view src/xgccache.c @ 2367:ecf1ebac70d8

[xemacs-hg @ 2004-11-04 23:05:23 by ben] commit mega-patch configure.in: Turn off -Winline and -Wchar-subscripts. Use the right set of cflags when compiling modules. Rewrite ldap configuration to separate the inclusion of lber (needed in recent Cygwin) from the basic checks for the needed libraries. add a function for MAKE_JUNK_C; initially code was added to generate xemacs.def using this, but it will need to be rewritten. add an rm -f for junk.c to avoid weird Cygwin bug with cp -f onto an existing file. Sort list of auto-detected functions and eliminate unused checks for stpcpy, setlocale and getwd. Add autodetection of Cygwin scanf problems BETA: Rewrite section on configure to indicate what flags are important and what not. digest-doc.c, make-dump-id.c, profile.c, sorted-doc.c: Add proper decls for main(). make-msgfile.c: Document that this is old junk. Move proposal to text.c. make-msgfile.lex: Move proposal to text.c. make-mswin-unicode.pl: Convert error-generating code so that the entire message will be seen as a single unrecognized token. mule/mule-ccl.el: Update docs. lispref/mule.texi: Update CCL docs. ldap/eldap.c: Mule-ize. Use EXTERNAL_LIST_LOOP_2 instead of deleted EXTERNAL_LIST_LOOP. * XEmacs 21.5.18 "chestnut" is released. --------------------------------------------------------------- MULE-RELATED WORK: --------------------------------------------------------------- --------------------------- byte-char conversion --------------------------- buffer.c, buffer.h, insdel.c, text.c: Port FSF algorithm for byte-char conversion, replacing broken previous version. Track the char position of the gap. Add functions to do char-byte conversion downwards as well as upwards. Move comments about algorithm workings to internals manual. --------------------------- work on types --------------------------- alloc.c, console-x-impl.h, dump-data.c, dump-data.h, dumper.c, dialog-msw.c, dired-msw.c, doc.c, editfns.c, esd.c, event-gtk.h, event-msw.c, events.c, file-coding.c, file-coding.h, fns.c, glyphs-eimage.c, glyphs-gtk.c, glyphs-msw.c, glyphs-shared.c, glyphs-x.c, glyphs.c, glyphs.h, gui.c, hpplay.c, imgproc.c, intl-win32.c, lrecord.h, lstream.c, keymap.c, lisp.h, libsst.c, linuxplay.c, miscplay.c, miscplay.h, mule-coding.c, nas.c, nt.c, ntheap.c, ntplay.c, objects-msw.c, objects-tty.c, objects-x.c, print.c, process-nt.c, process.c, redisplay.h, select-common.h, select-gtk.c, select-x.c, sgiplay.c, sound.c, sound.h, sunplay.c, sysfile.h, sysdep.c, syswindows.h, text.c, unexnt.c, win32.c, xgccache.c: Further work on types. This creates a full set of types for all the basic semantics of `char' that I have so far identified, so that its semantics can always be identified for the purposes of proper Mule-safe code, and the raw use of `char' always avoided. (1) More type renaming, for consistency of naming. Char_ASCII -> Ascbyte UChar_ASCII -> UAscbyte Char_Binary -> CBinbyte UChar_Binary -> Binbyte SChar_Binary -> SBinbyte (2) Introduce Rawbyte, CRawbyte, Boolbyte, Chbyte, UChbyte, and Bitbyte and use them. (3) New types Itext, Wexttext and Textcount for separating out the concepts of bytes and textual units (different under UTF-16 and UTF-32, which are potential internal encodings). (4) qxestr*_c -> qxestr*_ascii. lisp.h: New; goes with other qxe() functions. #### Maybe goes in a different section. lisp.h: Group generic int-type defs together with EMACS_INT defs. lisp.h: * lisp.h (WEXTTEXT_IS_WIDE) New defns. lisp.h: New type to replace places where int occurs as a boolean. It's signed because occasionally people may want to use -1 as an error value, and because unsigned ints are viral -- see comments in the internals manual against using them. dynarr.c: int -> Bytecount. --------------------------- Mule-izing --------------------------- device-x.c: Partially Mule-ize. dumper.c, dumper.h: Mule-ize. Use Rawbyte. Use