Remove division from inner loop
Michael Abbott
michael at araneidae.co.uk
Wed Jun 17 04:43:15 CDT 2009
On Wed, 17 Jun 2009, Henri Verbeet wrote:
> 2009/6/16 Michael Abbott <michael at araneidae.co.uk>:
> > - /* The depth data is normalized, so needs to be
> > scaled, the stencil data isn't. */
> Looks like the patch got wrapped. You'll probably want to just attach
> the output of git format-patch.
Oops! Thank you for spotting that. Here's a resubmission. My fault for
pasting into the mailer.
From 1cd94f6e852a53f6c5ad1c2084105a7562229e93 Mon Sep 17 00:00:00 2001
From: Michael Abbott <michael at araneidae.co.uk>
Date: Tue, 16 Jun 2009 16:20:05 +0100
Subject: [PATCH] Remove division from inner loop
When rescaling D15S1 data to D24 data it isn't necessary to do full
arithmetic, instead bit shifts are sufficient.
---
dlls/wined3d/surface.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/dlls/wined3d/surface.c b/dlls/wined3d/surface.c
index 6ab0443..f6c0f8c 100644
--- a/dlls/wined3d/surface.c
+++ b/dlls/wined3d/surface.c
@@ -2461,9 +2461,11 @@ static HRESULT d3dfmt_convert_surface(const BYTE *src, BYTE *dst, UINT pitch, UI
for (x = 0; x < width; ++x)
{
- /* The depth data is normalized, so needs to be scaled, the stencil data isn't. */
- WORD d15 = source[x] & 0xfffe;
- DWORD d24 = d15 * 0x100 + (d15 * 0xff80 + 0x3fff80) / 0x7fff00;
+ /* The depth data is normalized, so needs to be scaled,
+ * the stencil data isn't. Scale depth data by
+ * (2^24-1)/(2^15-1) ~~ (2^9 + 2^-6). */
+ WORD d15 = source[x] >> 1;
+ DWORD d24 = (d15 << 9) + (d15 >> 6);
dest[x] = (d24 << 8) | (source[x] & 0x1);
}
}
--
1.6.0.4
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