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/*
* sdram_malloc.c
* --------------
* Use SDRAM for a very limited sort of heap.
*
* Copyright (c) 2016, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* Allocate memory from SDRAM1. This is not a general allocator, and
* should only be used with the greatest of caution and care.
*
* This is intended for allocating memory that will either never be freed
* (e.g. thread stack buffers), or will be freed as soon as the requesting
* function is done with it (e.g. file upload buffers).
*
* Memory should be freed in reverse order of allocation (most
* recent first).
*
* There are no memory block control fields, so no protection to ensure
* that memory that is freed is actually the memory that was allocated.
*/
#include <stddef.h>
#include <stdint.h>
/* end of variables declared with __attribute__((section(".sdram1"))) */
extern uint8_t _esdram1 __asm ("_esdram1");
static uint8_t * const sdram_heap_base = &_esdram1;
/* end of sdram1 section */
extern uint8_t __end_sdram1 __asm ("__end_sdram1");
static uint8_t * const sdram_heap_end = &__end_sdram1;
/* current heap top */
static uint8_t *sdram_heap = &_esdram1;
/* Allocate some memory. Allocations are not padded, because file upload will
* call repeatedly to write blocks of data to a "file". OTOH, it's a good
* idea to allocate padding after the last write, so the next allocation
* will be aligned.
*/
uint8_t *sdram_malloc(size_t size)
{
uint8_t *p = sdram_heap;
if (p + size > sdram_heap_end)
return NULL;
sdram_heap += size;
return p;
}
/* Free some memory allocated from sdram. This does only the most basic of
* sanity checks.
*/
void sdram_free(uint8_t *s)
{
if (s < sdram_heap_base || s >= sdram_heap_end)
return;
if (s < sdram_heap)
sdram_heap = s;
}
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