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kern: simplify random bitmap selection to match latest Nintendo logic
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1 changed files with 9 additions and 28 deletions
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@ -48,39 +48,20 @@ namespace ams::kern {
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}
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size_t SelectRandomBit(u64 bitmap) {
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u64 selected = 0;
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u64 selected = 0;
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u64 cur_num_bits = BITSIZEOF(bitmap) / 2;
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u64 cur_mask = (1ull << cur_num_bits) - 1;
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for (size_t cur_num_bits = BITSIZEOF(bitmap) / 2; cur_num_bits != 0; cur_num_bits /= 2) {
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const u64 high = (bitmap >> cur_num_bits);
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const u64 low = (bitmap & (~(UINT64_C(0xFFFFFFFFFFFFFFFF) << cur_num_bits)));
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while (cur_num_bits) {
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const u64 low = (bitmap >> 0) & cur_mask;
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const u64 high = (bitmap >> cur_num_bits) & cur_mask;
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bool choose_low;
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if (high == 0) {
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/* If only low val is set, choose low. */
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choose_low = true;
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} else if (low == 0) {
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/* If only high val is set, choose high. */
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choose_low = false;
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} else {
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/* If both are set, choose random. */
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choose_low = this->GenerateRandomBit();
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}
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/* If we chose low, proceed with low. */
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if (choose_low) {
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bitmap = low;
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selected += 0;
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} else {
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/* Choose high if we have high and (don't have low or select high randomly). */
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if (high && (low == 0 || this->GenerateRandomBit())) {
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bitmap = high;
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selected += cur_num_bits;
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} else {
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bitmap = low;
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selected += 0;
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}
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/* Proceed. */
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cur_num_bits /= 2;
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cur_mask >>= cur_num_bits;
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}
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return selected;
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