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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
*
* Copyright (C) 2003 Tat Tang
*
* 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <string.h>
#include "font_cache.h"
#include "debug.h"
/*******************************************************************************
* font_cache_lru_init
******************************************************************************/
static void font_cache_lru_init(void* data)
{
struct font_cache_entry* p = data;
p->_char_code = 0xffff; /* assume invalid char */
}
/*******************************************************************************
* font_cache_create
******************************************************************************/
void font_cache_create(
struct font_cache* fcache,
void *buf,
int buf_size,
int bitmap_bytes_size)
{
int font_cache_entry_size =
sizeof(struct font_cache_entry) + bitmap_bytes_size;
/* make sure font cache entries are a multiple of 16 bits */
if (font_cache_entry_size % 2 != 0)
font_cache_entry_size++;
int cache_size = buf_size /
(font_cache_entry_size + LRU_SLOT_OVERHEAD + sizeof(short));
fcache->_size = 1;
fcache->_capacity = cache_size;
fcache->_prev_result = 0;
fcache->_prev_char_code = 0;
/* set up index */
fcache->_index = buf;
/* set up lru list */
unsigned char* lru_buf = buf;
lru_buf += sizeof(short) * cache_size;
lru_create(&fcache->_lru, lru_buf, cache_size, font_cache_entry_size);
/* initialise cache */
lru_traverse(&fcache->_lru, font_cache_lru_init);
short i;
for (i = 0; i < cache_size; i++)
fcache->_index[i] = i; /* small cheat here */
}
/*************************************************************************
* Binary search that attempts a primary lucky guess that succeeds
* when there are consecutive codes in the cache between previous
* search and new search. Returns a negative of insertion point if
* not found.
************************************************************************/
static int search(struct font_cache* fcache,
unsigned short char_code,
int size,
int *p_insertion_point )
{
struct font_cache_entry *p;
int left, right, mid=-1, c;
left = 0;
right = size;
/* go for a lucky guess */
mid = char_code +
fcache->_prev_result - fcache->_prev_char_code;
/* check bounds */
if ( mid < 0 || mid > right )
mid = ( left + right ) / 2;
do
{
p = lru_data(&fcache->_lru, fcache->_index[mid]);
c = p->_char_code - char_code;
if (c == 0)
{
fcache->_prev_result = mid;
fcache->_prev_char_code = char_code;
*p_insertion_point = mid;
return 1;
}
if (c < 0)
left = mid + 1;
else
right = mid - 1;
mid = (left + right) / 2;
}
while (left <= right);
/* not found */
*p_insertion_point = mid;
return 0;
}
/*******************************************************************************
* font_cache_get
******************************************************************************/
struct font_cache_entry* font_cache_get(
struct font_cache* fcache,
unsigned short char_code,
bool cache_only,
void (*callback) (struct font_cache_entry* p, void *callback_data),
void *callback_data)
{
struct font_cache_entry* p;
int insertion_point;
int index_to_replace;
/* check bounds */
p = lru_data(&fcache->_lru, fcache->_index[0]);
if( char_code < p->_char_code )
insertion_point = -1;
else
{
p = lru_data(&fcache->_lru, fcache->_index[fcache->_capacity - 1]);
if( char_code > p->_char_code )
{
insertion_point = fcache->_capacity - 1;
}
else
{
if( search(fcache, char_code, fcache->_size - 1, &insertion_point))
{
short lru_handle = fcache->_index[insertion_point];
p = lru_data(&fcache->_lru, lru_handle);
if (p->_char_code == char_code)
{
lru_touch(&fcache->_lru, lru_handle);
return lru_data(&fcache->_lru, lru_handle);
}
}
else
{
p = lru_data(&fcache->_lru,
fcache->_index[insertion_point+1]);
if ( char_code > p->_char_code )
insertion_point++;
}
}
}
/* not found */
if (cache_only)
return NULL;
/* find index to replace */
short lru_handle_to_replace = fcache->_lru._head;
p = lru_data(&fcache->_lru, lru_handle_to_replace);
search(fcache, p->_char_code, fcache->_size - 1, &index_to_replace);
if (insertion_point < index_to_replace)
{
/* shift memory up */
memmove(fcache->_index + insertion_point + 2,
fcache->_index + insertion_point + 1,
(index_to_replace - insertion_point - 1) * sizeof(short));
/* add to index */
fcache->_index[insertion_point + 1] = lru_handle_to_replace;
}
else if (insertion_point > index_to_replace)
{
/* shift memory down */
memmove(fcache->_index + index_to_replace,
fcache->_index + index_to_replace + 1,
(insertion_point - index_to_replace) * sizeof(short));
/* add to index */
fcache->_index[insertion_point] = lru_handle_to_replace;
}
/* load new entry into cache */
lru_touch(&fcache->_lru, lru_handle_to_replace);
if (fcache->_size < fcache->_capacity)
fcache->_size++;
p->_char_code = char_code;
/* fill bitmap */
callback(p, callback_data);
return p;
}
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