203 lines
8.0 KiB
C
203 lines
8.0 KiB
C
/****************************************************************************
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* include/nuttx/gran.h
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* General purpose granule memory allocator.
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*
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* Copyright (C) 2012 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* 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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****************************************************************************/
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#ifndef __INCLUDE_NUTTX_GRAN_H
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#define __INCLUDE_NUTTX_GRAN_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdint.h>
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#ifdef CONFIG_GRAN
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/****************************************************************************
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* Pre-Processor Definitions
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****************************************************************************/
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/* Configuration ************************************************************/
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/* CONFIG_GRAN - Enable granual allocator support
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* CONFIG_GRAN_SINGLE - Select if there is only one instance of the
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* granule allocator (i.e., gran_initialize will be called only once.
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* In this case, (1) there are a few optimizations that can can be done
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* and (2) the GRAN_HANDLE is not needed.
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* CONFIG_GRAN_INTR - Normally mutual exclusive access to granule allocator
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* data is assured using a semaphore. If this option is set then, instead,
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* mutual exclusion logic will disable interrupts. While this options is
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* more invasive to system performance, it will also support use of the
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* granule allocator from interrupt level logic.
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* CONFIG_DEBUG_GRAN - Just like CONFIG_DEBUG_MM, but only generates ouput
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* from the gran allocation logic.
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*/
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/****************************************************************************
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* Public Types
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****************************************************************************/
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#ifndef CONFIG_GRAN_SINGLE
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typedef FAR void *GRAN_HANDLE;
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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#ifdef __cplusplus
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#define EXTERN extern "C"
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extern "C" {
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#else
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#define EXTERN extern
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#endif
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/****************************************************************************
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* Name: gran_initialize
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*
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* Description:
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* Set up one granule allocator instance. Allocations will be aligned to
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* the alignment size (log2align; allocations will be in units of the
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* granule size (log2gran). Larger granules will give better performance
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* and less overhead but more losses of memory due to quantization waste.
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* Additional memory waste can occur from alignment; log2align should be
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* set to 0 unless you are using the granule allocator to manage DMA memory
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* and your hardware has specific memory alignment requirements.
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*
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* Geneneral Usage Summary. This is an example using the GCC section
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* attribute to position a DMA heap in memory (logic in the linker script
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* would assign the section .dmaheap to the DMA memory.
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*
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* FAR uint32_t g_dmaheap[DMAHEAP_SIZE] __attribute__((section(.dmaheap)));
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*
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* The heap is created by calling gran_initialize. Here the granual size
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* is set to 64 bytes and the alignment to 16 bytes:
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*
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* GRAN_HANDLE handle = gran_initialize(g_dmaheap, DMAHEAP_SIZE, 6, 4);
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*
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* Then the GRAN_HANDLE can be used to allocate memory (There is no
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* GRAN_HANDLE if CONFIG_GRAN_SINGLE=y):
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*
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* FAR uint8_t *dma_memory = (FAR uint8_t *)gran_alloc(handle, 47);
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*
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* The actual memory allocates will be 64 byte (wasting 17 bytes) and
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* will be aligned at least to (1 << log2align).
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*
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* NOTE: The current implementation also restricts the maximum allocation
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* size to 32 granules. That restriction could be eliminated with some
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* additional coding effort.
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*
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* Input Parameters:
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* heapstart - Start of the granule allocation heap
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* heapsize - Size of heap in bytes
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* log2gran - Log base 2 of the size of one granule. 0->1 byte,
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* 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc.
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* log2align - Log base 2 of required alignment. 0->1 byte,
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* 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc. Note that
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* log2gran must be greater than or equal to log2align
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* so that all contiguous granules in memory will meet
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* the minimum alignment requirement. A value of zero
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* would mean that no alignment is required.
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*
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* Returned Value:
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* On success, a non-NULL handle is returned that may be used with other
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* granual allocator interfaces.
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*
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****************************************************************************/
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#ifdef CONFIG_GRAN_SINGLE
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EXTERN int gran_initialize(FAR void *heapstart, size_t heapsize,
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uint8_t log2gran, uint8_t log2align);
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#else
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EXTERN GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize,
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uint8_t log2gran, uint8_t log2align);
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#endif
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/****************************************************************************
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* Name: gran_alloc
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*
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* Description:
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* Allocate memory from the granule heap.
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*
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* NOTE: The current implementation also restricts the maximum allocation
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* size to 32 granules. That restriction could be eliminated with some
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* additional coding effort.
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*
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* Input Parameters:
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* handle - The handle previously returned by gran_initialize
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* size - The size of the memory region to allocate.
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*
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* Returned Value:
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* On success, either a non-NULL pointer to the allocated memory (if
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* CONFIG_GRAN_SINGLE) or zero (if !CONFIG_GRAN_SINGLE) is returned.
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*
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****************************************************************************/
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#ifdef CONFIG_GRAN_SINGLE
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EXTERN FAR void *gran_alloc(size_t size);
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#else
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EXTERN FAR void *gran_alloc(GRAN_HANDLE handle, size_t size);
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#endif
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/****************************************************************************
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* Name: gran_free
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*
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* Description:
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* Return memory to the granule heap.
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*
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* Input Parameters:
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* handle - The handle previously returned by gran_initialize
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* memory - A pointer to memory previoiusly allocated by gran_alloc.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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#ifdef CONFIG_GRAN_SINGLE
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EXTERN void gran_free(FAR void *memory, size_t size);
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#else
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EXTERN void gran_free(GRAN_HANDLE handle, FAR void *memory, size_t size);
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#endif
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#undef EXTERN
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#ifdef __cplusplus
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}
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#endif
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#endif /* CONFIG_GRAN */
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#endif /* __INCLUDE_NUTTX_GRAN_H */
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