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logger—0.6.xml

[daemon.log]Every   daemon  without  a   separate  facility   logs  to
daemon.log.  The  priority of  log events is  not relevent.[debug]File
debug has messages useful for debugging.The priority of log events are
not relevent.[dmesg] After the  kernel has booted, all kernel messages
are written to dmesg for  later reference.This file is not rotated and
only exists for a single boot cycle before being overwritten.Note that
the choice of  the name is a little unfortunate,  as the dmesg command
prints  the  current  kernel  log ring  buffer,which  is  continuously
updated and new kernel events are logged.These messages are written to
kern.log; The dmesg file is not modified until the next restart of the
system.[kern.log] Log messages  with the kern facility end  up in this
file.The  contents are mostly  what the  kernel spits  out,after being
formatted by klogd.[lpr.log]Log messages  with the lpr facility end up
in this file.


[mail.log]  Log entries  related  to the  mail  system(using the  mail
facility) go into  this file.  For easier parsing  by scripts,mail log
entries    are    also    written    to    mail.info,    mail.warn,and
mail.err,according to  their priority.  Unfortunately,Debian's default
MTA,exim4,  does not  use this  file.[messages]Pretty  much everything
that  is not  an  error or  a  trivial log  entry,and  not related  to
authentication,daemons  ,cron(or other  automatic schedulers),mail,and
news goes here.

btmp auth.log syslog boot 

btmp shows a log of the file /var/log/btmp, which contains all the bad
login   attempts.    auth.log   receives   log  entries   related   to
authentication,and  other  events  that  are critical  to  privacy  or
security issues.   everything not related to authentication  end up in
syslog file.   syslog is  the catch-all log  file on a  debian system.
log  messages  produced during  the  initialization  sequence will  be
logged to boot.

[youtube=http://www.youtube.com/watch?v=WCHUb-n6hfw&fs=1&hl=en_US&rel=0]

proc asound devices 0.2

$cat /proc/asound/devices
  2:        : timer
  3:        : sequencer
  4: [ 0- 2]: digital audio capture
  5: [ 0- 1]: digital audio playback
  6: [ 0- 1]: digital audio capture
  7: [ 0- 0]: digital audio playback
  8: [ 0- 0]: digital audio capture
  9: [ 0- 0]: hardware dependent
 10: [ 0]   : control
$



devices
        Lists the ALSA native device mappings.

A music  sequencer is  a musical application  or a device  designed to
play  back musical  notation. The  original kind  of sequencer  is now
known  as a step  sequencer to  distinguish it  from the  modern kind,
which records a musician playing notes.


GNUsound - A sound editor  for Linux/x86. It supports multiple tracks,
multiple  outputs, and  8, 16,  or 24/32  bit samples.  It can  read a
number of audio formats through libaudiofile, and saves them as WAV.
GNU sound


Digital audio uses pulse-code modulation and digital signals for sound
reproduction.   This  includes  analog-to-digital   conversion  (ADC),
digital-to-analog  conversion  (DAC),  storage, and  transmission.  In
effect,  the system  commonly  referred to  as  digital is  in fact  a
discrete-time,   discrete-level  analog   of  a   previous  electrical
analog. While modern systems can be quite subtle in their methods, the
primary  usefulness of  a  digital  system is  the  ability to  store,
retrieve and transmit signals without any loss of quality.

Intel's  use  of  the  phrase  audio codec  refers  to  signals  being
encoded/decoded  to/from  analog  audio  from/to digital  audio,  thus
actually a combined audio AD/DA-converter. This should not be confused
with a  codec in  the sense  of converting from  one binary  format to
another,  such as  an audio  (MP3) or  video (Xvid)  codec in  a media
player.


