diff --git a/libraries/libmesosphere/include/mesosphere/kern_k_page_bitmap.hpp b/libraries/libmesosphere/include/mesosphere/kern_k_page_bitmap.hpp index 7f9cea68b..97934c534 100644 --- a/libraries/libmesosphere/include/mesosphere/kern_k_page_bitmap.hpp +++ b/libraries/libmesosphere/include/mesosphere/kern_k_page_bitmap.hpp @@ -48,39 +48,20 @@ namespace ams::kern { } size_t SelectRandomBit(u64 bitmap) { - u64 selected = 0; + u64 selected = 0; - u64 cur_num_bits = BITSIZEOF(bitmap) / 2; - u64 cur_mask = (1ull << cur_num_bits) - 1; + for (size_t cur_num_bits = BITSIZEOF(bitmap) / 2; cur_num_bits != 0; cur_num_bits /= 2) { + const u64 high = (bitmap >> cur_num_bits); + const u64 low = (bitmap & (~(UINT64_C(0xFFFFFFFFFFFFFFFF) << cur_num_bits))); - while (cur_num_bits) { - const u64 low = (bitmap >> 0) & cur_mask; - const u64 high = (bitmap >> cur_num_bits) & cur_mask; - - bool choose_low; - if (high == 0) { - /* If only low val is set, choose low. */ - choose_low = true; - } else if (low == 0) { - /* If only high val is set, choose high. */ - choose_low = false; - } else { - /* If both are set, choose random. */ - choose_low = this->GenerateRandomBit(); - } - - /* If we chose low, proceed with low. */ - if (choose_low) { - bitmap = low; - selected += 0; - } else { + /* Choose high if we have high and (don't have low or select high randomly). */ + if (high && (low == 0 || this->GenerateRandomBit())) { bitmap = high; selected += cur_num_bits; + } else { + bitmap = low; + selected += 0; } - - /* Proceed. */ - cur_num_bits /= 2; - cur_mask >>= cur_num_bits; } return selected;