public final static int intIndexBits(int number_of_indexes) {
		return minimumBitsToStore(number_of_indexes - 1);
	}
https://android.googlesource.com/platform/art/+/master/runtime/index_bss_mapping.h
Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/android/oat/IndexBssUtilities.java