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1 | 6 | kaklik | /*! \file xmodem.c \brief XModem Transmit/Receive Implementation with CRC and 1K support. */ |
2 | //***************************************************************************** |
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3 | // |
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4 | // File Name : 'xmodem.c' |
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5 | // Title : XModem Transmit/Receive Implementation with CRC and 1K support |
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6 | // Author : Pascal Stang - Copyright (C) 2006 |
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7 | // Created : 4/22/2006 |
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8 | // Revised : 7/22/2006 |
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9 | // Version : 0.1 |
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10 | // Target MCU : AVR processors |
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11 | // Editor Tabs : 4 |
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12 | // |
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13 | // This code is distributed under the GNU Public License |
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14 | // which can be found at http://www.gnu.org/licenses/gpl.txt |
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15 | // |
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16 | //***************************************************************************** |
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17 | |||
18 | #include <string.h> |
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19 | #include "rprintf.h" |
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20 | #include "timer.h" |
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21 | |||
22 | #include "xmodem.h" |
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23 | |||
24 | //#define XMODEM_BUFFER_SIZE 128 |
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25 | #define XMODEM_BUFFER_SIZE 1024 |
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26 | |||
27 | // pointers to stream I/O functions |
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28 | static void (*xmodemOut)(unsigned char c); |
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29 | static int (*xmodemIn)(void); |
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30 | |||
31 | void xmodemInit(void (*sendbyte_func)(unsigned char c), int (*getbyte_func)(void)) |
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32 | { |
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33 | // assign function pointers |
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34 | xmodemOut = sendbyte_func; |
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35 | xmodemIn = getbyte_func; |
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36 | } |
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37 | |||
38 | long xmodemReceive( int (*write)(unsigned char* buffer, int size) ) |
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39 | { |
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40 | // create xmodem buffer |
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41 | // 1024b for Xmodem 1K |
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42 | // 128 bytes for Xmodem std. |
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43 | // + 5b header/crc + NULL |
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44 | unsigned char xmbuf[XMODEM_BUFFER_SIZE+6]; |
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45 | unsigned char seqnum=1; // xmodem sequence number starts at 1 |
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46 | unsigned short pktsize=128; // default packet size is 128 bytes |
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47 | unsigned char response='C'; // solicit a connection with CRC enabled |
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48 | char retry=XMODEM_RETRY_LIMIT; |
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49 | unsigned char crcflag=0; |
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50 | unsigned long totalbytes=0; |
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51 | int i,c; |
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52 | |||
53 | while(retry > 0) |
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54 | { |
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55 | // solicit a connection/packet |
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56 | xmodemOut(response); |
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57 | // wait for start of packet |
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58 | if( (c = xmodemInTime(XMODEM_TIMEOUT_DELAY)) >= 0) |
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59 | { |
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60 | switch(c) |
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61 | { |
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62 | case SOH: |
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63 | pktsize = 128; |
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64 | break; |
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65 | #if(XMODEM_BUFFER_SIZE>=1024) |
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66 | case STX: |
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67 | pktsize = 1024; |
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68 | break; |
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69 | #endif |
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70 | case EOT: |
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71 | xmodemInFlush(); |
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72 | xmodemOut(ACK); |
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73 | // completed transmission normally |
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74 | return totalbytes; |
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75 | case CAN: |
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76 | if((c = xmodemInTime(XMODEM_TIMEOUT_DELAY)) == CAN) |
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77 | { |
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78 | xmodemInFlush(); |
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79 | xmodemOut(ACK); |
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80 | // transaction cancelled by remote node |
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81 | return XMODEM_ERROR_REMOTECANCEL; |
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82 | } |
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83 | default: |
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84 | break; |
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85 | } |
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86 | } |
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87 | else |
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88 | { |
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89 | // timed out, try again |
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90 | // no need to flush because receive buffer is already empty |
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91 | retry--; |
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92 | //response = NAK; |
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93 | continue; |
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94 | } |
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95 | |||
96 | // check if CRC mode was accepted |
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97 | if(response == 'C') crcflag = 1; |
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98 | // got SOH/STX, add it to processing buffer |
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99 | xmbuf[0] = c; |
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100 | // try to get rest of packet |
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101 | for(i=0; i<(pktsize+crcflag+4-1); i++) |
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102 | { |
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103 | if((c = xmodemInTime(XMODEM_TIMEOUT_DELAY)) >= 0) |
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104 | { |
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105 | xmbuf[1+i] = c; |
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106 | } |
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107 | else |
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108 | { |
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109 | // timed out, try again |
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110 | retry--; |
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111 | xmodemInFlush(); |
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112 | response = NAK; |
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113 | break; |
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114 | } |
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115 | } |
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116 | // packet was too small, retry |
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117 | if(i<(pktsize+crcflag+4-1)) |
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118 | continue; |
