Ajhc Haskell Compiler with Reentrant GC

Ajhc Haskell Compiler with　
Reentrant GC
Reentrant GC
Reentrant GC
Reentrant GC
Ajhc Haskell Compiler with
Reentrant GC
Kiwamu Okabe @ Metasepi ProjectKiwamu Okabe @ Metasepi ProjectKiwamu Okabe @ Metasepi ProjectKiwamu Okabe @ Metasepi ProjectKiwamu Okabe @ Metasepi Project

Who am I?Who am I?Who am I?Who am I?Who am I?
☆ http://www.masterq.net/☆ http://www.masterq.net/☆ http://www.masterq.net/☆ http://www.masterq.net/☆ http://www.masterq.net/
☆ Self employed software engineer☆ Self employed software engineer☆ Self employed software engineer☆ Self employed software engineer☆ Self employed software engineer
☆ Trade name := METASEPI DESIGN☆ Trade name := METASEPI DESIGN☆ Trade name := METASEPI DESIGN☆ Trade name := METASEPI DESIGN☆ Trade name := METASEPI DESIGN
☆ Founder of Metasepi Project☆ Founder of Metasepi Project☆ Founder of Metasepi Project☆ Founder of Metasepi Project☆ Founder of Metasepi Project
☆ A Debian Maintainer☆ A Debian Maintainer☆ A Debian Maintainer☆ A Debian Maintainer☆ A Debian Maintainer
☆ 10 years' experience in developing
OS using NetBSD
OS using NetBSD
OS using NetBSD
OS using NetBSD
OS using NetBSD

Demo: NetBSD driver in HaskellDemo: NetBSD driver in HaskellDemo: NetBSD driver in HaskellDemo: NetBSD driver in HaskellDemo: NetBSD driver in Haskell
☆ NetBSD audio driver play sound☆ NetBSD audio driver play sound☆ NetBSD audio driver play sound☆ NetBSD audio driver play sound☆ NetBSD audio driver play sound
☆ The driver's interrupt handler
rewrited using Haskell
☆ GC occurs in interrupt handler☆ GC occurs in interrupt handler☆ GC occurs in interrupt handler☆ GC occurs in interrupt handler☆ GC occurs in interrupt handler
☆ Watch the movie at following☆ Watch the movie at following☆ Watch the movie at following☆ Watch the movie at following☆ Watch the movie at following
https://www.youtube.com/watch?v=XEYcR5RG5cAhttps://www.youtube.com/watch?v=XEYcR5RG5cAhttps://www.youtube.com/watch?v=XEYcR5RG5cAhttps://www.youtube.com/watch?v=XEYcR5RG5cAhttps://www.youtube.com/watch?v=XEYcR5RG5cA
☆ Paper for Haskell Symposium 2014☆ Paper for Haskell Symposium 2014☆ Paper for Haskell Symposium 2014☆ Paper for Haskell Symposium 2014☆ Paper for Haskell Symposium 2014
http://metasepi.org/doc/metasepi-icfp2014.pdf
http://metasepi.org/doc/metasepi-icfp2014-demo.pdf

AgendaAgendaAgendaAgendaAgenda
☆ [1] Demo: NetBSD driver in Haskell☆ [1] Demo: NetBSD driver in Haskell☆ [1] Demo: NetBSD driver in Haskell☆ [1] Demo: NetBSD driver in Haskell☆ [1] Demo: NetBSD driver in Haskell
☆ [2] What's Metasepi?☆ [2] What's Metasepi?☆ [2] What's Metasepi?☆ [2] What's Metasepi?☆ [2] What's Metasepi?
☆ [3] What's Ajhc compiler?☆ [3] What's Ajhc compiler?☆ [3] What's Ajhc compiler?☆ [3] What's Ajhc compiler?☆ [3] What's Ajhc compiler?
☆ [4] Reentrancy and Context☆ [4] Reentrancy and Context☆ [4] Reentrancy and Context☆ [4] Reentrancy and Context☆ [4] Reentrancy and Context
☆ [5] Context Local Heap (CLHs)☆ [5] Context Local Heap (CLHs)☆ [5] Context Local Heap (CLHs)☆ [5] Context Local Heap (CLHs)☆ [5] Context Local Heap (CLHs)
☆ [6] How to write Haskell driver?☆ [6] How to write Haskell driver?☆ [6] How to write Haskell driver?☆ [6] How to write Haskell driver?☆ [6] How to write Haskell driver?
☆ [7] What's coming next?☆ [7] What's coming next?☆ [7] What's coming next?☆ [7] What's coming next?☆ [7] What's coming next?

