Ruchi Kandoi | c0cd1ab | 2017-04-17 17:23:56 -0700 | [diff] [blame] | 1 | /****************************************************************************** |
| 2 | * |
| 3 | * Copyright (C) 2017 Google Inc. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at: |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | ******************************************************************************/ |
| 18 | |
| 19 | #include <assert.h> |
| 20 | #include <stdlib.h> |
| 21 | |
| 22 | #include "ringbuffer.h" |
| 23 | |
| 24 | struct ringbuffer_t { |
| 25 | size_t total; |
| 26 | size_t available; |
| 27 | uint8_t* base; |
| 28 | uint8_t* head; |
| 29 | uint8_t* tail; |
| 30 | }; |
| 31 | |
| 32 | ringbuffer_t* ringbuffer_init(const size_t size) { |
| 33 | ringbuffer_t* p = static_cast<ringbuffer_t*>(calloc(1, sizeof(ringbuffer_t))); |
| 34 | |
| 35 | if (p == NULL) return p; |
| 36 | |
| 37 | p->base = static_cast<uint8_t*>(calloc(size, sizeof(uint8_t))); |
| 38 | p->head = p->tail = p->base; |
| 39 | p->total = p->available = size; |
| 40 | |
| 41 | return p; |
| 42 | } |
| 43 | |
| 44 | void ringbuffer_free(ringbuffer_t* rb) { |
| 45 | if (rb != NULL) free(rb->base); |
| 46 | free(rb); |
| 47 | } |
| 48 | |
| 49 | size_t ringbuffer_available(const ringbuffer_t* rb) { |
| 50 | assert(rb); |
| 51 | return rb->available; |
| 52 | } |
| 53 | |
| 54 | size_t ringbuffer_size(const ringbuffer_t* rb) { |
| 55 | assert(rb); |
| 56 | return rb->total - rb->available; |
| 57 | } |
| 58 | |
| 59 | size_t ringbuffer_insert(ringbuffer_t* rb, const uint8_t* p, size_t length) { |
| 60 | assert(rb); |
| 61 | assert(p); |
| 62 | |
| 63 | if (length > ringbuffer_available(rb)) length = ringbuffer_available(rb); |
| 64 | |
| 65 | for (size_t i = 0; i != length; ++i) { |
| 66 | *rb->tail++ = *p++; |
| 67 | if (rb->tail >= (rb->base + rb->total)) rb->tail = rb->base; |
| 68 | } |
| 69 | |
| 70 | rb->available -= length; |
| 71 | return length; |
| 72 | } |
| 73 | |
| 74 | size_t ringbuffer_delete(ringbuffer_t* rb, size_t length) { |
| 75 | assert(rb); |
| 76 | |
| 77 | if (length > ringbuffer_size(rb)) length = ringbuffer_size(rb); |
| 78 | |
| 79 | rb->head += length; |
| 80 | if (rb->head >= (rb->base + rb->total)) rb->head -= rb->total; |
| 81 | |
| 82 | rb->available += length; |
| 83 | return length; |
| 84 | } |
| 85 | |
| 86 | size_t ringbuffer_peek(const ringbuffer_t* rb, off_t offset, uint8_t* p, |
| 87 | size_t length) { |
| 88 | assert(rb); |
| 89 | assert(p); |
| 90 | assert(offset >= 0); |
| 91 | assert((size_t)offset <= ringbuffer_size(rb)); |
| 92 | |
| 93 | uint8_t* b = ((rb->head - rb->base + offset) % rb->total) + rb->base; |
| 94 | const size_t bytes_to_copy = (offset + length > ringbuffer_size(rb)) |
| 95 | ? ringbuffer_size(rb) - offset |
| 96 | : length; |
| 97 | |
| 98 | for (size_t copied = 0; copied < bytes_to_copy; ++copied) { |
| 99 | *p++ = *b++; |
| 100 | if (b >= (rb->base + rb->total)) b = rb->base; |
| 101 | } |
| 102 | |
| 103 | return bytes_to_copy; |
| 104 | } |
| 105 | |
| 106 | size_t ringbuffer_pop(ringbuffer_t* rb, uint8_t* p, size_t length) { |
| 107 | assert(rb); |
| 108 | assert(p); |
| 109 | |
| 110 | const size_t copied = ringbuffer_peek(rb, 0, p, length); |
| 111 | rb->head += copied; |
| 112 | if (rb->head >= (rb->base + rb->total)) rb->head -= rb->total; |
| 113 | |
| 114 | rb->available += copied; |
| 115 | return copied; |
| 116 | } |