CodeSourcery (lite) C-function printf

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Topic: Compiler, Software Development

Question. CodeSourcery (lite) C-function printf does not work properly when newlib is used with floating point numbers for bare board.

Answer. C-function printf uses memory allocation (malloc) especially for floating point numbers. Therefore please double check function _sbrk in syscalls.c. The simplest implementation is provided below.

extern char _end; /* Defined by the linker */

caddr_t _sbrk(int incr)

{

static char *heap_end = &_end;

char *return_heap_end;

if (heap_end == 0) { heap_end = &_end; }

return_heap_end = heap_end;

if (heap_end + incr > stack_ptr())

{_write (1, "Heap and stack collision\n", 25); return((void *) -1); }

heap_end += incr;

return (caddr_t) return_heap_end;

}

Also please pay attention on alignment of sections in linker file. An example may be found below.

ENTRY(ResetHandler)

SECTIONS

{

. = 0x8200000;

.text :

{ *(.vectors);

. = ALIGN(4);

*(.init);

. = ALIGN(4);

*(.text);

. = ALIGN(4);

}

.data : { . = ALIGN(4); *(.data) }

.bss :

{

. = ALIGN(4);

_bss_start = .;

*(.bss)

_bss_end = .;

}

. = ALIGN(4);

_end = .;

. = 0x8200000 + 512K ;

.stack :

{

. = ALIGN(4);

STACK_ADR = . ;

}