46 lines
1 KiB
C
46 lines
1 KiB
C
/*
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* Raspberry Pi support library for the ACK
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* © 2013 David Given
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* This file is redistributable under the terms of the 3-clause BSD license.
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* See the file 'Copying' in the root of the distribution for the full text.
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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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#include <pi.h>
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#define OUT_OF_MEMORY (void*)(-1) /* sbrk returns this on failure */
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#define STACK_BUFFER 1024 /* 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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/* Top of heap: we assume that the block of memory the binary is loaded in
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* is 256kB long. Because user pointers are always relative to the beginning
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* of the block, this makes the end address easy to calculate. */
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static char* max = (char*) (256*1024);
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int brk(void* newend)
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{
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if ((newend >= (void*)max) || (newend < (void*)_end))
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return -1;
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current = newend;
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return 0;
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}
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void* sbrk(intptr_t increment)
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{
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char* old;
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if (increment == 0)
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return current;
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old = current;
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if (brk(old + increment) < 0)
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return OUT_OF_MEMORY;
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return old;
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}
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