stderr_out not printf. Use wext_*(). sysdep.c, syswindows.h, text.c: New Wexttext API for manipulation of external text that may be Unicode (e.g. startup code under Windows). emacs.c: Mule-ize. Properly deal with argv in external encoding. Use wext_*() and Wexttext. Use Rawbyte. #if 0 some old junk on SCO that is unlikely to be correct. Rewrite allocation code in run-temacs. emacs.c, symsinit.h, win32.c: Rename win32 init function and call it even earlier, to initialize mswindows_9x_p even earlier, for use in startup code (XEUNICODE_P). process.c: Use _wenviron not environ under Windows, to get Unicode environment variables. event-Xt.c: Mule-ize drag-n-drop related stuff. dragdrop.c, dragdrop.h, frame-x.c: Mule-ize. text.h: Add some more stand-in defines for particular kinds of conversion; use in Mule-ization work in frame-x.c etc. --------------------------- Freshening --------------------------- intl-auto-encap-win32.c, intl-auto-encap-win32.h: Regenerate. --------------------------- Unicode-work --------------------------- intl-win32.c, syswindows.h: Factor out common options to MultiByteToWideChar and WideCharToMultiByte. Add convert_unicode_to_multibyte_malloc() and convert_unicode_to_multibyte_dynarr() and use. Add stuff for alloca() conversion of multibyte/unicode. alloc.c: Use dfc_external_data_len() in case of unicode coding system. alloc.c, mule-charset.c: Don't zero out and reinit charset Unicode tables. This fucks up dump-time loading. Anyway, either we load them at dump time or run time, never both. unicode.c: Dump the blank tables as well. --------------------------------------------------------------- DOCUMENTATION, MOSTLY MULE-RELATED: --------------------------------------------------------------- EmacsFrame.c, emodules.c, event-Xt.c, fileio.c, input-method-xlib.c, mule-wnnfns.c, redisplay-gtk.c, redisplay-tty.c, redisplay-x.c, regex.c, sysdep.c: Add comment about Mule work needed. text.h: Add more documentation describing why DFC routines were not written to return their value. Add some other DFC documentation. console-msw.c, console-msw.h: Add pointer to docs in win32.c. emacs.c: Add comments on sources of doc info. text.c, charset.h, unicode.c, intl-win32.c, intl-encap-win32.c, text.h, file-coding.c, mule-coding.c: Collect background comments and related to text matters and internationalization, and proposals for work to be done, in text.c or Internals manual, stuff related to specific textual API's in text.h, and stuff related to internal implementation of Unicode conversion in unicode.c. Put lots of pointers to the comments to make them easier to find. s/mingw32.h, s/win32-common.h, s/win32-native.h, s/windowsnt.h, win32.c: Add bunches of new documentation on the different kinds of builds and environments under Windows and how they work. Collect this info in win32.c. Add pointers to these docs in the relevant s/* files. emacs.c: Document places with long comments. Remove comment about exiting, move to internals manual, put in pointer. event-stream.c: Move docs about event queues and focus to internals manual, put in pointer. events.h: Move docs about event stream callbacks to internals manual, put in pointer. profile.c, redisplay.c, signal.c: Move documentation to the Internals manual. process-nt.c: Add pointer to comment in win32-native.el. lisp.h: Add comments about some comment conventions. lisp.h: Add comment about the second argument. device-msw.c, redisplay-msw.c: @@#### comments are out-of-date. --------------------------------------------------------------- PDUMP WORK (MOTIVATED BY UNICODE CHANGES) --------------------------------------------------------------- alloc.c, buffer.c, bytecode.c, console-impl.h, console.c, device.c, dumper.c, lrecord.h, elhash.c, emodules.h, events.c, extents.c, frame.c, glyphs.c, glyphs.h, mule-charset.c, mule-coding.c, objects.c, profile.c, rangetab.c, redisplay.c, specifier.c, specifier.h, window.c, lstream.c, file-coding.h, file-coding.c: