I hate syntax highlighting.

Monday, 28th November 2005

I spent this weekend completely rewriting the syntax highlighting control - this time, from scratch. It seems that all the free ones are rubbish. Mine is rubbish, but at least I can maintain it. Now all I have to do is wait for the people using the beta to start complaining that it's eating their source code...

My test project for it was a Lotus-like 3D racing engine.

I think I need to research the way it works a little better... still, not too bad for a little over 400 bytes.

Themes!

Wednesday, 23rd November 2005

Not the www2 theme though - a couple of XP theme glitches.

First up is the ListView control in .NET 2. If you switch on gridlines and scroll with the arrows on the scrollbar, it leaves the gridlines behind as nasty artefacts. This is what I came up with - and it appears to work.

Create a new class that inherits from ListView. Then add to it this code:

        /// <summary>
        /// Hacky override to fix the garbage lines.
        /// </summary>
        protected override void WndProc(ref Message m) {
            if (m.Msg == 0xF) { // 0xF is WM_PAINT
                GridLines = false;
                GridLines = true;
            }
            base.WndProc(ref m);
        }

...compile and that new class should appear in your toolbox. Use that instead of the normal ListView control.

If anyone could come up with a better solution, I'd love to hear it...

The other theme bug appeared last night in XP.

Click for big.

I guess it can't remember if it's using Windows Classic or Windows XP styling?

Latenite

Monday, 21st November 2005

Latenite - looking more and more like a VS ripoff.

Localisation

Thursday, 17th November 2005

Typing

One reason you'd want to connect a keyboard to your TI - or indeed any device - would be to type on it. After all, it offers a nice comfortable layout to type quickly on...

One easy way to deal with the keyboard as a typing device would be to write a function that converts the scancode into an ASCII code (or a special code in the 128→255 range for keys without sensible ASCII equivalents, such as the Windows or cursor keys). But here's the problem - not all keyboards have the same characters printed on the keys. A UK layout will be QWERTY, a French layout will be AZERTY and a German layout will be QWERTZ. A US keyboard will have @ over the 2, whereas my keyboard has " over the 2.

The way I get decided to get around this was a fairly inelegant (but simple) one - assume the calculator has a keyboard localisation file on it. A function call I have provided called keyi_load_table will attempt to find and load the keyboard layout definition file you can create (returning an error code if it can't find any). Any software that uses these routines can therefore instantly tailor themselves to match the keyboard layout of the individual user. The files themselves aren't very big - it contains two mappings for the entire keyboard (normal and shifted), a table of which keys Caps Lock affects (26 bytes - A→Z on an English keyboard) and a final table for alternate codes for when Num Lock is pressed.

With this all put together, a single call to keyi_translate will convert a scancode in the accumulator to the ASCII/special code, automatically adjusting for Shift/Caps Lock/Num Lock. You can even call the function keyi_check_printable to see if the code is in the printable character range, or keyi_get_status_icon to get a character code for a suitable cursor - no special status returns  , shift returns ↑, caps lock returns A and caps lock+shift returns a.

Getting it to work

Wednesday, 16th November 2005

Reliability

I'm sure you wouldn't want to use a keyboard that was inaccurate. Unfortunately, (as you might have seen me moaning in the past) the keyboard generates the clock signal. This basically means you need to be constantly checking the clock line to see if it goes low - that or use a hardware interrupt the jumps in and receives the scancode packet when the keyboard decides you want to stop sending something.

Well, I don't have the luxury of an extra keyboard chip or a hardware interrupt, so I needed to don my thinking cap. I had thought that one possible way around this would be to send a "disable" command to the keyboard after receiving bytes, running my handler code, then sending an "enable" command - these commands clear the keyboard's buffer, unfortunately, which is not good.

I downloaded another document on the AT protocol to see if they mentioned anything useful, and lo and behold:

The host may inhibit communication at any time by pulling the Clock line low for at least 100 microseconds.

I think I can spare 100µs - I added the line ld a,1 \ out (bport),a to the end of my buffer-filling code from earlier (it fills a scancode key buffer) - and the code doesn't drop a single scancode. Result!

Providing useful functionality

All these keyboard routines do at the moment is to display the data coming in on the screen - not exactly a great use of them. What is really needed is a simple two-way handler - it calls two different user-defined routines based on what a key is doing, whether it is being pushed down or released.

