/****************************************************************************
* mm/mm_granalloc.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX 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 OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <assert.h>
#include <nuttx/gran.h>
#include "mm_gran.h"
#ifdef CONFIG_GRAN
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Name: gran_common_alloc
*
* Description:
* Allocate memory from the granule heap.
*
* Input Parameters:
* priv - The granule heap state structure.
* alloc - The adress of the allocation.
* ngranules - The number of granules allocated
*
* Returned Value:
* None
*
****************************************************************************/
static inline void gran_mark_allocated(FAR struct gran_s *priv, uintptr_t alloc, unsigned int ngranules)
{
unsigned int granno;
unsigned int gatidx;
unsigned int gatbit;
unsigned int avail;
uint32_t mask;
/* Determine the granule number of the allocation */
granno = (alloc - priv->heapstart) >> priv->log2gran;
/* Determine the GAT table index associated with the allocation */
gatidx = granno >> 5;
gatbit = granno & 31;
/* Mark bits in the first GAT entry */
avail = 32 - gatbit;
if (ngranules > avail)
{
priv->gat[gatidx] |= (0xffffffff << gatbit);
ngranules -= avail;
}
/* Handle the case where where all of the granules come from one entry */
else
{
mask = 0xffffffff >> (32 - ngranules);
priv->gat[gatidx] |= (mask << gatbit);
return;
}
/* Mark bits in the second GAT entry */
mask = 0xffffffff >> (32 - ngranules);
priv->gat[gatidx+1] |= (mask << gatbit);
}
/****************************************************************************
* Name: gran_common_alloc
*
* Description:
* Allocate memory from the granule heap.
*
* Input Parameters:
* priv - The granule heap state structure.
* size - The size of the memory region to allocate.
*
* Returned Value:
* On success, a non-NULL pointer to the allocated memory is returned.
*
****************************************************************************/
static inline FAR void *gran_common_alloc(FAR struct gran_s *priv, size_t size)
{
unsigned int ngranules;
size_t tmpmask;
uintptr_t alloc;
uint32_t curr;
uint32_t next;
uint32_t mask;
int i;
int j;
DEBUGASSERT(priv && size <= 32 * (1 << priv->log2gran));
if (priv && size > 0)
{
/* Get exclusive access to the GAT */
gran_enter_critical(priv);
/* How many contiguous granules we we need to find? */
tmpmask = (1 << priv->log2gran) - 1;
ngranules = (size + tmpmask) >> priv->log2gran;
/* Then create mask for that number of granules */
DEBUGASSERT(ngranules <= 32);
mask = 0xffffffff >> (32 - ngranules);
/* Now search the granule allocation table for that number of contiguous */
alloc = priv->heapstart;
for (i = 0; i < priv->ngranules; i += 32)
{
/* Get the GAT index associated with the granule table entry [i] */
j = i >> 5;
curr = priv->gat[j];
/* Handle the case where there are no free granules in the entry */
if (curr == 0xffffffff)
{
alloc += (32 << priv->log2gran);
continue;
}
/* Get the next entry from the GAT to support a 64 bit shift */
if (i < priv->ngranules)
{
next = priv->gat[j + 1];
}
/* Use all zeroes when are at the last entry in the GAT */
else
{
next = 0;
}
for (j = 0; j < 32; j++)
{
/* Check if we have the allocation at this bit position (0
* means unallocated).
*/
if ((curr & mask) == 0)
{
/* Yes.. mark these granules allocated */
gran_mark_allocated(priv, alloc, ngranules);
/* And return the allocation address */
gran_leave_critical(priv);
return (FAR void *)alloc;
}
/* Set up for the next time through the loop. Perform a 64
* bit shift to move to the next gram position.
*/
curr >>= 1;
if ((next & 1) != 0)
{
curr |= 0x80000000;
}
next >>= 1;
/* Increment the next candidate allocation address */
alloc += (1 << priv->log2gran);
}
}
}
gran_leave_critical(priv);
return NULL;
}
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: gran_alloc
*
* Description:
* Allocate memory from the granule heap.
*
* NOTE: The current implementation also restricts the maximum allocation
* size to 32 granules. That restriction could be eliminated with some
* additional coding effort.
*
* Input Parameters:
* handle - The handle previously returned by gran_initialize
* size - The size of the memory region to allocate.
*
* Returned Value:
* On success, either a non-NULL pointer to the allocated memory (if
* CONFIG_GRAN_SINGLE) or zero (if !CONFIG_GRAN_SINGLE) is returned.
*
****************************************************************************/
#ifdef CONFIG_GRAN_SINGLE
FAR void *gran_alloc(size_t size)
{
return gran_common_alloc(g_graninfo, size);
}
#else
FAR void *gran_alloc(GRAN_HANDLE handle, size_t size)
{
return gran_common_alloc((FAR struct gran_s *)handle, size);
}
#endif
#endif /* CONFIG_GRAN */
