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#include <stdio.h>
#include "defs.h"
#include "global.h"
struct openfont_list {
struct font_entry *openfont_entry; /* font entry */
int use_count; /* count of "opens" */
int last_use;
} openfont_files[MAXOPEN]; /* list of open FNT file identifiers */
int nopen = 0; /* number of open FNT files */
int openfont_time = 0;
int priority(int i);
void
openfontfile(fe)
struct font_entry *fe;
/***********************************************************************
The original version of this dvi driver reopened the font file each
time the font changed, resulting in an enormous number of relatively
expensive file openings. This version keeps a cache of up to
MAXOPEN open files, so that when a font change is made, the file
pointer, fntfp, can usually be updated from the cache. When the
file is not found in the cache, it must be opened. In this case,
the next empty slot in the cache is assigned, or if the cache is
full, the least used font file is closed and its slot reassigned for
the new file. Identification of the least used file is based on the
counts of the number of times each file has been "opened" by this
routine. On return, the file pointer is always repositioned to the
beginning of the file.
***********************************************************************/
{
int i, least_used, current;
struct openfont_list *curopen;
int prio;
struct font_entry *lu_fe;
FILE *fntfp;
#ifdef DEBUG
/*if (Debug) (void)fprintf(stderr, "Open Font file\n");*/
#endif
openfont_time++;
if ((fntfp = fe->openfile) != NO_FILE) { /* file already open */
(void)fseek(fntfp, 0L, SEEK_SET); /* reposition to start of file */
curopen = fe->openlist;
#ifdef STATS
if (Stats)
(void)fprintf(stderr, "FNT file %s already open.\n", fe->name);
#endif
} else {
if (nopen < MAXOPEN) /* just add it to list */
current = nopen++;
else { /* list full -- find least used file, */
/* close it, and reuse slot for new file */
least_used = 0;
prio = priority(least_used);
for (i = 1; i < MAXOPEN; ++i)
if (prio > priority(i))
prio = priority(least_used = i);
lu_fe = openfont_files[least_used].openfont_entry;
#ifdef STATS
if (Stats)
(void)fprintf(stderr, "FNT file %s closed.\n", lu_fe->name);
#endif
(void)fclose(lu_fe->openfile);
lu_fe->openfile = NO_FILE;
current = least_used;
}
if ((fe->openfile = BINARYOPEN(fe->name)) == NULL) {
Fatal("FNT file %s could not be opened", fe->name);
} else {
#ifdef STATS
if (Stats)
(void)fprintf(stderr, "FNT file %s opened.\n", fe->name);
#endif
}
fe->openlist = curopen = &openfont_files[current];
curopen->openfont_entry = fe;
curopen->use_count = 0;
}
curopen->use_count++; /* update reference count */
curopen->last_use = openfont_time;
}
int
priority(i)
int i;
{
return (openfont_files[i].use_count -
(openfont_time-openfont_files[i].last_use));
}
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