/*      $NetBSD: wsdisplay_glyphcache.c,v 1.14 2024/12/06 11:46:11 macallan Exp $       */

/*
* Copyright (c) 2012 Michael Lorenz
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/*
* a simple glyph cache in offscreen memory
*/

#ifdef _KERNEL_OPT
#include "opt_glyphcache.h"
#endif

#include <sys/systm.h>
#include <sys/atomic.h>
#include <sys/errno.h>
#include <sys/kmem.h>
#include <dev/wscons/wsdisplayvar.h>
#include <dev/rasops/rasops.h>
#include <dev/wscons/wsdisplay_vconsvar.h>
#include <dev/wscons/wsdisplay_glyphcachevar.h>

#ifdef GLYPHCACHE_DEBUG
#define DPRINTF aprint_normal
#else
#define DPRINTF while (0) printf
#endif

#define NBUCKETS 32

static inline int
attr2idx(long attr)
{
       return (((attr >> 16) & 0x0f) | ((attr >> 20) & 0xf0));
}

int
glyphcache_init(glyphcache *gc, int first, int lines, int width,
   int cellwidth, int cellheight, long attr)
{
       return glyphcache_init_align(gc, first, lines, width, cellwidth, cellheight,
           attr, 0);
}

int
glyphcache_init_align(glyphcache *gc, int first, int lines, int width,
   int cellwidth, int cellheight, long attr, int alignment)
{

       /* first the geometry stuff */
       if (lines < 0) lines = 0;
       gc->gc_width = width;
       gc->gc_cellwidth = -1;
       gc->gc_cellheight = -1;
       gc->gc_firstline = first;
       gc->gc_firstcol = 0;
       gc->gc_lines = lines;
       gc->gc_cellalign = alignment;
       gc->gc_buckets = NULL;
       gc->gc_numbuckets = 0;
       // XXX: Never free?
       gc->gc_buckets = kmem_alloc(sizeof(*gc->gc_buckets) * NBUCKETS,
           KM_SLEEP);
       gc->gc_nbuckets = NBUCKETS;
       return glyphcache_reconfig(gc, cellwidth, cellheight, attr);

}

int
glyphcache_init_x(glyphcache *gc, int x, int y, int lines, int width,
   int cellwidth, int cellheight, long attr)
{

       /* first the geometry stuff */
       if (lines < 0) lines = 0;
       gc->gc_width = width;
       gc->gc_cellwidth = -1;
       gc->gc_cellheight = -1;
       gc->gc_firstline = y;
       gc->gc_firstcol = x;
       gc->gc_lines = lines;
       gc->gc_cellalign = 0;
       gc->gc_buckets = NULL;
       gc->gc_numbuckets = 0;
       // XXX: Never free?
       gc->gc_buckets = kmem_alloc(sizeof(*gc->gc_buckets) * NBUCKETS,
           KM_SLEEP);
       gc->gc_nbuckets = NBUCKETS;
       return glyphcache_reconfig(gc, cellwidth, cellheight, attr);

}

int
glyphcache_reconfig(glyphcache *gc, int cellwidth, int cellheight, long attr)
{
       int cache_lines, buckets, i, usedcells = 0, idx;
       gc_bucket *b;

       /* see if we actually need to reconfigure anything */
       if ((gc->gc_cellwidth == cellwidth) &&
           (gc->gc_cellheight == cellheight) &&
           ((gc->gc_buckets != NULL) &&
            (gc->gc_buckets[0].gb_index == attr2idx(attr)))) {
               return 0;
       }

       gc->gc_cellwidth = cellwidth;
       if (gc->gc_cellalign != 0) {
               /* alignment in bytes */
               gc->gc_cellstride =
                   (gc->gc_cellwidth + gc->gc_cellalign - 1) &
                   ~(gc->gc_cellalign - 1);
       } else
               gc->gc_cellstride = cellwidth;
       gc->gc_cellheight = cellheight;

       gc->gc_cellsperline = gc->gc_width / gc->gc_cellstride;

       cache_lines = gc->gc_lines / cellheight;
       gc->gc_numcells = cache_lines * gc->gc_cellsperline;

       /* now allocate buckets */
       buckets = (gc->gc_numcells / 223);
       if ((buckets * 223) < gc->gc_numcells)
               buckets++;

       /*
        * if we don't have enough video memory to cache at least a few glyphs
        * we stop right here
        */
       if (buckets < 1)
               return ENOMEM;

       buckets = uimin(buckets, gc->gc_nbuckets);
       gc->gc_numbuckets = buckets;

       DPRINTF("%s: using %d buckets\n", __func__, buckets);
       for (i = 0; i < buckets; i++) {
               b = &gc->gc_buckets[i];
               b->gb_firstcell = usedcells;
               b->gb_numcells = uimin(223, gc->gc_numcells - usedcells);
               usedcells += 223;
               b->gb_usedcells = 0;
               b->gb_index = -1;
       }

       /* initialize the attribute map... */
       for (i = 0; i < 256; i++) {
               gc->gc_attrmap[i] = -1;
       }

       /* first bucket goes to default attr */
       idx = attr2idx(attr);
       if (idx >= 0) {
               gc->gc_attrmap[idx] = 0;
               gc->gc_buckets[0].gb_index = idx;
       }

       glyphcache_wipe(gc);
       DPRINTF("%s: using %d cells total, from %d width %d\n", __func__,
           gc->gc_numcells, gc->gc_firstline, gc->gc_cellsperline);
       DPRINTF("%s: cell size %d x %d, stride %d\n", __func__,
           gc->gc_cellwidth, gc->gc_cellheight, gc->gc_cellstride);
       return 0;
}

void
glyphcache_adapt(struct vcons_screen *scr, void *cookie)
{
       glyphcache *gc = cookie;
       struct rasops_info *ri = &scr->scr_ri;

       if (ri->ri_wsfcookie != gc->gc_fontcookie) {
               glyphcache_wipe(gc);
               gc->gc_fontcookie = ri->ri_wsfcookie;
       }

       glyphcache_reconfig(gc, ri->ri_font->fontwidth,
                               ri->ri_font->fontheight, scr->scr_defattr);
}

void
glyphcache_wipe(glyphcache *gc)
{
       gc_bucket *b;
       int i, j, idx;

       if ((gc->gc_buckets == NULL) || (gc->gc_numbuckets < 1))
               return;

       idx = gc->gc_buckets[0].gb_index;

