/******************************************************************************
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*
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* Copyright (C) 2017 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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#include <assert.h>
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#include <stdlib.h>
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#include "ringbuffer.h"
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struct ringbuffer_t {
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size_t total;
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size_t available;
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uint8_t* base;
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uint8_t* head;
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uint8_t* tail;
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};
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ringbuffer_t* ringbuffer_init(const size_t size) {
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ringbuffer_t* p = static_cast<ringbuffer_t*>(calloc(1, sizeof(ringbuffer_t)));
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if (p == nullptr) return p;
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p->base = static_cast<uint8_t*>(calloc(size, sizeof(uint8_t)));
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p->head = p->tail = p->base;
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p->total = p->available = size;
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return p;
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}
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void ringbuffer_free(ringbuffer_t* rb) {
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if (rb != nullptr) free(rb->base);
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free(rb);
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}
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size_t ringbuffer_available(const ringbuffer_t* rb) {
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assert(rb);
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return rb->available;
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}
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size_t ringbuffer_size(const ringbuffer_t* rb) {
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assert(rb);
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return rb->total - rb->available;
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}
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size_t ringbuffer_insert(ringbuffer_t* rb, const uint8_t* p, size_t length) {
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assert(rb);
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assert(p);
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if (length > ringbuffer_available(rb)) length = ringbuffer_available(rb);
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for (size_t i = 0; i != length; ++i) {
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*rb->tail++ = *p++;
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if (rb->tail >= (rb->base + rb->total)) rb->tail = rb->base;
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}
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rb->available -= length;
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return length;
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}
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size_t ringbuffer_delete(ringbuffer_t* rb, size_t length) {
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assert(rb);
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if (length > ringbuffer_size(rb)) length = ringbuffer_size(rb);
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rb->head += length;
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if (rb->head >= (rb->base + rb->total)) rb->head -= rb->total;
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rb->available += length;
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return length;
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}
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size_t ringbuffer_peek(const ringbuffer_t* rb, off_t offset, uint8_t* p,
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size_t length) {
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assert(rb);
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assert(p);
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assert(offset >= 0);
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assert((size_t)offset <= ringbuffer_size(rb));
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uint8_t* b = ((rb->head - rb->base + offset) % rb->total) + rb->base;
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const size_t bytes_to_copy = (offset + length > ringbuffer_size(rb))
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? ringbuffer_size(rb) - offset
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: length;
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for (size_t copied = 0; copied < bytes_to_copy; ++copied) {
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*p++ = *b++;
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if (b >= (rb->base + rb->total)) b = rb->base;
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}
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return bytes_to_copy;
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}
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size_t ringbuffer_pop(ringbuffer_t* rb, uint8_t* p, size_t length) {
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assert(rb);
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assert(p);
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const size_t copied = ringbuffer_peek(rb, 0, p, length);
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rb->head += copied;
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if (rb->head >= (rb->base + rb->total)) rb->head -= rb->total;
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rb->available += copied;
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return copied;
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}
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