1 /* 2 * Copyright (C) 2005 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <stdlib.h> 18 #include <string.h> 19 20 #include <utils/SharedBuffer.h> 21 #include <utils/Atomic.h> 22 23 // --------------------------------------------------------------------------- 24 25 namespace android { 26 alloc(size_t size)27SharedBuffer* SharedBuffer::alloc(size_t size) 28 { 29 SharedBuffer* sb = static_cast<SharedBuffer *>(malloc(sizeof(SharedBuffer) + size)); 30 if (sb) { 31 sb->mRefs = 1; 32 sb->mSize = size; 33 } 34 return sb; 35 } 36 37 dealloc(const SharedBuffer * released)38ssize_t SharedBuffer::dealloc(const SharedBuffer* released) 39 { 40 if (released->mRefs != 0) return -1; // XXX: invalid operation 41 free(const_cast<SharedBuffer*>(released)); 42 return 0; 43 } 44 edit() const45SharedBuffer* SharedBuffer::edit() const 46 { 47 if (onlyOwner()) { 48 return const_cast<SharedBuffer*>(this); 49 } 50 SharedBuffer* sb = alloc(mSize); 51 if (sb) { 52 memcpy(sb->data(), data(), size()); 53 release(); 54 } 55 return sb; 56 } 57 editResize(size_t newSize) const58SharedBuffer* SharedBuffer::editResize(size_t newSize) const 59 { 60 if (onlyOwner()) { 61 SharedBuffer* buf = const_cast<SharedBuffer*>(this); 62 if (buf->mSize == newSize) return buf; 63 buf = (SharedBuffer*)realloc(buf, sizeof(SharedBuffer) + newSize); 64 if (buf != NULL) { 65 buf->mSize = newSize; 66 return buf; 67 } 68 } 69 SharedBuffer* sb = alloc(newSize); 70 if (sb) { 71 const size_t mySize = mSize; 72 memcpy(sb->data(), data(), newSize < mySize ? newSize : mySize); 73 release(); 74 } 75 return sb; 76 } 77 attemptEdit() const78SharedBuffer* SharedBuffer::attemptEdit() const 79 { 80 if (onlyOwner()) { 81 return const_cast<SharedBuffer*>(this); 82 } 83 return 0; 84 } 85 reset(size_t new_size) const86SharedBuffer* SharedBuffer::reset(size_t new_size) const 87 { 88 // cheap-o-reset. 89 SharedBuffer* sb = alloc(new_size); 90 if (sb) { 91 release(); 92 } 93 return sb; 94 } 95 acquire() const96void SharedBuffer::acquire() const { 97 android_atomic_inc(&mRefs); 98 } 99 release(uint32_t flags) const100int32_t SharedBuffer::release(uint32_t flags) const 101 { 102 int32_t prev = 1; 103 if (onlyOwner() || ((prev = android_atomic_dec(&mRefs)) == 1)) { 104 mRefs = 0; 105 if ((flags & eKeepStorage) == 0) { 106 free(const_cast<SharedBuffer*>(this)); 107 } 108 } 109 return prev; 110 } 111 112 113 }; // namespace android 114