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Many years ago on the Beeb I had a program that would take the output from one cassette recorder and send it out to another, allowing perfect tape copies of software. It was – of course – a good backup system for making safe copies of tapes that got used a lot, including protected stuff, like that motorracing game where the data blocks counted down instead of up.

Gavin, do you have any example Lua code to turn on/off the caps lock key? Or similar resources to point people at to help them on their RISC OS coding journey.

BTW for anyone curious about Lua, the resources Gavin has put together are impressive; as observed on the ROD and some ROOL distros.

There are also other code snippets needed, from displaying an image or draw file on the screen to networking and other areas. What we thought was important was to cover those things that are done differently in RISC OS.

Indulging my drive to completion (which usually fails me) I submit a further armbob program to manipulate CapsLock. Very simplistic I know, but this thread is aimed at developing people’s skills sets?

// an armbob app to switch caps lock and off

main(){
myflag = 0 ;
r=newvector(8);
    do { runmenu()  ;   }
    until( myflag == 1  ) ;
    print("\n that's all folks");
}  // end of main

runmenu(){
print("what do you want to do with capslock? \n\n");
print (" 1 - read it \n 2 - turn capslock on \n 3  - turn capslock off \n 4 - quit the program? \n");
print("\n Enter a number ");
choice = val(input())    ;
	// these should be a switch block, but I had problems with it!
    if( choice == 1 ) test_capslock() ;
    if( choice == 2 ) pokecaps_on() ;
    if( choice == 3 ) pokecaps_off() ;
    if( choice == 4 ) myflag = 1 ;
    choice = 0 ;
} // end of runmenu

test_capslock(){
//   run Os_Byte 202 but change nothing
    r[0]=202;
    r[1]=0 ;
    r[2]=255 ;
    swi("OS_Byte",r);
//       copy keyboard status byte and parse bit 4 of same.
capstat= (r[1] & 16 )/16   ;
print("\n capslock status byte is ", capstat ,"\n\n");
}

pokecaps_on(){
//  clear bit 4  of keyboard status byte in bitwise AND operation
    r[0]=202;
    r[1]=0 ;          // EOR does nothing here
    r[2]=255-16 ;    // AND mask clears bit 4
    swi("OS_Byte",r);
    r[0]=118;
    swi("OS_Byte",r);  // update keyboard LEDs
     print("\n Your keyboard is bright. \n\n");
}     // end of pokecaps_on

pokecaps_off(){
//  clear bit 4 with bitwise AND, to create a known state
// then flip it
    r[0]=202;
    r[1]=16 ;      // EOR toggle bit 4 to the ON state
    r[2]=255-16 ; // AND mask clears bit 4
    swi("OS_Byte",r);
    r[0]=118;
    swi("OS_Byte",r); // update keyboard LEDs
    print("\n your keyboard is dull.\n\n");
}     // end of pokecaps_off

I am finding the risc os journey quite an adventure. Joyous and frustrating in equal measure. I do wish the documentation was a little less dense however.

The documentation is dreadful, being mostly ‘Not even wrong’.

And your updated OS_Byte MOSvar wrangling is spot-on!

Following on from Nemo’s example, I thought I’d do something similar using the Ovation Pro Scrip Language.

I’ve used a loop instead of the repeat to flash the CapsLock LED 8 times – it actually toggles the CapsLock status on then off 16 times, so leaves it in the state it was at the start.

To try it out, copy the code and save it with a file type of &b24 (OvPScrpt). With Ovation Pro running, drag the file to the Ovation Pro icon bar icon. It may work by double-clicking the script file (doesn’t for me as I have StrongED set to intercept it and open the file for editing).

Oh and you can get Ovation Pro from here:
https://www.davidpilling.com/wiki/index.php/OvationPro

// Ovation Pro script - Flash Keyboard CapsLock
// Gavin Crawford

void main(void){          // create a function called 'main' - code in here gets executed when the scrip is run
  int i;                  // declare a variable called 'i'

  for(i=1; i<=16; i++){   // for-loop starting at 1 that will loop until 'i' is 16, incrementing by 1 each time
    swi13(6,202,16,255);  // call SWI 6 (OS_Byte) r0=202 Read/Write keyboard status byte - toggle bit 4
    swi13(6,118,0,0);     // call SWI 6 (OS_Byte) r0=118 Reflect keyboard status in LEDs - update keyboard LEDs
    pause(25);            // delay of 25 centi-seconds - allows the rest of the programs on the desktop to multitask
  }                       // close of the for-loop
}                         // close of the 'main' function

OP is also on Store.

Thanks Rick, forgot to mention Store.

Gavin generously gave

<OvPScrpt>

For those of us unfamiliar with this language, would I be right in guessing that swi13() is a function that calls a SWI with the first three registers and then returns the contents of R1?

