'*********************************
'  Very basic IP implementation  '
'   by john.timmins@link.co.nz   '
'  This file is  IP_GENERIC.BAS  '
'  Please let me know the bugs!  '
'*********************************
'
'
'UDP offset constants
Const Offset_udp_src_port = 17
Const Offset_udp_dst_port = 18
Const Offset_udp_length = 19
Const Offset_udp_checksum = 20
Const Offset_udp_data = 21

'ICMP offset constants
Const Offset_icmp_typecode = 17
Const Offset_icmp_checksum = 18
Const Offset_icmp_identifier = 19
Const Offset_icmp_sequence = 20
Const Offset_icmp_data = 21

'IP Header Offset Constants
Const Offset_ip_ver_len_tos = 7
Const Offset_ip_len = 8
Const Offset_ip_id = 9
Const Offset_ip_fragoffset = 10
Const Offset_ip_ttl_proto = 11
Const Offset_ip_hdr_chksum = 12
Const Offset_ip_srcadd_1 = 13
Const Offset_ip_srcadd_2 = 14
Const Offset_ip_dstadd_1 = 15
Const Offset_ip_dstadd_2 = 16

'Frame Data Offset Constants
Const Offset_frame_dst_mac_1 = 0
Const Offset_frame_dst_mac_2 = 1
Const Offset_frame_dst_mac_3 = 2
Const Offset_frame_src_mac_1 = 3
Const Offset_frame_src_mac_2 = 4
Const Offset_frame_src_mac_3 = 5
Const Offset_frame_type = 6

'ARP frame offset constants
Const Offset_ar_hwtype = 7
Const Offset_ar_prtype = 8
Const Offset_ar_hwlen_prlen = 9
Const Offset_ar_op = 10
Const Offset_ar_sha_1 = 11
Const Offset_ar_sha_2 = 12
Const Offset_ar_sha_3 = 13
Const Offset_ar_spa_1 = 14
Const Offset_ar_spa_2 = 15

'PacketPage constants
Const Rx_tx_data_port_0 = &H00
Const Tx_command_port = &H04
Const Tx_length_port = &H06
Const Packet_page_pointer_port = &H0A
Const Packet_page_data_port_0 = &H0C

'PacketPage Offset constants
Const Pp_eisa_registration_number = &H0000
Const Pp_product_identification_code = &H0002
Const Pp_receiver_configuration = &H0102
Const Pp_receiver_control = &H0104
Const Pp_transmitter_configuration = &H0106
Const Pp_buffer_configuration = &H010A
Const Pp_line_control = &H0112
Const Pp_self_control = &H0114
Const Pp_test_control = &H0118
Const Pp_receiver_event = &H0124
Const Pp_transmitter_event = &H0128
Const Pp_buffer_event = &H012C
Const Pp_line_status = &H0134
Const Pp_self_status = &H0136
Const Pp_bus_status = &H0138
Const Pp_transmit_command_request = &H0144
Const Pp_transmit_length = &H0146
Const Pp_individual_address = &H0158
'Receiver Event masks
Const Rx_event_receive_ok = &H0100
'Self Control masks
Const Self_control_reset = &H0040
'Self Status masks
Const Self_status_init_complete = &H0080
'Bus Status masks
Const Bus_status_transmit_bid_error = &H0080
Const Bus_status_rdy4txnow = &H0100
'Line Control masks
Const Line_control_receiver_on = &H0040
Const Line_control_transmitter_on = &H0080
Const Line_control_10baset = &H0000
'Test Control masks
Const Test_control_half_duplex = &H0000
'RX Config reg
Const Receiver_configuration_skip = &H0040
'RX Control reg
Const Rx_ctl_promiscuous = &H0080
Const Rx_ctl_rx_ok_a = &H0100
Const Rx_ctl_ind_addr = &H0400
Const Rx_ctl_bcast_a = &H0800
'TX Event reg
Const Tx_event_tx_ok = &H0100
Const Tx_event_out_win = &H0200
Const Tx_event_jabber = &H0400
Const Tx_event_16_coll = &H1000
'TX Command reg
Const Tx_cmd_start_all = &H00C0
'Buffer Config reg
Const Buf_cfg_sw_int = &H0040
Const Buf_cfg_rdy4tx_ie = &H0100
Const Buf_cfg_tx_undr_ie = &H0200

'Subroutine declarations
Declare Sub Chipver
Declare Sub Chipread
Declare Sub Chipwrite
Declare Sub Ppread
Declare Sub Ppwrite
Declare Sub Setpppointer
Declare Sub Swapvalue16
Declare Sub Resetcs8900
Declare Sub Initcs8900
Declare Sub Purge_frame
Declare Sub Txword
Declare Sub Rxword
Declare Sub Settxlen
Declare Sub Starttx
Declare Sub Wait_for_frame
Declare Sub Receive_frame
Declare Sub Transmit_frame
Declare Sub Arp_reply
Declare Sub Linkstatus

