diff options
| -rw-r--r-- | nuttx/mm/mm_granalloc.c | 160 | ||||
| -rw-r--r-- | nuttx/mm/mm_granfree.c | 22 |
2 files changed, 144 insertions, 38 deletions
diff --git a/nuttx/mm/mm_granalloc.c b/nuttx/mm/mm_granalloc.c index e8022bf72..e95709b31 100644 --- a/nuttx/mm/mm_granalloc.c +++ b/nuttx/mm/mm_granalloc.c @@ -67,13 +67,15 @@ * ****************************************************************************/ -static inline void gran_mark_allocated(FAR struct gran_s *priv, uintptr_t alloc, unsigned int ngranules) +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; + uint32_t gatmask; /* Determine the granule number of the allocation */ @@ -84,28 +86,41 @@ static inline void gran_mark_allocated(FAR struct gran_s *priv, uintptr_t alloc, gatidx = granno >> 5; gatbit = granno & 31; - /* Mark bits in the first GAT entry */ + /* Mark bits in the GAT entry or entries */ avail = 32 - gatbit; if (ngranules > avail) { - priv->gat[gatidx] |= (0xffffffff << gatbit); + /* Mark bits in the first GAT entry */ + + gatmask =0xffffffff << gatbit; + DEBUGASSERT((priv->gat[gatidx] & gatmask) == 0); + + priv->gat[gatidx] |= gatmask; ngranules -= avail; + + /* Mark bits in the second GAT entry */ + + gatmask = 0xffffffff >> (32 - ngranules); + DEBUGASSERT((priv->gat[gatidx+1] & gatmask) == 0); + + priv->gat[gatidx+1] |= gatmask; } /* Handle the case where where all of the granules come from one entry */ else { - mask = 0xffffffff >> (32 - ngranules); - priv->gat[gatidx] |= (mask << gatbit); + /* Mark bits in a single GAT entry */ + + gatmask = 0xffffffff >> (32 - ngranules); + gatmask <<= gatbit; + DEBUGASSERT((priv->gat[gatidx] & gatmask) == 0); + + priv->gat[gatidx] |= gatmask; return; } - /* Mark bits in the second GAT entry */ - - mask = 0xffffffff >> (32 - ngranules); - priv->gat[gatidx+1] |= (mask << gatbit); } /**************************************************************************** @@ -131,8 +146,10 @@ static inline FAR void *gran_common_alloc(FAR struct gran_s *priv, size_t size) uint32_t curr; uint32_t next; uint32_t mask; - int i; - int j; + int granidx; + int gatidx; + int bitidx; + int shift; DEBUGASSERT(priv && size <= 32 * (1 << priv->log2gran)); @@ -156,12 +173,12 @@ static inline FAR void *gran_common_alloc(FAR struct gran_s *priv, size_t size) alloc = priv->heapstart; - for (i = 0; i < priv->ngranules; i += 32) + for (granidx = 0; granidx < priv->ngranules; granidx += 32) { - /* Get the GAT index associated with the granule table entry [i] */ + /* Get the GAT index associated with the granule table entry */ - j = i >> 5; - curr = priv->gat[j]; + gatidx = granidx >> 5; + curr = priv->gat[gatidx]; /* Handle the case where there are no free granules in the entry */ @@ -173,25 +190,100 @@ static inline FAR void *gran_common_alloc(FAR struct gran_s *priv, size_t size) /* Get the next entry from the GAT to support a 64 bit shift */ - if (i < priv->ngranules) + if (granidx < priv->ngranules) { - next = priv->gat[j + 1]; + next = priv->gat[gatidx + 1]; } - /* Use all zeroes when are at the last entry in the GAT */ + /* Use all ones when are at the last entry in the GAT (meaning + * nothing can be allocated. + */ else { - next = 0; + next = 0xffffffff; } - for (j = 0; j < 32; j++) + /* Search through the allocations in the 'curr' GAT entry + * to see if we can satisfy the allocation starting in that + * entry. + * + * This loop continues until either all of the bits have been + * examined (bitidx >= 32), or until there are insufficient + * granules left to satisfy the allocation. + */ + + for (bitidx = 0; + bitidx < 32 && (granidx + bitidx + ngranules) <= priv->ngranules; + ) { - /* Check if we have the