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119 | |||
120 | // got whole packet |
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121 | // check validity of packet |
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122 | if( (xmbuf[1] == (unsigned char)(~xmbuf[2])) && // sequence number was transmitted w/o error |
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123 | xmodemCrcCheck(crcflag, &xmbuf[3], pktsize) ) // packet is not corrupt |
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124 | { |
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125 | // is this the packet we were waiting for? |
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126 | if(xmbuf[1] == seqnum) |
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127 | { |
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128 | // write/deliver data |
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129 | write(&xmbuf[3], pktsize); |
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130 | //spiflashWrite(flashaddr, pktsize, &xmbuf[3]); |
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131 | totalbytes += pktsize; |
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132 | // next sequence number |
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133 | seqnum++; |
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134 | // reset retries |
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135 | retry = XMODEM_RETRY_LIMIT; |
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136 | // reply with ACK |
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137 | response = ACK; |
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138 | continue; |
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139 | } |
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140 | else if(xmbuf[1] == (unsigned char)(seqnum-1)) |
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141 | { |
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142 | // this is a retransmission of the last packet |
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143 | // ACK and move on |
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144 | response = ACK; |
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145 | continue; |
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146 | } |
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147 | else |
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148 | { |
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149 | // we are completely out of sync |
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150 | // cancel transmission |
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151 | xmodemInFlush(); |
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152 | xmodemOut(CAN); |
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153 | xmodemOut(CAN); |
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154 | xmodemOut(CAN); |
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155 | return XMODEM_ERROR_OUTOFSYNC; |
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156 | } |
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157 | } |
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158 | else |
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159 | { |
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160 | // packet was corrupt |
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161 | // NAK it and try again |
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162 | retry--; |
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163 | xmodemInFlush(); |
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164 | response = NAK; |
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165 | continue; |
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166 | } |
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167 | } |
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168 | |||
169 | // exceeded retry count |
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170 | xmodemInFlush(); |
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171 | xmodemOut(CAN); |
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172 | xmodemOut(CAN); |
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173 | xmodemOut(CAN); |
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174 | return XMODEM_ERROR_RETRYEXCEED; |
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175 | } |
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176 | |||
177 | |||
178 | long xmodemTransmit( int (*read)(unsigned char* buffer, int size) ) |
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179 | { |
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180 | // still to be written |
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181 | return 0; |
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182 | } |
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183 | |||
184 | uint16_t crc_xmodem_update(uint16_t crc, uint8_t data) |
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185 | { |
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186 | int i; |
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187 | |||
188 | crc = crc ^ ((uint16_t)data << 8); |
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189 | for (i=0; i<8; i++) |
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190 | { |
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191 | if(crc & 0x8000) |
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192 | crc = (crc << 1) ^ 0x1021; |
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193 | else |
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194 | crc <<= 1; |
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195 | } |
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196 | |||
197 | return crc; |
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198 | } |
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199 | |||
200 | int xmodemCrcCheck(int crcflag, const unsigned char *buffer, int size) |
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201 | { |
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202 | // crcflag=0 - do regular checksum |
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203 | // crcflag=1 - do CRC checksum |
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204 | |||
205 | if(crcflag) |
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206 | { |
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207 | unsigned short crc=0; |
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208 | unsigned short pktcrc = (buffer[size]<<8)+buffer[size+1]; |
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209 | // do CRC checksum |
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210 | while(size--) |
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211 | crc = crc_xmodem_update(crc, *buffer++); |
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212 | // check checksum against packet |
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213 | if(crc == pktcrc) |
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214 | return 1; |
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215 | } |
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216 | else |
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217 | { |
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218 | int i; |
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219 | unsigned char cksum = 0; |
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220 | // do regular checksum |
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221 | for(i=0; i<size; ++i) |
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222 | { |
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223 | cksum += buffer[i]; |
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224 | } |
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225 | // check checksum against packet |
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226 | if(cksum == buffer[size]) |
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227 | return 1; |
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228 | } |
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229 | |||
230 | return 0; |
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231 | } |
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232 | |||
233 | |||
234 | int xmodemInTime(unsigned short timeout) |
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235 | { |
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236 | int c=-1; |
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237 | |||
238 | while( (timeout--) && ((c=xmodemIn()) < 0) ) |
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239 | timerPause(1); |
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240 | |||
241 | return c; |
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242 | } |
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243 | |||
244 | void xmodemInFlush(void) |
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245 | { |
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246 | while(xmodemInTime(XMODEM_TIMEOUT_DELAY) >= 0); |
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247 | } |
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