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121 lines
3.5 KiB
C
121 lines
3.5 KiB
C
/*
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* Copyright (c) 2015, Tido Klaassen. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. No personal names or organizations' names associated with the
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* Atomthreads project may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE ATOMTHREADS PROJECT AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/stat.h>
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#include <libopencm3/cm3/vector.h>
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#include "atomport.h"
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/**
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* _sbrk is needed by newlib for heap management.
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* The main stack usually starts at the top of RAM and grows downwards,
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* while the heap starts at the bottom and grows upwards. To prevent
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* the heap from colliding with the main stack, we reserve a certain amount
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* of memory and check that growing the heap won't touch that region.
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* The size of the protected area is set via the define MST_SIZE in the
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* board Makefile
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*/
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#ifndef MST_SIZE
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#error Main stack size not defined. Please define MST_SIZE in board Makefile
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#endif
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/**
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* The vector table is provided by libopencm3/cm3/vector.h and contains
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* the initial main stack pointer value
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*/
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extern vector_table_t vector_table;
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/**
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* The linker provides the start address of the unused system memory.
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* It is exported via the symbol 'end' and will be used as the bottom
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* of the heap
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*/
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extern char end;
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static char *heap_end = 0;
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caddr_t _sbrk(int incr)
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{
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char *prev_end;
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CRITICAL_STORE;
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prev_end = NULL;
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CRITICAL_START();
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if(unlikely(heap_end == 0)){
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heap_end = &end;
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}
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/* make sure new heap size does not collide with main stack area*/
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if(heap_end + incr + MST_SIZE <= (char *) vector_table.initial_sp_value){
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prev_end = heap_end;
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heap_end += incr;
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}
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CRITICAL_END();
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return (caddr_t) prev_end;
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}
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/**
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* dummy stubs needed by newlib when not linked with libnosys
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*/
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int _close(int file __maybe_unused)
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{
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return -1;
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}
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int _fstat(int file __maybe_unused, struct stat *st)
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{
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st->st_mode = S_IFCHR;
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return 0;
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}
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int _isatty(int file __maybe_unused)
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{
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return 1;
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}
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int _lseek(int file __maybe_unused,
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int ptr __maybe_unused,
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int dir __maybe_unused)
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{
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return 0;
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}
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int _open(const char *name __maybe_unused,
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int flags __maybe_unused,
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int mode __maybe_unused)
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{
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return -1;
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}
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