PDUMP: Properly implement dump_add_root_block(), which never worked before, and is necessary for dumping Unicode tables. Pdump name changes for accuracy: XD_STRUCT_PTR -> XD_BLOCK_PTR. XD_STRUCT_ARRAY -> XD_BLOCK_ARRAY. XD_C_STRING -> XD_ASCII_STRING. *_structure_* -> *_block_*. lrecord.h: some comments added about dump_add_root_block() vs dump_add_root_block_ptr(). extents.c: remove incorrect comment about pdump problems with gap array. --------------------------------------------------------------- ALLOCATION --------------------------------------------------------------- abbrev.c, alloc.c, bytecode.c, casefiddle.c, device-msw.c, device-x.c, dired-msw.c, doc.c, doprnt.c, dragdrop.c, editfns.c, emodules.c, file-coding.c, fileio.c, filelock.c, fns.c, glyphs-eimage.c, glyphs-gtk.c, glyphs-msw.c, glyphs-x.c, gui-msw.c, gui-x.c, imgproc.c, intl-win32.c, lread.c, menubar-gtk.c, menubar.c, nt.c, objects-msw.c, objects-x.c, print.c, process-nt.c, process-unix.c, process.c, realpath.c, redisplay.c, search.c, select-common.c, symbols.c, sysdep.c, syswindows.h, text.c, text.h, ui-byhand.c: New macros {alloca,xnew}_{itext,{i,ext,raw,bin,asc}bytes} for more convenient allocation of these commonly requested items. Modify functions to use alloca_ibytes, alloca_array, alloca_extbytes, xnew_ibytes, etc. also XREALLOC_ARRAY, xnew. alloc.c: Rewrite the allocation functions to factor out repeated code. Add assertions for freeing dumped data. lisp.h: Moved down and consolidated with other allocation stuff. lisp.h, dynarr.c: New functions for allocation that's very efficient when mostly in LIFO order. lisp.h, text.c, text.h: Factor out some stuff for general use by alloca()-conversion funs. text.h, lisp.h: Fill out convenience routines for allocating various kinds of bytes and put them in lisp.h. Use them in place of xmalloc(), ALLOCA(). text.h: Fill out the convenience functions so the _MALLOC() kinds match the alloca() kinds. --------------------------------------------------------------- ERROR-CHECKING --------------------------------------------------------------- text.h: Create ASSERT_ASCTEXT_ASCII() and ASSERT_ASCTEXT_ASCII_LEN() from similar Eistring checkers and change the Eistring checkers to use them instead. --------------------------------------------------------------- MACROS IN LISP.H --------------------------------------------------------------- lisp.h: Redo GCPRO declarations. Create a "base" set of functions that can be used to generate any kind of gcpro sets -- regular, ngcpro, nngcpro, private ones used in GC_EXTERNAL_LIST_LOOP_2. buffer.c, callint.c, chartab.c, console-msw.c, device-x.c, dialog-msw.c, dired.c, extents.c, ui-gtk.c, rangetab.c, nt.c, mule-coding.c, minibuf.c, menubar-msw.c, menubar.c, menubar-gtk.c, lread.c, lisp.h, gutter.c, glyphs.c, glyphs-widget.c, fns.c, fileio.c, file-coding.c, specifier.c: Eliminate EXTERNAL_LIST_LOOP, which does not check for circularities. Use EXTERNAL_LIST_LOOP_2 instead or EXTERNAL_LIST_LOOP_3 or EXTERNAL_PROPERTY_LIST_LOOP_3 or GC_EXTERNAL_LIST_LOOP_2 (new macro). Removed/redid comments on EXTERNAL_LIST_LOOP. --------------------------------------------------------------- SPACING FIXES --------------------------------------------------------------- callint.c, hftctl.c, number-gmp.c, process-unix.c: Spacing fixes. --------------------------------------------------------------- FIX FOR GEOMETRY PROBLEM IN FIRST FRAME --------------------------------------------------------------- unicode.c: Add workaround for newlib bug in sscanf() [should be fixed by release 1.5.12 of Cygwin]. toolbar.c: bug fix for problem of initial frame being 77 chars wide on Windows. will be overridden by my other ws. --------------------------------------------------------------- FIX FOR LEAKING PROCESS HANDLES: --------------------------------------------------------------- process-nt.c: