Bug 16128

Summary:	optimize swap functions/speed improvement possible
Product:	cairo	Reporter:	Arnaud Charlet <charlet>
Component:	xlib backend	Assignee:	Carl Worth <cworth>
Status:	RESOLVED FIXED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	enhancement
Priority:	medium
Version:	1.6.4
Hardware:	All
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	test program with various byteswap implementations

Description Arnaud Charlet 2008-05-28 01:56:43 UTC

In cairo-xlib-surface.c, it should be possible to get a 2x to 4x speed improvement
for _swap_ximage_[24]bytes by using facilities provided in <byteswap.h> (under
glibc systems), or by using recent GCC's builtin __builtin_bswap32.

Arno

Comment 1 Arnaud Charlet 2008-05-28 02:06:37 UTC

Created attachment 16783 [details]
test program with various byteswap implementations

The test program itself is too simple minded, but this attachment shows
several possible implementations of byteswapping which can be of interest.

$ gcc -O2 byteswap.c -o byteswap
$ ./byteswap 
UINT32_GCC_SWAP
time spent: 1114
cairo code
time spent: 2247
UINT32_SWAP
time spent: 2225
UINT32_GLIBC_SWAP
time spent: 747

Comment 2 Behdad Esfahbod 2008-05-28 08:32:43 UTC

commit 5de0650dbbed7a44789f25b0a5226593931a8ce8
Author: Behdad Esfahbod <behdad@behdad.org>
Date:   Wed May 28 10:43:47 2008 -0400

    [cairo-xlib] Add recently-added byteswap macros (#16128)

commit dd8f3a5690e92ac3421e5bbc475cc3e78865d8ef
Author: Behdad Esfahbod <behdad@behdad.org>
Date:   Wed May 28 10:43:22 2008 -0400

    Add support for byteswap macros bswap_16 and bswap_32

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