Adding the rest of files:

- ASM is disabled
- Neug needs full rewrite
- Flash is based on PiMoroni 4MB flash (needs adjust)

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

mod25638.h

@@ -0,0 +1,7 @@
+extern const bn256 p25519[1];
+
+void mod25638_add (bn256 *X, const bn256 *A, const bn256 *B);
+void mod25638_sub (bn256 *X, const bn256 *A, const bn256 *B);
+void mod25638_mul (bn256 *X, const bn256 *A, const bn256 *B);
+void mod25638_sqr (bn256 *X, const bn256 *A);
+void mod25519_reduce (bn256 *X);