mirror of git://git.sysmocom.de/ofono
503 lines
14 KiB
C
503 lines
14 KiB
C
/*
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*
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* AT chat library with GLib integration
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*
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* Copyright (C) 2009 Intel Corporation. All rights reserved.
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* Copyright (C) 2009 Trolltech ASA.
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*
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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 General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program 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 this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <alloca.h>
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#include <string.h>
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#include <stdio.h>
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#include "gsm0710.h"
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/* Frame types and subtypes */
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#define GSM0710_OPEN_CHANNEL 0x3F
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#define GSM0710_CLOSE_CHANNEL 0x53
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#define GSM0710_DATA 0xEF
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#define GSM0710_DATA_ALT 0x03
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#define GSM0710_STATUS_SET 0xE3
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#define GSM0710_STATUS_ACK 0xE1
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/* Initialize a GSM 07.10 context, in preparation for startup */
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void gsm0710_initialize(struct gsm0710_context *ctx)
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{
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ctx->mode = GSM0710_MODE_BASIC;
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ctx->frame_size = GSM0710_DEFAULT_FRAME_SIZE;
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ctx->buffer_used = 0;
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memset(ctx->used_channels, 0, sizeof(ctx->used_channels));
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ctx->user_data = NULL;
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ctx->read = NULL;
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ctx->write = NULL;
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ctx->deliver_data = NULL;
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ctx->deliver_status = NULL;
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ctx->debug_message = NULL;
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ctx->packet_filter = NULL;
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}
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/* Determine if a channel is in use */
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static int is_channel_used(struct gsm0710_context *ctx, int channel)
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{
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int index = channel / 32;
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return ((ctx->used_channels[index] & (1L << (channel % 32))) != 0);
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}
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/* Mark a channel as used */
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static void mark_channel_used(struct gsm0710_context *ctx, int channel)
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{
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int index = channel / 32;
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ctx->used_channels[index] |= (1L << (channel % 32));
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}
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/* Mark a channel as unused */
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static void mark_channel_unused(struct gsm0710_context *ctx, int channel)
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{
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int index = channel / 32;
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ctx->used_channels[index] &= ~(1L << (channel % 32));
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}
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/* Write a debug message */
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static void gsm0710_debug(struct gsm0710_context *ctx, const char *msg)
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{
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if (ctx->debug_message)
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ctx->debug_message(ctx, msg);
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}
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static const unsigned char crc_table[256] = {
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0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
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0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
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0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
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0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
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0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
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0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
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0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
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0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
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0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
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0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
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0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
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0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
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0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
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0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
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0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
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0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
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0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
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0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
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0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
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0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
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0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
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0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
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0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
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0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
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0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
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0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
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0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
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0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
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0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
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0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
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0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
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0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
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};
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static unsigned char gsm0710_compute_crc(const unsigned char *data, int len)
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{
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int sum = 0xFF;
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while (len > 0) {
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sum = crc_table[(sum ^ *data++) & 0xFF];
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--len;
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}
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return (~sum & 0xFF);
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}
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/* Write a raw GSM 07.10 frame to the underlying device */
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static void gsm0710_write_frame(struct gsm0710_context *ctx, int channel,
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int type, const unsigned char *data, int len)
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{
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unsigned char *frame = alloca(ctx->frame_size * 2 + 8);
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int size;
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if (len > ctx->frame_size)
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len = ctx->frame_size;
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if (ctx->mode) {
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int temp, crc;
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frame[0] = 0x7E;
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frame[1] = ((channel << 2) | 0x03);
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frame[2] = type;
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crc = gsm0710_compute_crc(frame + 1, 2);
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if (type == 0x7E || type == 0x7D) {
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/* Need to quote the type field now that crc has been computed */
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frame[2] = 0x7D;
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frame[3] = (type ^ 0x20);
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size = 4;
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} else {
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size = 3;
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}
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while (len > 0) {
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temp = *data++ & 0xFF;
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--len;
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if (temp != 0x7E && temp != 0x7D) {
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frame[size++] = temp;
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} else {
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frame[size++] = 0x7D;
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frame[size++] = (temp ^ 0x20);
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}
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}
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if (crc != 0x7E && crc != 0x7D) {
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frame[size++] = crc;
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} else {
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frame[size++] = 0x7D;
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frame[size++] = (crc ^ 0x20);
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}
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frame[size++] = 0x7E;
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} else {
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int header_size;
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frame[0] = 0xF9;
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frame[1] = ((channel << 2) | 0x03);
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frame[2] = type;
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if (len <= 127) {
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frame[3] = ((len << 1) | 0x01);
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header_size = size = 4;
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} else {
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frame[3] = (len << 1);
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frame[4] = (len >> 7);
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header_size = size = 5;
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}
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if (len > 0) {
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memcpy(frame + size, data, len);
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size += len;
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}
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/* Note: GSM 07.10 says that the CRC is only computed over the header */
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frame[size++] = gsm0710_compute_crc(frame + 1, header_size - 1);
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frame[size++] = 0xF9;
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}
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if (ctx->write)
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ctx->write(ctx, frame, size);
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}
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/* Start up the GSM 07.10 session on the underlying device.
