Chris made me aware that ASCII code 0 actually is a valid character (usually entered as Ctrl-Space or Ctrl-@) and that it is actually used (i.e. by EMACS).
The Apple II allows to natively enter the ASCII code 0 via Ctrl-@. However so far get_key_if_available returned 0 in accumulator to signal that no key was pressed. In order to allow the Apple II get_key_if_available to return the ASCII code 0 in the accumulator I changed it to use the carry flag to signal that no key was pressed.
Because get_key_if_available needs of course to behave the same on all targets I changed the other implementations to use the carry flag too.
Unfortunately I don't know enough about input capabilities of the C64 to decide on how to best get Telnet65 to send ASCII code 0 there.
On the C64 the cursor is flashing (driven by a timer interrupt routine). So in order to have the cursor appear all it takes is to make sure that the interrupt routine:
- understands that it should actually work on the cursor
- has a correct understanding about what char is "under" the cursor
On the Apple II on the other hand the cursor has always to be actively drawn. Therefore all the places where the C64 code just updates the char under the cursor the Apple II code needs to actually draw the cursor.
We learned this the hard way with 'nvi'. When pressing <enter> in insert mode it sends the following data:
0d 00 1b 5b 31 42 1b 5b 4b
This means to return the cursor (to col 1), do nothing, then move it down 1 row and finally remove all chars from the cursor to the end of the line. The latter is one of the instances requiring to actively redraw the cursor (when set to be visible) as it was removed (when set to be visible).
I would have expected that no matter what causes the TCP connection to be closed would be reported as a TCP call back with lenghth = -1. However there are scenarios where this isn't true. I.e. when the user aborts during a blocking TCP retransmit opration. I'm unsure if this behaviour is to be considered a bug or if this is by some design I don't understand.
So I opted to not change that behaviour but rather add an explicit check for tcp_send returning with an error indicating that the connection is closed. This way the users gets noticed on the closed connection at least on his next key press.
It might be welcome to be able to abort DHCP, DNS and TCP connect operations. However while we're connected to the remote host we need full control over the keyboard. If TCP send operations don't work immediately the user will just have to wait until they do (or the timeout).
It's imho in general a pretty unfortunate design to have IP65 check the keyboard during blocking operations. Rather it should call back into the application and have that decide what type of user abort it wants to offer.
Anyhow I don't want to change all that - at least not now. Therefore I just added the option to influence which key is considered the abort key - and provide a key value that isn't actually used and as such disables the abort check.
In order to allow setting the Apple II slot from host computer independent code the slot setting function was renamed and dummies were added for the other host computers.
The VT100 has (P)F1-(P)F4 keys. The C64 F1-F4 keys are mapped them. Additionally the C64 F5-F8 keys are mapped to the XTERM F5-F8 keys. However as we pretend to be a VT100 applications tend to ignore them.
Apple II: The MouseText chars only allow for a partial representation of the VT100 Special Graphics glyphs. Additionally the MouseText chars are not available for reversed video.
C64: The VT100 Special Graphics repurposes the ASCII(!) code points $60-$7f. And the C64 custom font used places them on the same code points. Therefore it makes sense to "tunnel" them through the usual ASCII->PETSCII->ScreenCode processing pipeline by moving them as-is to otherwise unused PETSCII code points ($80-$9f).
The currently used font doesn't contain any Latin-9 glyphs so it doesn't make sense to try to process Latin-9 chars. Instead now only 7-bit ASCII chars are processed - as the original VT100 does. Setting LANG=C in the host shell should make programs aware of the fact that only 7-bit ASCII chars are to be generated.
The reverse characters of the alternate char set are place in a somewhat strange arrangement in the Apple II character ROM. This is because of backward compatibility with the standard char set. Therefore it seems more efficient and hopefully easier to understand to use a table to select them.
http://vt100.net/docs/vt100-ug/table3-6.html says that ESC O A..D is to be send if Cursor Key Mode is set and http://vt100.net/docs/vt100-ug/chapter3.html says "A mode is considered set until it is reset by a reset mode (RM) control sequence.". So ESC O A..D is the default.