Absolutely correct!

My StongHelp manual for the OPro script language is available here:
https://gavincrawford.me/ovationpro/utilities/ovnprostronghelp/

Gavin, do you have any example Lua code to turn on/off the caps lock key?

I hope you do not mind another Gavin replying. There are one or two Gavins around.

local sys in require "riscos"
local kbd = \ (update, mask)
  -- PRM 1-883
  local _, status = sys (6, 202, update, mask)
  => status
end -- function
local mesg = "caps lock is %s\n"
local caps_mask = 1<<4
local quit
-- table of actions - uses kbd, quit, caps_mask, mesg
local capslock = { 
  on = \ ( )
       local s = kbd (0, 255)
       kbd (s | caps_mask, 1)
       print (mesg:format "ON")
       quit = true
     end;
  off = \ ( )
       local s = kbd (0, 255)
       kbd (s & ~caps_mask, 1)
       print (mesg:format "OFF")
       quit = true
     end;
 quit = \ ( ) quit = true end;
  }
  -- main program  - uses kbd, quit, capslock
local status = kbd (0, 255) -- read initial status
while not quit do
   print "Enter 'ON' 'OFF' or 'QUIT'\n  -->:"
   local command = (io.read "*l"):lower ( )
   local action = capslock[command]
   if action then  pcall (action)
   else print "sorry - what?\n"
   end -- if
end -- while
kbd (status, 1)  -- restore status at exit
print "   -- finished --\n"

 -- main program  - uses kbd, quit, capslock
      local status = kbd (0, 255) -- read initial status
      while not quit do
         print "Enter 'ON' 'OFF' or 'QUIT'\n  -->:"
         local command = (io.read "*l"):lower ( )
         local action = capslock[command]
         if action then  pcall (action)
         else print "sorry - what?\n"
         end -- if
      end -- while
      kbd (status, 1)  -- restore status at exit
      print "   -- finished --\n"

 -- table of actions - uses kbd, quit, caps_mask, mesg
      local capslock = { 
        on = \ ( )
             local s = kbd (0, 255)
             kbd (s | caps_mask, 1)
             print (mesg:format "ON")
             quit = true
           end;
        off = \ ( )
             local s = kbd (0, 255)
             kbd (s & ~caps_mask, 1)
             print (mesg:format "OFF")
             quit = true
           end;
       quit = \ ( ) quit = true end;
        }

local _, status = sys (6, 202, update, mask)

local sys in require "riscos"

Gavin, thank you for your contribution, it’s great! I also include everyone else whose input so far.

It’s so valuable because creating examples helps explain some of the trickier areas of RISC OS. That means we are not only passing down and sharing knowledge but laying the foundation of understanding for those that follow.

So, if you have a code snippet to share or are struggling with a RISC OS concept, come and join in.

@Gavin Crawford. I’ve run the script and it worked. I saved the text selection to disc from the browser, changed the file type to OvPScrpt. Double-clicked the file and behold a flashing caps lock LED. :)

@Colin McMurchie. As above, but changed file type to bob and double-click the file- it worked, a flashing caps lock key, Esc key to quit. :)

Thanks again, Andrew

@Andrew McCarthy I’ve edited the original post to remove the p.
It’s the first time I’ve posted code to these forums and thought I needed the P. to end the code block, but I didn’t have anything else to write in the post so it seems it showed up as part of the code – I didn’t notice it was in there.

Glad the script worked for you. I use a wireless keyboard on my system and it doesn’t actually respond quick enough the the changes in the OS, but I used the traffic lights system that is part of !HID that shows the keyboard status LEDs (similar to @Nemo’s offering)

Thank you, Gavin; it’s good to know we’ve helped each other. And you’ve highlighted that Ovation Pro has a powerful scripting language. I didn’t know that. :) I’ve only ever made good use of !TechWriter.

The task for next week, find out what is wrong with my installation of Lua- I get a “stick” error message, something to investigate with another build.

In the meantime, if anyone whose experienced cross-platform development has any code snippets that highlight the RISC OS way of doing things. Come and join in; it’s a bit of fun.

The LEDs module is finished, but in the process I discovered a regression in RO5 to do with translation tables, which I thought I’d document here. This was introduced in 5.2x but I’ve only just noticed.

Unlike all previous versions of the OS, SpriteExtend 1.65+ checks that all entries in a translation table are valid pixel values for the destination mode (i.e. no larger than BPP would suggest) and if not returns an error.

Are you able to provide some sample code to showcase this problem?

In a new API it would be pettifogging bureaucracy, but as a regression to a 30-year old API it’s indefensible. …. this is straw man engineering …. misguided make-work

If you’re going to make such claims then please provide evidence which supports them.