<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/lib/Makefile, branch v2.6.22.7</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>lib/hexdump</title>
<updated>2007-05-11T15:29:34+00:00</updated>
<author>
<name>Randy Dunlap</name>
<email>randy.dunlap@oracle.com</email>
</author>
<published>2007-05-11T05:22:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=99eaf3c45fe806c4a7f39b9be4a1bd0dfc617699'/>
<id>99eaf3c45fe806c4a7f39b9be4a1bd0dfc617699</id>
<content type='text'>
Based on ace_dump_mem() from Grant Likely for the Xilinx SystemACE
CompactFlash interface.

Add print_hex_dump() &amp; hex_dumper() to lib/hexdump.c and linux/kernel.h.

This patch adds the functions print_hex_dump() &amp; hex_dumper().
print_hex_dump() can be used to perform a hex + ASCII dump of data to
syslog, in an easily viewable format, thus providing a common text hex dump
format.

hex_dumper() provides a dump-to-memory function.  It converts one "line" of
output (16 bytes of input) at a time.

Example usages:
	print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame-&gt;data, frame-&gt;len);
	hex_dumper(frame-&gt;data, frame-&gt;len, linebuf, sizeof(linebuf));

Example output using %DUMP_PREFIX_OFFSET:
0009ab42: 40414243 44454647 48494a4b 4c4d4e4f-@ABCDEFG HIJKLMNO
Example output using %DUMP_PREFIX_ADDRESS:
ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f-pqrstuvw xyz{|}~.

[akpm@linux-foundation.org: cleanups, add export]
Signed-off-by: Randy Dunlap &lt;randy.dunlap@oracle.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Based on ace_dump_mem() from Grant Likely for the Xilinx SystemACE
CompactFlash interface.

Add print_hex_dump() &amp; hex_dumper() to lib/hexdump.c and linux/kernel.h.

This patch adds the functions print_hex_dump() &amp; hex_dumper().
print_hex_dump() can be used to perform a hex + ASCII dump of data to
syslog, in an easily viewable format, thus providing a common text hex dump
format.

hex_dumper() provides a dump-to-memory function.  It converts one "line" of
output (16 bytes of input) at a time.

Example usages:
	print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame-&gt;data, frame-&gt;len);
	hex_dumper(frame-&gt;data, frame-&gt;len, linebuf, sizeof(linebuf));

Example output using %DUMP_PREFIX_OFFSET:
0009ab42: 40414243 44454647 48494a4b 4c4d4e4f-@ABCDEFG HIJKLMNO
Example output using %DUMP_PREFIX_ADDRESS:
ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f-pqrstuvw xyz{|}~.

[akpm@linux-foundation.org: cleanups, add export]
Signed-off-by: Randy Dunlap &lt;randy.dunlap@oracle.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'juju' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6</title>
<updated>2007-05-10T20:30:08+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@woody.linux-foundation.org</email>
</author>
<published>2007-05-10T20:29:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9b6a51746ffe8d619f1097675d2dc5e303470024'/>
<id>9b6a51746ffe8d619f1097675d2dc5e303470024</id>
<content type='text'>
* 'juju' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6: (138 commits)
  firewire: Convert OHCI driver to use standard goto unwinding for error handling.
  firewire: Always use parens with sizeof.
  firewire: Drop single buffer request support.
  firewire: Add a comment to describe why we split the sg list.
  firewire: Return SCSI_MLQUEUE_HOST_BUSY for out of memory cases in queuecommand.
  firewire: Handle the last few DMA mapping error cases.
  firewire: Allocate scsi_host up front and allocate the sbp2_device as hostdata.
  firewire: Provide module aliase for backwards compatibility.
  firewire: Add to fw-core-y instead of assigning fw-core-objs in Makefile.
  firewire: Break out shared IEEE1394 constant to separate header file.
  firewire: Use linux/*.h instead of asm/*.h header files.
  firewire: Uppercase most macro names.
  firewire: Coding style cleanup: no spaces after function names.
  firewire: Convert card_rwsem to a regular mutex.
  firewire: Clean up comment style.
  firewire: Use lib/ implementation of CRC ITU-T.
  CRC ITU-T V.41
  firewire: Rename fw-device-cdev.c to fw-cdev.c and move header to include/linux.
  firewire: Future proof the iso ioctls by adding a handle for the iso context.
  firewire: Add read/write and size annotations to IOC numbers.
  ...