[2] What's Metasepi?[2] What's Metasepi?[2] What's Metasepi?[2] What's Metasepi?[2] What's Metasepi?
http://metasepi.org/http://metasepi.org/http://metasepi.org/http://metasepi.org/http://metasepi.org/
☆ Unix-like OS designed by strong type.☆ Unix-like OS designed by strong type.☆ Unix-like OS designed by strong type.☆ Unix-like OS designed by strong type.☆ Unix-like OS designed by strong type.
☆ Using ML or more strong type lang.☆ Using ML or more strong type lang.☆ Using ML or more strong type lang.☆ Using ML or more strong type lang.☆ Using ML or more strong type lang.
Haskell http://www.haskell.org/Haskell http://www.haskell.org/Haskell http://www.haskell.org/Haskell http://www.haskell.org/Haskell http://www.haskell.org/
OCaml http://caml.inria.fr/OCaml http://caml.inria.fr/OCaml http://caml.inria.fr/OCaml http://caml.inria.fr/OCaml http://caml.inria.fr/
MLton http://mlton.org/MLton http://mlton.org/MLton http://mlton.org/MLton http://mlton.org/MLton http://mlton.org/
. . . and suchlike.. . . and suchlike.. . . and suchlike.. . . and suchlike.. . . and suchlike.

Why need Metasepi?Why need Metasepi?Why need Metasepi?Why need Metasepi?Why need Metasepi?
☆ We have already Linux or Windows.☆ We have already Linux or Windows.☆ We have already Linux or Windows.☆ We have already Linux or Windows.☆ We have already Linux or Windows.
☆ But the developers are suffering.☆ But the developers are suffering.☆ But the developers are suffering.☆ But the developers are suffering.☆ But the developers are suffering.
☆ If use the kernel changed by you,☆ If use the kernel changed by you,☆ If use the kernel changed by you,☆ If use the kernel changed by you,☆ If use the kernel changed by you,
☆ you will get many runtime error.☆ you will get many runtime error.☆ you will get many runtime error.☆ you will get many runtime error.☆ you will get many runtime error.
☆ Difficult even to reproduce it.☆ Difficult even to reproduce it.☆ Difficult even to reproduce it.☆ Difficult even to reproduce it.☆ Difficult even to reproduce it.

Doesn't OSS have good quality?Doesn't OSS have good quality?Doesn't OSS have good quality?Doesn't OSS have good quality?Doesn't OSS have good quality?
☆ "The Cathedral and the Bazaar"☆ "The Cathedral and the Bazaar"☆ "The Cathedral and the Bazaar"☆ "The Cathedral and the Bazaar"☆ "The Cathedral and the Bazaar"
☆ "Given enough eyeballs, all bugs are
shallow."
shallow."
shallow."
shallow."
shallow."
http://cruel.org/freeware/cathedral.htmlhttp://cruel.org/freeware/cathedral.htmlhttp://cruel.org/freeware/cathedral.htmlhttp://cruel.org/freeware/cathedral.htmlhttp://cruel.org/freeware/cathedral.html
☆ But if you develop your own product
re-using OSS...
re-using OSS...
re-using OSS...
re-using OSS...
re-using OSS...

Low quality out of OSS umbrellaLow quality out of OSS umbrellaLow quality out of OSS umbrellaLow quality out of OSS umbrellaLow quality out of OSS umbrella

Type safetyType safetyType safetyType safetyType safety
☆ Less runtime errors.☆ Less runtime errors.☆ Less runtime errors.☆ Less runtime errors.☆ Less runtime errors.
☆ "数理科学的バグ撲滅方法論のすすめ"☆ "数理科学的バグ撲滅方法論のすすめ"☆ "数理科学的バグ撲滅方法論のすすめ"☆ "数理科学的バグ撲滅方法論のすすめ"☆ "数理科学的バグ撲滅方法論のすすめ"
http://itpro.nikkeibp.co.jp/article/COLUMN/20060915/248230/http://itpro.nikkeibp.co.jp/article/COLUMN/20060915/248230/http://itpro.nikkeibp.co.jp/article/COLUMN/20060915/248230/http://itpro.nikkeibp.co.jp/article/COLUMN/20060915/248230/http://itpro.nikkeibp.co.jp/article/COLUMN/20060915/248230/