'Dimension variables
Dim Addr As Word
Dim Ppoffset As Word
Dim Value8 As Byte
Dim Temp8 As Byte
Dim Value16 As Word
Dim Temp16 As Word
Dim Temp16_2 As Word
Dim Srcmac1 As Word
Dim Srcmac2 As Word
Dim Srcmac3 As Word
Dim Srcip1 As Word
Dim Srcip2 As Word
Dim Frame_length As Word
Dim Frame_type As Word
Dim Ip_protocol As Byte
Dim Ip_data_start As Word
Dim Ip_data_length As Word
Dim Ip_header_length As Word
Dim Srcport As Word
Dim Destport As Word
Dim Rx_packet(759) As Word                                         'RX & TX Packet buffers.
Dim Tx_packet(759) As Word                                         '759 Words = 1518 bytes.
Dim Byte_count As Word
Dim Word_count As Word
Dim Icmp_type As Word
Dim Checksum As Long
Dim Checksum16 As Word
Dim Udp_port As Word
Dim S As String * 1
Dim Ip1 As Byte
Dim Ip2 As Byte
Dim Ip3 As Byte
Dim Ip4 As Byte
Dim Individual_address_enable As Bit
Dim Promiscuous_enable As Bit
Dim Broadcast_enable As Bit


Sub Starttx
'Command to start transmission after all bytes have been sent to the CS8900 TX/RX port
Value16 = Tx_cmd_start_all
Addr = Tx_command_port
Value8 = Low(value16)
Chipwrite
Addr = Tx_command_port + 1
Value8 = High(value16)
Chipwrite
End Sub

Sub Settxlen
'Set length of data to send
Addr = Tx_length_port
Value8 = Low(value16)
Chipwrite
Addr = Tx_length_port + 1
Value8 = High(value16)
Chipwrite
End Sub

Sub Rxword
'Receive word from TX/RX data port into Value16
Addr = Rx_tx_data_port_0
Chipread
Value16 = Value8 * 256
Addr = Rx_tx_data_port_0 + 1
Chipread
Value16 = Value16 + Value8
End Sub

Sub Txword
'Send word in Value16 to TX/RX data port
Addr = Rx_tx_data_port_0
Value8 = High(value16)
Chipwrite
Addr = Rx_tx_data_port_0 + 1
Value8 = Low(value16)
Chipwrite
End Sub

Sub Purge_frame
'Purges current received frame from CS8900 internal buffer
Ppoffset = Pp_receiver_control                                     'Get RX status
Ppread
Value16 = Value16 Or Receiver_configuration_skip                   'Set Skip_1_Frame bit
Ppoffset = Pp_receiver_control                                     'Get RX status
Ppwrite
End Sub

Sub Resetcs8900
'Reset the CS8900
Print "Resetting CS8900..." ;
Ppoffset = Pp_self_control                                         'Send a soft-reset
Ppread
Value16 = Value16 Or Self_control_reset
Ppwrite
Wait_for_cs8900_reset:
Ppoffset = Pp_self_control                                         'Get self control status
Ppread
Value16 = Value16 And &H40                                         'Mask bit 6
If Value16 = &H40 Then Goto Wait_for_cs8900_reset                  'Is it clear?
Ppoffset = Pp_self_status
Ppread
Value16 = Value16 And &H80                                         'Mask bit 7
If Value16 = 0 Then Goto Wait_for_cs8900_reset                     'Is it set?
Print "  Complete."
End Sub

Sub Initcs8900
'Initialise the CS8900
Print "Initialising CS8900 parameters."
Ppoffset = Pp_line_control                                         'Set 10BaseT interface
Ppread
Value16 = Value16 Or Line_control_10baset
Ppwrite
Ppoffset = Pp_test_control                                         'Set half-duplex operation
Ppread
Value16 = Value16 Or Test_control_half_duplex
Ppwrite

Ppoffset = Pp_receiver_control
Ppread
Value16 = Value16 Or Rx_ctl_rx_ok_a                                'Enable reception of valid frames
Print "Broadcast Reception - ";
If Broadcast_enable = 1 Then
   Value16 = Value16 Or Rx_ctl_bcast_a                             'Enable reception of broadcast packets
   Print "Enabled"
Else
    Print "Disabled"
End If
Print "This MAC Address Reception - ";
If Individual_address_enable = 1 Then
   Value16 = Value16 Or Rx_ctl_ind_addr                            'Enable reception when Dest MAC = this MAC
   Print "Enabled"
Else
    Print "Disabled"
End If
Print "Promiscuous Reception - ";
If Promiscuous_enable = 1 Then
   Value16 = Value16 Or Rx_ctl_promiscuous                         'Enable reception of frames for any destination
   Print "Enabled"
Else
    Print "Disabled"
End If
Ppwrite                                                            'Write the settings