Fixes for leaking handles. Inspired by work done by Adrian Aichner <adrian@xemacs.org>. --------------------------------------------------------------- FIX FOR CYGWIN BUG (Unicode-related): --------------------------------------------------------------- unicode.c: Add workaround for newlib bug in sscanf() [should be fixed by release 1.5.12 of Cygwin]. --------------------------------------------------------------- WARNING FIXES: --------------------------------------------------------------- console-stream.c: `reinit' is unused. compiler.h, event-msw.c, frame-msw.c, intl-encap-win32.c, text.h: Add stuff to deal with ANSI-aliasing warnings I got. regex.c: Gather includes together to avoid warning. --------------------------------------------------------------- CHANGES TO INITIALIZATION ROUTINES: --------------------------------------------------------------- buffer.c, emacs.c, console.c, debug.c, device-x.c, device.c, dragdrop.c, emodules.c, eval.c, event-Xt.c, event-gtk.c, event-msw.c, event-stream.c, event-tty.c, events.c, extents.c, faces.c, file-coding.c, fileio.c, font-lock.c, frame-msw.c, glyphs-widget.c, glyphs.c, gui-x.c, insdel.c, lread.c, lstream.c, menubar-gtk.c, menubar-x.c, minibuf.c, mule-wnnfns.c, objects-msw.c, objects.c, print.c, scrollbar-x.c, search.c, select-x.c, text.c, undo.c, unicode.c, window.c, symsinit.h: Call reinit_*() functions directly from emacs.c, for clarity. Factor out some redundant init code. Move disallowed stuff that had crept into vars_of_glyphs() into complex_vars_of_glyphs(). Call init_eval_semi_early() from eval.c not in the middle of vars_of_() in emacs.c since there should be no order dependency in the latter calls. --------------------------------------------------------------- ARMAGEDDON: --------------------------------------------------------------- alloc.c, emacs.c, lisp.h, print.c: Rename inhibit_non_essential_printing_operations to inhibit_non_essential_conversion_operations. text.c: Assert on !inhibit_non_essential_conversion_operations. console-msw.c, print.c: Don't do conversion in SetConsoleTitle or FindWindow to avoid problems during armageddon. Put #errors for NON_ASCII_INTERNAL_FORMAT in places where problems would arise. --------------------------------------------------------------- CHANGES TO THE BUILD PROCEDURE: --------------------------------------------------------------- config.h.in, s/cxux.h, s/usg5-4-2.h, m/powerpc.h: Add comment about correct ordering of this file. Rearrange everything to follow this -- put all #undefs together and before the s&m files. Add undefs for HAVE_ALLOCA, C_ALLOCA, BROKEN_ALLOCA_IN_FUNCTION_CALLS, STACK_DIRECTION. Remove unused HAVE_STPCPY, HAVE_GETWD, HAVE_SETLOCALE. m/gec63.h: Deleted; totally broken, not used at all, not in FSF. m/7300.h, m/acorn.h, m/alliant-2800.h, m/alliant.h, m/altos.h, m/amdahl.h, m/apollo.h, m/att3b.h, m/aviion.h, m/celerity.h, m/clipper.h, m/cnvrgnt.h, m/convex.h, m/cydra5.h, m/delta.h, m/delta88k.h, m/dpx2.h, m/elxsi.h, m/ews4800r.h, m/gould.h, m/hp300bsd.h, m/hp800.h, m/hp9000s300.h, m/i860.h, m/ibmps2-aix.h, m/ibmrs6000.h, m/ibmrt-aix.h, m/ibmrt.h, m/intel386.h, m/iris4d.h, m/iris5d.h, m/iris6d.h, m/irist.h, m/isi-ov.h, m/luna88k.h, m/m68k.h, m/masscomp.h, m/mg1.h, m/mips-nec.h, m/mips-siemens.h, m/mips.h, m/news.h, m/nh3000.h, m/nh4000.h, m/ns32000.h, m/orion105.h, m/pfa50.h, m/plexus.h, m/pmax.h, m/powerpc.h, m/pyrmips.h, m/sequent-ptx.h, m/sequent.h, m/sgi-challenge.h, m/symmetry.h, m/tad68k.h, m/tahoe.h, m/targon31.h, m/tekxd88.h, m/template.h, m/tower32.h, m/tower32v3.h, m/ustation.h, m/vax.h, m/wicat.h, m/xps100.h: Delete C_ALLOCA, HAVE_ALLOCA, STACK_DIRECTION, BROKEN_ALLOCA_IN_FUNCTION_CALLS. All of this is auto-detected. When in doubt, I followed recent FSF sources, which also have these things deleted.
author ben
date Thu, 04 Nov 2004 23:08:28 +0000
parents a8d8f419b459
children 3d8143fc88e1
line wrap: on
line source