Kernel wants type desperatelyKernel wants type desperatelyKernel wants type desperatelyKernel wants type desperatelyKernel wants type desperately
☆ Kernels are developed with C lang.☆ Kernels are developed with C lang.☆ Kernels are developed with C lang.☆ Kernels are developed with C lang.☆ Kernels are developed with C lang.
☆ Error on user space => SEGV☆ Error on user space => SEGV☆ Error on user space => SEGV☆ Error on user space => SEGV☆ Error on user space => SEGV
☆ Error on kernel space => Halt!☆ Error on kernel space => Halt!☆ Error on kernel space => Halt!☆ Error on kernel space => Halt!☆ Error on kernel space => Halt!
☆ Should design kernel with the
greatest care.
greatest care.
greatest care.
greatest care.
greatest care.
☆ C language is safe?☆ C language is safe?☆ C language is safe?☆ C language is safe?☆ C language is safe?

Remember Heartbleed bug?Remember Heartbleed bug?Remember Heartbleed bug?Remember Heartbleed bug?Remember Heartbleed bug?
Should we use safer language than C?Should we use safer language than C?Should we use safer language than C?Should we use safer language than C?Should we use safer language than C?
== In English ==
"Preventing heartbleed bugs with safe programming languages"
http://bluishcoder.co.nz/2014/04/11/preventing-heartbleed-bugs-
with-safe-languages.html
== In Japanease ==
"安全なプログラミング言語を使って heartbleed を防ぐには"
https://github.com/jats-ug/translate/blob/master/Web/
bluishcoder.co.nz/2014/04/11/preventing-heartbleed-bugs-with-safe-
languages.md
== In English ==
== In Japanease ==
languages.md
== In English ==
== In Japanease ==
languages.md
== In English ==
== In Japanease ==
languages.md
== In English ==
== In Japanease ==
languages.md
"A safer systems programming language
could have prevented the bug."

[3] What's Ajhc compiler?[3] What's Ajhc compiler?[3] What's Ajhc compiler?[3] What's Ajhc compiler?[3] What's Ajhc compiler?
http://ajhc.metasepi.org/http://ajhc.metasepi.org/http://ajhc.metasepi.org/http://ajhc.metasepi.org/http://ajhc.metasepi.org/
☆ Ajhc := Arafura designed jhc☆ Ajhc := Arafura designed jhc☆ Ajhc := Arafura designed jhc☆ Ajhc := Arafura designed jhc☆ Ajhc := Arafura designed jhc
☆ jhc := John's Haskell Compiler☆ jhc := John's Haskell Compiler☆ jhc := John's Haskell Compiler☆ jhc := John's Haskell Compiler☆ jhc := John's Haskell Compiler
☆ http://repetae.net/computer/jhc/☆ http://repetae.net/computer/jhc/☆ http://repetae.net/computer/jhc/☆ http://repetae.net/computer/jhc/☆ http://repetae.net/computer/jhc/
☆ Jhc outputs binary that has low-
memory-footprint and runs fast.

Who is John?Who is John?Who is John?Who is John?Who is John?
☆ John Meacham☆ John Meacham☆ John Meacham☆ John Meacham☆ John Meacham
☆ http://repetae.net/☆ http://repetae.net/☆ http://repetae.net/☆ http://repetae.net/☆ http://repetae.net/

Why choose jhc?Why choose jhc?Why choose jhc?Why choose jhc?Why choose jhc?
Programs to print "hoge" on terminal.
The lesser depends on POSIX, the
smaller values.
smaller values.
smaller values.
smaller values.
smaller values.

Jhc is translator to C languageJhc is translator to C languageJhc is translator to C languageJhc is translator to C languageJhc is translator to C language

[4] Reentrancy and Context[4] Reentrancy and Context[4] Reentrancy and Context[4] Reentrancy and Context[4] Reentrancy and Context
☆ Metasepi needs language
implementation supporting reentrancy.
☆ Why?☆ Why?☆ Why?☆ Why?☆ Why?

