SkFloatConvert

src/core/SkHalf.h

Index: src/core/SkHalf.h
diff --git a/src/core/SkHalf.h b/src/core/SkHalf.h
index 5f5575ae1aeaede7f1fd6bde72c8df549f8557bf..2b64d353437c9db870d2d8ebbc65e07a9b7a57cd 100644
--- a/src/core/SkHalf.h
+++ b/src/core/SkHalf.h
@@ -8,6 +8,7 @@
 #ifndef SkHalf_DEFINED
 #define SkHalf_DEFINED
 
+#include "SkOpts.h"
 #include "SkNx.h"
 #include "SkTypes.h"
 
@@ -29,6 +30,37 @@ SkHalf SkFloatToHalf(float f);
 static inline     Sk4f SkHalfToFloat_01(uint64_t);
 static inline uint64_t SkFloatToHalf_01(const Sk4f&);
 
+struct SkFloatConvert {
+    // The compiler can't hoist SkOpts::has_f16c out of loops, so we cache it locally.
+    // TODO: similar has_fp16 for ARMv7
+    const bool has_f16c = SkOpts::has_f16c;
+
+    Sk4f halfToFloat(uint64_t h) const {
+    #if !defined(SKNX_NO_SIMD) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+        if (has_f16c) {
+            __m128 v = _mm_castsi128_ps(_mm_loadl_epi64((const __m128i*)&h));
+            asm("vcvtph2ps %[v], %[v]" : [v] "+x" (v));
+            return v;
+        }
+    #endif
+        return SkHalfToFloat_01(h);
+    }
+
+    uint64_t floatToHalf(const Sk4f& f) const {
+    #if !defined(SKNX_NO_SIMD) && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+        if (has_f16c) {
+            __m128 v = f.fVec;
+            asm("vcvtps2ph $0, %[v], %[v]" : [v] "+x" (v));
+
+            uint64_t h;
+            _mm_storel_epi64((__m128i*)&h, _mm_castps_si128(v));
+            return h;
+        }
+    #endif
+        return SkFloatToHalf_01(f);
+    }
+};
+
 // ~~~~~~~~~~~ impl ~~~~~~~~~~~~~~ //
 
 // Like the serial versions in SkHalf.cpp, these are based on