98 lines
3.5 KiB
C
98 lines
3.5 KiB
C
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// midi for embedded chips,
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// Copyright 2010 Alex Norman
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//
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// This file is part of avr-midi.
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//
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// avr-midi is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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//(at your option) any later version.
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//
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// avr-midi is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with avr-midi. If not, see <http://www.gnu.org/licenses/>.
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#include "sysex_tools.h"
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uint16_t sysex_encoded_length(uint16_t decoded_length) {
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uint8_t remainder = decoded_length % 7;
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if (remainder)
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return (decoded_length / 7) * 8 + remainder + 1;
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else
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return (decoded_length / 7) * 8;
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}
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uint16_t sysex_decoded_length(uint16_t encoded_length) {
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uint8_t remainder = encoded_length % 8;
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if (remainder)
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return (encoded_length / 8) * 7 + remainder - 1;
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else
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return (encoded_length / 8) * 7;
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}
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uint16_t sysex_encode(uint8_t *encoded, const uint8_t *source, const uint16_t length) {
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uint16_t encoded_full = length / 7; // number of full 8 byte sections from 7 bytes of input
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uint16_t i, j;
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// fill out the fully encoded sections
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for (i = 0; i < encoded_full; i++) {
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uint16_t encoded_msb_idx = i * 8;
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uint16_t input_start_idx = i * 7;
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encoded[encoded_msb_idx] = 0;
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for (j = 0; j < 7; j++) {
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uint8_t current = source[input_start_idx + j];
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encoded[encoded_msb_idx] |= (0x80 & current) >> (1 + j);
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encoded[encoded_msb_idx + 1 + j] = 0x7F & current;
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}
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}
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// fill out the rest if there is any more
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uint8_t remainder = length % 7;
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if (remainder) {
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uint16_t encoded_msb_idx = encoded_full * 8;
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uint16_t input_start_idx = encoded_full * 7;
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encoded[encoded_msb_idx] = 0;
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for (j = 0; j < remainder; j++) {
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uint8_t current = source[input_start_idx + j];
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encoded[encoded_msb_idx] |= (0x80 & current) >> (1 + j);
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encoded[encoded_msb_idx + 1 + j] = 0x7F & current;
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}
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return encoded_msb_idx + remainder + 1;
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} else {
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return encoded_full * 8;
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}
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}
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uint16_t sysex_decode(uint8_t *decoded, const uint8_t *source, const uint16_t length) {
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uint16_t decoded_full = length / 8;
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uint16_t i, j;
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if (length < 2) return 0;
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// fill out the fully encoded sections
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for (i = 0; i < decoded_full; i++) {
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uint16_t encoded_msb_idx = i * 8;
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uint16_t output_start_index = i * 7;
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for (j = 0; j < 7; j++) {
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decoded[output_start_index + j] = 0x7F & source[encoded_msb_idx + j + 1];
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decoded[output_start_index + j] |= (0x80 & (source[encoded_msb_idx] << (1 + j)));
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}
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}
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uint8_t remainder = length % 8;
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if (remainder) {
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uint16_t encoded_msb_idx = decoded_full * 8;
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uint16_t output_start_index = decoded_full * 7;
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for (j = 0; j < (remainder - 1); j++) {
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decoded[output_start_index + j] = 0x7F & source[encoded_msb_idx + j + 1];
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decoded[output_start_index + j] |= (0x80 & (source[encoded_msb_idx] << (1 + j)));
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}
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return decoded_full * 7 + remainder - 1;
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} else {
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return decoded_full * 7;
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}
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}
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