id3ed/util/bits.go

package util

// Tells if bit is set in given byte,
// if bitN <= 0 - always returns false
func GetBit(b byte, bitN int) bool {
	if bitN <= 0 {
		return false
	}
	return b&byte(1<<bitN-1) != 0
}

// Sets bit to 1 in provided byte, if bitN <= 0
// returns original b without modifications.
// bitN is the position of the bit FROM THE LAST RIGHT one!
// ie: byte := 0 // 00000000
// newbyte := SetBit(byte, 1) // 1 // 00000001
func SetBit(b byte, bitN int) byte {
	if bitN <= 0 {
		return b
	}
	return b | byte(1<<byte(bitN)-1)
}