243 lines
8.7 KiB
C
243 lines
8.7 KiB
C
/****************************************************************************
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* include/nuttx/mm/gran.h
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* General purpose granule memory allocator.
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __INCLUDE_NUTTX_MM_GRAN_H
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#define __INCLUDE_NUTTX_MM_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 granule allocator support
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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 output
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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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/* An opaque reference to an instance of a granule allocator state */
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typedef FAR void *GRAN_HANDLE;
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/* Form in which the state of the granule allocator is returned */
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struct graninfo_s
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{
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uint8_t log2gran; /* Log base 2 of the size of one granule */
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uint16_t ngranules; /* The total number of (aligned) granules in the heap */
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uint16_t nfree; /* The number of free granules */
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uint16_t mxfree; /* The longest sequence of free granules */
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};
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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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{
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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
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* or page-aligned memory and your hardware has specific memory alignment
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* requirements.
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*
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* General 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] locate_data(.dmaheap);
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*
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* The heap is created by calling gran_initialize. Here the granule 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:
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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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* granule allocator interfaces.
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*
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****************************************************************************/
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GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize,
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uint8_t log2gran, uint8_t log2align);
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/****************************************************************************
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* Name: gran_release
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*
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* Description:
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* Uninitialize a gram memory allocator and release resources held by the
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* allocator.
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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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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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void gran_release(GRAN_HANDLE handle);
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/****************************************************************************
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* Name: gran_reserve
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*
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* Description:
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* Reserve memory in the granule heap. This will reserve the granules
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* that contain the start and end addresses plus all of the granules
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* in between. This should be done early in the initialization sequence
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* before any other allocations are made.
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*
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* Reserved memory can never be allocated (it can be freed however which
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* essentially unreserves the memory).
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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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* start - The address of the beginning of the region to be reserved.
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* size - The size of the region to be reserved
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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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void gran_reserve(GRAN_HANDLE handle, uintptr_t start, size_t size);
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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, a non-NULL pointer to the allocated memory is returned;
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* NULL is returned on failure.
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*
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****************************************************************************/
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FAR void *gran_alloc(GRAN_HANDLE handle, size_t size);
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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 previously 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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void gran_free(GRAN_HANDLE handle, FAR void *memory, size_t size);
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/****************************************************************************
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* Name: gran_info
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*
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* Description:
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* Return information about 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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* info - Memory location to return the gran allocator info.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is return on
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* any failure.
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*
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****************************************************************************/
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void gran_info(GRAN_HANDLE handle, FAR struct graninfo_s *info);
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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_MM_GRAN_H */
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