumes that the DATA size is a multiple of 4.
*/
ldr r1, =_textdata
ldr r2, =_data
ldr r3, =_edata
dloop:
cmp r2, r3
bge enddloop
ldr r0, [r1]
str r0, [r2]
adds r1, r1, #4
adds r2, r2, #4
b dloop
enddloop:
/*
* BSS initialization.
* NOTE: It assumes that the BSS size is a multiple of 4.
*/
movs r0, #0
ldr r1, =_bss_start
ldr r2, =_bss_end
bloop:
cmp r1, r2
bge endbloop
str r0, [r1]
adds r1, r1, #4
b bloop
endbloop:
/*
* Switches to the Process Stack and uses a barrier just to be safe.
*/
movs r0, #CONTROL_MODE_PRIVILEGED | CONTROL_USE_PSP
msr CONTROL, r0
isb
/*
* Main program invocation.
*/
bl main
b _main_exit_handler
/*
* Default main exit code, just a loop.
* It is a weak symbol, the application code can redefine the behavior.
*/
.thumb_func
.global _main_exit_handler
.weak _main_exit_handler
_main_exit_handler:
.loop: b .loop
/*
* Default early initialization code. It is declared weak in order to be
* replaced by the real initialization code.
* The arly initialization is performed just after stacks setup and before BSS
* and DATA segments initialization.
*/
.thumb_func
.global __early_init
.weak __early_init
__early_init:
bx lr
#endif
/** @} */
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