1 /*
2 * This file is part of the MicroPython project, http://micropython.org/
3 *
4 * The MIT License (MIT)
5 *
6 * Copyright (c) 2021 Robert Hammelrath
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27 #include "dma_channel.h"
28
29 // List of channel flags: true: channel used, false: channel available
30 static bool channel_list[32] = { true, true, true, true, false, false, false, false,
31 false, false, false, false, false, false, false, false,
32 false, false, false, false, false, false, false, false,
33 false, false, false, false, false, false, false, false };
34
35 // allocate_channel(): retrieve an available channel. Return the number or -1
allocate_dma_channel(void)36 int allocate_dma_channel(void) {
37 for (int i = 0; i < ARRAY_SIZE(channel_list); i++) {
38 if (channel_list[i] == false) { // Channel available
39 channel_list[i] = true;
40 return i;
41 }
42 }
43 return -1;
44 }
45
46 // free_channel(n): Declare channel as free
free_dma_channel(int n)47 void free_dma_channel(int n) {
48 if (n >= 0 && n <= ARRAY_SIZE(channel_list)) {
49 channel_list[n] = false;
50 }
51 }
52