Why need Reentrancy?Why need Reentrancy?Why need Reentrancy?Why need Reentrancy?Why need Reentrancy?
☆ There are 2 way for multitasking☆ There are 2 way for multitasking☆ There are 2 way for multitasking☆ There are 2 way for multitasking☆ There are 2 way for multitasking
☆ [A] Nonpreemptive multitasking☆ [A] Nonpreemptive multitasking☆ [A] Nonpreemptive multitasking☆ [A] Nonpreemptive multitasking☆ [A] Nonpreemptive multitasking
☆ [B] Preemptive multitasking☆ [B] Preemptive multitasking☆ [B] Preemptive multitasking☆ [B] Preemptive multitasking☆ [B] Preemptive multitasking
☆ Unix-like OS needs [B]☆ Unix-like OS needs [B]☆ Unix-like OS needs [B]☆ Unix-like OS needs [B]☆ Unix-like OS needs [B]
☆ [B] needs the hardware interrupts☆ [B] needs the hardware interrupts☆ [B] needs the hardware interrupts☆ [B] needs the hardware interrupts☆ [B] needs the hardware interrupts
☆ Interrupt handler should be reentrant☆ Interrupt handler should be reentrant☆ Interrupt handler should be reentrant☆ Interrupt handler should be reentrant☆ Interrupt handler should be reentrant

What's Reentrancy?What's Reentrancy?What's Reentrancy?What's Reentrancy?What's Reentrancy?
Reentrant code can be interrupted in the middle of its execution
and then safely called again ("re-entered") before its previous
invocations complete execution.

What's Context on C language?What's Context on C language?What's Context on C language?What's Context on C language?What's Context on C language?
☆ A set of registers and call stacks☆ A set of registers and call stacks☆ A set of registers and call stacks☆ A set of registers and call stacks☆ A set of registers and call stacks

Where Context come from?Where Context come from?Where Context come from?Where Context come from?Where Context come from?

What's Context switch?What's Context switch?What's Context switch?What's Context switch?What's Context switch?
The process of storing and restoring the state (context) of a
process or thread so that execution can be resumed from the same
point at a later time.

Support reentrancy with GCSupport reentrancy with GCSupport reentrancy with GCSupport reentrancy with GCSupport reentrancy with GC
☆ Metasepi uses strongly typed
language
language
language
language
language
☆ Strongly typed language sometimes
needs GC
needs GC
needs GC
needs GC
needs GC
☆ Most languages doesn't support
reentrancy with GC
reentrancy with GC
reentrancy with GC
reentrancy with GC
reentrancy with GC
☆ How to support reentrancy with GC?☆ How to support reentrancy with GC?☆ How to support reentrancy with GC?☆ How to support reentrancy with GC?☆ How to support reentrancy with GC?

Problem: Interrupt and GCProblem: Interrupt and GCProblem: Interrupt and GCProblem: Interrupt and GCProblem: Interrupt and GC

[5] Context Local Heap (CLHs)[5] Context Local Heap (CLHs)[5] Context Local Heap (CLHs)[5] Context Local Heap (CLHs)[5] Context Local Heap (CLHs)
☆ Idea: Isolate contexts by local heap☆ Idea: Isolate contexts by local heap☆ Idea: Isolate contexts by local heap☆ Idea: Isolate contexts by local heap☆ Idea: Isolate contexts by local heap

Isolated contexts are reentrant?Isolated contexts are reentrant?Isolated contexts are reentrant?Isolated contexts are reentrant?Isolated contexts are reentrant?

Let's define "Haskell Context"Let's define "Haskell Context"Let's define "Haskell Context"Let's define "Haskell Context"Let's define "Haskell Context"

Haskell Context on jhcHaskell Context on jhcHaskell Context on jhcHaskell Context on jhcHaskell Context on jhc

Haskell Context life cycle (jhc)Haskell Context life cycle (jhc)Haskell Context life cycle (jhc)Haskell Context life cycle (jhc)Haskell Context life cycle (jhc)

Interaction with C on jhcInteraction with C on jhcInteraction with C on jhcInteraction with C on jhcInteraction with C on jhc

Haskell Context on AjhcHaskell Context on AjhcHaskell Context on AjhcHaskell Context on AjhcHaskell Context on Ajhc