Acked-by: Christoph Hellwig &lt;hch@infradead.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'juju' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6: (138 commits)
  firewire: Convert OHCI driver to use standard goto unwinding for error handling.
  firewire: Always use parens with sizeof.
  firewire: Drop single buffer request support.
  firewire: Add a comment to describe why we split the sg list.
  firewire: Return SCSI_MLQUEUE_HOST_BUSY for out of memory cases in queuecommand.
  firewire: Handle the last few DMA mapping error cases.
  firewire: Allocate scsi_host up front and allocate the sbp2_device as hostdata.
  firewire: Provide module aliase for backwards compatibility.
  firewire: Add to fw-core-y instead of assigning fw-core-objs in Makefile.
  firewire: Break out shared IEEE1394 constant to separate header file.
  firewire: Use linux/*.h instead of asm/*.h header files.
  firewire: Uppercase most macro names.
  firewire: Coding style cleanup: no spaces after function names.
  firewire: Convert card_rwsem to a regular mutex.
  firewire: Clean up comment style.
  firewire: Use lib/ implementation of CRC ITU-T.
  CRC ITU-T V.41
  firewire: Rename fw-device-cdev.c to fw-cdev.c and move header to include/linux.
  firewire: Future proof the iso ioctls by adding a handle for the iso context.
  firewire: Add read/write and size annotations to IOC numbers.
  ...

Acked-by: Christoph Hellwig &lt;hch@infradead.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>CRC ITU-T V.41</title>
<updated>2007-05-10T16:24:13+00:00</updated>
<author>
<name>Ivo van Doorn</name>
<email>IvDoorn@gmail.com</email>
</author>
<published>2006-06-12T14:17:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3e7cbae7c6dda18d427335b3ad98f1a0d40ef30c'/>
<id>3e7cbae7c6dda18d427335b3ad98f1a0d40ef30c</id>
<content type='text'>
This will add the CRC calculation according
to the CRC ITU-T V.41 to the kernel lib/ folder.

This code has been derived from the rt2x00 driver,
currently found only in the wireless-dev tree, but
this library is generic and could be used by more
drivers who currently use their own implementation.

Signed-off-by: Ivo van Doorn &lt;IvDoorn@gmail.com&gt;

Also useful for the new firewire stack.

Signed-off-by: Kristian Hoegsberg &lt;krh@redhat.com&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This will add the CRC calculation according
to the CRC ITU-T V.41 to the kernel lib/ folder.

This code has been derived from the rt2x00 driver,
currently found only in the wireless-dev tree, but
this library is generic and could be used by more
drivers who currently use their own implementation.

Signed-off-by: Ivo van Doorn &lt;IvDoorn@gmail.com&gt;

Also useful for the new firewire stack.

Signed-off-by: Kristian Hoegsberg &lt;krh@redhat.com&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[NET]: div64_64 consolidate (rev3)</title>
<updated>2007-04-26T05:23:33+00:00</updated>
<author>
<name>Stephen Hemminger</name>
<email>shemminger@linux-foundation.org</email>
</author>
<published>2007-03-26T02:54:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3927f2e8f9afa3424bb51ca81f7abac01ffd0005'/>
<id>3927f2e8f9afa3424bb51ca81f7abac01ffd0005</id>
<content type='text'>
Here is the current version of the 64 bit divide common code.

Signed-off-by: Stephen Hemminger &lt;shemminger@linux-foundation.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Here is the current version of the 64 bit divide common code.

Signed-off-by: Stephen Hemminger &lt;shemminger@linux-foundation.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[PATCH] sort the devres mess out</title>
<updated>2007-02-11T19:18:07+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@ftp.linux.org.uk</email>
</author>
<published>2007-02-11T15:41:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5ea8176994003483a18c8fed580901e2125f8a83'/>
<id>5ea8176994003483a18c8fed580901e2125f8a83</id>
<content type='text'>
* Split the implementation-agnostic stuff in separate files.
* Make sure that targets using non-default request_irq() pull
  kernel/irq/devres.o
* Introduce new symbols (HAS_IOPORT and HAS_IOMEM) defaulting to positive;
  allow architectures to turn them off (we needed these symbols anyway for
  dependencies of quite a few drivers).
* protect the ioport-related parts of lib/devres.o with CONFIG_HAS_IOPORT.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* Split the implementation-agnostic stuff in separate files.
* Make sure that targets using non-default request_irq() pull
  kernel/irq/devres.o
* Introduce new symbols (HAS_IOPORT and HAS_IOMEM) defaulting to positive;
  allow architectures to turn them off (we needed these symbols anyway for
  dependencies of quite a few drivers).
* protect the ioport-related parts of lib/devres.o with CONFIG_HAS_IOPORT.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[PATCH] Consolidate bust_spinlocks()</title>
<updated>2007-02-11T18:51:34+00:00</updated>
<author>
<name>Kirill Korotaev</name>
<email>dev@sw.ru</email>
</author>
<published>2007-02-10T09:46:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=cefc8be82403cfc4325e7b9b063f77dc0f34e19e'/>
<id>cefc8be82403cfc4325e7b9b063f77dc0f34e19e</id>
<content type='text'>
Part of long forgotten patch
http://groups.google.com/group/fa.linux.kernel/msg/e98e941ce1cf29f6?dmode=source
Since then, m32r grabbed two copies.