/* Efficient caching of X GCs (graphics contexts).
   Copyright (C) 1993 Free Software Foundation, Inc.
   Copyright (C) 1994, 1995 Board of Trustees, University of Illinois.

This file is part of XEmacs.

XEmacs 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, or (at your option) any
later version.

XEmacs 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 XEmacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Synched up with: Not in FSF. */

/* Emacs uses a lot of different display attributes; for example, assume
   that only four fonts are in use (normal, bold, italic, and bold-italic).
   Then assume that one stipple or background is used for text selections,
   and another is used for highlighting mousable regions.  That makes 16
   GCs already.  Add in the fact that another GC may be needed to display
   the text cursor in any of those regions, and you've got 32.  Add in
   more fonts, and it keeps increasing exponentially.

   We used to keep these GCs in a cache of merged (fully qualified) faces.
   However, a lot of other code in xterm.c used XChangeGC of existing GCs,
   which is kind of slow and kind of random.  Also, managing the face cache
   was tricky because it was hard to know when a face was no longer visible
   on the frame -- we had to mark all frames as garbaged whenever a face
   was changed, which caused an unpleasant amount of flicker (since faces are
   created/destroyed (= changed) whenever a frame is created/destroyed.

   So this code maintains a cache at the GC level instead of at the face
   level.  There is an upper limit on the size of the cache, after which we
   will stop creating GCs and start reusing them (reusing the least-recently-
   used ones first).  So if faces get changed, their GCs will eventually be
   recycled.  Also more sharing of GCs is possible.

   This code uses hash tables.  It could be that, if the cache size is small
   enough, a linear search might be faster; but I doubt it, since we need
   `equal' comparisons, not `eq', and I expect that the optimal cache size
   will be ~100.

   Written by jwz, 14 jun 93
 */

#include <config.h>
#include <X11/Xlib.h>
#include "xgccache.h"


#define GC_CACHE_SIZE 100

#define GCCACHE_HASH


#ifdef GCCACHE_HASH
#include "lisp.h"
#include "hash.h"
#endif

struct gcv_and_mask {
  XGCValues gcv;
  unsigned long mask;
};

struct gc_cache_cell {
  GC gc;
  struct gcv_and_mask gcvm;
  struct gc_cache_cell *prev, *next;
};

struct gc_cache {
  Display *dpy;		/* used only as arg to XCreateGC/XFreeGC */
  Window window;	/* used only as arg to XCreateGC */
  int size;
  struct gc_cache_cell *head;
  struct gc_cache_cell *tail;
#ifdef GCCACHE_HASH
  struct hash_table *table;
#endif

  int create_count;
  int delete_count;
};

