sinsemilla::message.rs: Add MessageSubPiece.to_field_elem() method

zcash · Jun 6, 2021 · 42eadef · 42eadef
1 parent 2b254f8
commit 42eadef
Showing 1 changed file with 14 additions and 0 deletions.
diff --git a/src/circuit/gadget/sinsemilla/message.rs b/src/circuit/gadget/sinsemilla/message.rs
@@ -128,3 +128,17 @@ impl<F: FieldExt, const K: usize> From<(Option<F>, std::ops::Range<usize>)>
         }
     }
 }
+
+impl<F: FieldExt, const K: usize> MessageSubPiece<F, K> {
+    pub fn to_field_elem(self) -> Option<F> {
+        self.field_elem.map(|value| {
+            let bits = &value
+                .to_le_bits()
+                .iter()
+                .by_val()
+                .take(F::NUM_BITS as usize)
+                .collect::<Vec<_>>()[self.bit_range];
+            bits_to_field_elem(bits)
+        })
+    }
+}