Add some more to the csharp interface

min-bindings/C#/Makefile

@@ -1,7 +1,7 @@
 INCLUDE_DIRS = .. ../../min-src ../../inc
 
 test: tests.cs ckzg.dll
-	mcs tests.cs
+	mcs tests.cs -r:System.Numerics
 	./tests.exe
 
 ckzg.dll: ckzg.c ../../min-src/c_kzg_4844.o ../../lib/libblst.a

min-bindings/C#/ckzg.c

@@ -1,8 +1,21 @@
 #include <inttypes.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include "c_kzg_4844.h"
 
 uint64_t hello(uint64_t a) {
   printf("Hello World! %lu\n", a);
   return 42;
 }
+
+BLSFieldElement* bytes_to_bls_field_wrap(const uint8_t bytes[]) {
+  BLSFieldElement* out = (BLSFieldElement*)malloc(sizeof(BLSFieldElement));
+  bytes_to_bls_field(out, bytes);
+  return out;
+}
+
+uint64_t* uint64s_from_bls_field(BLSFieldElement *fr) {
+  uint64_t *r = (uint64_t*)calloc(4, sizeof(uint64_t));
+  uint64s_from_BLSFieldElement(r, fr);
+  return r;
+}

min-bindings/C#/tests.cs

@@ -1,11 +1,38 @@
 using System;
+using System.Numerics;
 using System.Text;
+using System.Runtime.InteropServices;
 
 class ckzg {
-  [global::System.Runtime.InteropServices.DllImport("ckzg.dll", EntryPoint="hello")]
+  [DllImport("ckzg.dll", EntryPoint="hello")]
   public static extern uint hello(uint a);
-  [global::System.Runtime.InteropServices.DllImport("ckzg.dll", EntryPoint="bytes_to_bls_field_wrap")]
-  public static extern void bytes_to_bls_field(byte[] b);
+
+  [DllImport("ckzg.dll", EntryPoint="bytes_to_bls_field_wrap")]
+  private static extern IntPtr bytes_to_bls_field_wrap(byte[] bytes);
+
+  public static IntPtr bytes_to_bls_field(byte[] bytes) {
+    return bytes_to_bls_field_wrap(bytes);
+  }
+
+  [DllImport("ckzg.dll", EntryPoint="uint64s_from_bls_field")]
+  private static extern IntPtr uint64s_from_bls_field(IntPtr fr);
+
+  [DllImport("ckzg.dll", EntryPoint="free")]
+  private static extern void free(IntPtr p);
+
+  public static BigInteger int_from_bls_field(IntPtr fr) {
+    IntPtr uptr = uint64s_from_bls_field(fr);
+    Int64[] int64s = new Int64[4];
+    Marshal.Copy(uptr, int64s, 0, 4);
+    free(uptr);
+    BigInteger result = new BigInteger(0);
+    BigInteger mult = new BigInteger(1);
+    for (int i = 0; i < 4; i++) {
+      result += Convert.ToUInt64(int64s[i]) * mult;
+      mult *= BigInteger.Pow(2, 64);
+    }
+    return result;
+  }
 }
 
 class tests {
@@ -13,5 +40,10 @@ class tests {
   {
     Console.WriteLine("OK");
     Console.WriteLine(ckzg.hello(32));
+    byte[] b = new byte[32];
+    b[0] = 11;
+    b[8] = 1;
+    IntPtr fr = ckzg.bytes_to_bls_field(b);
+    Console.WriteLine(ckzg.int_from_bls_field(fr));
   }
 }