Leave s390 copy because of important absence of CONFIG_VT, but remove
references to non-existent timerlist_lock.  ia64 also loses timerlist_lock.

Signed-off-by: Alexey Dobriyan &lt;adobriyan@openvz.org&gt;
Acked-by: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Andi Kleen &lt;ak@muc.de&gt;
Cc: "Luck, Tony" &lt;tony.luck@intel.com&gt;
Cc: Hirokazu Takata &lt;takata@linux-m32r.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Part of long forgotten patch
http://groups.google.com/group/fa.linux.kernel/msg/e98e941ce1cf29f6?dmode=source
Since then, m32r grabbed two copies.

Leave s390 copy because of important absence of CONFIG_VT, but remove
references to non-existent timerlist_lock.  ia64 also loses timerlist_lock.

Signed-off-by: Alexey Dobriyan &lt;adobriyan@openvz.org&gt;
Acked-by: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Andi Kleen &lt;ak@muc.de&gt;
Cc: "Luck, Tony" &lt;tony.luck@intel.com&gt;
Cc: Hirokazu Takata &lt;takata@linux-m32r.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>iomap: iomap should be in obj-y not in lib-y</title>
<updated>2007-02-09T22:39:37+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>htejun@gmail.com</email>
</author>
<published>2007-01-31T13:48:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ca2997885219486cf91a369233c909fbd555bdf7'/>
<id>ca2997885219486cf91a369233c909fbd555bdf7</id>
<content type='text'>
devres change moved iomap.o from obj-$(CONFIG_GENERIC_IOMAP) to lib-y
making it not linked if no in-kernel driver uses it.  Fix it.

Signed-off-by: Tejun Heo &lt;htejun@gmail.com&gt;
Signed-off-by: Jeff Garzik &lt;jeff@garzik.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
devres change moved iomap.o from obj-$(CONFIG_GENERIC_IOMAP) to lib-y
making it not linked if no in-kernel driver uses it.  Fix it.

Signed-off-by: Tejun Heo &lt;htejun@gmail.com&gt;
Signed-off-by: Jeff Garzik &lt;jeff@garzik.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>devres: device resource management</title>
<updated>2007-02-09T22:39:36+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>htejun@gmail.com</email>
</author>
<published>2007-01-20T07:00:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9ac7849e35f705830f7b016ff272b0ff1f7ff759'/>
<id>9ac7849e35f705830f7b016ff272b0ff1f7ff759</id>
<content type='text'>
Implement device resource management, in short, devres.  A device
driver can allocate arbirary size of devres data which is associated
with a release function.  On driver detach, release function is
invoked on the devres data, then, devres data is freed.

devreses are typed by associated release functions.  Some devreses are
better represented by single instance of the type while others need
multiple instances sharing the same release function.  Both usages are
supported.

devreses can be grouped using devres group such that a device driver
can easily release acquired resources halfway through initialization
or selectively release resources (e.g. resources for port 1 out of 4
ports).

This patch adds devres core including documentation and the following
managed interfaces.

* alloc/free	: devm_kzalloc(), devm_kzfree()
* IO region	: devm_request_region(), devm_release_region()
* IRQ		: devm_request_irq(), devm_free_irq()
* DMA		: dmam_alloc_coherent(), dmam_free_coherent(),
		  dmam_declare_coherent_memory(), dmam_pool_create(),
		  dmam_pool_destroy()
* PCI		: pcim_enable_device(), pcim_pin_device(), pci_is_managed()
* iomap		: devm_ioport_map(), devm_ioport_unmap(), devm_ioremap(),
		  devm_ioremap_nocache(), devm_iounmap(), pcim_iomap_table(),
		  pcim_iomap(), pcim_iounmap()

Signed-off-by: Tejun Heo &lt;htejun@gmail.com&gt;
Signed-off-by: Jeff Garzik &lt;jeff@garzik.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Implement device resource management, in short, devres.  A device
driver can allocate arbirary size of devres data which is associated
with a release function.  On driver detach, release function is
invoked on the devres data, then, devres data is freed.

devreses are typed by associated release functions.  Some devreses are
better represented by single instance of the type while others need
multiple instances sharing the same release function.  Both usages are
supported.

devreses can be grouped using devres group such that a device driver
can easily release acquired resources halfway through initialization
or selectively release resources (e.g. resources for port 1 out of 4
ports).

This patch adds devres core including documentation and the following
managed interfaces.

