software bugs .

knowledge drop

Bugs due to conceptual error
syntactically incorrect program, wrong or inappropriate design or concept employed.
Math bugs
Division by zero, arithmetic overflow or underflow, lack of arithmetic precision due to rounding etc.
Logic bugs
infinite loops and infinite recursion.
Syntax bugs.
Resource bugs
Buffer overflow, access violations, usage of an uninitialized variable.
Co-programming bugs
concurrency errors, deadlock, race condition.
Team-working bugs
non-matching of documentation and product, out-of-date comments etc.
source: http://www.articlesbase.com/programming-articles/software-bug-and-their-common-types-895408.html

kernel space and user space

Kernel  space. Linux  (which  is a  kernel)  manages the  machine's
hardware  in a  simple and  efficient manner,  offering the  user a
simple  and uniform  programming interface.  In the  same  way, the
kernel,  and in  particular its  device drivers,  form a  bridge or
interface  between the  end-user/programmer and  the  hardware. Any
subroutines or  functions forming part  of the kernel  (modules and
device  drivers,  for  example)   are  considered  to  be  part  of
kernelspace.

User space.  End-user programs,  like the UNIX  shell or  other GUI
based applications  (kpresenter for example), are part  of the user
space.  Obviously, these  applications  need to  interact with  the
system's hardware . However, they  don't so directly, but
through the kernel supported functions.

source :http://www.freesoftwaremagazine.com/articles/drivers_linux

irb interactive ruby and ruby files

commandline session

$ 4.2.20 9 508---> irb
irb(main):001:0> 10+10
=> 20
irb(main):002:0> 34*5
=> 170
irb(main):003:0> 9-8
=> 1
irb(main):004:0> ()
=> nil
irb(main):005:0>
$ 4.2.20 12 511---> ruby sum.rb
3
$ 4.2.20 13 512---> cat sum.rb
a = 1 + 2
puts a
$ 4.2.20 14 513--->



$ 4.2.20 15 514---> irb
irb(main):001:0> Dir.entries('/home/jeffrin/shelter/symmel/')
=> ["Docs", "books", "..", "https:", "debian-howtos", "language", ".git", "linux", "ovlfose", "bugs-general", "Algorithms", "firewall", "config-files", "README", "beautifulwork", ".", "bookmark"]
irb(main):002:0>

kernel sources and RE with cut and head

commandline session

$ 4.2.20 26 526---> time grep -r '^Linus' * | head -n20 | cut -c 1-31
arch/x86/math-emu/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus
debian/pkg/headers/README:Linus

real	0m1.110s
user	0m0.444s
sys	0m0.608s
$ 4.2.20 27 527--->

using regular expressions in kernel source

commandline session

$ 4.2.20 67 568---> 
grep  -r '^kernel'  * | head -n20

arch/alpha/kernel/entry.S:kernel_thread:
arch/alpha/kernel/entry.S:kernel_execve:
arch/avr32/kernel/head.S:kernel_entry:
arch/avr32/kernel/head.S:kernel_start_addr:
arch/sh/boot/compressed/head_32.S:kernel_start_addr:
arch/mn10300/kernel/kernel_execve.S:kernel_execve:
arch/mn10300/kernel/kthread.S:kernel_thread_helper:
arch/um/.gitignore:kernel/config.c
arch/um/.gitignore:kernel/config.tmp
arch/um/.gitignore:kernel/vmlinux.lds
arch/cris/arch-v32/kernel/process.c:kernel_thread_helper(void* dummy, int (*fn)(void *), void * arg)
arch/cris/arch-v32/kernel/process.c:kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
arch/cris/arch-v32/kernel/entry.S:kernel_execve:
arch/cris/include/arch-v32/arch/bitops.h:kernel_ffs(unsigned long w)
arch/cris/arch-v10/kernel/entry.S:kernel_execve:
arch/cris/arch-v10/README.mm:kernel segments like the i386, need to setup swapper_pg_dir directly in head.S
arch/cris/arch-v10/README.mm:kernel's internal paged memory system, vmalloc/vfree.
arch/frv/kernel/kernel_thread.S:kernel_thread_emsg:
arch/frv/kernel/kernel_thread.S:kernel_thread:
arch/frv/kernel/kernel_thread.S:kernel_thread_error:
$ 4.2.20 68 569--->

