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_C0, 51 SLIP_ENCODER_SEND_DC, 52 SLIP_ENCODER_SEND_DD 53 } btstack_slip_encoder_state_t; 54 55 // h5 slip state machine 56 typedef enum { 57 SLIP_DECODER_UNKNOWN = 1, 58 SLIP_DECODER_ACTIVE, 59 SLIP_DECODER_X_C0, 60 SLIP_DECODER_X_DB, 61 SLIP_DECODER_COMPLETE 62 } btstack_slip_decoder_state_t; 63 64 65 // encoder 66 static btstack_slip_encoder_state_t encoder_state; 67 static const uint8_t * encoder_data; 68 static uint16_t encoder_len; 69 70 // decoder 71 static btstack_slip_decoder_state_t decoder_state; 72 static uint8_t * decoder_buffer; 73 static uint16_t decoder_max_size; 74 static uint16_t decoder_pos; 75 76 77 // ENCODER 78 79 /** 80 * @brief Initialise SLIP encoder with data 81 * @param data 82 * @param len 83 */ 84 void btstack_slip_encoder_start(const uint8_t * data, uint16_t len){ 85 // start with C0 SOF 86 encoder_state = SLIP_ENCODER_SEND_C0; 87 encoder_data = data; 88 encoder_len = len; 89 } 90 91 /** 92 * @brief Check if encoder has data ready 93 * @return True if data ready 94 */ 95 int btstack_slip_encoder_has_data(void){ 96 if (encoder_state != SLIP_ENCODER_DEFAULT) return 1; 97 return encoder_len > 0u; 98 } 99 100 /** 101 * @brief Get next byte from encoder 102 * @return Next bytes from encoder 103 */ 104 uint8_t btstack_slip_encoder_get_byte(void){ 105 uint8_t next_byte; 106 switch (encoder_state){ 107 case SLIP_ENCODER_DEFAULT: 108 next_byte = *encoder_data++; 109 encoder_len--; 110 switch (next_byte){ 111 case BTSTACK_SLIP_SOF: 112 encoder_state = SLIP_ENCODER_SEND_DC; 113 next_byte = 0xdb; 114 break; 115 case 0xdb: 116 encoder_state = SLIP_ENCODER_SEND_DD; 117 next_byte = 0xdb; 118 default: 119 break; 120 } 121 break; 122 case SLIP_ENCODER_SEND_C0: 123 encoder_state = SLIP_ENCODER_DEFAULT; 124 return 0xc0; 125 case SLIP_ENCODER_SEND_DC: 126 encoder_state = SLIP_ENCODER_DEFAULT; 127 next_byte = 0xdc; 128 break; 129 case SLIP_ENCODER_SEND_DD: 130 encoder_state = SLIP_ENCODER_DEFAULT; 131 next_byte = 0x0dd; 132 break; 133 default: 134 log_error("btstack_slip_encoder_get_byte invalid state %x", encoder_state); 135 return 0x00; 136 } 137 138 // After last byte, send CO SOF again 139 if ((encoder_state == SLIP_ENCODER_DEFAULT) && (encoder_len == 0)){ 140 encoder_state = SLIP_ENCODER_SEND_C0; 141 } 142 return next_byte; 143 } 144 145 // Decoder 146 147 static void btstack_slip_decoder_reset(void){ 148 decoder_state = SLIP_DECODER_UNKNOWN; 149 decoder_pos = 0; 150 } 151 152 static void btstack_slip_decoder_store_byte(uint8_t input){ 153 if (decoder_pos >= decoder_max_size){ 154 log_error("btstack_slip_decoder_store_byte: packet to long"); 155 btstack_slip_decoder_reset(); 156 } 157 decoder_buffer[decoder_pos++] = input; 158 } 159 160 /** 161 * @brief Initialise SLIP decoder with buffer 162 * @param buffer to store received data 163 * @param max_size of buffer 164 */ 165 void btstack_slip_decoder_init(uint8_t * buffer, uint16_t max_size){ 166 decoder_buffer = buffer; 167 decoder_max_size = max_size; 168 btstack_slip_decoder_reset(); 169 } 170 171 /** 172 * @brief Process received byte 173 * @param data 174 */ 175 176 void btstack_slip_decoder_process(uint8_t input){ 177 switch(decoder_state){ 178 case SLIP_DECODER_UNKNOWN: 179 if (input != BTSTACK_SLIP_SOF) break; 180 btstack_slip_decoder_reset(); 181 decoder_state = SLIP_DECODER_X_C0; 182 break; 183 case SLIP_DECODER_COMPLETE: 184 log_error("btstack_slip_decoder_process called in state COMPLETE"); 185 btstack_slip_decoder_reset(); 186 break; 187 case SLIP_DECODER_X_C0: 188 switch(input){ 189 case BTSTACK_SLIP_SOF: 190 break; 191 case 0xdb: 192 decoder_state = SLIP_DECODER_X_DB; 193 break; 194 default: 195 btstack_slip_decoder_store_byte(input); 196 decoder_state = SLIP_DECODER_ACTIVE; 197 break; 198 } 199 break; 200 case SLIP_DECODER_X_DB: 201 switch(input){ 202 case 0xdc: 203 btstack_slip_decoder_store_byte(BTSTACK_SLIP_SOF); 204 decoder_state = SLIP_DECODER_ACTIVE; 205 break; 206 case 0xdd: 207 btstack_slip_decoder_store_byte(0xdb); 208 decoder_state = SLIP_DECODER_ACTIVE; 209 break; 210 default: 211 btstack_slip_decoder_reset(); 212 break; 213 } 214 break; 215 case SLIP_DECODER_ACTIVE: 216 switch(input){ 217 case BTSTACK_SLIP_SOF: 218 if (decoder_pos != 0){ 219 decoder_state = SLIP_DECODER_COMPLETE; 220 } else { 221 btstack_slip_decoder_reset(); 222 } 223 break; 224 case 0xdb: 225 decoder_state = SLIP_DECODER_X_DB; 226 break; 227 default: 228 btstack_slip_decoder_store_byte(input); 229 break; 230 } 231 break; 232 default: 233 btstack_assert(false); 234 break; 235 } 236 } 237 238 /** 239 * @brief Get size of decoded frame 240 * @return size of frame. Size = 0 => frame not complete 241 */ 242 243 uint16_t btstack_slip_decoder_frame_size(void){ 244 switch (decoder_state){ 245 case SLIP_DECODER_COMPLETE: 246 return decoder_pos; 247 default: 248 return 0; 249 } 250 } 251