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font_cache.c: Optimize and simplify cache search. ~25% font rendering boost

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30763 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Fred Bauer 2011-10-16 20:17:44 +00:00
parent 4f3e1d6b48
commit cd0102ba14
2 changed files with 49 additions and 75 deletions
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118
firmware/font_cache.c
View file

@ -68,92 +68,55 @@ void font_cache_create(
fcache->_index[i] = i; /* small cheat here */ fcache->_index[i] = i; /* small cheat here */
} }
/******************************************************************************* /*************************************************************************
* font_cache_index_of * Binary search that attempts a primary lucky guess that succeeds
******************************************************************************/ * when there are consecutive codes in the cache between previous
static int font_cache_index_of( * search and new search. Returns a negative of insertion point if
struct font_cache* fcache, * not found.
unsigned short char_code) ************************************************************************/
int search( struct font_cache* fcache,
unsigned short char_code,
int *p_insertion_point )
{ {
struct font_cache_entry* p; struct font_cache_entry *p;
int left, right, mid, c; int left, right, mid=-1, c;
left = 0; left = 0;
right = fcache->_size - 1; right = fcache->_size - 1;
/* go for a lucky guess */
if ( fcache->_prev_char_code != -1 )
mid = char_code +
fcache->_prev_result - fcache->_prev_char_code;
/* check bounds or unset */
if ( mid < 0 || mid > right )
mid = ( left + right ) / 2;
do do
{ {
mid = (left + right) / 2;
p = lru_data(&fcache->_lru, fcache->_index[mid]); p = lru_data(&fcache->_lru, fcache->_index[mid]);
c = p->_char_code - char_code; c = p->_char_code - char_code;
if (c == 0) if (c == 0)
return mid; {
fcache->_prev_result = mid;
fcache->_prev_char_code = char_code;
*p_insertion_point = mid;
return 1;
}
if (c < 0) if (c < 0)
left = mid + 1; left = mid + 1;
else else
right = mid - 1; right = mid - 1;
}
while (left <= right);
return -1;
}
/*******************************************************************************
* font_cache_insertion_point
******************************************************************************/
static int font_cache_insertion_point(
struct font_cache* fcache,
unsigned short char_code)
{
struct font_cache_entry* p;
short *index = fcache->_index;
p = lru_data(&fcache->_lru, index[0]);
if (char_code < p->_char_code)
return -1;
p = lru_data(&fcache->_lru, index[fcache->_capacity - 1]);
if (char_code > p->_char_code)
return fcache->_capacity - 1;
int left, right, mid, c;
left = 0;
right = fcache->_capacity - 1;
do
{
mid = (left + right) / 2; mid = (left + right) / 2;
p = lru_data(&fcache->_lru, index[mid]);
c = char_code - p->_char_code;
if (c >= 0)
{
p = lru_data(&fcache->_lru, index[mid+1]);
int z = char_code - p->_char_code;
if (z < 0)
return mid;
if (z == 0)
return mid + 1;
}
if (c > 0)
left = mid + 1;
else
right = mid - 1;
} }
while (left <= right); while (left <= right);
/* not found */ /* not found */
return -2; *p_insertion_point = mid;
return 0;
} }
/******************************************************************************* /*******************************************************************************
* font_cache_get * font_cache_get
******************************************************************************/ ******************************************************************************/
@ -163,23 +126,32 @@ struct font_cache_entry* font_cache_get(
void (*callback) (struct font_cache_entry* p, void *callback_data), void (*callback) (struct font_cache_entry* p, void *callback_data),
void *callback_data) void *callback_data)
{ {
int insertion_point = font_cache_insertion_point(fcache, char_code); struct font_cache_entry* p;
if (insertion_point >= 0) int insertion_point;
int index_to_replace;
if( search(fcache, char_code, &insertion_point))
{ {
short lru_handle = fcache->_index[insertion_point]; short lru_handle = fcache->_index[insertion_point];
struct font_cache_entry* p = lru_data(&fcache->_lru, lru_handle); p = lru_data(&fcache->_lru, lru_handle);
if (p->_char_code == char_code) if (p->_char_code == char_code)
{ {
lru_touch(&fcache->_lru, lru_handle); lru_touch(&fcache->_lru, lru_handle);
return lru_data(&fcache->_lru, lru_handle); return lru_data(&fcache->_lru, lru_handle);
} }
} }
else /* not found */
{
p = lru_data(&fcache->_lru,
fcache->_index[insertion_point+1]);
if ( char_code > p->_char_code )
insertion_point++;
}
/* not found */ /* find index to replace */
short lru_handle_to_replace = fcache->_lru._head; short lru_handle_to_replace = fcache->_lru._head;
struct font_cache_entry* p = p = lru_data(&fcache->_lru, lru_handle_to_replace);
lru_data(&fcache->_lru, lru_handle_to_replace); search(fcache, p->_char_code, &index_to_replace);
int index_to_replace = font_cache_index_of(fcache, p->_char_code);
if (insertion_point < index_to_replace) if (insertion_point < index_to_replace)
{ {
@ -209,7 +181,7 @@ struct font_cache_entry* font_cache_get(
fcache->_size++; fcache->_size++;
p->_char_code = char_code; p->_char_code = char_code;
/* fill bitmap */
callback(p, callback_data); callback(p, callback_data);
return p; return p;
} }

2
firmware/include/font_cache.h
View file

@ -29,6 +29,8 @@ struct font_cache
struct lru _lru; struct lru _lru;
int _size; int _size;
int _capacity; int _capacity;
int _prev_char_code;
int _prev_result;
short *_index; /* index of lru handles in char_code order */ short *_index; /* index of lru handles in char_code order */
}; };