46 lines
1.1 KiB
C
46 lines
1.1 KiB
C
#include <_ansi.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "regs.S"
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extern char _end[];
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/* FIXME: This is not ideal, since we do a get_mem_info() call for
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every sbrk() call. */
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char *
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sbrk (nbytes)
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int nbytes;
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{
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static char *heap_ptr = _end;
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static char *heap_start = _end;
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char *base;
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struct s_mem {
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unsigned int size;
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unsigned int icsize;
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unsigned int dcsize;
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} mem;
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unsigned int avail = 0;
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/* The sizeof (s_mem.size) must be 4 bytes. The compiler should be
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able to eliminate this check */
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if (sizeof (unsigned int) != 4)
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return (char *)-1;
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get_mem_info(&mem);
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/* NOTE: The value returned from the get_mem_info call is the amount
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of memory, and not the address of the (last byte + 1) */
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if (((size_t)heap_ptr >= heap_start) && ((size_t)heap_ptr < (heap_start + mem.size))) {
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avail = (heap_start + mem.size) - (size_t)heap_ptr;
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base = heap_ptr;
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} /* else will fail since "nbytes" will be greater than zeroed "avail" value */
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if ((nbytes > avail) || (heap_ptr + nbytes < _end))
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base = (char *)-1;
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else
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heap_ptr += nbytes;
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return base;
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}
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