::: Area #157 (comp.sys.acorn.programmer)
Message: #39434 (Read 7 times, has 0 replies, 4716 bytes)
Date   : Thu Jan 28 21:26:05 1999
From   : Rik Griffin of fidonet#2:254/27.2
To     : All
Subject: Re: Wimptask modules
Message-ID: <19990128.212605.71@cheesey.demon.co.uk>

In article <be44a5cb48%Jeremy@golden.argonet.co.uk>,
	   Jeremy@unforgettable.com (Jeremy Poulter) wrote:

> Cheers, I should have specified that I was using C, any ideas?

Assuming you're also using CMHG ...

In your cmhg file specify something like this:

  initialisation-code:          initialise
  finalisation-code:            finalise
  module-is-runnable:
  service-call-handler:         service_handler &11 &27 &49 &4a &7e
  command-keyword-table:        cmd_handler
    Desktop_MyModule(help-text: "Do not use Desktop_MyModule.
    Use *Desktop instead"),

C code:

int Quit = 0;
int Task_Handle = 0;
int Wimp_Version = 0;
int Wimp_Messages[] = {
  /* wimp message list terminated by 0, for example: */
  Wimp_MPreQuit,
  Wimp_MQuit
}

/* do initialisation stuff (not Wimp). Called in SVC mode       */
_kernel_oserror *initialise(char *cmd_tail, int podule, void *pw) {
  /* whatever you need to do    */
  return NULL;
}

/* called to shut down the module. Eg when RMKill is used. If   */
/* the wimp task is active, that needs to be killed too.        */
/* Also called in SVC mode.                                     */
_kernel_oserror *finalise(int fatal, int podule, void *pw) {
  if (Task_Handle > 0) wimp_close_down(Task_Handle);
  Task_Handle = 0;
  return NULL;
}

/* Called to start the Wimp part of the module, eg when         */
/* OS_Module 2 (Enter) is called. Called in User mode.          */
int main(int argc, char *argv[]) {
  _kernel_swi_regs r;
  WimpPollBlock    block;
  _kernel_oserror  *e;
  int event;
  if (Task_Handle > 0) wimp_close_down(Task_Handle);
  Task_Handle = 0;
  if ((e = wimp_initialise("MyModule", Wimp_Messages, &Wimp_Version,
    &Task_Handle)) != NULL) goto fail;
  /* set our required Wimp slot size    */
  r.r[0] = 32*1024;     // 32 k
  r.r[1] = -1;
  if ((e = _kernel_swi(Wimp_SlotSize, &r, &r)) != NULL) return e;
  /* now go into a Poll loop            */
  while (!Quit) {
    if ((e = wimp_poll(Poll_Mask, &block, NULL, &event)) != NULL) goto fail2;
    switch (event) {
      case Wimp_ENull:
	 /* blah blah */
	 break;
      /* handle whatever wimp events you need to here */
    }
  }
  if (Task_Handle > 0) wimp_close_down(Task_Handle);
  Task_Handle = 0;
  exit(EXIT_SUCCESS);

fail:
  fprintf(stderr, "error from wimp_init: %s\n", e->errmess);
  exit(EXIT_FAILURE);
fail2:
  fprintf(stderr, "error from wimp_poll: %s\n", e->errmess);
  exit(EXIT_FAILURE);
}

/* service call handler function. Called in SVC mode    */
void service_handler(int number, _kernel_swi_regs *r, void *pw) {
  switch (number) {
    case Service_Memory:
      if (r->r[2] == (int)Image__RO_Base) {
	 r->r[1] = 0;            // 0 to prevent app space remapping
      }
      break;
    case Service_StartWimp:
      if (Task_Handle == 0) {
	 Task_Handle = -1;
	 r->r[0] = (int)"Desktop_MyModule";      // start wimp task
	 r->r[1] = 0;                            // claim service call
      }
      break;
    case Service_StartedWimp:
      if (Task_Handle == -1) Task_Handle = 0;
      break;
    case Service_Reset:
      Task_Handle = 0;
      break;
    case Service_ShutDown:
      finalise(1, 0, NULL);
      break;
  }
}

_kernel_oserror *cmd_handler(char *arg_string, int argc, int cmd_no,
void *pw) {
  int l, i;
  _kernel_oserror *e = NULL;
  switch (cmd_no) {
    case 0: {
	 /* this command tells us to start our wimp task */
	 /* by calling OS_Module Enter on ourself        */
	 _kernel_swi_regs r;
	 r.r[0] = 2;
	 r.r[1] = (int) "MyModule";
	 r.r[2] = (int) arg_string;
	 e = _kernel_swi(OS_Module, &r, &r);
      }
      break;
    default : /* bad command */
      break;
  }
  return e;
}

In assembler:

	 EXPORT  Image__RO_Base
	 IMPORT  |Image$$RO$$Base|

Image__RO_Base
	 DCD     |Image$$RO$$Base|


I hope all that makes sense. The code is snipped (with minor alterations)
from a working module of mine. However, I don't guarantee that it's correct,
merely that it works for me! :)

You'll need to define a few macros and write a few SWI veneers (or use
Acorn's WimpLib) to get that code working.

If anyone has any comments, I'd be glad to hear them.

--
"This moment hangs, like your ragged hair."
Celebrate - Fields of the Nephilim

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