phoxis Coding Discussions, Computer Science

An ID3v1 Tag Parsing Library

id3_logo

ID3 tag is an mp3 audio media file tagging system. The ID3 tags are stored in a pre-defined location in the mp3 media file, either in the start or at the end (or both). There are two major versions of the ID3 tags. ID3v1 and ID3v2. The tag store data about the song, like track name, album name, artist name, genre, track no, year, composer, licensing information, lyrics, even multiple images inside the tag. To get more information about ID3 tag please check the official website of ID3 tag: http://www.id3.org/, also check this article What are ID3 Tags all about?

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phoxis Coding Discussions, Computer Science

Synchronization Safe Integer

Synchronization safe integers are related to ID3v2 tags. ID3v2 tags has a dynamic structure where the length of the tag is variable and inside the tag, there can stay a lot of frames which again can be of dynamic sizes. The size of the tag is stored in the ID3v2 tag header is of length 4 bytes long. These 4 bytes are stored in a special format which is called a synchronization safe integer. Also from ID3v2.4 tags also the frame size bytes which are stored in the frame headers, describing the frame’s length, are stored as 4 byte synchronization safe integer.

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phoxis Coding Discussions, Computer Science

Hero’s Method : Evaluating square root of a real number

A floating point number is given. the task is to evaluate the value of its square root. We will discuss how to find the square root of a real number in this post, and also present a C Language code which does this job. The value of the root will be evaluated with the Hero’s method.
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phoxis Computer Science, Others

Counting Rectangles in an n X m Checked Board

We have a checked board like a chess board, but instead of 8 x 8 it has a dimension of n x m . The task is to count the number of rectangles of all possible dimensions i x j in that checked board. Also the question arises how many squares of all possible dimensions are there. We will solve this problem by establishing formulas by construction. After this we can calculate the number of rectangles and squares of a Chess Board or any other such checked board.

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phoxis Computer Science, Linux / Unix Shell

Bash Script : Finding Digital Root of an Integer

To find a digital roots of an integer is a very common question in high school when doing introductory programming. Digital roots are defined as follows. First an integer is taken if the number of digits are greater than 1, then the sum of its digits are done, if the sum has more than one digits then again the sum of digits are done, and so on until a sum of digit has only 1 digit. This last value of the sum of digits containing a one digit value is defined as the digital root of a number. First we describe in brief what a digital root is then present a shell script.
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phoxis Coding Discussions, Computer Science

Little and Big Endian conversion

Problem: Convert an integer from a given endian to its opposite endian

Endian

In computation endian refer to the ordering of bytes within a single word of 16-bit, 32-bit, or 64-bit. A 16-bit word contains 2 bytes. Say 0x12AB is a 16-bit hexadecimal integer. It’s most significant byte is 12 and the least significant byte is AB. When it is stored with the most significant byte 12 first in lower memory address, and the least significant byte AB is stored next to it, in higher memory address, then this storing format is called the big-endian. If the leas significant byte AB is stored first in higher memory address and the most significant byte is stored next to it, that is in the lower memory address then this format is known as the little-endian. Similarly for a 32-bit word say 0x1A2B3C4D , for little-endian format the least significant byte 4D would be stored first in lower memory address, and next would be 3C, next 2B and then at last the most significant byte would be stored 1A.

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phoxis Computer Science, Linux / Unix Shell

Bash Script : Check for palindrome

When learning shell script, a very common script which is given as a task in schools is to write a script to check if a string is a palindrome or not. I am presenting two solutions of this simple problem. A palindrome is a string whose reverse is same as the string itself. Like “madam” is a palindrome but “hello” is not

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phoxis Computer Science, Linux / Unix Shell

Floating point math operations in bash

When writing scripts in bash, sometimes we need to work with basic math functions. Like the trigonometric functions, square root, cube root, logarithms. Bash does not support floating point operations. This is where the problem is encountered, and we cannot write a math function of our own. There must be a way to do this, and yes. Bash supports redirections so we can feed the floating point computations and the math functions into some other program’s input who understands it. The program which can be used is the bc, which is an arbitrary precision calculator language. bc can do floating point operations, and also can do basic math functions. With bash and bc we can do the above. Continue reading to know how.

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