* alloc/free	: devm_kzalloc(), devm_kzfree()
* IO region	: devm_request_region(), devm_release_region()
* IRQ		: devm_request_irq(), devm_free_irq()
* DMA		: dmam_alloc_coherent(), dmam_free_coherent(),
		  dmam_declare_coherent_memory(), dmam_pool_create(),
		  dmam_pool_destroy()
* PCI		: pcim_enable_device(), pcim_pin_device(), pci_is_managed()
* iomap		: devm_ioport_map(), devm_ioport_unmap(), devm_ioremap(),
		  devm_ioremap_nocache(), devm_iounmap(), pcim_iomap_table(),
		  pcim_iomap(), pcim_iounmap()

Signed-off-by: Tejun Heo &lt;htejun@gmail.com&gt;
Signed-off-by: Jeff Garzik &lt;jeff@garzik.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[PATCH] uml problems with linux/io.h</title>
<updated>2006-12-13T17:05:52+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@ftp.linux.org.uk</email>
</author>
<published>2006-12-13T08:35:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ee36c2bf8edb1c3e3855a928b348d29c6359093d'/>
<id>ee36c2bf8edb1c3e3855a928b348d29c6359093d</id>
<content type='text'>
Remove useless includes of linux/io.h, don't even try to build iomap_copy
on uml (it doesn't have readb() et.al., so...)

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Acked-by: Jeff Dike &lt;jdike@addtoit.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Remove useless includes of linux/io.h, don't even try to build iomap_copy
on uml (it doesn't have readb() et.al., so...)

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Acked-by: Jeff Dike &lt;jdike@addtoit.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[PATCH] SLAB: use a multiply instead of a divide in obj_to_index()</title>
<updated>2006-12-13T17:05:49+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>dada1@cosmosbay.com</email>
</author>
<published>2006-12-13T08:34:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6a2d7a955d8de6cb19ed9cd194b3c83008a22c32'/>
<id>6a2d7a955d8de6cb19ed9cd194b3c83008a22c32</id>
<content type='text'>
When some objects are allocated by one CPU but freed by another CPU we can
consume lot of cycles doing divides in obj_to_index().

(Typical load on a dual processor machine where network interrupts are
handled by one particular CPU (allocating skbufs), and the other CPU is
running the application (consuming and freeing skbufs))

Here on one production server (dual-core AMD Opteron 285), I noticed this
divide took 1.20 % of CPU_CLK_UNHALTED events in kernel.  But Opteron are
quite modern cpus and the divide is much more expensive on oldest
architectures :

On a 200 MHz sparcv9 machine, the division takes 64 cycles instead of 1
cycle for a multiply.

Doing some math, we can use a reciprocal multiplication instead of a divide.

If we want to compute V = (A / B)  (A and B being u32 quantities)
we can instead use :

V = ((u64)A * RECIPROCAL(B)) &gt;&gt; 32 ;

where RECIPROCAL(B) is precalculated to ((1LL &lt;&lt; 32) + (B - 1)) / B

Note :

I wrote pure C code for clarity. gcc output for i386 is not optimal but
acceptable :

mull   0x14(%ebx)
mov    %edx,%eax // part of the &gt;&gt; 32
xor     %edx,%edx // useless
mov    %eax,(%esp) // could be avoided
mov    %edx,0x4(%esp) // useless
mov    (%esp),%ebx

[akpm@osdl.org: small cleanups]
Signed-off-by: Eric Dumazet &lt;dada1@cosmosbay.com&gt;
Cc: Christoph Lameter &lt;clameter@sgi.com&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When some objects are allocated by one CPU but freed by another CPU we can
consume lot of cycles doing divides in obj_to_index().

(Typical load on a dual processor machine where network interrupts are
handled by one particular CPU (allocating skbufs), and the other CPU is
running the application (consuming and freeing skbufs))

Here on one production server (dual-core AMD Opteron 285), I noticed this
divide took 1.20 % of CPU_CLK_UNHALTED events in kernel.  But Opteron are
quite modern cpus and the divide is much more expensive on oldest
architectures :

On a 200 MHz sparcv9 machine, the division takes 64 cycles instead of 1
cycle for a multiply.

Doing some math, we can use a reciprocal multiplication instead of a divide.

If we want to compute V = (A / B)  (A and B being u32 quantities)
we can instead use :

V = ((u64)A * RECIPROCAL(B)) &gt;&gt; 32 ;

where RECIPROCAL(B) is precalculated to ((1LL &lt;&lt; 32) + (B - 1)) / B

Note :

I wrote pure C code for clarity. gcc output for i386 is not optimal but
acceptable :

mull   0x14(%ebx)
mov    %edx,%eax // part of the &gt;&gt; 32
xor     %edx,%edx // useless
mov    %eax,(%esp) // could be avoided
mov    %edx,0x4(%esp) // useless
mov    (%esp),%ebx

[akpm@osdl.org: small cleanups]
Signed-off-by: Eric Dumazet &lt;dada1@cosmosbay.com&gt;
Cc: Christoph Lameter &lt;clameter@sgi.com&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
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