[cairo] [patch] Accelerate CAIRO_BITSWAP8 on 64 bit machines

[Xing, Dongsheng]

> > From: Chris Wilson
> > Sent: Tuesday, May 29, 2012 3:25 PM
> > To: Xing, Dongsheng; cairo at cairographics.org
> > Subject: Re: [cairo] [patch] Accelerate CAIRO_BITSWAP8 on 64 bit 
> > machines
> > 
> > > On Tue, 29 May 2012 02:03:58 +0000, "Xing, Dongsheng" wrote:
> > > > Hi, CAIRO_BITSWAP8 costs seven operations on a 32 bit machine, 
> > > > but it can be done with only four operations on 64 bit machines.
> > > > This patch accelerates CAIRO_BITSWAP8 on 64 bit machines.
> > >
> > > This doesn't apply to master. Care to resend?
> 
> It justs means that the parent of this patch is not known upstream and by my repository so git can not reconstruct the right patch for me.
> > > A more appropriate test here would be that "SIZEOF_LONG_LONG >= 8" as that is the condition used in the macro.
> 
> > I think SIZEOF_LONG >= 8 is better. Because sizeof(long long)==8 on a 32 bit machine. And SIZEOF_LONG is the length of a native processor word.
> Ok, if we can use SIZEOF_LONG here, wouuld 0x80200802LU suffice?
> -Chris

Sorry. My last email is interpreted WRONG by the mail server. Hence I send the mail again.

To Chris: Yes, 0x80200802LU is suffice. The patch has been modified accordingly. The patch is now known upstream.

To Zhigang: I am installing Visual Studio Express 2011 64bits on Windows. I will verify whether sizeof(long)==4 on Windows 64.

Best regards,
Dongsheng

Signed-off-by: Dongsheng Xing <dongsheng.xing at intel.com>
---
 src/cairoint.h |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/cairoint.h b/src/cairoint.h index 2c9f2dd..96e2c1f 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -169,7 +169,11 @@ do {					\
  * Devised by Sean Anderson, July 13, 2001.
  * Source: http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith32Bits
  */
+#if (SIZEOF_LONG >= 8)
+#define CAIRO_BITSWAP8(c) ((((c) * 0x80200802LU & 0x884422110LU) * 
+0x101010101LU) >> 32) #else
 #define CAIRO_BITSWAP8(c) ((((c) * 0x0802LU & 0x22110LU) | ((c) * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16)
+#endif
 
 /* Return the number of 1 bits in mask.
  *
--
1.7.9.5