root / trunk / cardbox / packet.c @ 213
History | View | Annotate | Download (4.02 KB)
| 1 | 189 | kwoo | #include <packet.h> |
|---|---|---|---|
| 2 | |||
| 3 | |||
| 4 | /**
|
||
| 5 | * @brief Packet handler states
|
||
| 6 | * @param sd Looking for a start delimiter
|
||
| 7 | * @param src Looking for a source
|
||
| 8 | * @param dest Looking for a destination
|
||
| 9 | * @param comd Looking for a command
|
||
| 10 | * @param read Reading data payload
|
||
| 11 | * @param cs Calcualting the checksum and returning
|
||
| 12 | */
|
||
| 13 | typedef enum { |
||
| 14 | sd, |
||
| 15 | src, |
||
| 16 | dest, |
||
| 17 | comd, |
||
| 18 | read, |
||
| 19 | cs |
||
| 20 | } state_t; |
||
| 21 | |||
| 22 | /**
|
||
| 23 | * @brief Parses a tooltron packet
|
||
| 24 | *
|
||
| 25 | * This is a state machine that parses the packet. It uses a software
|
||
| 26 | * counter to track timeout status. The timeout is not reset unless
|
||
| 27 | * a fully valid packet is found. It will fail if there is a timeout,
|
||
| 28 | * crc error, or any error in the packet. All data will be placed in
|
||
| 29 | * mbuf. Note that mbuf must be able to handle PROGD_PACKET_SIZE
|
||
| 30 | * bytes.
|
||
| 31 | *
|
||
| 32 | * @pre mbuf is PROGD_PACKET_SIZE bytes large
|
||
| 33 | * @param mbuf Buffer to write the packet data payload to if there is one
|
||
| 34 | 199 | kwoo | * @param addr The address of the sending node
|
| 35 | 189 | kwoo | * @return the command received or TT_BAD on any error
|
| 36 | */
|
||
| 37 | 199 | kwoo | char parse_packet(uint8_t *mbuf, uint8_t addr) {
|
| 38 | 189 | kwoo | uint8_t r; // Byte from the network
|
| 39 | uint8_t crc; // Running checksum of the packet
|
||
| 40 | uint8_t cmd; // The command received
|
||
| 41 | uint8_t pos; // Position in the message buffer
|
||
| 42 | uint8_t lim; // Max number of bytes to read into the message buf
|
||
| 43 | state_t state; // State machine
|
||
| 44 | uint16_t count; |
||
| 45 | |||
| 46 | r = 0;
|
||
| 47 | crc = 0;
|
||
| 48 | cmd = 0;
|
||
| 49 | pos = 0;
|
||
| 50 | lim = 0;
|
||
| 51 | state = sd; |
||
| 52 | count = 0;
|
||
| 53 | |||
| 54 | while (1) { |
||
| 55 | // Wait for the next byte
|
||
| 56 | while ((rs485_get_byte(&r)) < 0) { |
||
| 57 | if (count >= MAX_TIMEOUT) {
|
||
| 58 | return TT_BAD;
|
||
| 59 | } else {
|
||
| 60 | count++; |
||
| 61 | } |
||
| 62 | } |
||
| 63 | |||
| 64 | switch (state) {
|
||
| 65 | case sd:
|
||
| 66 | if (r == DELIM) {
|
||
| 67 | state = src; |
||
| 68 | } |
||
| 69 | break;
|
||
| 70 | |||
| 71 | case src:
|
||
| 72 | if (r == DELIM) {
|
||
| 73 | state = src; |
||
| 74 | } else {
|
||
| 75 | crc = r; |
||
| 76 | state = dest; |
||
| 77 | } |
||
| 78 | break;
|
||
| 79 | |||
