OUTPUT_FORMAT ("elf32-littlearm", "elf32-bigarm", "elf32-littlearm")
SEARCH_DIR(.)
/*INCLUDE "memory.ld"*/

MEMORY
{
rom (rx) : ORIGIN = 0x00000000, LENGTH = 0x00020000
ram (rwx) : ORIGIN = 0x10000000, LENGTH = 0x00004000
ram1 (rwx) : ORIGIN = 0x2007C000, LENGTH = 0x00004000
}

_eram = 0x10000000 + 0x00004000;

/* Section Definitions */
SECTIONS
{
.text :
{
KEEP(*(.isr_vector))
KEEP(*(.hware))
KEEP(*(.offset))
KEEP(*(.templ))
KEEP(*(.swvers1))
KEEP(*(.swvers2))
KEEP(*(.swvers3))

*(.text*)

KEEP(*(.init))
KEEP(*(.fini))

/* .ctors */
*crtbegin.o(.ctors)
*crtbegin?.o(.ctors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)
*(SORT(.ctors.*))
*(.ctors)

/* .dtors */
*crtbegin.o(.dtors)
*crtbegin?.o(.dtors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)
*(SORT(.dtors.*))
*(.dtors)

*(.rodata*)

KEEP(*(.eh_frame*))
} > rom

.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} > rom

__exidx_start = .;
.ARM.exidx :
{
*(.ARM.exidx* .gnu.linkonce.armexidx.*)
} > rom
__exidx_end = .;

. = ALIGN(4);
_etext = .;
_sidata = .;

.data : AT (_etext)
{
_sdata = .;
*(.data .data.*)
. = ALIGN(4);
_edata = .;
} > ram

/* .bss section which is used for uninitialized data */
.bss (NOLOAD) :
{
_sbss = .;
*(.bss .bss.*)
*(COMMON)
. = ALIGN(4);
_ebss = .;
} > ram

/* heap section */
.heap (COPY):
{
__Heap_Start = .;
_end = __Heap_Start;
end = __Heap_Start;
*(.heap*)
__Heap_End = .;

} > ram

/* .stack_dummy section doesn't contains any symbols. It is only
* used for linker to calculate size of stack sections, and assign
* values to stack symbols later */
.co_stack (NOLOAD):
{
. = ALIGN(8);
*(.co_stack .co_stack.*)
} > ram

/* Set stack top to end of ram , and stack limit move down by
* size of stack_dummy section */
__StackTop = ORIGIN(ram ) + LENGTH(ram );
__StackLimit = __StackTop - SIZEOF(.co_stack);
PROVIDE(__stack = __StackTop);

/* Check if data + heap + stack exceeds ram limit */
ASSERT(__StackLimit >= __Heap_End, "region ram overflowed with stack")

.data_dma (COPY): ALIGN(4)
{
__data_dma_start = .;
KEEP(*(.dma_vars))
} > ram1
. = ALIGN(4);

__data_dma_finish = .;
}

#define SECOND_BANK_END (0x2007FFFFUL)

void init_system_heap(void) {
    extern unsigned long __Heap_Start;
    extern unsigned long __Heap_End;
    extern unsigned long __data_dma_finish;
    system_heap.start = (heap_mcb *) (&__Heap_Start);
    system_heap.freem = (heap_mcb *) (&__Heap_Start);
    system_heap.hsize = (unsigned long) (&__Heap_End) - (unsigned long) (&__Heap_Start) + (unsigned long) 1;

    heapinit(&system_heap);
    heapadd(&system_heap, (heap_mcb *) (&__data_dma_finish), (unsigned long) SECOND_BANK_END - (unsigned long) (&__data_dma_finish));
}

#define STACK_SIZE       0x00000100      /*!< The Stack size suggest using even number   */
__attribute__ ((section(".co_stack")))
unsigned long pulStack[STACK_SIZE];

......
__attribute__ ((used,section(".isr_vector")))
void (* const g_pfnVectors[])(void) =
{
    /*----------Core Exceptions------------------------------------------------ */
    (void *)&pulStack[STACK_SIZE], /*!< The initial stack pointer         */
    Reset_Handler, /*!< Reset Handler                               */
    NMI_Handler, /*!< NMI Handler                                 */
    HardFault_Handler, /*!< Hard Fault Handler                          */
    MemManage_Handler, /*!< MPU Fault Handler                           */
    BusFault_Handler, /*!< Bus Fault Handler                           */
    UsageFault_Handler, /*!< Usage Fault Handler                         */
    0,0,0,0, /*!< Reserved                                    */
    SVC_Handler, /*!< SVCall Handler                              */
    DebugMon_Handler, /*!< Debug Monitor Handler                       */
    0, /*!< Reserved                                    */
    PendSV_Handler, /*!< PendSV Handler                              */
    SysTick_Handler, /*!< SysTick Handler                             */
....

; *************************************************************
; *** Scatter-Loading Description File generated by uVision ***
; *************************************************************


LOAD_ROM 0x08000000 0x0005FFFF ; load region size_region
{
EXEC_ROM 0x08000000 0x0005FFFF ; load address = execution address
{
*.o (START, +First)
*(InRoot$$Sections)
.ANY (+RO )
}
HEAP_RAM 0x20000400 0x00007BFF ; Heap region Heap_size = 31K
{
*(HEAP)
}
SRAM 0x20008000 0x000FFFF ; RW region RW_size = 64K
{
.ANY (+RW +ZI)
}
STACK_RAM 0x20018000 0x00007FFF ; Stack region Stack_size = 32K
{
*(STACK)
}
}

int main(void)
{
     unsigned int sp = __current_sp();

     ...
     for(int a = 0; a < 8; a++)
     {
         unsigned int n = sp >> 28;

         uart_putc(n > 9 ? n + 'A' - 10 : n + '0');
         sp <<= 4;
     }
}