Haskell Context life cycle (Ajhc)Haskell Context life cycle (Ajhc)Haskell Context life cycle (Ajhc)Haskell Context life cycle (Ajhc)Haskell Context life cycle (Ajhc)

Interaction with C on AjhcInteraction with C on AjhcInteraction with C on AjhcInteraction with C on AjhcInteraction with C on Ajhc

[6] How to write Haskell driver?[6] How to write Haskell driver?[6] How to write Haskell driver?[6] How to write Haskell driver?[6] How to write Haskell driver?
☆ Language: Ajhc Haskell compiler☆ Language: Ajhc Haskell compiler☆ Language: Ajhc Haskell compiler☆ Language: Ajhc Haskell compiler☆ Language: Ajhc Haskell compiler
☆ Base code: NetBSD kernel☆ Base code: NetBSD kernel☆ Base code: NetBSD kernel☆ Base code: NetBSD kernel☆ Base code: NetBSD kernel
☆ Method: Snatch-driven development☆ Method: Snatch-driven development☆ Method: Snatch-driven development☆ Method: Snatch-driven development☆ Method: Snatch-driven development

Snatch-driven development #1Snatch-driven development #1Snatch-driven development #1Snatch-driven development #1Snatch-driven development #1
http://en.wikipedia.org/wiki/Snatcherhttp://en.wikipedia.org/wiki/Snatcherhttp://en.wikipedia.org/wiki/Snatcherhttp://en.wikipedia.org/wiki/Snatcherhttp://en.wikipedia.org/wiki/Snatcher

Snatch-driven development #2Snatch-driven development #2Snatch-driven development #2Snatch-driven development #2Snatch-driven development #2

To access out of GC heepTo access out of GC heepTo access out of GC heepTo access out of GC heepTo access out of GC heep

Generate code to access C structGenerate code to access C structGenerate code to access C structGenerate code to access C structGenerate code to access C struct
https://github.com/ajhc/struct2hshttps://github.com/ajhc/struct2hshttps://github.com/ajhc/struct2hshttps://github.com/ajhc/struct2hshttps://github.com/ajhc/struct2hs
$ struct2hs sys/dev/pci/auich_extern_SNATCHED.h | tail$ struct2hs sys/dev/pci/auich_extern_SNATCHED.h | tail$ struct2hs sys/dev/pci/auich_extern_SNATCHED.h | tail$ struct2hs sys/dev/pci/auich_extern_SNATCHED.h | tail$ struct2hs sys/dev/pci/auich_extern_SNATCHED.h | tail
offsetOf_Pdevinit_pdev_attach :: Int
p_Pdevinit_pdev_attach :: Ptr Pdevinit -> IO (Ptr (Ptr (FunPtr
(Int -> IO ()))))
p_Pdevinit_pdev_attach p = return $ plusPtr p $
offsetOf_Pdevinit_pdev_attach
foreign import ccall "dynamic" call_Pdevinit_pdev_attach ::
FunPtr (Int -> IO ()) -> Int -> IO ()
foreign import primitive "const.offsetof(struct pdevinit,
pdev_count)"
offsetOf_Pdevinit_pdev_count :: Int
p_Pdevinit_pdev_count :: Ptr Pdevinit -> IO (Ptr Int)
p_Pdevinit_pdev_count p = return $ plusPtr p $
offsetOf_Pdevinit_pdev_count
(Int -> IO ()))))
pdev_count)"
(Int -> IO ()))))
pdev_count)"
(Int -> IO ()))))
pdev_count)"
(Int -> IO ()))))
pdev_count)"

Access C struct in kernelAccess C struct in kernelAccess C struct in kernelAccess C struct in kernelAccess C struct in kernel
/* C code */
static int
auich_set_port(void *v, mixer_ctrl_t *cp)
{
struct auich_softc *sc;
sc = v;
return sc->codec_if->vtbl->mixer_set_port(sc->codec_if, cp);
}
/* C code */
static int
{
sc = v;
}
/* C code */
static int
{
sc = v;
}
/* C code */
static int
{
sc = v;
}
/* C code */
static int
{
sc = v;
}
-- Haskell code
foreign export ccall "auichSetPort"
auichSetPort :: Ptr AuichSoftc -> Ptr MixerCtrl -> IO Int
auichSetPort sc cp = do
codecif <- peek =<< p_AuichSoftc_codec_if sc
f <- peek =<< p_Ac97CodecIfVtbl_mixer_set_port =<< peek
=<< p_Ac97CodecIf_vtbl codecif
call_Ac97CodecIfVtbl_mixer_set_port f codecif cp
-- Haskell code
-- Haskell code
-- Haskell code
-- Haskell code