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The underlying device is assumed to already be in
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multiplexing mode. Returns zero on failure */
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int gsm0710_startup(struct gsm0710_context *ctx)
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{
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/* Discard any data in the buffer, in case of restart */
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ctx->buffer_used = 0;
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/* Open the control channel */
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gsm0710_write_frame(ctx, 0, GSM0710_OPEN_CHANNEL, NULL, 0);
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return 1;
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}
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/* Shut down the GSM 07.10 session, closing all channels */
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void gsm0710_shutdown(struct gsm0710_context *ctx)
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{
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int channel;
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for (channel = 1; channel <= GSM0710_MAX_CHANNELS; ++channel) {
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if (is_channel_used(ctx, channel) == 0)
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continue;
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gsm0710_write_frame(ctx, channel,
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GSM0710_CLOSE_CHANNEL, NULL, 0);
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}
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gsm0710_write_frame(ctx, 0, GSM0710_CLOSE_CHANNEL, NULL, 0);
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memset(ctx->used_channels, 0, sizeof(ctx->used_channels));
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}
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/* Open a specific channel. Returns non-zero if successful */
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int gsm0710_open_channel(struct gsm0710_context *ctx, int channel)
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{
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if (channel <= 0 || channel > GSM0710_MAX_CHANNELS)
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return 0; /* Invalid channel number */
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if (is_channel_used(ctx, channel))
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return 1; /* Channel is already open */
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mark_channel_used(ctx, channel);
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gsm0710_write_frame(ctx, channel, GSM0710_OPEN_CHANNEL, NULL, 0);
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return 1;
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}
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/* Close a specific channel */
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void gsm0710_close_channel(struct gsm0710_context *ctx, int channel)
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{
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if (channel <= 0 || channel > GSM0710_MAX_CHANNELS)
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return; /* Invalid channel number */
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if (!is_channel_used(ctx, channel))
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return; /* Channel is already closed */
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mark_channel_unused(ctx, channel);
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gsm0710_write_frame(ctx, channel, GSM0710_CLOSE_CHANNEL, NULL, 0);
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}
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/* Determine if a specific channel is open */
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int gsm0710_is_channel_open(struct gsm0710_context *ctx, int channel)
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{
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if (channel <= 0 || channel > GSM0710_MAX_CHANNELS)
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return 0; /* Invalid channel number */
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return is_channel_used(ctx, channel);
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}
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/* Process an incoming GSM 07.10 packet */
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static int gsm0710_packet(struct gsm0710_context *ctx, int channel, int type,
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const unsigned char *data, int len)
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{
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if (ctx->packet_filter &&
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ctx->packet_filter(ctx, channel, type, data, len)) {
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/* The filter has extracted and processed the packet */
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return 1;
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}
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if (type == 0xEF || type == 0x03) {
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if (channel >= 1 && channel <= GSM0710_MAX_CHANNELS &&
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is_channel_used(ctx, channel)) {
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/* Ordinary data packet */
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if (ctx->deliver_data)
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ctx->deliver_data(ctx, channel, data, len);
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} else if (channel == 0) {
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/* An embedded command or response on channel 0 */
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if (len >= 2 && data[0] == GSM0710_STATUS_SET) {
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return gsm0710_packet(ctx, channel,
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GSM0710_STATUS_ACK,
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data + 2, len - 2);
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} else if (len >= 2 && data[0] == 0x43) {
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/* Test command from other side - send the same bytes back */
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unsigned char *resp = alloca(len);
