315 lines
10 KiB
C
315 lines
10 KiB
C
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/*---------------------------------------------------------------------------*\
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FILE........: freedv_data_channel.c
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AUTHOR......: Jeroen Vreeken
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DATE CREATED: 03 March 2016
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Data channel for ethernet like packets in freedv VHF frames.
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Currently designed for-
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* 2 control bits per frame
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* 4 byte counter bits per frame
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* 64 bits of data per frame
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2016 Jeroen Vreeken
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All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License version 2.1, as
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published by the Free Software Foundation. This program is
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distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "freedv_data_channel.h"
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#include <stdlib.h>
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#include <string.h>
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static unsigned char fdc_header_bcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
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/* CCIT CRC table (0x1201 polynomal) */
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static unsigned short fdc_crc_table[256] = {
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0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
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0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
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0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
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0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
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0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
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0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
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0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
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0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
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0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
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0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
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0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
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0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
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0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
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0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
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0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
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0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
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0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
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0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
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0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
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0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
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0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
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0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
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0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
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0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
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0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
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0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
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0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
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0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
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0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
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0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
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0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
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0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
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};
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static unsigned short fdc_crc(unsigned char *buffer, size_t len)
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{
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unsigned short crc = 0xffff;
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size_t i;
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for (i = 0; i < len; i++, buffer++) {
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crc = (crc >> 8) ^ fdc_crc_table[(crc ^ *buffer) & 0xff];
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}
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return crc ^ 0xffff;
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}
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/* CRC4 0x03 polynomal */
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static unsigned char fdc_crc4(unsigned char *buffer, size_t len)
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{
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unsigned char crc = 0x0f;
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size_t i;
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for (i = 0; i < len; i++, buffer++) {
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int shift;
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for (shift = 7; shift <= 0; shift--) {
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crc <<= 1;
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if ((*buffer >> shift) & 0x1)
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crc |= 1;
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if (crc & 0x10)
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crc ^= 0x03;
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}
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}
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return crc & 0x0f;
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}
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struct freedv_data_channel *freedv_data_channel_create(void)
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{
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struct freedv_data_channel *fdc;
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fdc = malloc(sizeof(struct freedv_data_channel));
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if (!fdc)
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return NULL;
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fdc->cb_rx = NULL;
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fdc->cb_tx = NULL;
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fdc->packet_tx_size = 0;
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freedv_data_set_header(fdc, fdc_header_bcast);
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memcpy(fdc->rx_header, fdc->tx_header, 8);
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return fdc;
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}
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void freedv_data_channel_destroy(struct freedv_data_channel *fdc)
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{
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free(fdc);
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}
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void freedv_data_set_cb_rx(struct freedv_data_channel *fdc, freedv_data_callback_rx cb, void *state)
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{
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fdc->cb_rx = cb;
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fdc->cb_rx_state = state;
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}
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void freedv_data_set_cb_tx(struct freedv_data_channel *fdc, freedv_data_callback_tx cb, void *state)
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{
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fdc->cb_tx = cb;
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fdc->cb_tx_state = state;
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}
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void freedv_data_channel_rx_frame(struct freedv_data_channel *fdc, unsigned char *data, size_t size, int from_bit, int bcast_bit, int crc_bit, int end_bits)
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{
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int copy_bits;
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if (end_bits) {
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copy_bits = end_bits;
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} else {
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copy_bits = size;
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}
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/* New packet? */
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if (fdc->packet_rx_cnt == 0) {
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/* Does the packet have a compressed from field? */
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if (from_bit) {
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/* Compressed from: take the previously received header */
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memcpy(fdc->packet_rx + fdc->packet_rx_cnt, fdc->rx_header, 6);
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fdc->packet_rx_cnt += 6;
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}
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if (bcast_bit) {
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if (!from_bit) {
