/** * PdaLink -- Connect Palm with Amiga * * SLP (Serial Link Protocol) * * (C) 1998-2000 Richard Körber * *------------------------------------------------------------------ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * You must not use this source code to gain profit of any kind! */ #include "pdalink_glob.h" /*------------------------------------------------------** ** Name: CRC16 private ** ** Funktion: Calculate CRC16 checksum ** ** Parameter: buf Start des Buffers ** len Länge des Buffers ** crc CRC aus vorigem Bufferabschnitt, ** 0 beim ersten mal ** Ergebnis: CRC-Prüfsumme //> ** Bemerkungen: ** ** Revision: 31. Mai 1998, 22:01:39 */ static UWORD CRC16(UBYTE *buf, UWORD len, UWORD crc) { register UWORD i; while(len--) { crc ^= (UWORD)(*buf++ << 8); for(i=0; i<8; i++) { if(crc & 0x8000) crc = (crc<<1) ^ 0x1021; else crc = crc<<1; } } return(crc); } //< /*------------------------------------------------------** ** Name: PL_SLPWrite public ** ** Funktion: Verschickt ein SLP-Paket ** ** Parameter: socket Socket für die Übertragung ** buffer zu übertragener Puffer ** length Länge des Puffers ** header SLP-Header ** PADP Optional: PADP-Header ** Ergebnis: length Verschickte Daten oder ** -1: Fehler //> ** Bemerkungen: ** ** Revision: 31. Mai 1998, 21:14:30 */ __saveds __asm LONG PL_SLPWrite ( register __a0 APTR socket, register __a1 APTR buffer, register __d0 LONG length, register __a2 struct PL_SLP_Header *header, register __a3 struct PL_PADP_Header *padp ) { struct PL_Socket *sock = (struct PL_Socket *)socket; UWORD i; UBYTE hdrsum; UWORD checksum; sock->lastError = PLERR_OKAY; /* Create signature */ header->signature[0] = 0xBE; header->signature[1] = 0xEF; header->signature[2] = 0xED; header->dataSize = (padp ? length+sizeof(struct PL_PADP_Header) : length) ; /* Calculate header checksum */ for(hdrsum = i = 0; i<(sizeof(struct PL_SLP_Header)-1); i++) { hdrsum += ((UBYTE *)header)[i]; } header->checksum = hdrsum; /* Calculate data checksum */ checksum = CRC16((UBYTE *)header,sizeof(struct PL_SLP_Header),0); if(padp) checksum = CRC16((UBYTE *)padp,sizeof(struct PL_PADP_Header),checksum); checksum = CRC16((UBYTE *)buffer,length,checksum); /* Send packet, and we are done */ if(PL_RawWrite(socket,(UBYTE *)header,sizeof(struct PL_SLP_Header))) { if(!padp || PL_RawWrite(socket,padp,sizeof(struct PL_PADP_Header))) { if(PL_RawWrite(socket,buffer,length)) { if(PL_RawWrite(socket,(UBYTE *)&checksum,2)) { #ifdef SLPDEBUG Printf("SLP A->P: dest=%ld src=%ld type=%ld dataSize=%ld transID=0x%02lx sum=0x%02lx\n",header->destSocket,header->srcSocket,header->pckType,header->dataSize,header->transID,header->checksum); #endif return(length); // Success } } } } return(-1); // Failure } //< /*------------------------------------------------------** ** Name: PL_SLPRead public ** ** Funktion: Holt ein SLP-Paket ** ** Parameter: socket Socket für die Übertragung ** buffer Empfangspuffer ** length Länge des Empfangsbuffer ** header SLP-Header-Puffer ** padp Optional: PADP-Header ** Ergebnis: length Länge des empfangenen Puffers ** (ohne SLP-Header), -1: Fehler //> ** Bemerkungen: ** ** Revision: 1. Juni 1998, 16:01:46 */ __saveds __asm LONG PL_SLPRead ( register __a0 APTR socket, register __a1 APTR buffer, register __d0 LONG length, register __a2 struct PL_SLP_Header *header, register __a3 struct PL_PADP_Header *padp ) { struct PL_Socket *sock = (struct PL_Socket *)socket; UBYTE read; // Reading into this variable UBYTE hdrsum; UWORD i; UWORD readChecksum; UWORD checksum; sock->lastError = PLERR_OKAY; // No error occured yet /* State machine: wait for header */ if(PL_RawRead(socket,&read,1)) { for(;;) { /* wait for 0xBEEFED */ if(read==0xBE) { header->signature[0] = read; if(!PL_RawRead(socket,&read,1)) return(-1); // <--- Failed --- if(read!=0xEF) continue; header->signature[1] = read; if(!PL_RawRead(socket,&read,1)) return(-1); // <--- Failed --- if(read!=0xED) continue; header->signature[2] = read; } else { if(!PL_RawRead(socket,&read,1)) return(-1); // <--- Failed --- continue; } /* Looks promising, read rest of the header */ if(!PL_RawRead(socket,&header->destSocket,7)) return(-1); // <--- Failed --- /* Check sum okay? */ for(hdrsum = i = 0; i<(sizeof(struct PL_SLP_Header)-1); i++) { hdrsum += ((UBYTE *)header)[i]; } /* LOOP packet ? */ if(header->pckType == PLSLPTYPE_LOOP) // is ignored { for(i=0; i<(header->dataSize+2); i++) { if(!PL_RawRead(socket,&read,1)) return(-1); // <--- Failure --- } continue; // Wait for next packet } if(header->checksum == hdrsum) break; // Found a good header } } /* Fetch rest of data */ if(padp) { length = min(header->dataSize - sizeof(struct PL_PADP_Header), length); if(!PL_RawRead(socket,padp,sizeof(struct PL_PADP_Header))) return(-1); if(!PL_RawRead(socket,buffer,length)) return(-1); // Read error } else { length = min(header->dataSize,length); if(!PL_RawRead(socket,buffer,length)) return(-1); // read error } /* Read CRC16 */ if(!PL_RawRead(socket,(UBYTE *)&readChecksum,2)) return(-1); // read error /* Compare data checksum */ checksum = CRC16((UBYTE *)header,sizeof(struct PL_SLP_Header),0); if(padp) checksum = CRC16((UBYTE *)padp,sizeof(struct PL_PADP_Header),checksum); checksum = CRC16((UBYTE *)buffer,length,checksum); if(checksum!=readChecksum) { sock->lastError = PLERR_CHECKSUM; return(-1); // bad checksum } #ifdef SLPDEBUG Printf("SLP A<-P: dest=%ld src=%ld type=%ld dataSize=%ld transID=0x%02lx sum=0x%02lx\n",header->destSocket,header->srcSocket,header->pckType,header->dataSize,header->transID,header->checksum); #endif return(length); // Packet received } //< /********************************************************************/