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memcpy(resp, data, len);
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resp[0] = 0x41; /* Clear the C/R bit in the response */
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gsm0710_write_frame(ctx, 0, GSM0710_DATA,
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resp, len);
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}
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}
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} else if (type == GSM0710_STATUS_ACK && channel == 0) {
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unsigned char resp[33];
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/* Status change message */
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if (len >= 2) {
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/* Handle status changes on other channels */
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channel = ((data[0] & 0xFC) >> 2);
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if (channel >= 1 && channel <= GSM0710_MAX_CHANNELS &&
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is_channel_used(ctx, channel)) {
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if (ctx->deliver_status)
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ctx->deliver_status(ctx, channel,
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data[1] & 0xFF);
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}
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}
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/* Send the response to the status change request to ACK it */
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gsm0710_debug(ctx,
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"received status line signal, sending response");
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if (len > 31)
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len = 31;
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resp[0] = GSM0710_STATUS_ACK;
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resp[1] = ((len << 1) | 0x01);
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memcpy(resp + 2, data, len);
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gsm0710_write_frame(ctx, 0, GSM0710_DATA, resp, len + 2);
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}
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return 1;
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}
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/* Function that is called when the underlying device is ready to be read.
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A callback will be made to ctx->read to get the data for processing */
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void gsm0710_ready_read(struct gsm0710_context *ctx)
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{
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int len, posn, posn2, header_size, channel, type;
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/* Read more data from the underlying serial device */
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if (!ctx->read)
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return;
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len = ctx->read(ctx, ctx->buffer + ctx->buffer_used,
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sizeof(ctx->buffer) - ctx->buffer_used);
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if (len <= 0)
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return;
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/* Update the buffer size */
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ctx->buffer_used += len;
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/* Break the incoming data up into packets */
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posn = 0;
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while (posn < ctx->buffer_used) {
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if (ctx->buffer[posn] == 0xF9) {
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/* Basic format: skip additional 0xF9 bytes between frames */
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while ((posn + 1) < ctx->buffer_used &&
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ctx->buffer[posn + 1] == 0xF9) {
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++posn;
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}
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/* We need at least 4 bytes for the header */
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if ((posn + 4) > ctx->buffer_used)
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break;
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/* The low bit of the second byte should be 1,
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which indicates a short channel number */
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if ((ctx->buffer[posn + 1] & 0x01) == 0) {
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++posn;
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continue;
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}
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/* Get the packet length and validate it */
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len = (ctx->buffer[posn + 3] >> 1) & 0x7F;
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if ((ctx->buffer[posn + 3] & 0x01) != 0) {
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/* Single-byte length indication */
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header_size = 3;
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} else {
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/* Double-byte length indication */
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if ((posn + 5) > ctx->buffer_used)
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break;
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len |= ((int)(ctx->buffer[posn + 4])) << 7;
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header_size = 4;
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}
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if ((posn + header_size + 2 + len) > ctx->buffer_used)
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break;
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/* Verify the packet header checksum */
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if (((gsm0710_compute_crc(ctx->buffer + posn + 1,
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header_size) ^ ctx->buffer[posn + len + header_size + 1]) & 0xFF) != 0) {
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gsm0710_debug(ctx,
