/* -*-C-*-

$Id: scheme32.c,v 1.17 1999/01/02 06:11:34 cph Exp $

Copyright (c) 1993-1999 Massachusetts Institute of Technology

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* MIT Scheme under Windows system utiltities DLL source.
   True NT (vs. Win32s) version 
 */

#include "ntscmlib.h"
#include <stdlib.h>
#include <process.h>

static void __cdecl win32_flush_async_timer (void *);
static unsigned int WINAPI timer_thread_proc (void *);

#ifndef WIN32_TIMER_INTERVAL
#define WIN32_TIMER_INTERVAL 50
#endif

static BOOL __cdecl
win32_under_win32s_p (void)
{
  return ((BOOL) 0);
}

//char *
//win32_allocate_heap (unsigned long size, unsigned long * handle)
//{
//#ifdef CL386
//  extern char * malloc (unsigned long);
//#endif
//  * handle = 0L;
//  return ((char *) (malloc (size)));
//}
//
//void
//win32_release_heap (char * base, unsigned long handle)
//{
//  extern void free (char *);
//
//  free (base);
//  return;
//}


static char * __cdecl
win32_allocate_heap (unsigned long size, unsigned long * handle)
{
  LPVOID base;

  base = (VirtualAlloc (((LPVOID) NULL),
			((DWORD) size),
			((DWORD) (MEM_RESERVE | MEM_COMMIT)),
			((DWORD) PAGE_READWRITE)));
  * handle = size;
  return ((char *) base);
}

static void __cdecl
win32_release_heap (char * area, unsigned long handle)
{
  VirtualFree (((LPVOID) area),
	       ((DWORD) handle),
	       ((DWORD) MEM_DECOMMIT));
  VirtualFree (((LPVOID) area),
	       ((DWORD) 0),
	       ((DWORD) MEM_RELEASE));
  return;
}

static BOOL __cdecl
win32_lock_memory_area (void * area, unsigned long size)
{
  return (VirtualLock (area, size));
}

static void __cdecl
win32_unlock_memory_area (void * area, unsigned long size)
{
  (void) VirtualUnlock (area, size);
}

/* Asynchronous timer interrupt based on auxiliary thread.  */

struct win32_timer_closure_s
{
  unsigned long interval;	/* timer interval in milliseconds */
  unsigned long * base;		/* register-block base address */
  long memtop_off;		/* offset to memtop register */
  long int_code_off;		/* offset to int_code register */
  long int_mask_off;		/* offset to int_mask register */
  unsigned long bit_mask;	/* interrupt bits to signal */
  long ctr_off;			/* offset to catatonia-counter register */
  unsigned long catatonia_message; /* message to send for catatonia */
  unsigned long interrupt_message; /* message to send for interrupt */
  HWND window;			/* window to send the messages to */
  void (*grab_int_regs) (void);	/* grab interrupt registers */
  void (*release_int_regs) (void); /* release interrupt registers */
  HANDLE thread_handle;		/* handle of timer thread */
  int exit_thread;		/* set this true to terminate thread */
};

static UINT __cdecl
win32_install_async_timer (void ** state_ptr,
			   unsigned long * base,
			   long memtop_off,
			   long int_code_off,
			   long int_mask_off,
			   unsigned long bit_mask,
			   long ctr_off,
			   unsigned long catatonia_message,
			   unsigned long interrupt_message,
			   HWND window,
			   void (*grab_int_regs) (void),
			   void (*release_int_regs) (void))
{
  struct win32_timer_closure_s * scm_timer;
  unsigned int id;

  scm_timer
    = ((struct win32_timer_closure_s *)
       (malloc (sizeof (struct win32_timer_closure_s))));
  if (scm_timer == 0)
    return (WIN32_ASYNC_TIMER_NOMEM);
  (scm_timer -> interval) = WIN32_TIMER_INTERVAL;
  (scm_timer -> base) = base;
  (scm_timer -> memtop_off) = memtop_off;
  (scm_timer -> int_code_off) = int_code_off;
  (scm_timer -> int_mask_off) = int_mask_off;
  (scm_timer -> bit_mask) = bit_mask;
  (scm_timer -> ctr_off) = ctr_off;
  (scm_timer -> catatonia_message) = catatonia_message;
  (scm_timer -> interrupt_message) = interrupt_message;
  (scm_timer -> window) = window;
  (scm_timer -> grab_int_regs) = grab_int_regs;
  (scm_timer -> release_int_regs) = release_int_regs;
  (scm_timer -> exit_thread) = 0;
  (scm_timer -> thread_handle)
    = ((HANDLE)
       (_beginthreadex (0, 0x2000, timer_thread_proc, scm_timer, 0, (&id))));
  if (scm_timer -> thread_handle)
    {
      (*state_ptr) = scm_timer;
      return (WIN32_ASYNC_TIMER_OK);
    }
  else
    {
      win32_flush_async_timer (scm_timer);
      return (WIN32_ASYNC_TIMER_EXHAUSTED);
    }
}

