circuitpython/ports/mimxrt/dma_channel.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2021 Robert Hammelrath
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "dma_channel.h"
// List of channel flags: true: channel used, false: channel available
static bool channel_list[32] = { true, true, true, true, false, false, false, false,
false, false, false, false, false, false, false, false,
false, false, false, false, false, false, false, false,
false, false, false, false, false, false, false, false };
// allocate_channel(): retrieve an available channel. Return the number or -1
int allocate_dma_channel(void) {
for (int i = 0; i < ARRAY_SIZE(channel_list); i++) {
if (channel_list[i] == false) { // Channel available
channel_list[i] = true;
return i;
}
}
return -1;
}
// free_channel(n): Declare channel as free
void free_dma_channel(int n) {
if (n >= 0 && n <= ARRAY_SIZE(channel_list)) {
channel_list[n] = false;
}
}