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/* Copy from header and modify size and end_bits accordingly */
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memcpy(fdc->packet_rx + fdc->packet_rx_cnt, data, 6);
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fdc->packet_rx_cnt += 6;
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copy_bits -= 6;
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if (copy_bits < 0)
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copy_bits = 0;
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data += 6;
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}
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/* Compressed to: fill in broadcast address */
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memcpy(fdc->packet_rx + fdc->packet_rx_cnt, fdc_header_bcast, sizeof(fdc_header_bcast));
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fdc->packet_rx_cnt += 6;
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}
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if (crc_bit) {
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unsigned char calc_crc = fdc_crc4(data, size);
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if (calc_crc == end_bits) {
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/* It is a single header field, remember it for later */
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memcpy(fdc->packet_rx + 6, data, 6);
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memcpy(fdc->packet_rx, fdc_header_bcast, 6);
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if (fdc->cb_rx) {
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fdc->cb_rx(fdc->cb_rx_state, fdc->packet_rx, 12);
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}
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}
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fdc->packet_rx_cnt = 0;
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return;
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}
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}
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if (fdc->packet_rx_cnt + copy_bits >= FREEDV_DATA_CHANNEL_PACKET_MAX) {
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/* Something went wrong... this can not be a real packet */
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fdc->packet_rx_cnt = 0;
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return;
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}
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memcpy(fdc->packet_rx + fdc->packet_rx_cnt, data, copy_bits);
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fdc->packet_rx_cnt += copy_bits;
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if (end_bits != 0 && fdc->packet_rx_cnt >= 2) {
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unsigned short calc_crc = fdc_crc(fdc->packet_rx, fdc->packet_rx_cnt - 2);
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unsigned short rx_crc;
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rx_crc = fdc->packet_rx[fdc->packet_rx_cnt - 1] << 8;
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rx_crc |= fdc->packet_rx[fdc->packet_rx_cnt - 2];
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if (rx_crc == calc_crc) {
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if (fdc->packet_rx_cnt == size) {
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/* It is a single header field, remember it for later */
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memcpy(fdc->rx_header, fdc->packet_rx, 6);
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}
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/* callback */
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if (fdc->cb_rx) {
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unsigned char tmp[6];
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memcpy(tmp, fdc->packet_rx, 6);
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memcpy(fdc->packet_rx, fdc->packet_rx + 6, 6);
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memcpy(fdc->packet_rx + 6, tmp, 6);
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size_t size = fdc->packet_rx_cnt - 2;
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if (size < 12)
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size = 12;
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fdc->cb_rx(fdc->cb_rx_state, fdc->packet_rx, size);
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}
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}
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fdc->packet_rx_cnt = 0;
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}
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}
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void freedv_data_channel_tx_frame(struct freedv_data_channel *fdc, unsigned char *data, size_t size, int *from_bit, int *bcast_bit, int *crc_bit, int *end_bits)
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{
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*from_bit = 0;
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*bcast_bit = 0;
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*crc_bit = 0;
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if (!fdc->packet_tx_size) {
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fdc->packet_tx_cnt = 0;
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if (fdc->cb_tx) {
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fdc->packet_tx_size = FREEDV_DATA_CHANNEL_PACKET_MAX;
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fdc->cb_tx(fdc->cb_tx_state, fdc->packet_tx, &fdc->packet_tx_size);
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}
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if (!fdc->packet_tx_size) {
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/* Nothing to send, insert a header frame */
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memcpy(fdc->packet_tx, fdc->tx_header, size);
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if (size < 8) {
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*end_bits = fdc_crc4(fdc->tx_header, size);
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*crc_bit = 1;
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memcpy(data, fdc->tx_header, size);
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return;
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} else {
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fdc->packet_tx_size = size;
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}
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} else {
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/* new packet */
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unsigned short crc;
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unsigned char tmp[6];
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*from_bit = !memcmp(fdc->packet_tx + 6, fdc->tx_header, 6);
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*bcast_bit = !memcmp(fdc->packet_tx, fdc_header_bcast, 6);
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memcpy(tmp, fdc->packet_tx, 6);
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memcpy(fdc->packet_tx, fdc->packet_tx + 6, 6);
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memcpy(fdc->packet_tx + 6, tmp, 6);
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crc = fdc_crc(fdc->packet_tx, fdc->packet_tx_size);
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fdc->packet_tx[fdc->packet_tx_size] = crc & 0xff;
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fdc->packet_tx_size++;
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fdc->packet_tx[fdc->packet_tx_size] = (crc >> 8) & 0xff;
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fdc->packet_tx_size++;
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if (*from_bit) {
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fdc->packet_tx_cnt = 6;
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} else {
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if (*bcast_bit) {
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memcpy(fdc->packet_tx + 6, fdc->packet_tx, 6);
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}
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}
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if (*bcast_bit) {
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fdc->packet_tx_cnt += 6;
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}
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}
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}
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if (fdc->packet_tx_size) {
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int copy = fdc->packet_tx_size - fdc->packet_tx_cnt;
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if (copy > size) {
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copy = size;
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*end_bits = 0;
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} else {
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*end_bits = copy;
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fdc->packet_tx_size = 0;
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}
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memcpy(data, fdc->packet_tx + fdc->packet_tx_cnt, copy);
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fdc->packet_tx_cnt += copy;
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}
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}
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void freedv_data_set_header(struct freedv_data_channel *fdc, unsigned char *header)
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{
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unsigned short crc = fdc_crc(header, 6);
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memcpy(fdc->tx_header, header, 6);
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fdc->tx_header[6] = crc & 0xff;
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fdc->tx_header[7] = (crc >> 8) & 0xff;
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}
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int freedv_data_get_n_tx_frames(struct freedv_data_channel *fdc, size_t size)
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{
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if (fdc->packet_tx_size == 0)
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return 0;
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/* packet will be send in 'size' byte frames */
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return (fdc->packet_tx_size - fdc->packet_tx_cnt + size-1) / size;
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}
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