AC'97 sound driverAC'97 sound driverAC'97 sound driverAC'97 sound driverAC'97 sound driver

HD Audio sound driverHD Audio sound driverHD Audio sound driverHD Audio sound driverHD Audio sound driver

BenchmarkBenchmarkBenchmarkBenchmarkBenchmark
(O) Original NetBSD 6.1.2 kernel
(S) The kernel includes AC'97 and HD Audio driver snatched by Ajhc
(N) (S) + using naive GC
(B4) (S) + having GC block 16 Byte

[7] What's coming next?[7] What's coming next?[7] What's coming next?[7] What's coming next?[7] What's coming next?

What's ATS language?What's ATS language?What's ATS language?What's ATS language?What's ATS language?
http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/
☆ Dependent types☆ Dependent types☆ Dependent types☆ Dependent types☆ Dependent types
☆ Linear types☆ Linear types☆ Linear types☆ Linear types☆ Linear types
☆ Without any runtime☆ Without any runtime☆ Without any runtime☆ Without any runtime☆ Without any runtime
☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC
☆ Developing at Boston University☆ Developing at Boston University☆ Developing at Boston University☆ Developing at Boston University☆ Developing at Boston University
☆ Designer := Hongwei Xi☆ Designer := Hongwei Xi☆ Designer := Hongwei Xi☆ Designer := Hongwei Xi☆ Designer := Hongwei Xi

Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)
Date: Mon Dec 23 11:40 JST 2013
Hi Metasepi-chan,
I spent quite some time today browsing metasepi.org.
I am really interested in your Metasepi project, partly because I
myself wanted to implement NetBSD in ATS about 5 years ago.
Unfortunately, I never had time to get the project started as I
needed to spend so much time on ATS2. By the way, I had planned to
use the very same approach which you call "Snatch". I had also
considered Minix but I chose NetBSD because it was a real OS.
I think I know first-handedly the dilemma you are currently in. On
one hand, you want to be able to fully focus on writing the
kernel. On the other hand, you also need to add features to Ajhc
constantly to address all kinds of issues that keep popping up,
which undoubtedly makes it very difficult for you to focus.
Hi Metasepi-chan,
Hi Metasepi-chan,
Hi Metasepi-chan,
Hi Metasepi-chan,

Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)Hongwei said... (cont.)
I would highly recommend that you use ATS to implement NetBSD
kernel. Unlike jhc, there is no semantics gap between ATS and C.
In particular, they both use the same native unboxed data
representation. Once you become familiar with ATS, you can readily
visualize the C code that your ATS source is to be compiled into.
ATS is truly an ideal language for the kind of "Snatch" approach
you want to take to re-write NetBSD. If you take the lead, then I
will be happy to "chip in" :)
I also spent some time reading documentation on jhc. Personally, I
feel that there is simply too much uncertainty to use it in real
kernel implementation. Features like GC could make the kernel
highly unpredictable, scaring away potential users.
I think that we both believe C is the right language for systems
programming. The problem with C is that it is too difficult to
write correct C programs. ATS is designed to allow the programmer
to correctly write the kind of C programs he or she wanted to
write in the first place. While jhc generates C code, the kind of
C code it generates may not be suited for kernel. This is what I
call a semantics gap.

Hongwei said...Hongwei said...Hongwei said...Hongwei said...Hongwei said...
I write this message in the hope that we could join effort in
doing something that has not been done up to now: Writing a real
kernel in (largely) functional style that can truly deliever
safety-wise as well as performance-wise.
Cheers,
--Hongwei
Cheers,
--Hongwei
Cheers,
--Hongwei
Cheers,
--Hongwei
Cheers,
--Hongwei

Follow me!Follow me!Follow me!Follow me!Follow me!
☆ http://jats-ug.metasepi.org/☆ http://jats-ug.metasepi.org/☆ http://jats-ug.metasepi.org/☆ http://jats-ug.metasepi.org/☆ http://jats-ug.metasepi.org/
☆ https://twitter.com/jats_ug☆ https://twitter.com/jats_ug☆ https://twitter.com/jats_ug☆ https://twitter.com/jats_ug☆ https://twitter.com/jats_ug