Ppoffset = Pp_individual_address                                   'Set first MAC word
Value16 = Mac1                                                     'Get first MAC word
Swapvalue16                                                        'reverse the bytes
Ppwrite
Ppoffset = Pp_individual_address + 2                               'Set second MAC word
Value16 = Mac2                                                     'Get second MAC word
Swapvalue16
Ppwrite
Ppoffset = Pp_individual_address + 4                               'Set third MAC word
Value16 = Mac3                                                     'Get third MAC word
Swapvalue16
Ppwrite
Ppoffset = Pp_line_control                                         'Get line control status
Ppread
Value16 = Value16 Or &B0000000001000000                            'Serial RX on
Value16 = Value16 Or &B0000000010000000                            'Serial TX on
Ppwrite                                                            'Update line control status
End Sub

Sub Chipver
'Get CS8900 version
'Get EISA info
Ppoffset = Pp_eisa_registration_number                             'Point to EISA PPage address
Ppread                                                             'Get EISA info
If Value16 = &H630E Then                                           'Check for Product ID code
   Print "CS8900 found, Great!"
Else
   Print "*** CS8900 NOT found ***"
   Print "EISA data=";
   Printhex Value16
   'Get product ID
   Ppoffset = Pp_product_identification_code
   Ppread
   Swapvalue16
   Print "Product ID=";
   Printhex Value16
End If
End Sub


Sub Chipread
'8-bit I/O Read from CS8900
'Result in Value8
Addr = Addr + Cs8900base
Value8 = Inp(addr)
End Sub

Sub Chipwrite
'8-bit I/O Write to CS8900
'Data in Value8
Addr = Addr + Cs8900base
Out Addr , Value8
End Sub

Sub Ppread
'PPread from CS8900
'PacketPage offset in PPoffset
'Low,High byte read order
Setpppointer
Value16 = 0                                                        'Clear value
Addr = Packet_page_data_port_0                                     'Locate PPdata LOW address
Chipread                                                           'Get low byte
Value16 = Value8                                                   'Store lower byte
Addr = Packet_page_data_port_0 + 1                                 'Locate PPdata HIGH address
Chipread                                                           'Get high byte
Temp16 = Value8 * 256                                              'Move to higher byte
Value16 = Value16 + Temp16                                         'Add high byte to low byte
End Sub

Sub Ppwrite
'PPwrite to CS8900
'PacketPage offset in PPoffset
'Low,High byte write order
Setpppointer
Value8 = Low(value16)                                              'Get LOW byte to be written
Addr = Packet_page_data_port_0                                     'Locate PPdata LOW address
Chipwrite                                                          'Write LOW byte to PP
Value8 = High(value16)                                             'Get HIGH byte to be written
Addr = Packet_page_data_port_0 + 1                                 'Locate PPdata HIGH address
Chipwrite                                                          'Write HIGH byte to PP
End Sub

Sub Setpppointer
'Set PP pointer
Value8 = Low(ppoffset)                                             'Get LOW offset byte
Addr = Packet_page_pointer_port                                    'Locate PPportPointer
Chipwrite                                                          'Write LOW byte to PPportPointer
Value8 = High(ppoffset)                                            'Get HIGH offset byte
Addr = Packet_page_pointer_port + 1                                'Locate next PPpointerAddress
Chipwrite                                                          'Write HIGH byte to PPportPointer
End Sub


Sub Swapvalue16
'Swap high & low bytes in value16
Temp16 = Low(value16)                                              'Save high byte to low byte
Temp8 = High(value16)                                              'Move & save high byte
Value16 = Temp16 * 256                                             'Move low byte to high byte
Value16 = Value16 + Temp8                                          'Add low byte
End Sub

Sub Linkstatus
Ppoffset = Pp_line_status
Ppread                                                             'Get line status
Value16 = Value16 And &B0000000010000000                           'Mask LinkOK bit
Print "Link ";
If Value16 = 0 Then
   Print "DOWN"
Else
   Print "UP"
End If
End Sub


Sub Wait_for_frame
'Wait for valid frame to be received
Wait_for_frame_1:
Ppoffset = Pp_receiver_event
Ppread
Temp16 = Value16
Value16 = Value16 And Rx_event_receive_ok                          'Mask Rx OK bit
If Value16 = 0 Then Goto Wait_for_frame_1                          'Is an 'OK' frame there?
End Sub

