lib: Add halffloat implementation

Probe for and make an API available for tests to use f16c intrinsics to
generate needed fp16 pixel data.

Also import a pure c fp32 <-> fp16 conversion implementation from Mesa
18.3.4, which will act as a fallback when f16c is unavailable.

rfc2:
- Change API to reduce number of function calls (Maarten)

v1:
- Move pragma so AVX code isn't emitted for fallbacks (Ville)
- Change edx to ecx (Ville)

Signed-off-by: Kevin Strasser <kevin.strasser@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/igt_x86.h b/lib/igt_x86.h
index d4f8c343..c7b84dec 100644
--- a/lib/igt_x86.h
+++ b/lib/igt_x86.h
@@ -39,6 +39,7 @@
 #define SSE4_2	0x40
 #define AVX	0x80
 #define AVX2	0x100
+#define F16C	0x200
 
 #if defined(__x86_64__) || defined(__i386__)
 unsigned igt_x86_features(void);