diff options
Diffstat (limited to 'libgloss/cr16/sbrk.c')
-rw-r--r-- | libgloss/cr16/sbrk.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/libgloss/cr16/sbrk.c b/libgloss/cr16/sbrk.c new file mode 100644 index 000000000..7c9604726 --- /dev/null +++ b/libgloss/cr16/sbrk.c @@ -0,0 +1,56 @@ +/* sbrk.c -- Implementation of the low-level sbrk() routine + * + * Copyright (c) 2004 National Semiconductor Corporation + * + * The authors hereby grant permission to use, copy, modify, distribute, + * and license this software and its documentation for any purpose, provided + * that existing copyright notices are retained in all copies and that this + * notice is included verbatim in any distributions. No written agreement, + * license, or royalty fee is required for any of the authorized uses. + * Modifications to this software may be copyrighted by their authors + * and need not follow the licensing terms described here, provided that + * the new terms are clearly indicated on the first page of each file where + * they apply. + */ + +#include <errno.h> +#include <stddef.h> /* where ptrdiff_t is defined */ +#include <stdlib.h> + +/* Extend heap space by size bytes. + Return start of new space allocated, or -1 for errors + Error cases: + 1. Allocation is not within heap range */ + +void * _sbrk (ptrdiff_t size) +{ + /* + * The following two memory locations should be defined in the linker script file + */ + extern const char _HEAP_START; /* start of heap */ + extern const char _HEAP_MAX; /* end of heap (maximum value of heap_ptr) */ + + static const char * heap_ptr; /* pointer to head of heap */ + const char * old_heap_ptr; + static unsigned char init_sbrk = 0; + + /* heap_ptr is initialized to HEAP_START */ + if (init_sbrk == 0) + { + heap_ptr = &_HEAP_START; + init_sbrk = 1; + } + + old_heap_ptr = heap_ptr; + + if ((heap_ptr + size) > &_HEAP_MAX) + { + /* top of heap is bigger than _HEAP_MAX */ + errno = ENOMEM; + return (void *) -1; + } + + /* success: update heap_ptr and return previous value */ + heap_ptr += size; + return (void *)old_heap_ptr; +} |