1 #include <_ansi.h> 2 #include <sys/types.h> 3 #include <sys/stat.h> 4 5 #include "regs.S" 6 7 extern char _end[]; 8 9 /* FIXME: This is not ideal, since we do a get_mem_info() call for 10 every sbrk() call. */ 11 char * sbrk(nbytes)12sbrk (nbytes) 13 int nbytes; 14 { 15 static char *heap_ptr = _end; 16 static char *heap_start = _end; 17 char *base; 18 struct s_mem { 19 unsigned int size; 20 unsigned int icsize; 21 unsigned int dcsize; 22 } mem; 23 unsigned int avail = 0; 24 25 /* The sizeof (s_mem.size) must be 4 bytes. The compiler should be 26 able to eliminate this check */ 27 if (sizeof (unsigned int) != 4) 28 return (char *)-1; 29 30 get_mem_info(&mem); 31 /* NOTE: The value returned from the get_mem_info call is the amount 32 of memory, and not the address of the (last byte + 1) */ 33 34 if (((size_t)heap_ptr >= heap_start) && ((size_t)heap_ptr < (heap_start + mem.size))) { 35 avail = (heap_start + mem.size) - (size_t)heap_ptr; 36 base = heap_ptr; 37 } /* else will fail since "nbytes" will be greater than zeroed "avail" value */ 38 39 if ((nbytes > avail) || (heap_ptr + nbytes < _end)) 40 base = (char *)-1; 41 else 42 heap_ptr += nbytes; 43 44 return base; 45 } 46