For this, I should translate the scancodes into a new format - there are less than 256 keys, so there's no reason why I can't fit every single key into a byte.

As well as user-defined keyboard events, I'll have to add my own to handle toggling the status of the keyboard - the num/caps/scroll lock as well as the shift/alt/ctrl.

It's really quite simple to do.

	; Now we need to run through all the keyboard events!

	ld ix,_buffer	; Start at the beginning of the buffer.

_handle_next_scancode:

	; Let's assume it's a normal key:

	ld hl,_scancode_lut
	ld bc,_scancode_lut_end-_scancode_lut

_key_down_handler:
	ld de,_null_handler


	ld a,(ix+0)
	or a
	jr z,_handled_all_keys

	cp at_scs_enhance	; Is it an enhanced key?
	jr nz,_not_enhanced

		inc ix	; We know it's enhanced, so move along.
		ld a,(ix+0)
		or a
		jr z,_handled_all_keys
		ld hl,_scancode_e_lut
		ld bc,_scancode_e_lut_end-_scancode_e_lut
_not_enhanced:

	; Now HL points to our LUT, BC is the correct length
	; and IX points to the next byte.

	cp at_scs_keyup ; Is it a key UP event?
	jr nz,_not_keyup

		inc ix
		ld a,(ix+0)
		or a
		jr z,_handled_all_keys
_key_up_handler:
		ld de,_null_handler

_not_keyup:

	; Move to next chunk before we do anything
	inc ix
	; At this point, A=scancode, HL->translation table, DE->handler, BC=table size, IX->next scancode.

	; We now need to run the translation.

	cpir	; Simple as that!

	jr nz,_handle_next_scancode	; Not found

	; So HL->scancode+1
	; Here is where the magic happens:

	push de
	ld de,0-_scancode_lut
	add hl,de
	ld a,l
	pop de

	; Now, A = 'real' scancode.

	; We need to 'call' DE.
	; We can spoof this easily:

	ld hl,_handle_next_scancode
	push hl	; _h_n_s is on TOP of the stack.
	push de ; our event handler is on top of the stack;
	ret	; POP back off stack and jump to it.
		; When the handler RETs it'll pop off _h_n_s and carry on scanning!


_handled_all_keys:

_null_handler:
	ret

I created a couple of very basic event handlers - the key down event displays ↓ followed by the adjusted key code, the key up event displays ↑ followed by the adjusted key code.

What would be ideal would be to provide internal event handlers that could be called on keyup/keydown which would then jump over to the user's custom handler. These event handlers could look for special keys and adjust the keyboard LEDs and set internal flags that could be used to detect the status of certain keys. I'd need:

• Num Lock
• Caps Lock
• Scroll Lock
• Shift
• Ctrl
• Alt

Unfortunately, I think that there is a problem with my byte-sending code. Setting the keyboard LEDs starts to do strange things - I now have two options;

1. After switching status, ignore the LEDs. The status flag is set correctly internally, but you can't see it on the keyboard (which is a bit pants).
2. Update the status flags every single time we run through the loop to check for any new bytes (which makes the keyboard lag like crazy - there's up to half a second of buffering going on!)

Mixing-and-matching the two - rewriting the branch before we bring the clock high again (for maximum speed) confuses the keyboard - the status LEDs never change and it decides to disable itself in a strop until I send $FF (the reset command) again. I think it's time to revisit the at_send_byte routine again to see what it's doing wrong!

Well, comparing it to my new notes - it's actually completely wrong at the end, when it comes to sending the parity/stop/ACK bits! A quick rewrite to how I think it should go isn't too hopeful - the keyboard LEDs flash like mad. Tweaking the timing by throwing in a few calls to _wait_bit_low and _wait_bit_high to synchronise my data to the clock stop this completely - and now the code is as it was before, at 100% accuracy - but about twice as fast.

Replacing my branch code still doesn't work all the time - sometimes the LEDs change, sometimes they do not. Not believing it would work, I threw in a check for the ACK bytes returned - if they were $FE, the 'repeat last command' byte, I'd send again.

My routines were clearly not as broken as I thought - the keyboard LEDs now change status perfectly, and as much as I hammer the Num Lock, Caps Lock and Scroll Lock keys, I cannot lock up the program or get the keyboard LEDs to display the wrong value. Not to mention that keying in other keys is back to the lightning fast response they used to be...