       /* empty all the buckets */
       for (i = 0; i < gc->gc_numbuckets; i++) {
               b = &gc->gc_buckets[i];
               b->gb_usedcells = 0;
               b->gb_index = -1;
               for (j = 0; j < b->gb_numcells; j++)
                       b->gb_map[j] = -1;
       }

       for (i = 0; i < 256; i++) {
               gc->gc_attrmap[i] = -1;
       }

       /* now put the first bucket back where it was */
       gc->gc_attrmap[idx] = 0;
       gc->gc_buckets[0].gb_index = idx;
}

/*
* add a glyph drawn at (x,y) to the cache as (c)
* call this only if glyphcache_try() returned GC_ADD
* caller or gc_bitblt must make sure the glyph is actually completely drawn
*/
int
glyphcache_add(glyphcache *gc, int c, int x, int y)
{
       gc_bucket *b = gc->gc_next;
       int cell;
       int cx, cy;

       if (b->gb_usedcells >= b->gb_numcells)
               return ENOMEM;
       cell = atomic_add_int_nv(&b->gb_usedcells, 1) - 1;
       cell += b->gb_firstcell;
       cy = gc->gc_firstline +
           (cell / gc->gc_cellsperline) * gc->gc_cellheight;
       cx = gc->gc_firstcol +
           (cell % gc->gc_cellsperline) * gc->gc_cellstride;
       b->gb_map[c - 33] = (cx << 16) | cy;
       gc->gc_bitblt(gc->gc_blitcookie, x, y, cx, cy,
           gc->gc_cellwidth, gc->gc_cellheight, gc->gc_rop);
       if (gc->gc_underline & 1) {
               glyphcache_underline(gc, x, y, gc->gc_underline);
       }
       return 0;
}

void
glyphcache_underline(glyphcache *gc, int x, int y, long attr)
{
       if (gc->gc_rectfill == NULL)
               return;

       gc->gc_rectfill(gc->gc_blitcookie, x, y + gc->gc_cellheight - 2,
           gc->gc_cellwidth, 1, attr);
}
/*
* check if (c) is in the cache, if so draw it at (x,y)
* return:
* - GC_OK when the glyph was found
* - GC_ADD when the glyph wasn't found but can be added
* - GC_NOPE when the glyph can't be cached
*/
int
glyphcache_try(glyphcache *gc, int c, int x, int y, long attr)
{
       int cell, cx, cy, idx, bi;
       gc_bucket *b;

       idx = attr2idx(attr);
       /* see if we're in range */
       if ((c < 33) || (c > 255) || (idx < 0))
               return GC_NOPE;
       /* see if there's already a bucket for this attribute */
       bi = gc->gc_attrmap[idx];
       if (bi == -1) {
               /* nope, see if there's an empty one left */
               bi = 1;
               while ((bi < gc->gc_numbuckets) &&
                      (gc->gc_buckets[bi].gb_index != -1)) {
                       bi++;
               }
               if (bi < gc->gc_numbuckets) {
                       /* found one -> grab it */
                       gc->gc_attrmap[idx] = bi;
                       b = &gc->gc_buckets[bi];
                       b->gb_index = idx;
                       b->gb_usedcells = 0;
                       /* make sure this doesn't get evicted right away */
                       b->gb_lastread = time_uptime;
               } else {
                       /*
                        * still nothing
                        * steal the least recently read bucket
                        */
                       time_t moo = time_uptime;
                       int i, oldest = 1;

                       for (i = 1; i < gc->gc_numbuckets; i++) {
                               if (gc->gc_buckets[i].gb_lastread < moo) {
                                       oldest = i;
                                       moo = gc->gc_buckets[i].gb_lastread;
                               }
                       }

                       /* if we end up here all buckets must be in use */
                       b = &gc->gc_buckets[oldest];
                       gc->gc_attrmap[b->gb_index] = -1;
                       b->gb_index = idx;
                       b->gb_usedcells = 0;
                       gc->gc_attrmap[idx] = oldest;
                       /* now scrub it */
                       for (i = 0; i < b->gb_numcells; i++)
                               b->gb_map[i] = -1;
                       /* and set the time stamp */
                       b->gb_lastread = time_uptime;
               }
       } else {
               /* found one */
               b = &gc->gc_buckets[bi];
       }

       /* see if there's room in the bucket */
       if (b->gb_usedcells >= b->gb_numcells)
               return GC_NOPE;

       cell = b->gb_map[c - 33];
       if (cell == -1) {
               gc->gc_next = b;
               gc->gc_underline = attr;
               return GC_ADD;
       }

       /* it's in the cache - draw it */
       cy = cell & 0xffff;
       cx = (cell >> 16) & 0xffff;
       gc->gc_bitblt(gc->gc_blitcookie, cx, cy, x, y,
           gc->gc_cellwidth, gc->gc_cellheight, gc->gc_rop);
       /* and underline it if needed */
       if (attr & 1)
               glyphcache_underline(gc, x, y, attr);
       /* update bucket's time stamp */
       b->gb_lastread = time_uptime;
       return GC_OK;
}

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