ref: 33afddadb9af6569bd8296ef1d48d0511b651e9d
dir: /vpx_mem/memory_manager/hmm_base.c/
/* * Copyright (c) 2010 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ /* This code is in the public domain. ** Version: 1.1 Author: Walt Karas */ #include "hmm_intrnl.h" void U(init)(U(descriptor) *desc) { desc->avl_tree_root = 0; desc->last_freed = 0; } /* Remove a free block from a bin's doubly-linked list when it is not, ** the first block in the bin. */ void U(dll_remove)( /* Pointer to pointer record in the block to be removed. */ ptr_record *to_remove) { to_remove->prev->next = to_remove->next; if (to_remove->next) to_remove->next->prev = to_remove->prev; } /* Put a block into the free collection of a heap. */ void U(into_free_collection)( /* Pointer to heap descriptor. */ U(descriptor) *desc, /* Pointer to head record of block. */ head_record *head_ptr) { ptr_record *ptr_rec_ptr = HEAD_TO_PTR_REC(head_ptr); ptr_record *bin_front_ptr = U(avl_insert)((U(avl_avl) *) & (desc->avl_tree_root), ptr_rec_ptr); if (bin_front_ptr != ptr_rec_ptr) { /* The block was not inserted into the AVL tree because there is ** already a bin for the size of the block. */ MARK_SUCCESSIVE_BLOCK_IN_FREE_BIN(head_ptr) ptr_rec_ptr->self = ptr_rec_ptr; /* Make the block the new second block in the bin's doubly-linked ** list. */ ptr_rec_ptr->prev = bin_front_ptr; ptr_rec_ptr->next = bin_front_ptr->next; bin_front_ptr->next = ptr_rec_ptr; if (ptr_rec_ptr->next) ptr_rec_ptr->next->prev = ptr_rec_ptr; } else /* Block is first block in new bin. */ ptr_rec_ptr->next = 0; } /* Allocate a block from a given bin. Returns a pointer to the payload ** of the removed block. The "last freed" pointer must be null prior ** to calling this function. */ void *U(alloc_from_bin)( /* Pointer to heap descriptor. */ U(descriptor) *desc, /* Pointer to pointer record of first block in bin. */ ptr_record *bin_front_ptr, /* Number of BAUs needed in the allocated block. If the block taken ** from the bin is significantly larger than the number of BAUs needed, ** the "extra" BAUs are split off to form a new free block. */ U(size_bau) n_baus) { head_record *head_ptr; U(size_bau) rem_baus; if (bin_front_ptr->next) { /* There are multiple blocks in this bin. Use the 2nd block in ** the bin to avoid needless change to the AVL tree. */ ptr_record *ptr_rec_ptr = bin_front_ptr->next; head_ptr = PTR_REC_TO_HEAD(ptr_rec_ptr); #ifdef AUDIT_FAIL AUDIT_BLOCK(head_ptr) #endif U(dll_remove)(ptr_rec_ptr); } else { /* There is only one block in the bin, so it has to be removed ** from the AVL tree. */ head_ptr = PTR_REC_TO_HEAD(bin_front_ptr); U(avl_remove)( (U(avl_avl) *) & (desc->avl_tree_root), BLOCK_BAUS(head_ptr)); } MARK_BLOCK_ALLOCATED(head_ptr) rem_baus = BLOCK_BAUS(head_ptr) - n_baus; if (rem_baus >= MIN_BLOCK_BAUS) { /* Since there are enough "extra" BAUs, split them off to form ** a new free block. */ head_record *rem_head_ptr = (head_record *) BAUS_FORWARD(head_ptr, n_baus); /* Change the next block's header to reflect the fact that the ** block preceeding it is now smaller. */ SET_PREV_BLOCK_BAUS( BAUS_FORWARD(head_ptr, head_ptr->block_size), rem_baus) head_ptr->block_size = n_baus; rem_head_ptr->previous_block_size = n_baus; rem_head_ptr->block_size = rem_baus; desc->last_freed = rem_head_ptr; } return(HEAD_TO_PTR_REC(head_ptr)); } /* Take a block out of the free collection. */ void U(out_of_free_collection)( /* Descriptor of heap that block