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Forum: ARM programming with GCC/GNU tools Trying to get C++ projct running on AT91SAM9G20-EK on SDRAM


von Robin Mueller (Guest)


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Hi there,

I've been trying for some days to get a C++ project running. 
Unfortunately, there appears to be a problem with the board startup 
script and the linker script which were provided and are propably 
generated. These files we initially not intended to incorporate C++ code 
so now we're trying to adapt them to do just that. We are also using 
freeRTOS. I attached the code of the two files
1
/* ----------------------------------------------------------------------------
2
 *         ATMEL Microcontroller Software Support
3
 * ----------------------------------------------------------------------------
4
 * Copyright (c) 2008, Atmel Corporation
5
6
 * ----------------------------------------------------------------------------
7
 */
8
9
/*------------------------------------------------------------------------------
10
 *      Linker script for running in external SDRAM on the AT91SAM9G20
11
 *----------------------------------------------------------------------------*/
12
 
13
_Min_Heap_Size = 0x400;      /* required amount of heap. Added manually  */
14
_Min_Stack_Size = 0x800;    /* required amount of stack. Added manually */
15
16
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
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OUTPUT_ARCH(arm)
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ENTRY(entry)
19
20
MEMORY
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{
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    sram0 (W!RX) : ORIGIN = 0x200000, LENGTH = 16K
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    sram1 (W!RX) : ORIGIN = 0x300000, LENGTH = 16K
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    sdram (W!RX) : ORIGIN = 0x20000000, LENGTH = 32M /* this board provided 64M, but we are just using  32M to model another device which only has 32M external SDRAM */
25
 }
26
27
SECTIONS
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{
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    .fixed :
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  {
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        . = ALIGN(4);      /* tells the linker that these section ought to be word aligned */
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        _sfixed = .;
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    KEEP(*(.startup));
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        *(.text*)        /* Code is placed in .text */
35
        *(.rodata*)        /* global variables marked as const. are placed in .rodata */
36
        *(.glue_7)        /* glue arm to thumb code */
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        *(.glue_7t)        /* glue thumb to arm code */
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        *(.eh_frame)
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        *(.data)
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        *(.data*)        /* contains all initialized global and static variables */
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        *(.CP15_*)  /* required for system control coprocessor? */
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        KEEP (*(.init))
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      KEEP (*(.fini))
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        . = ALIGN(4);
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    /* preinit data */
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    PROVIDE_HIDDEN (__preinit_array_start = .);
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    KEEP(*(.preinit_array))
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    PROVIDE_HIDDEN (__preinit_array_end = .);
49
    
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    . = ALIGN(4);
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    /* init data, the constructors are placed in this sections */
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    PROVIDE_HIDDEN (__init_array_start = .);
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    KEEP(*(SORT(.init_array.)))
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    KEEP(*(.init_array))
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    PROVIDE_HIDDEN (__init_array_end = .);
56
    
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    . = ALIGN(4);
58
    /* finit data, destructors are placed in this section */
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    PROVIDE_HIDDEN (__fini_array_start = .);
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    KEEP(*(SORT(.fini_array.)))
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    KEEP(*(.fini_array))
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    PROVIDE_HIDDEN (__fini_array_end = .);
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  } >sdram
64
65
  .ARM.extab (NOLOAD) : {
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    *(.ARM.extab* .gnu.linkonce.armextab.*)
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  } >sdram 
68
    
