Bit-Field manipulation library

Table of Contents

• Structure
• Functions
  • Instance setup
  • Single-bit
  • Multiple-bits
  • Dump
• Working with bitfields

qBitField is a library of functions for creating and manipulating bit fields also known as bit arrays. These are series of zeroes and ones spread across an array of storage units, such as unsigned long integers.

Structure

Bit arrays are stored in data structures of type qBitField_t. This structure has two elements: an array of unsigned long integers called field for storing the bits and an integer size for storing the number of bits in the array.

Functions

Instance setup

• QBITFIELD_SIZE Use it to determine the number of bytes required for a BitField.
• qBitField_Setup() Setup a initialize a BitField instance.

Single-bit

• qBitField_SetBit() Sets one bit in a BitField.
• qBitField_ClearBit() Clears one bit in a BitField.
• qBitField_ToggleBit() Toggles (i.e. reverses the state of) a bit in a BitField.
• qBitField_ReadBit() Retrieve the state of a bit in a bitfield.
• qBitField_WriteBit() Writes one bit in a bitfield.

Multiple-bits

• qBitField_ClearAll() Clear all the bits in the BitField.
• qBitField_SetAll() Set all the bits in the BitField.
• qBitField_ReadUINTn() Reads an unsigned 32-bit value from the BitField.
• qBitField_WriteUINTn() Writes an unsigned n-bit value from the BitField.
• qBitField_ReadFloat() Reads a 32-bit floating point value from the BitField.
• qBitField_WriteFloat() Writes a 32-bit floating point value to the BitField.

Dump

• qBitField_Dump() Copies n bytes from the bit-field instance to a designed memory area.

Working with bitfields

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "qbitfield.h"
 
int main( int argc, char *argv[] )
{
    qBitField_t vPort; // create the bitfield instance
    uint8_t vPortArea[ QBITFIELD_SIZE(48) ] = { 0 }; // Create the bitfield storage area to hold 48bits
    uint16_t rWord; 
 
    qBitField_Setup( &vPort, vPortArea, sizeof(vPortArea) );
    qBitField_ClearAll( &vPort);
    //we are going to write the following value in the bitfield = 0x8177AA55FF88
    qBitField_WriteUINTn( &vPort, 0, 0xAA55FF88, 32 ); // write the first 32 bits
    qBitField_WriteUINTn( &vPort, 32, 0x77, 8 ); // write one of the last two bytes
    qBitField_WriteBit( &vPort, 47, 1 );         // write the last bit of the last byte
    qBitField_WriteBit( &vPort, 40, 1 );         // write the first bit of the last byte
    rWord = (uint16_t)qBitField_ReadUINTn( &vPort, 20, 16 ); // read a word at offset 24
    printf("%02X %02X %02X %02X %02X %02X\r\n", vPortArea[0], vPortArea[1], vPortArea[2], vPortArea[3], vPortArea[4], vPortArea[5]);
    return EXIT_SUCCESS;
}