$ 4.2.20 68 569---> 
grep  -r 'kernel$'  * | head -n20 

arch/hexagon/mm/copy_from_user.S: * User memory copy functions for kernel
arch/hexagon/mm/strnlen_user.S: * User string length functions for kernel
arch/hexagon/kernel/vmlinux.lds.S: * Linker script for Hexagon kernel
arch/hexagon/kernel/head.S:	call start_kernel
arch/hexagon/include/asm/pgalloc.h:	 * that new address spaces always contain the kernel
arch/hexagon/include/asm/pgalloc.h: * Hexagon VM spec has a "monolithic" L1 table for user and kernel
arch/alpha/boot/bootp.c: * This file is used for creating a bootp file for the Linux/AXP kernel
arch/alpha/boot/main.c: * This file is the bootloader for the Linux/AXP kernel
arch/alpha/boot/bootpz.c: * Linux/AXP kernel
arch/alpha/boot/bootpz.c:   copy area, because there needs to be a buffer area after the kernel
arch/alpha/boot/bootpz.c:	   occur when using the normal START_ADDR of the kernel
arch/alpha/boot/head.S:	jsr	$26,start_kernel
arch/alpha/Kconfig:	  singleprocessor machines. On a singleprocessor machine, the kernel
arch/alpha/mm/fault.c:	/* Send a sigbus, regardless of whether we were in kernel
arch/alpha/kernel/vmlinux.lds.S:	} :kernel
arch/alpha/kernel/vmlinux.lds.S:	} :kernel
arch/alpha/kernel/err_marvel.c:	 *	1) a uniprocessor kernel
arch/alpha/kernel/head.S:	jsr	$26,start_kernel
arch/alpha/kernel/entry.S:	beq	$0, ret_to_kernel
arch/alpha/kernel/entry.S:	br	ret_to_kernel
$ 4.2.20 69 570--->

send patches using git using yahoo mail server

ABOUT git

Git (/ɡɪt/[7]) is a distributed version control system for tracking changes in source code during software development.[8] It is designed for coordinating work among programmers, but it can be used to track changes in any set of files. Its goals include speed,[9] data integrity,[10] and support for distributed, non-linear workflows.

MAY BE CORRECT SETTINGS for “PLUS”
[bash]
git config –global sendemail.smtpserver plus.smtp.mail.yahoo.com
git config –global sendemail.smtpserverport 465
git config –global sendemail.smtpencryption ssl
[/bash]

I THINK FOLLOWING SETTING ARE NOT FULLY CORRECT
[bash]
$ git config –global sendemail.smtpserver smtp.mail.yahoo.com
$ git config –global sendemail.smtpserverport 4100
$ git config –global sendemail.smtpencryption ssl
$ git config –global sendemail.smtpuser your_yahoo_mail_address
[/bash]
Now it’s ready: the command git send-email patch-name will ask you for some info about the email sender (you can change the From: field) and recipient, your Gmail password and then it will send the email.

Optionally, it is possible to skip the password prompt by adding it to the configuration with:
$ git config –global sendemail.smtppass your_password

SOURCE : NOT TYPICALLY MINE

LINK
https://en.wikipedia.org/wiki/Git

&~ operation in C

commandline session

 switch (_NSIG_WORDS) {
        default:
                for (i = _NSIG_WORDS, ready = 0; --i >= 0 ; )
                        ready |= signal->sig[i] &~ blocked->sig[i];
                break;

        case 4: ready  = signal->sig[3] &~ blocked->sig[3];
                ready |= signal->sig[2] &~ blocked->sig[2];
                ready |= signal->sig[1] &~ blocked->sig[1];
                ready |= signal->sig[0] &~ blocked->sig[0];
                break;

        case 2: ready  = signal->sig[1] &~ blocked->sig[1];
                ready |= signal->sig[0] &~ blocked->sig[0];
                break;

        case 1: ready  = signal->sig[0] &~ blocked->sig[0];
        }

Related Note : Bitwise Logical Operators and Complex Conjugation Operators.
code source: Linux Kernel Related.
http://www.gnu.org/software/gnu-c-manual/gnu-c-manual.html

(java) bubble sort testing… 0.00003 Ver — 27 No.’s Related

$ 4.2.20 5 505---> time java BubbleSort

real	0m0.247s
user	0m0.172s
sys	0m0.052s
$ 4.2.20 6 506---> time java BubbleSort

real	0m0.204s
user	0m0.148s
sys	0m0.036s
$ 4.2.20 7 507---> time java BubbleSort

real	0m0.207s
user	0m0.152s
sys	0m0.032s
$ 4.2.20 8 508---> time java BubbleSort

real	0m0.222s
user	0m0.168s
sys	0m0.032s
$ 4.2.20 9 509---> time java BubbleSort

real	0m0.230s
user	0m0.172s
sys	0m0.036s
$ 4.2.20 10 510---> time java BubbleSort

real	0m0.241s
user	0m0.180s
sys	0m0.036s
$ 4.2.20 11 511---> time java BubbleSort

real	0m0.255s
user	0m0.188s
sys	0m0.040s
$ 4.2.20 12 512--->