| 80 | case dest:
|
||
| 81 | if (r == DELIM) {
|
||
| 82 | state = src; |
||
| 83 | 199 | kwoo | } else if (r == addr) { |
| 84 | 189 | kwoo | crc ^= r; |
| 85 | state = comd; |
||
| 86 | } else {
|
||
| 87 | state = sd; |
||
| 88 | } |
||
| 89 | break;
|
||
| 90 | |||
| 91 | case comd:
|
||
| 92 | cmd = r; |
||
| 93 | crc ^= r; |
||
| 94 | |||
| 95 | if (r == DELIM) {
|
||
| 96 | state = src; |
||
| 97 | } else if (r == TT_PROGM) { |
||
| 98 | lim = PROGM_PACKET_SIZE; |
||
| 99 | state = read; |
||
| 100 | } else if (r == TT_PROGD) { |
||
| 101 | lim = PROGD_PACKET_SIZE; |
||
| 102 | state = read; |
||
| 103 | 211 | kwoo | } else if (r == TT_SEND_KEY) { |
| 104 | lim = SEND_KEY_PACKET_SIZE; |
||
| 105 | state = read; |
||
| 106 | 189 | kwoo | } else {
|
| 107 | state = cs; |
||
| 108 | } |
||
| 109 | break;
|
||
| 110 | |||
| 111 | case read:
|
||
| 112 | mbuf[pos] = r; |
||
| 113 | crc ^= r; |
||
| 114 | pos++; |
||
| 115 | |||
| 116 | if (pos == lim) {
|
||
| 117 | state = cs; |
||
| 118 | } |
||
| 119 | |||
| 120 | break;
|
||
| 121 | |||
| 122 | case cs:
|
||
| 123 | if (r == crc) {
|
||
| 124 | 213 | bneuman | return cmd;
|
| 125 | 189 | kwoo | } else {
|
| 126 | return TT_BAD;
|
||
| 127 | } |
||
| 128 | |||
| 129 | break;
|
||
| 130 | |||
| 131 | default:
|
||
| 132 | return TT_BAD;
|
||
| 133 | } |
||
| 134 | } |
||
| 135 | } |
||
| 136 | |||
| 137 | /**
|
||
| 138 | * @brief Sends a packet of type cmd onto the network
|
||
| 139 | * @param cmd The command to send
|
||
| 140 | 199 | kwoo | * @param addr The address of the sending node
|
| 141 | 189 | kwoo | */
|
| 142 | 199 | kwoo | void send_packet(uint8_t cmd, uint8_t addr) {
|
| 143 | 189 | kwoo | rs485_send_byte(DELIM); |
| 144 | 199 | kwoo | rs485_send_byte(addr); |
| 145 | 189 | kwoo | rs485_send_byte(SERVER); |
| 146 | rs485_send_byte(cmd); |
||
| 147 | 199 | kwoo | rs485_send_byte(addr ^ SERVER ^ cmd); |
| 148 | 189 | kwoo | } |
| 149 | |||
| 150 | 211 | kwoo | /**
|
| 151 | * @brief Sends a packet of type cmd onto the network
|
||
| 152 | * @param cmd The command to send
|
||
| 153 | * @param addr The address of the sending node
|
||
| 154 | * @param data Pointer to data
|
||
| 155 | * @param len Number of bytes to send
|
||
| 156 | */
|
||
| 157 | void send_packet_data(uint8_t cmd, uint8_t addr, uint8_t* data, uint8_t len) {
|
||
| 158 | uint8_t i; |
||
| 159 | uint8_t crc = 0;
|
||
| 160 | |||
| 161 | rs485_send_byte(DELIM); |
||
| 162 | rs485_send_byte(addr); |
||
| 163 | rs485_send_byte(SERVER); |
||
| 164 | rs485_send_byte(cmd); |
||
| 165 | for (i = 0; i < len; i++) { |
||
| 166 | crc ^= data[i]; |
||
| 167 | rs485_send_byte(data[i]); |
||
| 168 | } |
||
| 169 | rs485_send_byte(addr ^ SERVER ^ cmd ^ crc); |
||
| 170 | } |