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  __exidx_start = .;
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    .ARM.exidx (NOLOAD) : {
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    *(.ARM.exidx* .gnu.linkonce.armexidx.*)
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  } > sdram
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    __exidx_end = .;
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    _efixed = .;
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    .prerelocate : AT (_efixed) /* all relocation stuff is pretty much taken from atmel */
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    {
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        . = ALIGN(4);
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        _sprerelocate = .;
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        . = ALIGN(4);
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        _eprerelocate = .;
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    }
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    .postrelocate : AT (_sprerelocate + SIZEOF(.prerelocate))
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    {
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        . = ALIGN(4);
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        _spostrelocate = .;
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        KEEP(*(.vectors));
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    *(.sramfunc)
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        *(.ramfunc)
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        . = ALIGN(4);
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        _epostrelocate = .;
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    } >sram0
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    /* this section holds uninitialized global and static data  */
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   . = ALIGN(4);
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  .bss :
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    {
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      /* This is used by the startup in order to initialize the .bss secion */
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      _sbss = .;         /* define a global symbol at bss start */
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      __bss_start__ = _sbss;
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      *(.bss)
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      *(.bss*)
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      *(COMMON)
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      . = ALIGN(4);
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      _ebss = .;         /* define a global symbol at bss end */
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      __bss_end__ = _ebss;
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    } >sdram
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    /* User_heap_stack section, used to check that there is enough RAM left */
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    ._user_heap_stack :
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    {
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      . = ALIGN(4);
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      PROVIDE ( end = . );
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      PROVIDE ( _end = . );
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      . = . + _Min_Heap_Size;
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      . = . + _Min_Stack_Size;
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      . = ALIGN(4);
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    } >sdram
122
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  /* top of stack */
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    _sstack = 0x22000000 - 1024;
125
}


And the start up script:
1
/* ----------------------------------------------------------------------------
2
 *         ATMEL Microcontroller Software Support 
3
 * --------------------------------------------------------------------------
4
  * Copyright (c) 2008, Atmel Corporation
5
* ----------------------------------------------------------------------------
6
 */
7
8
//------------------------------------------------------------------------------
9
//         Headers
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//------------------------------------------------------------------------------
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12
#include "board.h"
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//------------------------------------------------------------------------------
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//         Definitions
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//------------------------------------------------------------------------------
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#define IRQ_STACK_SIZE   8*3*4
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#define ARM_MODE_ABT     0x17
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#define ARM_MODE_FIQ     0x11
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#define ARM_MODE_IRQ     0x12
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#define ARM_MODE_SVC     0x13
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#define I_BIT            0x80
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#define F_BIT            0x40
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//------------------------------------------------------------------------------
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//         Startup routine
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//------------------------------------------------------------------------------
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            .align      4
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            .arm
34
        
