texture_cache: Optimize GetMipBlockHeight and GetMipBlockDepth

1 files changed, 44 insertions, 0 deletions

diff --git a/src/common/bit_util.h b/src/common/bit_util.h
index d032df413..6f7d5a947 100644
--- a/src/common/bit_util.h
+++ b/src/common/bit_util.h
@@ -97,4 +97,48 @@ inline u32 CountTrailingZeroes64(u64 value) {
 }
 #endif
 
+#ifdef _MSC_VER
+
+inline u32 MostSignificantBit32(const u32 value) {
+    unsigned long result;
+    _BitScanReverse(&result, value);
+    return static_cast<u32>(result);
+}
+
+inline u32 MostSignificantBit64(const u64 value) {
+    unsigned long result;
+    _BitScanReverse64(&result, value);
+    return static_cast<u32>(result);
+}
+
+#else
+
+inline u32 MostSignificantBit32(const u32 value) {
+    return 31U - static_cast<u32>(__builtin_clz(value));
+}
+
+inline u32 MostSignificantBit64(const u64 value) {
+    return 63U - static_cast<u32>(__builtin_clzll(value));
+}
+
+#endif
+
+inline u32 Log2Floor32(const u32 value) {
+    return MostSignificantBit32(value);
+}
+
+inline u32 Log2Ceil32(const u32 value) {
+    const u32 log2_f = Log2Floor32(value);
+    return log2_f + ((value ^ (1U << log2_f)) != 0U);
+}
+
+inline u32 Log2Floor64(const u64 value) {
+    return MostSignificantBit64(value);
+}
+
+inline u32 Log2Ceil64(const u64 value) {
+    const u64 log2_f = static_cast<u64>(Log2Floor64(value));
+    return static_cast<u32>(log2_f + ((value ^ (1ULL << log2_f)) != 0ULL));
+}
+
 } // namespace Common