60 lines
946 B
C
60 lines
946 B
C
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/* $Source$
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* $State$
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* $Revision$
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <unistd.h>
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#define OUT_OF_MEMORY (void*)(-1) /* sbrk returns this on failure */
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#define STACK_BUFFER 128 /* number of bytes to leave for stack */
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extern char _end[1];
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static char* current = _end;
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int brk(void* newend)
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{
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/* This variable is used to figure out the current stack pointer,
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* by taking its address. */
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char dummy;
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char* p = newend;
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if ((p > (&dummy - STACK_BUFFER)) ||
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(p < _end))
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{
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errno = ENOMEM;
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return -1;
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}
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current = p;
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return 0;
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}
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void* sbrk(int increment)
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{
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char* old;
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char* new;
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if (increment == 0)
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return current;
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old = current;
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new = old + increment;
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if ((increment > 0) && (new <= old))
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goto out_of_memory;
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else if ((increment < 0) && (new >= old))
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goto out_of_memory;
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if (brk(new) < 0)
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goto out_of_memory;
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return old;
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out_of_memory:
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errno = ENOMEM;
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return OUT_OF_MEMORY;
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}
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