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/* Exception vectors
36
 *******************/
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            .section    .vectors, "a", %progbits
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resetVector:
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        ldr     pc, =resetHandler       /* Reset */
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undefVector:
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        b       undefVector             /* Undefined instruction */
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swiVector:
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    ldr     pc, =vPortYieldProcessor /* Software interrupt */
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prefetchAbortVector:
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        b       prefetchAbortVector     /* Prefetch abort */
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dataAbortVector:
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        b       dataAbortVector         /* Data abort */
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reservedVector:
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        b       reservedVector          /* Reserved for future use */
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irqVector:
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        b       irqHandler              /* Interrupt */
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fiqVector:
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                                        /* Fast interrupt */
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//------------------------------------------------------------------------------
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/// Handles a fast interrupt request by branching to the address defined in the
58
/// AIC.
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//------------------------------------------------------------------------------
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fiqHandler:
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        b       fiqHandler
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//------------------------------------------------------------------------------
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/// Handles incoming interrupt requests by branching to the corresponding
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/// handler, as defined in the AIC. Supports interrupt nesting.
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//------------------------------------------------------------------------------
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irqHandler:
68
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/* Save interrupt context on the stack to allow nesting */
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        sub     lr, lr, #4
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        stmfd   sp!, {lr}
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        mrs     lr, SPSR
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        stmfd   sp!, {r0, lr}
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/* Write in the IVR to support Protect Mode */
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        ldr     lr, =AT91C_BASE_AIC
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        ldr     r0, [lr, #AIC_IVR]
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        str     lr, [lr, #AIC_IVR]
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80
/* Branch to interrupt handler in Supervisor mode */
81
        msr     CPSR_c, #ARM_MODE_SVC
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        stmfd   sp!, {r1-r3, r4, r12, lr}
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        blx     r0
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/* Restore scratch/used registers and LR from User Stack */
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/* Disable Interrupt and switch back in IRQ mode */      
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        ldmia   sp!, {r1-r3, r4, r12, lr}
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        msr     CPSR_c, #ARM_MODE_IRQ | I_BIT
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/* Acknowledge interrupt */
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        ldr     lr, =AT91C_BASE_AIC
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        str     lr, [lr, #AIC_EOICR]
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/* Restore interrupt context and branch back to calling code */
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        ldmia   sp!, {r0, lr}
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        msr     SPSR_cxsf, lr
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        ldmia   sp!, {pc}^
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//------------------------------------------------------------------------------
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/// Initializes the chip and branches to the main() function.
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//------------------------------------------------------------------------------
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            .section    .text
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            .global     entry
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105
entry:
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resetHandler:
107
108
/* Useless instruction for referencing the .vectors section */
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        ldr     r0, =resetVector
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/* Set pc to actual code location (i.e. not in remap zone) */
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      ldr     pc, =1f
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/* Initialize the prerelocate segment */
115
1:
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        ldr     r0, =_efixed
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        ldr     r1, =_sprerelocate
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        ldr     r2, =_eprerelocate
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1:
120
        cmp     r1, r2
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        ldrcc   r3, [r0], #4
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        strcc   r3, [r1], #4
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        bcc     1b
124
125
/* Perform low-level initialization of the chip using LowLevelInit() */
126
        ldr     sp, =_sstack
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        stmfd   sp!, {r0}
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      ldr     r0, =LowLevelInit
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        blx     r0
130
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/* Initialize the postrelocate segment */
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        ldmfd   sp!, {r0}
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        ldr     r1, =_spostrelocate
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        ldr     r2, =_epostrelocate
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1:
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        cmp     r1, r2
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        ldrcc   r3, [r0], #4
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        strcc   r3, [r1], #4
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        bcc     1b
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/* Clear the zero segment */
143
      ldr     r0, =__bss_start__
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        ldr     r1, =__bss_end__
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        mov     r2, #0
146
1:
147
        cmp     r0, r1
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        strcc   r2, [r0], #4
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        bcc     1b
150
151
/* Setup stacks
152
 **************/
153
/* IRQ mode */
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        msr     CPSR_c, #ARM_MODE_IRQ | I_BIT | F_BIT
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        ldr     sp, =_sstack
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        sub     r4, sp, #IRQ_STACK_SIZE
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158
/* Supervisor mode (interrupts enabled) */
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        msr     CPSR_c, #ARM_MODE_SVC | F_BIT
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        mov     sp, r4
161
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/* Call static constructors */
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      ldr r0,=__libc_init_array
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    mov lr,pc /* set the return address */
165
    bx r0 /* the target code can be ARM or THUMB */
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/* Branch to main()
167
 ******************/
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        ldr     r0, =main
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        blx     r0
170
171
/* Loop indefinitely when program is finished */
172
1:
173
        b       1b

Do you have any idea why are program is crashing randomly? Right now it 
always crashes and jumps to an adress it is not intended to be. I 
attached the dissassembly when  this happends while debugging.
My guess is that this relates to the two files shown above. Maybe 
something is missing so that C++ is working properly? The program 
crashes when the freeRTOS task scheduler has already started. I hope 
someone has a clue how  to get this working. Especially someone who 
managed to get C++ working on ARM processors. Thanks a lot in advance !

Kind Regards,
Robin

von Robin M. (spacefish)


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The program does not crash anymore when I comment out code related to 
hardware drivers. The program does not crash when performing these 
functions but crashes at the adresses I have shown in the 2 pictures. 
This is really confusing.
I use the AT91SAM9G20-EK board and provided drivers. This is inside a 
function which is called by performOperation() which crashed
1
//ATMEL
2
AT91S_USART * rs232; // do not initialize this register handle, causes problems !
3
USART_Configure(rs232, AT91C_US_USMODE_NORMAL,9600,BOARD_MCK);
4
USART_SetReceiverEnabled(rs232, true);
5
USART_SetTransmitterEnabled(rs232,true);
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result = USART_IsDataAvailable(rs232);
7
if(result==1) {
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  info << "Data available !" << std::endl;
9
}

: Edited by User

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