Add top-level "f16" feature + add datatype support

Author: aldanor

hdf5/Cargo.toml

@@ -20,6 +20,7 @@ lzf = ["dep:lzf-sys", "dep:errno"]
 blosc = ["dep:blosc-sys"]
 static = ["hdf5-sys/static"]
 zlib = ["hdf5-sys/zlib"]
+f16 = ["hdf5-types/f16"]
 # The features with version numbers such as 1.10.3, 1.12.0 are metafeatures
 # and is only available when the HDF5 library is at least this version.
 # Features have_direct and have_parallel are also metafeatures and dependent

hdf5/src/hl/datatype.rs

@@ -327,6 +327,16 @@ impl Datatype {
             Ok(string_id)
         }
 
+        #[cfg(feature = "f16")]
+        unsafe fn f16_type() -> Result<hid_t> {
+            use hdf5_sys::h5t::{H5Tset_ebias, H5Tset_fields};
+            let f16_id = be_le!(H5T_IEEE_F32BE, H5T_IEEE_F32LE);
+            h5try!(H5Tset_fields(f16_id, 15, 10, 5, 0, 10)); // cf. h5py/h5py#339
+            h5try!(H5Tset_size(f16_id, 2));
+            h5try!(H5Tset_ebias(f16_id, 15));
+            Ok(f16_id)
+        }
+
         let datatype_id: Result<_> = h5lock!({
             match *desc {
                 TD::Integer(size) => Ok(match size {
@@ -342,6 +352,8 @@ impl Datatype {
                     IntSize::U8 => be_le!(H5T_STD_U64BE, H5T_STD_U64LE),
                 }),
                 TD::Float(size) => Ok(match size {
+                    #[cfg(feature = "f16")]
+                    FloatSize::U2 => f16_type()?,
                     FloatSize::U4 => be_le!(H5T_IEEE_F32BE, H5T_IEEE_F32LE),
                     FloatSize::U8 => be_le!(H5T_IEEE_I16BE, H5T_IEEE_F64LE),
                 }),

tests/test_datatypes.rs

@@ -26,6 +26,8 @@ pub fn test_datatype_roundtrip() {
     check_roundtrip!(u16, TD::Unsigned(IntSize::U2));
     check_roundtrip!(u32, TD::Unsigned(IntSize::U4));
     check_roundtrip!(u64, TD::Unsigned(IntSize::U8));
+    #[cfg(feature = "f16")]
+    check_roundtrip!(::half::f16, TD::Float(FloatSize::U2));
     check_roundtrip!(f32, TD::Float(FloatSize::U4));
     check_roundtrip!(f64, TD::Float(FloatSize::U8));
     check_roundtrip!(bool, TD::Boolean);