private void allocateZeroBitField(DataTypeComponent dtc, int bitIndex) {

			// determine placement attribute index within allocationBytes which
			// may have been reduced from allocationByteSize based upon visibility.

			int index = bitIndex - (8 * leftChopBytes);
			if (index >= 0 && index < bitAttributes.length) {
				bitAttributes[index] = new BitAttributes(dtc, bitAttributes[index]);
			}
		}
Allocate {@link #bitAttributes} for the specified component within
the byte range covered by {@link #allocationBytes}.
@param dtc composite component
@param leftBit left bit index within the full {@link #allocationByteSize}
               where 0 is the left-most bit index.
@param rightBit right bit index within the full {@link #allocationByteSize}
                where 0 is the left-most bit index.
@param truncatedLeft true if leftBit has been truncated by the full
                     allocation range
@param truncatedRight true if rightBit has been truncated by the full
                     allocation range
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/BitFieldPlacementComponent.java