edit test to include normalization after add

Cargo.toml

@@ -64,3 +64,5 @@ simd_backend = ["nightly", "u64_backend", "packed_simd"]
 # DEPRECATED: this is now an alias for `simd_backend` and may be removed
 # in some future release.
 avx2_backend = ["simd_backend"]
+
+[workspace]

src/field.rs

@@ -482,7 +482,10 @@ mod test {
 
         let mcode = assemble_engine25519!(
             start:
-                add %0, %1, %2
+                add %2, %0, %1
+                trd %3, %2
+                sub %31, %2, %3
+                fin
         );
 
         let path = Path::new("test_vectors.bin");
@@ -490,15 +493,21 @@ mod test {
 
         // insert machine code
         // Metadata record:
-        //   0x0 [31   load address   16]                                 [15  length of code  0]
-        //   0x4 [31  N registers to load  27] [26 W window 23] [22  X number of vectors sets  0]
-        //   0x8 [microcode] (variable length)
+        //   0x0 0x56454354   "VECT" - indicates a valid vector set
+        //   0x4 [31   load address   16]                                 [15  length of code  0]
+        //   0x8 [31  N registers to load  27] [26 W window 23] [22  X number of vectors sets  0]
+        //   0xC [microcode] (variable length)
         //   [ padding of 0x0 until 0x20 * align ]
         //   0x20*align [X test vectors]
+        // Records can repeat, and each one represents a new test
+        // End of records MUST end with a word that is NOT 0x56454354
+        //    This is because the ROM read can "wrap around" and the test will run forever
+        //    We use 0xFFFF_FFFF to indicate this
         // Convention:
         //   Check result is always in r31
         //   N Registers loaded starting at r0 into window W
         let mcode_len = mcode.len();
+        let _ = file.write(&(0x5645_4354 as u32).to_le_bytes());
         let _ = file.write(&( ((0x0 & 0xFFFF << 16)
                              | (mcode_len & 0xFFFF)
                              ) as u32)
@@ -514,7 +523,7 @@ mod test {
         }
 
         // pad with 0's to a 256-bit stride
-        for _ in 0..(8 - ((2 + mcode_len) % 8)) {  // 2 words for metadata + code length
+        for _ in 0..(8 - ((3 + mcode_len) % 8)) {  // 3 words for metadata + code length
             let _ = file.write(&[0,0,0,0]); // write out 32-bit words of 0 (as array of u8)
         }
 
@@ -522,5 +531,8 @@ mod test {
         write_helper(&mut file, a);
         write_helper(&mut file, b);
         write_helper(&mut file, q);
+
+        // end sequence
+        let _ = file.write(&(0xFFFF_FFFF as u32).to_le_bytes());
     }
 }