#ifdef GCCACHE_HASH
static unsigned long
gc_cache_hash (const void *arg)
{
  const struct gcv_and_mask *gcvm = (const struct gcv_and_mask *) arg;
  unsigned long *longs = (unsigned long *) &gcvm->gcv;
  unsigned long hash = gcvm->mask;
  int i;
  /* This could look at the mask and only use the used slots in the
     hash code.  That would win in that we wouldn't have to initialize
     every slot of the gcv when calling gc_cache_lookup.  But we need
     the hash function to be as fast as possible; some timings should
     be done. */
  for (i = 0; i < (int) (sizeof (XGCValues) / sizeof (unsigned long)); i++)
    hash = (hash<<1) ^ *longs++;
  return hash;
}

#endif /* GCCACHE_HASH */

static int
gc_cache_eql (const void *arg1, const void *arg2)
{
  /* See comment in gc_cache_hash */
  return !memcmp (arg1, arg2, sizeof (struct gcv_and_mask));
}

struct gc_cache *
make_gc_cache (Display *dpy, Window window)
{
  struct gc_cache *cache = xnew (struct gc_cache);
  cache->dpy = dpy;
  cache->window = window;
  cache->size = 0;
  cache->head = cache->tail = 0;
  cache->create_count = cache->delete_count = 0;
#ifdef GCCACHE_HASH
  cache->table =
    make_general_hash_table (GC_CACHE_SIZE, gc_cache_hash, gc_cache_eql);
#endif
  return cache;
}

void
free_gc_cache (struct gc_cache *cache)
{
  struct gc_cache_cell *rest, *next;
  rest = cache->head;
  while (rest)
    {
      XFreeGC (cache->dpy, rest->gc);
      next = rest->next;
      xfree (rest, struct gc_cache_cell *);
      rest = next;
    }
#ifdef GCCACHE_HASH
  free_hash_table (cache->table);
#endif
  xfree (cache, struct gc_cache *);
}

GC
gc_cache_lookup (struct gc_cache *cache, XGCValues *gcv, unsigned long mask)
{
  struct gc_cache_cell *cell, *next, *prev;
  struct gcv_and_mask gcvm;

  if ((!!cache->head) != (!!cache->tail)) abort ();
  if (cache->head && (cache->head->prev || cache->tail->next)) abort ();

  gcvm.mask = mask;
  gcvm.gcv = *gcv;	/* this copies... */

#ifdef GCCACHE_HASH

  /* The intermediate cast fools gcc into not outputting strict-aliasing
     complaints */
  if (gethash (&gcvm, cache->table, (const void **) (void *) &cell))

#else /* !GCCACHE_HASH */

  cell = cache->tail;	/* start at the end (most recently used) */
  while (cell)
    {
      if (gc_cache_eql (&gcvm, &cell->gcvm))
	break;
      else
	cell = cell->prev;
    }

  /* #### This whole file needs some serious overhauling. */
  if (!(mask | GCTile) && cell->gc->values.tile)
    cell = 0;
  else if (!(mask | GCStipple) && cell->gc->values.stipple)
    cell = 0;

  if (cell)

#endif /* !GCCACHE_HASH */

    {
      /* Found a cell.  Move this cell to the end of the list, so that it
	 will be less likely to be collected than a cell that was accessed
	 less recently.
       */
      if (cell == cache->tail)
	return cell->gc;

      next = cell->next;
      prev = cell->prev;
      if (prev) prev->next = next;
      if (next) next->prev = prev;
      if (cache->head == cell) cache->head = next;
      cell->next = 0;
      cell->prev = cache->tail;
      cache->tail->next = cell;
      cache->tail = cell;
      if (cache->head == cell) abort ();
      if (cell->next) abort ();
      if (cache->head->prev) abort ();
      if (cache->tail->next) abort ();
      return cell->gc;
    }