is in. */ U(descriptor) *desc, /* Pointer to head of block to take out of free collection. */ head_record *head_ptr) { ptr_record *ptr_rec_ptr = HEAD_TO_PTR_REC(head_ptr); if (ptr_rec_ptr->self == ptr_rec_ptr) /* Block is not the front block in its bin, so all we have to ** do is take it out of the bin's doubly-linked list. */ U(dll_remove)(ptr_rec_ptr); else { ptr_record *next = ptr_rec_ptr->next; if (next) /* Block is the front block in its bin, and there is at least ** one other block in the bin. Substitute the next block for ** the front block. */ U(avl_subst)((U(avl_avl) *) & (desc->avl_tree_root), next); else /* Block is the front block in its bin, but there is no other ** block in the bin. Eliminate the bin. */ U(avl_remove)( (U(avl_avl) *) & (desc->avl_tree_root), BLOCK_BAUS(head_ptr)); } } void U(free)(U(descriptor) *desc, void *payload_ptr) { /* Flags if coalesce with adjacent block. */ int coalesce; head_record *fwd_head_ptr; head_record *free_head_ptr = PTR_REC_TO_HEAD(payload_ptr); desc->num_baus_can_shrink = 0; #ifdef HMM_AUDIT_FAIL AUDIT_BLOCK(free_head_ptr) /* Make sure not freeing an already free block. */ if (!IS_BLOCK_ALLOCATED(free_head_ptr)) HMM_AUDIT_FAIL if (desc->avl_tree_root) /* Audit root block in AVL tree. */ AUDIT_BLOCK(PTR_REC_TO_HEAD(desc->avl_tree_root)) #endif fwd_head_ptr = (head_record *) BAUS_FORWARD(free_head_ptr, free_head_ptr->block_size); if (free_head_ptr->previous_block_size) { /* Coalesce with backward block if possible. */ head_record *bkwd_head_ptr = (head_record *) BAUS_BACKWARD( free_head_ptr, free_head_ptr->previous_block_size); #ifdef HMM_AUDIT_FAIL AUDIT_BLOCK(bkwd_head_ptr) #endif if (bkwd_head_ptr == (head_record *)(desc->last_freed)) { desc->last_freed = 0; coalesce = 1; } else if (IS_BLOCK_ALLOCATED(bkwd_head_ptr)) coalesce = 0; else { U(out_of_free_collection)(desc, bkwd_head_ptr); coalesce = 1; } if (coalesce) { bkwd_head_ptr->block_size += free_head_ptr->block_size; SET_PREV_BLOCK_BAUS(fwd_head_ptr, BLOCK_BAUS(bkwd_head_ptr)) free_head_ptr = bkwd_head_ptr; } } if (fwd_head_ptr->block_size == 0) { /* Block to be freed is last block before dummy end-of-chunk block. */ desc->end_of_shrinkable_chunk = BAUS_FORWARD(fwd_head_ptr, DUMMY_END_BLOCK_BAUS); desc->num_baus_can_shrink = BLOCK_BAUS(free_head_ptr); if (PREV_BLOCK_BAUS(free_head_ptr) == 0) /* Free block is the entire chunk, so shrinking can eliminate ** entire chunk including dummy end block. */ desc->num_baus_can_shrink += DUMMY_END_BLOCK_BAUS; } else { /* Coalesce with forward block if possible. */ #ifdef HMM_AUDIT_FAIL AUDIT_BLOCK(fwd_head_ptr) #endif if (fwd_head_ptr == (head_record *)(desc->last_freed)) { desc->last_freed = 0; coalesce = 1; } else if (IS_BLOCK_ALLOCATED(fwd_head_ptr)) coalesce = 0; else { U(out_of_free_collection)(desc, fwd_head_ptr); coalesce = 1; } if (coalesce) { free_head_ptr->block_size += fwd_head_ptr->block_size; fwd_head_ptr = (head_record *) BAUS_FORWARD( fwd_head_ptr, BLOCK_BAUS(fwd_head_ptr)); SET_PREV_BLOCK_BAUS(fwd_head_ptr, BLOCK_BAUS(free_head_ptr)) if (fwd_head_ptr->block_size == 0) { /* Coalesced block to be freed is last block before dummy ** end-of-chunk block. */ desc->end_of_shrinkable_chunk = BAUS_FORWARD(fwd_head_ptr, DUMMY_END_BLOCK_BAUS); desc->num_baus_can_shrink = BLOCK_BAUS(free_head_ptr); if (PREV_BLOCK_BAUS(free_head_ptr) == 0) /* Free block is the entire chunk, so shrinking can ** eliminate entire chunk including dummy end