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* jumping for the sunset | Flickr - Photo Sharing!
https://www.flickr.com/photos/jorgempf/233188420
Copyright: 2006 Jorge / License: CC BY-SA 2.0
* DIY: Shutter Release Switch for Canon DSLRs | Flickr - Photo
Sharing!
https://www.flickr.com/photos/ivyfield/4763965911
Copyright: 2010 Yutaka Tsutano / License: CC BY 2.0
Sharing!
Sharing!
Sharing!
Sharing!

* 72C Duna SHEER MADNESS Lab Re-entry | Flickr - Photo Sharing!
Copyright: 2014 TheBullethead / License: CC BY 2.0
* Supernova Remnant W49B | Flickr - Photo Sharing!
https://www.flickr.com/photos/gsfc/4479812068
Copyright: 2009 NASA Goddard Space Flight Center / License: CC
BY 2.0
* The Great Wall of China | Flickr - Photo Sharing!
https://www.flickr.com/photos/kk/2149165957
Copyright: 2007 kris krüg / License: CC BY-SA 2.0
* Headshift business card discussion | Flickr - Photo Sharing!
https://www.flickr.com/photos/criminalintent/2744040362
Copyright: 2008 Lars Plougmann / License: CC BY-SA 2.0
* Bali Indonesia | Flickr - Photo Sharing!
https://www.flickr.com/photos/julzart/9266448615
Copyright: 2013 julia Chapple / License: CC BY 2.0
* Scuba diving Indonesia - Bali - Komodo - Bunaken 2008 | Flickr -
Photo Sharing!
Copyright: 2008 Ilse Reijs and Jan-Noud Hutten / License: CC BY
2.0
BY 2.0
Photo Sharing!
2.0
BY 2.0
Photo Sharing!
2.0
BY 2.0
Photo Sharing!
2.0
BY 2.0
Photo Sharing!
2.0

* Scuba diving Bali Nusa Lembongan | Flickr - Photo Sharing!
2.0
* Project 365 #56: 250210 Thanks For The Memory | Flickr - Photo
Sharing!
https://www.flickr.com/photos/comedynose/4388430444
Copyright: 2010 Pete / License: CC BY 2.0
* Audio Codec 97 - Wikipedia
http://ja.wikipedia.org/wiki/Audio_Codec_97#mediaviewer/%E3%83%
95%E3%82%A1%E3%82%A4%E3%83%AB:Realtek_alc655.jpg
Copyright: 2007 Futase tdkr / License: CC BY-SA 3.0
* 紙飛行機 | Flickr - Photo Sharing!
Copyright: 2010 バイク便八王子立川所沢 / License: CC BY 2.0
* Antares Rocket With Cygnus Spacecraft Launches | Flickr - Photo
Sharing!
BY 2.0
2.0
Sharing!
Sharing!
BY 2.0
2.0
Sharing!
Sharing!
BY 2.0
2.0
Sharing!
Sharing!
BY 2.0
2.0
Sharing!
Sharing!
BY 2.0

* Boston à l'heure bleue | Flickr - Photo Sharing!
https://www.flickr.com/photos/ensh/4769294947
Copyright: 2010 Emmanuel Huybrechts / License: CC BY 2.0
* e-mail symbol | Flickr - Photo Sharing!
https://www.flickr.com/photos/gsi-r/5341765493
Copyright: 2007 Micky Aldridge / License: CC BY 2.0
* File:Göteborg in moon light.jpg - Wikipedia, the free
encyclopedia
http://en.wikipedia.org/wiki/File:G%C3%B6teborg_in_moon_light.jpg
Copyright: 2004 Amjad Sheikh / License: CC BY-SA 3.0
* Creative Commons BBB | Flickr - Photo Sharing!
https://www.flickr.com/photos/steren/2732488224
Copyright: 2008 Steren Giannini / License: CC BY 2.0
* Full body | Flickr - Photo Sharing!
https://www.flickr.com/photos/timothytsuihin/2852272823
Copyright: 2008 Timothy Tsui / License: CC BY-SA 2.0
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