let some time to the system.

Hi.

I’ve test this simple programme

int main()
{
	while (1)
	{
	... // somme computation
	};
}

This simple program will freeze the system because it take all the cpu time.

What is the correct method to realise huge quantity of computation without taking 100% of speed.
It seem’s that the sleep function do not exists under RiscOS.

thank’s

You need a SYS “Wimp_Poll” loop to do cooperative multitasking. Wimp_Poll returns to your programme after polling others.

Alternatively, run the program in a Task Window.

Or you might like to download RiscLua, put the seven lines below into a textfile, give it filetype Lua and doubleclick on the file’s icon.

local s = "Hello Etienne"
local task, QUIT in require "task"
local x = task (s)
x.handler[0] = QUIT
x:init ( )
x:alert (s)
x:run ( )

I’m suffering from a rather nasty bunged up sinus with a headache only marginally less than that time I had my wisdom teeth out, so maybe I’m missing something obvious, but…

…Lua’s syntax looks really weird…

Odd little mini programs always look a little weird though. Programming in Lua
I just grabbed the first thing I found. Copypasted below.

-- defines a factorial function
    function fact (n)
      if n == 0 then
        return 1
      else
        return n * fact(n-1)
      end
    end

print(“enter a number:”)
a = io.read(“*number”)        — read a number
print(fact(a))

See? Not so bad.

Something about that whole x.handler thing reminds me vaguely of Windows 3.1. I vaguely recall having to do some funny little thing in code to allow task switching.

Thank you everybody.
I found this http://www.stevefryatt.org.uk/docs/wimp/usingc.html where it’s explain how to use wimp_poll

while (!quit) {
        reason = wimp_poll(wimp_MASK_NULL | wimp_MASK_ENTERING |
                        wimp_MASK_LEAVING | wimp_MASK_GAIN |
                        wimp_MASK_LOSE | wimp_MASK_POLLWORD,
                        &block, NULL);

        switch (reason) {
        case wimp_USER_MESSAGE:
        case wimp_USER_MESSAGE_RECORDED:
                if (block.message.action == message_QUIT)
                        quit = TRUE;
                break;
        }
}

Where should I put parts of my calculations ?
In the default: of the switch ?

This simple program will freeze the system because it take all the cpu time.

If you are running the program in a taskwindow it freezes because there are no swis or functions which call swis in the while loop. Taskwindows only multitask when swis are called. So

#include "swis.h"

extern unsigned int __swi(OS_ReadMonotonicTime) os_readmonotonictime(void);

int main()
{
	while (1)
	{
	... // somme computation
                os_readmonotonictime();
	};
}

should work. You don’t need to call the swi every iteration of the loop.

Where should I put parts of my calculations

If you were using an application you’d multitask on a null event something like this

int poll(void)
{
    int reason;
    while (1)
    {
       reason = wimp_poll(wimp_MASK_ENTERING |
                        wimp_MASK_LEAVING | wimp_MASK_GAIN |
                        wimp_MASK_LOSE | wimp_MASK_POLLWORD,
                        &block, NULL);

        switch (reason) {
        case wimp_ENULL: return FALSE;

        case wimp_USER_MESSAGE:
        case wimp_USER_MESSAGE_RECORDED:
                if (block.message.action == message_QUIT)
                        return TRUE;
                break;
        }
    }
    return FALSE;
}

int main()
{
	while (1)
	{
	... // somme computation
                if (poll()) break;
	};
}

Note wimp_poll no longer masks the null event.

The Steve Fryatt example is the normal way of using wimp_poll in an application but if you want to multitask some complex calculation the above should work.

Tristan: while your little example isn’t bad and resembles many other languages… an example from Gavin’s own pages is:

curry = \ (f) => \ (x) => \ (y) => f (x, y) end end end

I rest my case. ;)

Etienne: ignore cert message, nous parlons de Lua

@Rick Sorry about the sinuses. I used to have hell with those.

…Lua’s syntax looks really weird…

Two reasons here: 1. Lua lets you modify the syntax quite a bit. 2. What you are seeing is not Lua but RiscLua. So for example the construction in the second line

local task, QUIT in require "task"

local mylib = require "task"
local task, QUIT = mylib.task, mylib.QUIT

What I am trying to show with things like the task library is how RiscLua can conceal a great deal of messy detail, which is what libraries are for, and let the programmer get on with describing what the program really does. Yes, I know that in the end the programmer may in some circumstances have to grapple with the details, and the pain of those will be the same in any language. If you look at my notes you will see my arguments for why higher-order languages are better equipped for abstracting complicated things like wimp-tasks.

Thank’s colin.

I prefer this code (but this is the same thing)

int main()
{
	...

	while (!quit) {
		reason = wimp_poll(wimp_MASK_NULL | wimp_MASK_ENTERING |
			wimp_MASK_LEAVING | wimp_MASK_GAIN |
			wimp_MASK_LOSE | wimp_MASK_POLLWORD,
			&block, NULL);
		
		switch (reason) {
		case wimp_ENULL:
			compute_a_little_bit();
			break;
		case wimp_USER_MESSAGE:
		case wimp_USER_MESSAGE_RECORDED:
			if (block.message.action == message_QUIT)
				quit = TRUE;
			break;
		}
	};

	...
}

I’ll try this evening…

You need to remove the wimp_MASK_NULL from wimp_poll.

oups.
ok. understood :)

Time to join in the simplicity game. ;-)

*BasaltInit
REGW @Wimp_Null FNcalculate
INITIALISE "Calculate"
POLL
END

DEFFNcalculate
 ...
ENDFN

I am not sure where the output goes, though.

The point is that Riscos is a cooperative multitasking system, not preemptive.
So your task has to “play nicely”.
Also, you’ll need to use Wimp_Initialise to register your task in the first place.

The Task Window Application allows ordinary programs to run by preempting them as a single task in the window.
So the C compiler for instance runs in a special sort of task window that gives the appearance of the compiler multitasking.

@Rick A propos curry google Haskell Brooks Curry.
@Steve I am impressed. Can you point me to a URL for browsing about Basalt?

colin

case wimp_ENULL:

doesn’t exists

I used

case wimp_NULL_REASON_CODE

instead.

It seem’s to work.

The program works. I still not know how to stop it but, it let the desktop working.
I will put it int a window. that should allow me to stop it !

thx

I don’t use the library you are using so I just guessed the name.

You can quit the program from the task manager.

1) click on task manager icon – bottom right of screen.
2) click menu over the application task
3) select task 'your program name' -> quit

The task manager sends the message_QUIT message which you have set to quit the program.