byte: functions module for shellfire

This module provides an immature framework for manipulating byte and bit values from shell script.

Compatibility

• Tag release_2015.0117.1750-1 is compatible with shellfire release release_2015.0117.1750-1.

Overview

For example, to test if a bit is set:-

# tests if bit 1 (zero based) of value 3 is set
if byte_isBitSet 3 1; then
	echo "Success"
fi

Importing

To import this module, add a git submodule to your repository. From the root of your git repository in the terminal, type:-

mkdir -p lib/shellfire
cd lib/shellfire
git submodule add "https://github.com/shellfire-dev/byte.git"
cd -
git submodule init --update

You may need to change the url https://github.com/shellfire-dev/byte.git" above if using a fork.

You will also need to add paths - include the module paths.d.

Namespace byte

To use in code

If calling from another shellfire module, add to your shell code the line

core_usesIn byte

in the global scope (ie outside of any functions). A good convention is to put it above any function that depends on functions in this module. If using it directly in a program, put this line inside the _program() function:-

_program()
{
	core_usesIn byte
	…
}

Functions

---

byte_isBitSet()

Parameter	Value	Optional
value	Byte value as a number. Signed or unsigned irrelevant.	No
bitIndex	Zero based bit between 7 and 0 inclusive (not validated)	No

Return code is zero if set, non-zero it otherwise.

---

byte_printBinary()

Parameter	Value	Optional
value	Byte value as a number. Signed or unsigned irrelevant.	No

Writes eight binary digits of 0 or 1 to standard out.

---

byte_setBit()

Parameter	Value	Optional
value	Byte value as a number. Signed or unsigned irrelevant.	No
bitIndex	Zero based bit between 7 and 0 inclusive (not validated)	No

Takes the value value, sets the bit bitIndex to 1 and writes the resultant value to standard out.