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From: Christophe Jaillet [mailto:christophe.jaillet@wanadoo.fr]

Browse Source 
Sent: Wed 9/24/2008 2:00 PM
To: submit@mamedev.org
Subject: Speed up fillbitmap
Hi,

there are many places in mame which make use of "fill_bitmap" or the
equivalent "fillbitmap"

An optimisation is done when the depth of the bitmap is 16 or 32 bpp and
when the UINT16 or UINT32 corresponding to the color is composed of same
bytes (i.e 0xffff for example). This is usefull because most of the calls
are for color 0 (black).

In all other cases, the bitmap is filled one pixel at a time using a loop
with a code like :
================
    for (y = fill.min_y; y <= fill.max_y; y++)
    {
     UINT16 *destrow = BITMAP_ADDR16(dest, y, 0);
     for (x = fill.min_x; x <= fill.max_x; x++)
      destrow[x] = (UINT16)color;
    }

================


However, each rows of the final bitmap will be the same. So I modified this
simple assigned to work as follow :
    1) fill the first row one pixel at a time
    2) fill all the other rows by copying the first one.
This makes us use memcpy instead of a hard coded loop for most of the
filling process.
This commit is contained in:
Aaron Giles 2008-09-26 05:31:34 +00:00
parent 07d208cbbd
commit 0f775dc84e
1 changed files with 24 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/lib/util/bitmap.c
View File

@ -198,11 +198,19 @@ void bitmap_fill(bitmap_t *dest, const rectangle *cliprect, UINT32 color)
}
else
{
for (y = fill.min_y; y <= fill.max_y; y++)
UINT16 *destrow, *destrow0;
/* Fill the first line the hard way */
destrow = BITMAP_ADDR16(dest, fill.min_y, 0);
for (x = fill.min_x; x <= fill.max_x; x++)
destrow[x] = (UINT16)color;
/* For the other lines, just copy the first one */
destrow0 = BITMAP_ADDR16(dest, fill.min_y, fill.min_x);
for (y = fill.min_y + 1; y <= fill.max_y; y++)
{
UINT16 *destrow = BITMAP_ADDR16(dest, y, 0);
for (x = fill.min_x; x <= fill.max_x; x++)
destrow[x] = (UINT16)color;
destrow = BITMAP_ADDR16(dest, y, fill.min_x);
memcpy(destrow, destrow0, (fill.max_x + 1 - fill.min_x) * 2);
}
}
break;
@ -216,11 +224,19 @@ void bitmap_fill(bitmap_t *dest, const rectangle *cliprect, UINT32 color)
}
else
{
for (y = fill.min_y; y <= fill.max_y; y++)
UINT32 *destrow, *destrow0;
/* Fill the first line the hard way */
destrow = BITMAP_ADDR32(dest, fill.min_y, 0);
for (x = fill.min_x; x <= fill.max_x; x++)
destrow[x] = (UINT32)color;
/* For the other lines, just copy the first one */
destrow0 = BITMAP_ADDR32(dest, fill.min_y, fill.min_x);
for (y = fill.min_y + 1; y <= fill.max_y; y++)
{
UINT32 *destrow = BITMAP_ADDR32(dest, y, 0);
for (x = fill.min_x; x <= fill.max_x; x++)
destrow[x] = (UINT32)color;
destrow = BITMAP_ADDR32(dest, y, fill.min_x);
memcpy(destrow, destrow0, (fill.max_x + 1 - fill.min_x) * 4);
}
}
break;