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author | patacongo <patacongo@7fd9a85b-ad96-42d3-883c-3090e2eb8679> | 2012-09-14 18:14:40 +0000 |
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committer | patacongo <patacongo@7fd9a85b-ad96-42d3-883c-3090e2eb8679> | 2012-09-14 18:14:40 +0000 |
commit | 2c2ba7f0c5f99aef3fac0eaa8a2c7a79c5faa74d (patch) | |
tree | 42e784046dde6eabe94ecb7922a0abf494592d8c /nuttx/mm | |
parent | 857d2a770b39162c43604bfc1cccf431d592ff9b (diff) | |
download | px4-firmware-2c2ba7f0c5f99aef3fac0eaa8a2c7a79c5faa74d.tar.gz px4-firmware-2c2ba7f0c5f99aef3fac0eaa8a2c7a79c5faa74d.tar.bz2 px4-firmware-2c2ba7f0c5f99aef3fac0eaa8a2c7a79c5faa74d.zip |
Missed one file in last checking; Gran allocator alignment decoupled from granule size
git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@5152 7fd9a85b-ad96-42d3-883c-3090e2eb8679
Diffstat (limited to 'nuttx/mm')
-rw-r--r-- | nuttx/mm/mm_graninit.c | 77 |
1 files changed, 64 insertions, 13 deletions
diff --git a/nuttx/mm/mm_graninit.c b/nuttx/mm/mm_graninit.c index cde2370d0..16cebdcf3 100644 --- a/nuttx/mm/mm_graninit.c +++ b/nuttx/mm/mm_graninit.c @@ -78,7 +78,13 @@ FAR struct gran_s *g_graninfo; * heapstart - Start of the granule allocation heap * heapsize - Size of heap in bytes * log2gran - Log base 2 of the size of one granule. 0->1 byte, - * 1->2 bytes, 2->4 bytes, 3-> 8bytes, etc. + * 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc. + * log2align - Log base 2 of required alignment. 0->1 byte, + * 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc. Note that + * log2gran must be greater than or equal to log2align + * so that all contiguous granules in memory will meet + * the minimum alignment requirement. A value of zero + * would mean that no alignment is required. * * Returned Value: * On success, a non-NULL info structure is returned that may be used with @@ -86,9 +92,9 @@ FAR struct gran_s *g_graninfo; * ****************************************************************************/ -static inline FAR struct gran_s *gran_common_initialize(FAR void *heapstart, - size_t heapsize, - uint8_t log2gran) +static inline FAR struct gran_s * +gran_common_initialize(FAR void *heapstart, size_t heapsize, uint8_t log2gran, + uint8_t log2align) { FAR struct gran_s *priv; uintptr_t heapend; @@ -97,13 +103,24 @@ static inline FAR struct gran_s *gran_common_initialize(FAR void *heapstart, unsigned int alignedsize; unsigned int ngranules; - DEBUGASSERT(heapstart && heapsize > 0 && log2gran > 0 && log2gran < 32); + /* Check parameters if debug is on. Note the the size of a granual is + * limited to 2**31 bytes and that the size of the granule must be greater + * than the alignment size. + */ + + DEBUGASSERT(heapstart && heapsize > 0 && + log2gran > 0 && log2gran < 32 && + log2gran > log2align); + + /* Get the aligned start of the heap */ + mask = (1 << log2align) - 1; + alignedstart = ((uintptr_t)heapstart + mask) & ~mask; + /* Determine the number of granules */ mask = (1 << log2gran) - 1; heapend = (uintptr_t)heapstart + heapsize; - alignedstart = ((uintptr_t)heapstart + mask) & ~mask; alignedsize = (heapend - alignedstart) & ~mask; ngranules = alignedsize >> log2gran; @@ -139,9 +156,32 @@ static inline FAR struct gran_s *gran_common_initialize(FAR void *heapstart, * * Description: * Set up one granule allocator instance. Allocations will be aligned to - * the granule size; allocations will be in units of the granule size. - * Larger granules will give better performance and less overhead but more - * losses of memory due to alignment and quantization waste. + * the alignment size (log2align; allocations will be in units of the + * granule size (log2gran). Larger granules will give better performance + * and less overhead but more losses of memory due to alignment + * quantization waste. Additional memory waste can occur form alignment; + * log2align should be set to 0 unless you are using the granule allocator + * to manage DMA memory and your hardware has specific memory alignment + * requirements. + * + * Geneneral Usage Summary. This is an example using the GCC section + * attribute to position a DMA heap in memory (logic in the linker script + * would assign the section .dmaheap to the DMA memory. + * + * FAR uint32_t g_dmaheap[DMAHEAP_SIZE] __attribute__((section(.dmaheap))); + * + * The heap is created by calling gran_initialize(). Here the granual size + * is set to 64 bytes (2**6) and the alignment to 16 bytes (2**4): + * + * GRAN_HANDLE handle = gran_initialize(g_dmaheap, DMAHEAP_SIZE, 6, 4); + * + * Then the GRAN_HANDLE can be used to allocate memory (There is no + * GRAN_HANDLE if CONFIG_GRAN_SINGLE=y): + * + * FAR uint8_t *dma_memory = (FAR uint8_t *)gran_alloc(handle, 47); + * + * The actual memory allocates will be 64 byte (wasting 17 bytes) and + * will be aligned at least to (1 << log2align). * * NOTE: The current implementation also restricts the maximum allocation * size to 32 granules. That restriction could be eliminated with some @@ -151,7 +191,13 @@ static inline FAR struct gran_s *gran_common_initialize(FAR void *heapstart, * heapstart - Start of the granule allocation heap * heapsize - Size of heap in bytes * log2gran - Log base 2 of the size of one granule. 0->1 byte, - * 1->2 bytes, 2->4 bytes, 3-> 8bytes, etc. + * 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc. + * log2align - Log base 2 of required alignment. 0->1 byte, + * 1->2 bytes, 2->4 bytes, 3-> 8 bytes, etc. Note that + * log2gran must be greater than or equal to log2align + * so that all contiguous granules in memory will meet + * the minimum alignment requirement. A value of zero + * would mean that no alignment is required. * * Returned Value: * On success, a non-NULL handle is returned that may be used with other @@ -160,9 +206,12 @@ static inline FAR struct gran_s *gran_common_initialize(FAR void *heapstart, ****************************************************************************/ #ifdef CONFIG_GRAN_SINGLE +int gran_initialize(FAR void *heapstart, size_t heapsize, uint8_t log2gran, + uint8_t log2align) int gran_initialize(FAR void *heapstart, size_t heapsize, uint8_t log2gran) { - g_graninfo = gran_common_initialize(heapstart, heapsize, log2gran); + g_graninfo = gran_common_initialize(heapstart, heapsize, log2gran, + log2align); if (!g_graninfo) { return -ENOMEM; @@ -171,9 +220,11 @@ int gran_initialize(FAR void *heapstart, size_t heapsize, uint8_t log2gran) return OK; } #else -GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize, uint8_t log2gran) +GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize, + uint8_t log2gran, uint8_t log2align) { - return (GRAN_HANDLE)gran_common_initialize(heapstart, heapsize, log2gran); + return (GRAN_HANDLE)gran_common_initialize(heapstart, heapsize, + log2gran, log2align); } #endif |