X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=fp16.h;h=5417e020b82cdfc039e78a1124b3c98833604e77;hp=4e6652f689fb79affad6bb5d0c3cc0765afa5a3c;hb=d2050acb601e0d16bb33b1c1e7cf443dce2d3c93;hpb=cea222cc88f1e210cd73331d74d0b33a67de3d81

diff --git a/fp16.h b/fp16.h
index 4e6652f..5417e02 100644
--- a/fp16.h
+++ b/fp16.h
@@ -1,6 +1,10 @@
 #ifndef _MOVIT_FP16_H
 #define _MOVIT_FP16_H 1
 
+#ifdef __F16C__
+#include <immintrin.h>
+#endif
+
 // Code for converting to and from fp16 (from fp64), without any particular
 // machine support, with proper IEEE round-to-even behavior (and correct
 // handling of NaNs and infinities). This is needed because some OpenGL
@@ -13,9 +17,29 @@ namespace movit {
 typedef unsigned int fp32_int_t;
 typedef unsigned short fp16_int_t;
 
+#ifdef __F16C__
+
+// Use the f16c instructions from Haswell if available (and we know that they
+// are at compile time).
+static inline double fp16_to_fp64(fp16_int_t x)
+{
+	return _cvtsh_ss(x);
+}
+
+static inline fp16_int_t fp64_to_fp16(double x)
+{
+	// NOTE: Strictly speaking, there are some select values where this isn't correct,
+	// since we first round to fp32 and then to fp16.
+	return _cvtss_sh(x, 0);
+}
+
+#else
+
 double fp16_to_fp64(fp16_int_t x);
 fp16_int_t fp64_to_fp16(double x);
 
+#endif
+
 // These are not very useful by themselves, but are implemented using the same
 // code as the fp16 ones (just with different constants), so they are useful
 // for verifying against the FPU in unit tests.