static void __cdecl
win32_flush_async_timer (void * state)
{
  if (state != 0)
    {
      struct win32_timer_closure_s * scm_timer = state;
      if (scm_timer -> thread_handle)
	{
	  (scm_timer -> exit_thread) = 1;
	  (void) WaitForSingleObject ((scm_timer -> thread_handle), INFINITE);
	}
      (void) free (state);
    }
}

#define INTERRUPT_CODE(scm_timer)					\
  ((scm_timer -> base) [scm_timer -> int_code_off])

#define INTERRUPT_MASK(scm_timer)					\
  ((scm_timer -> base) [scm_timer -> int_mask_off])

#define MEMTOP(scm_timer)						\
  ((scm_timer -> base) [scm_timer -> memtop_off])

#define CATATONIA_COUNTER(scm_timer)					\
  ((scm_timer -> base) [scm_timer -> ctr_off])

#define CATATONIA_LIMIT(scm_timer)					\
  ((scm_timer -> base) [(scm_timer -> ctr_off) + 1])

#define CATATONIA_FLAG(scm_timer)					\
  ((scm_timer -> base) [(scm_timer -> ctr_off) + 2])

static unsigned int WINAPI
timer_thread_proc (void * envptr)
{
  struct win32_timer_closure_s * scm_timer = envptr;
  while (! (scm_timer -> exit_thread))
    {
      Sleep (scm_timer -> interval);
      (* (scm_timer -> grab_int_regs)) ();
      (INTERRUPT_CODE (scm_timer)) |= (scm_timer -> bit_mask);
      if (((INTERRUPT_CODE (scm_timer)) & (INTERRUPT_MASK (scm_timer))) != 0L)
	{
	  (MEMTOP (scm_timer)) = ((unsigned long) -1L);
	  /* Post an interrupt message to the window.  This forces it to
	     wake up and exit MsgWaitForMultipleObjects if needed.  */
	  (* (scm_timer -> release_int_regs)) ();
	  PostMessage ((scm_timer -> window),
		       (scm_timer -> interrupt_message),
		       ((WPARAM) 0),
		       ((LPARAM) 0));
	}
      else
	(* (scm_timer -> release_int_regs)) ();
      (CATATONIA_COUNTER (scm_timer)) += 1L;
      if (((CATATONIA_COUNTER (scm_timer)) > (CATATONIA_LIMIT (scm_timer)))
	  && ((CATATONIA_LIMIT (scm_timer)) != 0L))
	{
	  if ((CATATONIA_FLAG (scm_timer)) == 0L)
	    {
	      (CATATONIA_FLAG (scm_timer)) = 1L;
	      PostMessage ((scm_timer -> window),
			   (scm_timer -> catatonia_message),
			   ((WPARAM) 0),
			   ((LPARAM) 0));
	    }
	  (CATATONIA_COUNTER (scm_timer)) = 0L;
	}
    }
  return (0);
}

/* These are NOPs in this version. */

static BOOL __cdecl
win32_alloc_scheme_selectors (unsigned long base,
			      unsigned long size,
			      unsigned short * scheme_cs,
			      unsigned short * scheme_ds,
			      unsigned short * scheme_ss)
{
  return (FALSE);
}

static void __cdecl
win32_release_scheme_selectors (unsigned short scheme_cs,
				unsigned short scheme_ds,
				unsigned short scheme_ss)
{
  return;
}


void FAR WINAPI
install_win32_system_utilities (WIN32_SYSTEM_UTILITIES *utils)
{
#define EXPORT(field) utils->field = win32_##field
  EXPORT (under_win32s_p);
  EXPORT (allocate_heap);
  EXPORT (release_heap);
  EXPORT (lock_memory_area);
  EXPORT (unlock_memory_area);
  EXPORT (install_async_timer);
  EXPORT (flush_async_timer);
  EXPORT (alloc_scheme_selectors);
  EXPORT (release_scheme_selectors);
}