{An SPX API.  Send any questions or corrections to:
gmiller@ius.indiana.edu
gmiller@grendel.ius.indiana.edu
greg.miller@shivasys.com}

unit spx_api;

interface
uses DOS;

const
 {constants for ECB in use flag}
 available = 0;
 AES_temporary = $e0;
 special = $f6;
 IPX_in_critical_section = $f8;
 SPX_listening = $f9;
 processing = $fa;
 holding = $fb;
 AES_waiting = $fc;
 AES_couning_down = $fd;
 awaiting_packet_receive = $fe;
 sending_packet = $ff;

 {constants for ECB completion code}
 success = 0;
 terminated_connection_noack = $ec; {remote terminated connection without
                                     acknowledging last packet}
 abnormal_termination = $ed;
 invalid_connection_ID = $ee;
 connection_table_full = $ef;
 cancel_event = $f9; {the event should be canceled}
 cannot_establish_connection = $fa;
 cancelled = $fc;
 malformed_packet = $fd;
 packet_undeliverable = $fe;
 physical_error = $ff;

 {constants for packet type}
 unkown_packet_type = 0;
 routing_information_packet = 1;
 echo_packet = 2;
 error_packet = 3;
 packet_exchange = 4; {normal}
 SPX_packet = 5;
 NCP_packet = $11;
 propegated_packet = $14;

 {constants for connection control (should be ORed together}
 end_of_message = $16;
 reserved = $32;
 ack_required = $64;
 system_packet = $128;

type fragment = record
 data: pointer;
 size: word;
end;

type ecb = record
 link: longint;
 esr: longint; {FAR procedure to invoke when ECB is handled}
 in_use: byte; {00=available, others=in use}
 completion_code: byte; {see constants}
 socket_number: word; {big endian socket number}
 reserved: longint;
 reserved1: array[1..12] of byte;
 local_address: array[1..6] of byte;
 fragment_count: word; {should be 2}
 frags: array[1..2] of fragment; {first fragment is the header, the second
                                  is the actual data you wish to send}
end;

type SPX_header = record
 checksum:word; {should be 0}
 length:word;
 transport_control: byte;
 packet_type: byte;
 desination_address: array[1..10] of byte;
 destination_socket: word;
 connection_control: byte;
 datastream_type: byte;
 source_connection_ID: word;
 destination_connection_ID:word;
 sequence_number: word;
 allocation_number: word;
end;

function SPX_installed(var version,max_spx_connections,
                       available_spx_connections:word):boolean;

procedure establish_spx_connection(retry_count,watchdog_flag:byte;
                                   e:ecb;
                                   var connection_id:word;
                                   var error:byte);

implementation

function SPX_installed(var version,max_spx_connections,
                       available_spx_connections:word):boolean;
var r:registers;
begin
 r.bx:=$0010;
 r.al:=0;
 intr($7a,r);
 SPX_installed := (r.al = $ff);
 version := r.bx;
 max_spx_connections := r.cx;
 available_spx_connections := r.dx;
end;

procedure establish_spx_connection(retry_count,watchdog_flag:byte;
                                   e:ecb;
                                   var connection_id:word;
                                   var error:byte);
var r:registers;
begin
 r.bx:=$11;
 r.al:=retry_count;
 r.ah:=watchdog_flag;
 r.es:=Seg(e);
 r.si:=ofs(e);
 intr($7a,r);
 error:=r.al;
 connection_id:=r.dx;
end;

procedure listen_for_spx_connection(retry_count,watchdog_flag:byte;
                                    var e:ecb);
var r:registers;
begin
 r.bx:=$12;
 r.ah:=watchdog_flag;
 r.al:=retry_count;
 r.es:=Seg(e);
 r.si:=ofs(e);
 intr($7a,r);
end;

procedure terminate_spx_connection(connection_ID:word;
                                   var e:ecb);
var r:registers;
begin
 r.bx:=$13;
 r.dx:=connection_ID;
 r.es:=seg(e);
 r.si:=ofs(e);
 intr($7a,r);
end;

procedure abort_spx_connection(connection_ID:word);
var r:registers;
begin
 r.bx:=$14;
 r.dx:=connection_ID;
 intr($7a,r);
end;

procedure send_spx_packet(connection_ID:word;
                          var e:ecb);
var r:registers;
begin
 r.bx:=$16;
 r.cx:=1;
 r.dx:=connection_ID;
 r.es:=seg(e);
 r.si:=ofs(e);
 intr($7a,r);
end;

procedure listen_for_spx_packet(connection_ID:word;
                                var e:ecb);
var r:registers;
begin
 r.bx:=$17;
 r.dx:=connection_ID;
 r.es:=seg(e);
 r.si:=ofs(e);
 intr($7a,r);
end;


end.