A timer is a specialized type of clock. A timer can be used to control
the  sequence of  an  event  or process.  Whereas  a stopwatch  counts
upwards from zero for measuring elapsed time, a timer counts down from
a  specified   time  interval,  like  an  hourglass.   Timers  can  be
mechanical, electromechanical,  electronic (quartz), or  even software
as  all  modern  computers  include  digital timers  of  one  kind  or
another. When  the set period  expires some timers simply  indicate so
(e.g.,  by  an  audible   signal),  while  others  operate  electrical
switches, such as a time switch, which cuts electrical power.

proc filesystem with alsa.



$cat /proc/asound/cards
0 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xf5000000 irq 22
$

The HD-audio component consists of  two parts: the controller chip and
the codec chips on the HD-audio Linux provides a single driver for all
controllers, snd-hda-intel.  Although the  driver name contains a word
of a well-known  hardware vendor, it's not specific to  it but for all
controller chips  by other companies.  Since  the HD-audio controllers
are supposed  to be compatible, the single  snd-hda-driver should work
in most cases.


Reference/Source:
Linux kernel documentation 2.6.32 related.

advanced linux sound architecture

The ALC883 series 7.1+2 Channel High Definition Audio (HDA) codecs are
compliant  with Microsoft's  UAA (Universal  Audio  Architecture). The
ALC883 series provide 10  DAC channels that simultaneously support 7.1
sound  playback, plus 2  channels of  independent stereo  sound output
(multiple streaming) through the  front panel stereo output.  Flexible
mixing,  mute, and  fine  gain control  functions  provide a  complete
integrated  audio  solution  for  home  entertainment  PCs.   A  modem
(modulator-demodulator) is  a device that modulates  an analog carrier
signal  to encode  digital information,  and also  demodulates  such a
carrier signal to  decode the transmitted information. The  goal is to
produce  a  signal that  can  be  transmitted  easily and  decoded  to
reproduce the original digital data. Modems can be used over any means
of  transmitting analog  signals,  from driven  diodes  to radio.   In
electronics,  modulation  is  the  process  of  varying  one  or  more
properties of  a high frequency periodic waveform,  called the carrier
signal, with respect to a modulating signal. This is done in a similar
fashion as a musician may modulate a tone (a periodic waveform) from a
musical instrument by varying its volume, timing and pitch.

acpi with proc

AC Adapter in Proc Filesystem 

Alternating current  (AC) adapters  are used to  power or  charge many
common electronic devices, such as mobile phones, laptop computers, or
external  hard  drives.  An  AC  adapter  changes  AC  power  from  an
electrical outlet into the type of power or voltage that an electronic
device needs to work. Typically,  each device has a designated adapter
that is  pre-set to  the proper voltage  conversion. For  this reason,
among others, AC adapters generally are not interchangeable.


$cat /proc/acpi/ac_adapter/ACAD/state
state: on-line
$
ACAD is the name of the adapter.

code optimizer

code optimization

optimization  is  the  strategy  of  examining  intermediate  code  as
produced  by or  during  the code  generation  phase with  the aim  of
producing code that runs  very efficiently.Production of code that use
very  little  space   has  also  been  a  goal   of  some  optimizers;
nevertheless, the main emphasis has  traditionally been and will be in
this chapter on the generation of very fast executing code.


Reference/Source :
Theory and Practice of Compiler Writing.
Jean-Paul Tremblay and Paul G. Sorenson.

semantic analysis

Semantic Analysis

Semantic analysis is the phase in which the compiler adds semantic information
to the parse tree and builds the symbol table.This phase performs semantic
checks such as type checking (checking for type errors), or object binding
(associating variable and function references with their definitions), or definite assignment (requiring all local variables to be initialized before use), rejecting
incorrect programs or issuing warnings.

Semantic analysis usually requires a complete parse tree,
meaning that this phase logically follows the parsing phase,
and logically precedes the code generation phase, though it
is often possible to fold multiple phases into one pass over
the code in a compiler implementation.


Reference/Source:
http://en.wikipedia.org/wiki/Semantic_analysis_(compilers)#Front_end