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annotate loadagent/libnosys/sbrk.c @ 2:ddda170fa6f4

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loadagent.elf compiled and linked, no printf yet
author Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
date Mon, 29 Apr 2013 05:21:05 +0000
parents da98dc08f575
children
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da98dc08f575 loadagent: beginning to lay the foundation
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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1 /* sbrk.c -- allocate memory dynamically.
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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2 *
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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3 * Copyright (c) 1995,1996 Cygnus Support
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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4 *
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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5 * The authors hereby grant permission to use, copy, modify, distribute,
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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6 * and license this software and its documentation for any purpose, provided
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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7 * that existing copyright notices are retained in all copies and that this
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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8 * notice is included verbatim in any distributions. No written agreement,
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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9 * license, or royalty fee is required for any of the authorized uses.
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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10 * Modifications to this software may be copyrighted by their authors
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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11 * and need not follow the licensing terms described here, provided that
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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12 * the new terms are clearly indicated on the first page of each file where
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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13 * they apply.
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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14 */
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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15 #include <errno.h>
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16 #include "glue.h"
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17
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18 /* just in case, most boards have at least some memory */
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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19 #ifndef RAMSIZE
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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20 # define RAMSIZE (caddr_t)0x100000
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21 #endif
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22
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23 char *heap_ptr;
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24
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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25 /*
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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26 * sbrk -- changes heap size size. Get nbytes more
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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27 * RAM. We just increment a pointer in what's
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28 * left of memory on the board.
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29 */
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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30 char *
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31 _sbrk (nbytes)
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32 int nbytes;
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33 {
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34 char *base;
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35
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36 if (!heap_ptr)
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37 heap_ptr = (char *)&_end;
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38 base = heap_ptr;
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39 heap_ptr += nbytes;
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40
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41 return base;
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42 /* FIXME: We really want to make sure we don't run out of RAM, but this
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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43 * isn't very portable.
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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44 */
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45 #if 0
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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46 if ((RAMSIZE - heap_ptr - nbytes) >= 0) {
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47 base = heap_ptr;
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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48 heap_ptr += nbytes;
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49 return (base);
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50 } else {
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51 errno = ENOMEM;
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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52 return ((char *)-1);
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53 }
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Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
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54 #endif
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55 }