allocation at this bit position (0 - * means unallocated). + /* Break out if there are no further free bits in 'curr'. + * All of the zero bits might have gotten shifted out. */ - if ((curr & mask) == 0) + if (curr == 0xffffffff) + { + break; + } + + /* Check for the first zero bit in the lower or upper 16-bits. + * From the test above, we know that at least one of the 32- + * bits in 'curr' is zero. + */ + + else if ((curr & 0x0000ffff) == 0x0000ffff) + { + /* Not in the lower 16 bits. The first free bit must be + * in the upper 16 bits. + */ + + shift = 16; + } + + /* We know that the first free bit is now within the lower 16 + * bits of 'curr'. Is it in the upper or lower byte? + */ + + else if ((curr & 0x0000ff) == 0x000000ff) + { + /* Not in the lower 8 bits. The first free bit must be in + * the upper 8 bits. + */ + + shift = 8; + } + + /* We know that the first free bit is now within the lower 4 + * bits of 'curr'. Is it in the upper or lower nibble? + */ + + else if ((curr & 0x00000f) == 0x0000000f) + { + /* Not in the lower 4 bits. The first free bit must be in + * the upper 4 bits. + */ + + shift = 4; + } + + /* We know that the first free bit is now within the lower 4 bits + * of 'curr'. Is it in the upper or lower pair? + */ + + else if ((curr & 0x000003) == 0x00000003) + { + /* Not in the lower 2 bits. The first free bit must be in + * the upper 2 bits. + */ + + shift = 2; + } + + /* We know that the first free bit is now within the lower 4 bits + * of 'curr'. Check if we have the allocation at this bit position. + */ + + else if ((curr & mask) == 0) { /* Yes.. mark these granules allocated */ @@ -203,20 +295,22 @@ static inline FAR void *gran_common_alloc(FAR struct gran_s *priv, size_t size) 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. - */ + /* The free allocation does not start at this position */ - curr >>= 1; - if ((next & 1) != 0) + else { - curr |= 0x80000000; + shift = 1; } - next >>= 1; - /* Increment the next candidate allocation address */ + /* Set up for the next time through the loop. Perform a 64 + * bit shift to move to the next gram position andi ncrement + * to the next candidate allocation address. + */ - alloc += (1 << priv->log2gran); + alloc += (shift << priv->log2gran); + curr = (curr >> shift) | (next << (32 - shift)); + next >>= shift; + bitidx += shift; } } } diff --git a/nuttx/mm/mm_granfree.c b/nuttx/mm/mm_granfree.c index aa14207f3..fcab11af9 100644 --- a/nuttx/mm/mm_granfree.c +++ b/nuttx/mm/mm_granfree.c @@ -99,26 +99,38 @@ static inline void gran_common_free(FAR struct gran_s *priv, granmask = (1 << priv->log2gran) - 1; ngranules = (size + granmask) >> priv->log2gran; - /* Clear bits in the first GAT entry */ + /* Clear bits in the GAT entry or entries */ avail = 32 - gatbit; if (ngranules > avail) { - priv->gat[gatidx] &= ~(0xffffffff << gatbit); + /* Clear bits in the first GAT entry */ + + gatmask = (0xffffffff << gatbit); + DEBUGASSERT((priv->gat[gatidx] & gatmask) == gatmask); + + priv->gat[gatidx] &= ~gatmask; ngranules -= avail; /* Clear bits in the second GAT entry */ gatmask = 0xffffffff >> (32 - ngranules); - priv->gat[gatidx+1] &= ~(gatmask << gatbit); + DEBUGASSERT((priv->gat[gatidx+1] & gatmask) == gatmask); + + priv->gat[gatidx+1] &= ~gatmask; } /* Handle the case where where all of the granules came from one entry */ else { - gatmask = 0xffffffff >> (32 - ngranules); - priv->gat[gatidx] &= ~(gatmask << gatbit); + /* Clear bits in a single GAT entry */ + + gatmask = 0xffffffff >> (32 - ngranules); + gatmask <<= gatbit; + DEBUGASSERT((priv->gat[gatidx] & gatmask) == gatmask); + + priv->gat[gatidx] &= ~gatmask; } gran_leave_critical(priv); |