1 /* 2 * Copyright (C) 2014 BlueKitchen GmbH 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the copyright holders nor the names of 14 * contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 4. Any redistribution, use, or modification is done solely for 17 * personal benefit and not for any commercial purpose or for 18 * monetary gain. 19 * 20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS 24 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * Please inquire about commercial licensing options at 34 * [email protected] 35 * 36 */ 37 38 #define BTSTACK_FILE__ "btstack_slip.c" 39 40 /* 41 * btstack_slip.c 42 * SLIP encoder/decoder 43 */ 44 45 #include "btstack_slip.h" 46 #include "btstack_debug.h" 47 48 typedef enum { 49 SLIP_ENCODER_DEFAULT, 50 SLIP_ENCODER_SEND_DC, 51 SLIP_ENCODER_SEND_DD 52 } btstack_slip_encoder_state_t; 53 54 // h5 slip state machine 55 typedef enum { 56 SLIP_DECODER_UNKNOWN = 1, 57 SLIP_DECODER_ACTIVE, 58 SLIP_DECODER_X_C0, 59 SLIP_DECODER_X_DB, 60 SLIP_DECODER_COMPLETE 61 } btstack_slip_decoder_state_t; 62 63 64 // encoder 65 static btstack_slip_encoder_state_t encoder_state; 66 static const uint8_t * encoder_data; 67 static uint16_t encoder_len; 68 69 // decoder 70 static btstack_slip_decoder_state_t decoder_state; 71 static uint8_t * decoder_buffer; 72 static uint16_t decoder_max_size; 73 static uint16_t decoder_pos; 74 75 76 // ENCODER 77 78 /** 79 * @brief Initialise SLIP encoder with data 80 * @param data 81 * @param len 82 */ 83 void btstack_slip_encoder_start(const uint8_t * data, uint16_t len){ 84 encoder_state = SLIP_ENCODER_DEFAULT; 85 encoder_data = data; 86 encoder_len = len; 87 } 88 89 /** 90 * @brief Check if encoder has data ready 91 * @return True if data ready 92 */ 93 int btstack_slip_encoder_has_data(void){ 94 if (encoder_state != SLIP_ENCODER_DEFAULT) return 1; 95 return encoder_len > 0u; 96 } 97 98 /** 99 * @brief Get next byte from encoder 100 * @return Next bytes from encoder 101 */ 102 uint8_t btstack_slip_encoder_get_byte(void){ 103 uint8_t next_byte; 104 switch (encoder_state){ 105 case SLIP_ENCODER_DEFAULT: 106 next_byte = *encoder_data++; 107 encoder_len--; 108 switch (next_byte){ 109 case BTSTACK_SLIP_SOF: 110 encoder_state = SLIP_ENCODER_SEND_DC; 111 return 0xdb; 112 case 0xdb: 113 encoder_state = SLIP_ENCODER_SEND_DD; 114 return 0xdb; 115 default: 116 break; 117 } 118 return next_byte; 119 case SLIP_ENCODER_SEND_DC: 120 encoder_state = SLIP_ENCODER_DEFAULT; 121 return 0x0dc; 122 case SLIP_ENCODER_SEND_DD: 123 encoder_state = SLIP_ENCODER_DEFAULT; 124 return 0x0dd; 125 default: 126 log_error("btstack_slip_encoder_get_byte invalid state %x", encoder_state); 127 return 0x00; 128 } 129 } 130 131 // Decoder 132 133 static void btstack_slip_decoder_reset(void){ 134 decoder_state = SLIP_DECODER_UNKNOWN; 135 decoder_pos = 0; 136 } 137 138 static void btstack_slip_decoder_store_byte(uint8_t input){ 139 if (decoder_pos >= decoder_max_size){ 140 log_error("btstack_slip_decoder_store_byte: packet to long"); 141 btstack_slip_decoder_reset(); 142 } 143 decoder_buffer[decoder_pos++] = input; 144 } 145 146 /** 147 * @brief Initialise SLIP decoder with buffer 148 * @param buffer to store received data 149 * @param max_size of buffer 150 */ 151 void btstack_slip_decoder_init(uint8_t * buffer, uint16_t max_size){ 152 decoder_buffer = buffer; 153 decoder_max_size = max_size; 154 btstack_slip_decoder_reset(); 155 } 156 157 /** 158 * @brief Process received byte 159 * @param data 160 */ 161 162 void btstack_slip_decoder_process(uint8_t input){ 163 switch(decoder_state){ 164 case SLIP_DECODER_UNKNOWN: 165 if (input != BTSTACK_SLIP_SOF) break; 166 btstack_slip_decoder_reset(); 167 decoder_state = SLIP_DECODER_X_C0; 168 break; 169 case SLIP_DECODER_COMPLETE: 170 log_error("btstack_slip_decoder_process called in state COMPLETE"); 171 btstack_slip_decoder_reset(); 172 break; 173 case SLIP_DECODER_X_C0: 174 switch(input){ 175 case BTSTACK_SLIP_SOF: 176 break; 177 case 0xdb: 178 decoder_state = SLIP_DECODER_X_DB; 179 break; 180 default: 181 btstack_slip_decoder_store_byte(input); 182 decoder_state = SLIP_DECODER_ACTIVE; 183 break; 184 } 185 break; 186 case SLIP_DECODER_X_DB: 187 switch(input){ 188 case 0xdc: 189 btstack_slip_decoder_store_byte(BTSTACK_SLIP_SOF); 190 decoder_state = SLIP_DECODER_ACTIVE; 191 break; 192 case 0xdd: 193 btstack_slip_decoder_store_byte(0xdb); 194 decoder_state = SLIP_DECODER_ACTIVE; 195 break; 196 default: 197 btstack_slip_decoder_reset(); 198 break; 199 } 200 break; 201 case SLIP_DECODER_ACTIVE: 202 switch(input){ 203 case BTSTACK_SLIP_SOF: 204 if (decoder_pos){ 205 decoder_state = SLIP_DECODER_COMPLETE; 206 } else { 207 btstack_slip_decoder_reset(); 208 } 209 break; 210 case 0xdb: 211 decoder_state = SLIP_DECODER_X_DB; 212 break; 213 default: 214 btstack_slip_decoder_store_byte(input); 215 break; 216 } 217 break; 218 default: 219 btstack_assert(false); 220 break; 221 } 222 } 223 224 /** 225 * @brief Get size of decoded frame 226 * @return size of frame. Size = 0 => frame not complete 227 */ 228 229 uint16_t btstack_slip_decoder_frame_size(void){ 230 switch (decoder_state){ 231 case SLIP_DECODER_COMPLETE: 232 return decoder_pos; 233 default: 234 return 0; 235 } 236 } 237