block. */ desc->num_baus_can_shrink += DUMMY_END_BLOCK_BAUS; } } } if (desc->last_freed) { /* There is a last freed block, but it is not adjacent to the ** block being freed by this call to free, so put the last ** freed block into the free collection. */ #ifdef HMM_AUDIT_FAIL AUDIT_BLOCK(desc->last_freed) #endif U(into_free_collection)(desc, (head_record *)(desc->last_freed)); } desc->last_freed = free_head_ptr; } void U(new_chunk)(U(descriptor) *desc, void *start, U(size_bau) n_baus) { #ifdef HMM_AUDIT_FAIL if (desc->avl_tree_root) /* Audit root block in AVL tree. */ AUDIT_BLOCK(PTR_REC_TO_HEAD(desc->avl_tree_root)) #endif #undef HEAD_PTR #define HEAD_PTR ((head_record *) start) /* Make the chunk one big free block followed by a dummy end block. */ n_baus -= DUMMY_END_BLOCK_BAUS; HEAD_PTR->previous_block_size = 0; HEAD_PTR->block_size = n_baus; U(into_free_collection)(desc, HEAD_PTR); /* Set up the dummy end block. */ start = BAUS_FORWARD(start, n_baus); HEAD_PTR->previous_block_size = n_baus; HEAD_PTR->block_size = 0; #undef HEAD_PTR } #ifdef HMM_AUDIT_FAIL /* Function that does audit fail actions defined my preprocessor symbol, ** and returns a dummy integer value. */ int U(audit_block_fail_dummy_return)(void) { HMM_AUDIT_FAIL /* Dummy return. */ return(0); } #endif /* AVL Tree instantiation. */ #ifdef HMM_AUDIT_FAIL /* The AVL tree generic package passes an ACCESS of 1 when it "touches" ** a child node for the first time during a particular operation. I use ** this feature to audit only one time (per operation) the free blocks ** that are tree nodes. Since the root node is not a child node, it has ** to be audited directly. */ /* The pain you feel while reading these macros will not be in vain. It ** will remove all doubt from you mind that C++ inline functions are ** a very good thing. */ #define AVL_GET_LESS(H, ACCESS) \ (((ACCESS) ? AUDIT_BLOCK_AS_EXPR(PTR_REC_TO_HEAD(H)) : 0), (H)->self) #define AVL_GET_GREATER(H, ACCESS) \ (((ACCESS) ? AUDIT_BLOCK_AS_EXPR(PTR_REC_TO_HEAD(H)) : 0), (H)->prev) #else #define AVL_GET_LESS(H, ACCESS) ((H)->self) #define AVL_GET_GREATER(H, ACCESS) ((H)->prev) #endif #define AVL_SET_LESS(H, LH) (H)->self = (LH); #define AVL_SET_GREATER(H, GH) (H)->prev = (GH); /* high bit of high bit of ** block_size previous_block_size balance factor ** ----------- ------------------- -------------- ** 0 0 n/a (block allocated) ** 0 1 1 ** 1 0 -1 ** 1 1 0 */ #define AVL_GET_BALANCE_FACTOR(H) \ ((((head_record *) (PTR_REC_TO_HEAD(H)))->block_size & \ HIGH_BIT_BAU_SIZE) ? \ (((head_record *) (PTR_REC_TO_HEAD(H)))->previous_block_size & \ HIGH_BIT_BAU_SIZE ? 0 : -1) : 1) #define AVL_SET_BALANCE_FACTOR(H, BF) \ { \ register head_record *p = \ (head_record *) PTR_REC_TO_HEAD(H); \ register int bal_f = (BF); \ \ if (bal_f <= 0) \ p->block_size |= HIGH_BIT_BAU_SIZE; \ else \ p->block_size &= ~HIGH_BIT_BAU_SIZE; \ if (bal_f >= 0) \ p->previous_block_size |= HIGH_BIT_BAU_SIZE; \ else \ p->previous_block_size &= ~HIGH_BIT_BAU_SIZE; \ } #define COMPARE_KEY_KEY(K1, K2) ((K1) == (K2) ? 0 : ((K1) > (K2) ? 1 : -1)) #define AVL_COMPARE_KEY_NODE(K, H) \ COMPARE_KEY_KEY(K, BLOCK_BAUS(PTR_REC_TO_HEAD(H))) #define AVL_COMPARE_NODE_NODE(H1, H2) \ COMPARE_KEY_KEY(BLOCK_BAUS(PTR_REC_TO_HEAD(H1)), \ BLOCK_BAUS(PTR_REC_TO_HEAD(H2))) #define AVL_NULL ((ptr_record *) 0) #define AVL_IMPL_MASK \ ( AVL_IMPL_INSERT | AVL_IMPL_SEARCH | AVL_IMPL_REMOVE | AVL_IMPL_SUBST ) #include "cavl_impl.h"