private byte adjustByte(byte b, byte newb, int charPosition) {
		if (charPosition % 2 == 0) {
			// its the high order byte
			b &= 0x0f;
			newb <<= 4;
		}
		else {
			b &= 0xf0;
		}
		b += newb;
		return b;
	}
adjust byte b to use either the upper 4 bits or
the lower 4 bits of newb according to charPosition.
Ghidra/Features/ByteViewer/src/main/java/ghidra/app/plugin/core/format/HexValueFormatModel.java