2013-01-08 22:40:58 +08:00
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/***************************************************************************//**
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* @file start_gcc.S
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* @brief Context switch functions
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* COPYRIGHT (C) 2012, RT-Thread Development Team
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* @author onelife
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* @version 1.0
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*******************************************************************************
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* @section License
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* The license and distribution terms for this file may be found in the file
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* LICENSE in this distribution or at http://www.rt-thread.org/license/LICENSE
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*******************************************************************************
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* @section Change Logs
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* Date Author Notes
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* 2010-12-21 onelife Initial creation for EFM32
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* 2011-07-06 onelife Modify to make use the start code in libraries
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* 2012-05-15 onelife Modified to compatible with CMSIS v3
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******************************************************************************/
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/***************************************************************************//**
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* @addtogroup cortex-m3
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* @{
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*******************************************************************************/
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.syntax unified
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.cpu cortex-m3
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.fpu softvfp
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.thumb
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/* start address for the initialization values of the .data section.
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defined in linker script */
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.word __etext
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/* start address for the .data section. defined in linker script */
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.word __data_start__
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/* end address for the .data section. defined in linker script */
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.word __data_end__
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/* start address for the .bss section. defined in linker script */
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.word __bss_start__
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/* end address for the .bss section. defined in linker script */
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.word __bss_end__
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/***************************************************************************//**
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* @brief This is the code that gets called when the processor first
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* starts execution following a reset event. Only the absolutely
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* necessary set is performed, after which the application
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* supplied main() routine is called.
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* @param None
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* @retval None
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*******************************************************************************/
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.thumb
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.thumb_func
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.section .cs3.init,"ax", %progbits
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.globl _start
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.type _start, %function
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_start:
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/* Copy the data segment initializers from flash to SRAM */
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movs r1, #0
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b LoopCopyDataInit
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CopyDataInit:
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ldr r3, =__etext
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ldr r3, [r3, r1]
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str r3, [r0, r1]
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adds r1, r1, #4
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LoopCopyDataInit:
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ldr r0, =__data_start__
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ldr r3, =__data_end__
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adds r2, r0, r1
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cmp r2, r3
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bcc CopyDataInit
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ldr r2, =__bss_start__
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b LoopFillZerobss
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/* Zero fill the bss segment. */
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FillZerobss:
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movs r3, #0
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str r3, [r2], #4
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LoopFillZerobss:
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ldr r3, = __bss_end__
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cmp r2, r3
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bcc FillZerobss
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/* Call the application's entry point.*/
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bl main
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bx lr
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.size _start, .-_start
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/***************************************************************************//**
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* @}
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*******************************************************************************/
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