vpx_mem/memory_manager/hmm_largest.c

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11
  12 /* This code is in the public domain.
  13 ** Version: 1.1  Author: Walt Karas
  14 */
  15
  16 #include "hmm_intrnl.h"
  17
  18 U(size_aau) U(largest_available)(U(descriptor) *desc)
  19 {
  20     U(size_bau) largest;
  21
  22     if (!(desc->avl_tree_root))
  23         largest = 0;
  24     else
  25     {
  26 #ifdef HMM_AUDIT_FAIL
  27         /* Audit root block in AVL tree. */
  28         AUDIT_BLOCK(PTR_REC_TO_HEAD(desc->avl_tree_root))
  29 #endif
  30
  31         largest =
  32             BLOCK_BAUS(
  33                 PTR_REC_TO_HEAD(
  34                     U(avl_search)(
  35                         (U(avl_avl) *) & (desc->avl_tree_root),
  36                         (U(size_bau)) ~(U(size_bau)) 0, AVL_LESS)));
  37     }
  38
  39     if (desc->last_freed)
  40     {
  41         /* Size of last freed block. */
  42         register U(size_bau) lf_size;
  43
  44 #ifdef HMM_AUDIT_FAIL
  45         AUDIT_BLOCK(desc->last_freed)
  46 #endif
  47
  48         lf_size = BLOCK_BAUS(desc->last_freed);
  49
  50         if (lf_size > largest)
  51             largest = lf_size;
  52     }
  53
  54     /* Convert largest size to AAUs and subract head size leaving payload
  55     ** size.
  56     */
  57     return(largest ?
  58            ((largest * ((U(size_aau)) HMM_BLOCK_ALIGN_UNIT)) - HEAD_AAUS) :
  59            0);
  60 }