  /* else, cache miss. */

  if (cache->size == GC_CACHE_SIZE)
    /* Reuse the first cell on the list (least-recently-used).
       Remove it from the list, and unhash it from the table.
     */
    {
      cell = cache->head;
      cache->head = cell->next;
      cache->head->prev = 0;
      if (cache->tail == cell) cache->tail = 0; /* only one */
      XFreeGC (cache->dpy, cell->gc);
      cache->delete_count++;
#ifdef GCCACHE_HASH
      remhash (&cell->gcvm, cache->table);
#endif
    }
  else if (cache->size > GC_CACHE_SIZE)
    abort ();
  else
    {
      /* Allocate a new cell (don't put it in the list or table yet). */
      cell = xnew (struct gc_cache_cell);
      cache->size++;
    }

  /* Now we've got a cell (new or reused).  Fill it in. */
  memcpy (&cell->gcvm.gcv, gcv, sizeof (XGCValues));
  cell->gcvm.mask = mask;

  /* Put the cell on the end of the list. */
  cell->next = 0;
  cell->prev = cache->tail;
  if (cache->tail) cache->tail->next = cell;
  cache->tail = cell;
  if (! cache->head) cache->head = cell;

  cache->create_count++;
#ifdef GCCACHE_HASH
  /* Hash it in the table */
  puthash (&cell->gcvm, cell, cache->table);
#endif

  /* Now make and return the GC. */
  cell->gc = XCreateGC (cache->dpy, cache->window, mask, gcv);

  /* debug */
  assert (cell->gc == gc_cache_lookup (cache, gcv, mask));

  return cell->gc;
}


#ifdef DEBUG_XEMACS

void describe_gc_cache (struct gc_cache *cache);
void
describe_gc_cache (struct gc_cache *cache)
{
  int count = 0;
  struct gc_cache_cell *cell = cache->head;
  stderr_out ("\nsize:    %d", cache->size);
  stderr_out ("\ncreated: %d", cache->create_count);
  stderr_out ("\ndeleted: %d", cache->delete_count);
  while (cell)
  {
    struct gc_cache_cell *cell2;
    int i = 0;
    stderr_out ("\n%d:\t0x%lx  GC: 0x%08lx  hash: 0x%08lx\n",
	     count, (long) cell, (long) cell->gc, gc_cache_hash (&cell->gcvm));
    for (cell2 = cache->head; cell2; cell2 = cell2->next, i++)
      if (count != i &&
	  gc_cache_hash (&cell->gcvm) == gc_cache_hash (&cell2->gcvm))
	stderr_out ("\tHASH COLLISION with cell %d\n", i);
    stderr_out ("\tmask:       %8lx\n", cell->gcvm.mask);

#define FROB(field) do {						\
  if ((int)cell->gcvm.gcv.field != (~0))				\
    stderr_out ("\t%-12s%8x\n", #field ":", (int)cell->gcvm.gcv.field);	\
} while (0)
    FROB (function);
    FROB (plane_mask);
    FROB (foreground);
    FROB (background);
    FROB (line_width);
    FROB (line_style);
    FROB (cap_style);
    FROB (join_style);
    FROB (fill_style);
    FROB (fill_rule);
    FROB (arc_mode);
    FROB (tile);
    FROB (stipple);
    FROB (ts_x_origin);
    FROB (ts_y_origin);
    FROB (font);
    FROB (subwindow_mode);
    FROB (graphics_exposures);
    FROB (clip_x_origin);
    FROB (clip_y_origin);
    FROB (clip_mask);
    FROB (dash_offset);
#undef FROB

    count++;
    if (cell->next && cell == cache->tail)
      stderr_out ("\nERROR!  tail is here!\n\n");
    else if (!cell->next && cell != cache->tail)
      stderr_out ("\nERROR!  tail is not at the end\n\n");
    cell = cell->next;
  }
  if (count != cache->size)
    stderr_out ("\nERROR!  count should be %d\n\n", cache->size);
}

#endif /* DEBUG_XEMACS */