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"*** GSM 07.10 checksum check failed ***");
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posn += len + header_size + 2;
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continue;
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}
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/* Get the channel number and packet type from the header */
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channel = (ctx->buffer[posn + 1] >> 2) & 0x3F;
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type = ctx->buffer[posn + 2] & 0xEF; /* Strip "PF" bit */
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/* Dispatch data packets to the appropriate channel */
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if (!gsm0710_packet(ctx, channel, type,
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ctx->buffer + posn + header_size + 1, len)) {
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/* Session has been terminated */
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ctx->buffer_used = 0;
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return;
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}
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posn += len + header_size + 2;
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} else if (ctx->buffer[posn] == 0x7E) {
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/* Advanced format: skip additional 0x7E bytes between frames */
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while ((posn + 1) < ctx->buffer_used &&
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ctx->buffer[posn + 1] == 0x7E) {
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++posn;
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}
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/* Search for the end of the packet (the next 0x7E byte) */
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len = posn + 1;
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while (len < ctx->buffer_used &&
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ctx->buffer[len] != 0x7E) {
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++len;
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}
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if (len >= ctx->buffer_used) {
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/* There are insufficient bytes for a packet at present */
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if (posn == 0 && len >= (int)sizeof(ctx->buffer)) {
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/* The buffer is full and we were unable to find a
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legitimate packet. Discard the buffer and restart */
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posn = len;
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}
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break;
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}
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/* Undo control byte quoting in the packet */
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posn2 = 0;
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++posn;
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while (posn < len) {
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if (ctx->buffer[posn] == 0x7D) {
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++posn;
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if (posn >= len)
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break;
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ctx->buffer[posn2++] = (ctx->buffer[posn++] ^ 0x20);
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} else {
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ctx->buffer[posn2++] = ctx->buffer[posn++];
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}
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}
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/* Validate the checksum on the packet header */
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if (posn2 >= 3) {
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if (((gsm0710_compute_crc(ctx->buffer, 2) ^
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ctx->buffer[posn2 - 1]) & 0xFF) != 0) {
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gsm0710_debug(ctx,
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"*** GSM 07.10 advanced checksum "
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"check failed ***");
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continue;
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}
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} else {
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gsm0710_debug(ctx,
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"*** GSM 07.10 advanced packet "
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"is too small ***");
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continue;
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}
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/* Decode and dispatch the packet */
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channel = (ctx->buffer[0] >> 2) & 0x3F;
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type = ctx->buffer[1] & 0xEF; /* Strip "PF" bit */
|
|
if (!gsm0710_packet(ctx, channel, type,
|
|
ctx->buffer + 2, posn2 - 3)) {
|
|
/* Session has been terminated */
|
|
ctx->buffer_used = 0;
|
|
return;
|
|
}
|
|
|
|
} else {
|
|
++posn;
|
|
}
|
|
}
|
|
if (posn < ctx->buffer_used) {
|
|
memmove(ctx->buffer, ctx->buffer + posn,
|
|
ctx->buffer_used - posn);
|
|
ctx->buffer_used -= posn;
|
|
} else {
|
|
ctx->buffer_used = 0;
|
|
}
|
|
}
|
|
|
|
/* Write a block of data to the the underlying device. It will be split
|
|
into several frames according to the frame size, if necessary */
|
|
void gsm0710_write_data(struct gsm0710_context *ctx, int channel,
|
|
const void *data, int len)
|
|
{
|
|
int temp;
|
|
while (len > 0) {
|
|
temp = len;
|
|
if (temp > ctx->frame_size)
|
|
temp = ctx->frame_size;
|
|
gsm0710_write_frame(ctx, channel, GSM0710_DATA, data, temp);
|
|
data = ((const unsigned char *) data) + temp;
|
|
len -= temp;
|
|
}
|
|
}
|
|
|
|
/* Set the modem status lines on a channel */
|
|
void gsm0710_set_status(struct gsm0710_context *ctx, int channel, int status)
|
|
{
|
|
unsigned char data[4];
|
|
data[0] = GSM0710_STATUS_SET;
|
|
data[1] = 0x03;
|
|
data[2] = ((channel << 2) | 0x03);
|
|
data[3] = status;
|
|
gsm0710_write_frame(ctx, 0, GSM0710_DATA, data, 4);
|
|
}
|