Sub Receive_frame
'Read RxStatus word.  Read these high byte first!
'These will always be of zero value because of previous RX Event read operation resets them.
Addr = Rx_tx_data_port_0 + 1                                       'Read RX status high byte
Chipread
Addr = Rx_tx_data_port_0                                           'Read RX status low byte
Chipread
'Read frame length.  Read these high byte first!
Addr = Rx_tx_data_port_0 + 1                                       'Read frame length high byte
Chipread
Value16 = Value8 * 256                                             'And save it
Addr = Rx_tx_data_port_0                                           'Read frame length low byte
Chipread
Value16 = Value16 + Value8                                         'And save it
Frame_length = Value16                                             'Save length for later

Byte_count = Frame_length
Word_count = 0

'Loop back to here
Receive_frame_1:
Rxword                                                             'Read in packet data as Words
Rx_packet(word_count) = Value16                                    'Save word to array
Incr Word_count                                                    'update array counter
Decr Byte_count                                                    'Update counter
Decr Byte_count                                                    'Dual-byte (word) read
If Byte_count > 1 Then Goto Receive_frame_1                        'Get the next frame byte
Rxword                                                             'Get last word / byte
Rx_packet(word_count) = Value16                                    'Save word to array
End Sub



Sub Arp_reply
Value16 = Rx_packet(offset_ar_hwtype)
If Value16 <> 1 Then Goto Arp_drop
Value16 = Rx_packet(offset_ar_prtype)
If Value16 <> &H0800 Then Goto Arp_drop                            'IP ARP?
Value16 = Rx_packet(offset_ar_hwlen_prlen)
If Value16 <> &H0604 Then Goto Arp_drop
Value16 = Rx_packet(offset_ar_op)
If Value16 <> 1 Then Goto Arp_drop                                 'ARP Request?
'Build ARP frame to be sent
Value16 = Rx_packet(offset_frame_src_mac_1)                        'Frame Destination MAC
Tx_packet(0) = Value16
Value16 = Rx_packet(offset_frame_src_mac_2)
Tx_packet(1) = Value16
Value16 = Rx_packet(offset_frame_src_mac_3)
Tx_packet(2) = Value16
Tx_packet(3) = Mac1                                                'Frame Source MAC
Tx_packet(4) = Mac1
Tx_packet(5) = Mac1
Tx_packet(6) = &H0806                                              'Frame Type
Tx_packet(7) = &H0001                                              'offset_Ar_hwtype
Tx_packet(8) = &H0800                                              'offset_Ar_prtype
Tx_packet(9) = &H0604                                              'ar_hwlen=6  ar_prlen=4
Tx_packet(10) = &H0002                                             'offset_Ar_op  2=ARP Reply
Tx_packet(11) = Mac1                                               'ar_sha
Tx_packet(12) = Mac2
Tx_packet(13) = Mac3
Value16 = Ip1 * 256                                                'ar_spa
Value16 = Value16 + Ip2
Tx_packet(14) = Value16
Value16 = Ip3 * 256
Value16 = Value16 + Ip4
Tx_packet(15) = Value16
Value16 = Rx_packet(offset_ar_sha_1)                               'ar_tha
Tx_packet(16) = Value16
Value16 = Rx_packet(offset_ar_sha_2)
Tx_packet(17) = Value16
Value16 = Rx_packet(offset_ar_sha_3)
Tx_packet(18) = Value16
Value16 = Rx_packet(offset_ar_spa_1)                               'ar_tpa
Tx_packet(19) = Value16
Value16 = Rx_packet(offset_ar_spa_2)
Tx_packet(20) = Value16
Value16 = 42                                                       'Set packet length
Transmit_frame                                                     'Send packet
Temp8 = 0
Goto Arp_reply_ok

Arp_drop:
Temp8 = 255
Arp_reply_ok:
End Sub

Sub Transmit_frame
'Sends frame from buffer, length in Value16
Temp16 = Value16                                                   'Save packet length
Starttx                                                            'Send start TX command
Value16 = Temp16                                                   'Restore packet length
Settxlen
'Wait for CS8900 to be ready for frame TX...
'May lock up in here due to lack of on-chip buffer space.
'Needs a timeout timer.
Arp_wait_for_tx:
Ppoffset = Pp_bus_status                                           'Get status
Ppread
Value16 = Value16 And Bus_status_rdy4txnow                         'Mask bit 8
If Value16 = 0 Then Goto Arp_wait_for_tx

Byte_count = Temp16
Word_count = 0

'Loop back to here
Transmit_frame_1:
Value16 = Tx_packet(word_count)                                    'Save word to array
Txword
Incr Word_count                                                    'update array counter
Decr Byte_count                                                    'Update counter
Decr Byte_count                                                    'Dual-byte (word) read
If Byte_count > 1 Then Goto Transmit_frame_1                       'Get the next frame byte
Value16 = Tx_packet(word_count)
Txword

End Sub

Set_ip_address:
'Set IP address from data stored in ROM.
Ip1 = Ip1c
Ip2 = Ip2c
Ip3 = Ip3c
Ip4 = Ip4c
Return                                                             '
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