Beside this spec perspective sending ESC O A..D instead of ESC [ A..D makes i.e. aptitude and midnight commander work out-of-the-box.
On the Apple II the timer_read function is actually a delay function. Therefore we want to avoid calling it if we're busy processing incoming data. Fortunately timer_read is only necessary to trigger a TCP keep alive message. But if we're busy processing incoming data then we for sure need no TCP keep alive. So we simply mark if we just processed incoming data and skip the timeout check.
The commit e1a29ae411 was missing the font file. It sports the VT100 'special graphics and line drawing' glyphs in the chars $60-$7F. However so far the code to make use of them isn't implemented.
Re-added VT100 test that was created for KIPPERTERM development. Not very usefully as-is but a good template for any offline VT100 rendering test/debugging.
Additionally the disk images were renamed to distinguish them from the disk images created in the apps directory.
The file telnet.s in the 'ip65' directory for sure wasn't belonging into a library as it contained a main loop. So I introduced an 'apps' directory for actual apps coming with IP65. The file telnet.s was moved to apps, renamed telnet65.s and heavily modified.
The file c64vt100.s was made up from several files taken from CaTer (www.opppf.de/Cater) and adjusted for the new use case. The was done before for KIPPERTERM. However this time I deliberately avoided unnecessary code reformatting to allow for as easy as possible integration of potential upcoming changes in CaTer.
The file a2vt100.s was copied from c64vt100.s and adjusted to the monochrome 80 column screen of the Apple //e. Again unnecessary code changes were avoided to allow to easily merge upcoming changes from c64vt100.s.
The files atrvt100.s and vic20vt100.s are for now just dummies to allow to successfully link Telnet65. Work for an actually functional Telnet65 would start with a copy of c64vt100.s (as it was done with a2vt100.s).
The ][ doesn't have lower case but the //e defaults to lower case so we need to allow both upper case and lower case (and convert to lower case before DNS lookup).
So far the error value was set to KPR_ERROR_TIMEOUT_ON_RECEIVE on negative answer from the DNS server. Now KPR_ERROR_DNS_LOOKUP_FAILED (which was already defined) is set.
In general I consider the approach of a netmask length a typical case of over-optimzation - incl. the typical downside of an "unnecessary" bug. However as the optimization is already present I opted to not remove it but rather fix the bug:
So far the gateway was in usual environments only used if the target IP address differed already in the first byte from the local net IP addresses. Now the gateway is used correctly - even for i.e. the address 192.168.1.1 from the local net 192.168.0.x
On the A2 get_key deletes any already pressed key. Therefore it's a bad idea(tm) to call it to retrieve the key detected in get_key_if_available. So now get_key_if_available insteads retrieves the key on its own via direct hw access. This was already done the very same way in check_for_abort_key. And apart from not working as expected the benefit of get_key displaying a cursor wasn't useful here anyway because get_key was supposed to return right away with the pressed key so the cursor wouldn't have been visible at all.
- The C64 variant already used get_key and I don't see a reason why the A2 has different requirements when it comes to the question when it is necessary to call ip65_process.
- On the A2 get_key does display a cursor while get_key_ip65 does not. However get_filtered_input is used to get a string of characters. This is exactly the scenario asking for a cursor.
It's not save to presume any zero page variable to stay intact after using the Ethernet drivers to perform actual network I/O. In example a necessary ARP lookup may require network I/O in not anticipated scenarios. Therefore the tftp_filename is rather to be placed in a normal variable and copied to a zero page variable just-in-time.
If the setup of socket 0 to 3 with 4+2+1+1KB is detected then the W5100 is _not_ initialized, otherwise it does set up socket 0 and 1 with 4KB each. Either way socket 0 is used - now with 4KB instead of 8KB as before.
