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