1/* Copyright (c) 2013-2014 Jeffrey Pfau
 2 *
 3 * This Source Code Form is subject to the terms of the Mozilla Public
 4 * License, v. 2.0. If a copy of the MPL was not distributed with this
 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 6#include "ring-fifo.h"
 7
 8#include "util/memory.h"
 9
10void RingFIFOInit(struct RingFIFO* buffer, size_t capacity, size_t maxalloc) {
11	buffer->data = anonymousMemoryMap(capacity);
12	buffer->capacity = capacity;
13	buffer->maxalloc = maxalloc;
14	RingFIFOClear(buffer);
15}
16
17void RingFIFODeinit(struct RingFIFO* buffer) {
18	mappedMemoryFree(buffer->data, buffer->capacity);
19	buffer->data = 0;
20}
21
22size_t RingFIFOCapacity(const struct RingFIFO* buffer) {
23	return buffer->capacity;
24}
25
26void RingFIFOClear(struct RingFIFO* buffer) {
27	buffer->readPtr = buffer->data;
28	buffer->writePtr = buffer->data;
29}
30
31size_t RingFIFOWrite(struct RingFIFO* buffer, const void* value, size_t length) {
32	void* data = buffer->writePtr;
33	void* end = buffer->readPtr;
34	size_t remaining;
35	if ((intptr_t) data - (intptr_t) buffer->data + buffer->maxalloc >= buffer->capacity) {
36		data = buffer->data;
37	}
38	if (data >= end) {
39		remaining = (intptr_t) buffer->data + buffer->capacity - (intptr_t) data;
40	} else {
41		remaining = (intptr_t) end - (intptr_t) data;
42	}
43	if (remaining <= length) {
44		return 0;
45	}
46	if (value) {
47		memcpy(data, value, length);
48	}
49	buffer->writePtr = (void*) ((intptr_t) data + length);
50	return length;
51}
52
53size_t RingFIFORead(struct RingFIFO* buffer, void* output, size_t length) {
54	void* data = buffer->readPtr;
55	void* end = buffer->writePtr;
56	size_t remaining;
57	if ((intptr_t) data - (intptr_t) buffer->data + buffer->maxalloc >= buffer->capacity) {
58		data = buffer->data;
59	}
60	if (data > end) {
61		remaining = (intptr_t) buffer->data + buffer->capacity - (intptr_t) data;
62	} else {
63		remaining = (intptr_t) end - (intptr_t) data;
64	}
65	if (remaining <= length) {
66		return 0;
67	}
68	if (output) {
69		memcpy(output, data, length);
70	}
71	buffer->readPtr = (void*) ((intptr_t) data + length);
72	return length;
73}