Merge pull request #74 from mirage/add-casts-int32

Add {to,of}_int32 with a documentation about the semantic of value

Author: dinosaure

src-c/checkseum.ml

@@ -212,6 +212,8 @@ module Make (F : FOREIGN) (D : DESC) = struct
   let equal a b = Optint.equal a b
   let default = D.default
   let unsafe_digest_bytes a o l v = F.unsafe_bytes v a o l
+  let to_int32 = Optint.to_unsigned_int32
+  let of_int32 = Optint.of_unsigned_int32
 
   let unsafe_digest_string a o l v =
     F.unsafe_bytes v (Bytes.unsafe_of_string a) o l
@@ -248,6 +250,8 @@ module type S = sig
   val unsafe_digest_string : String.t -> int -> int -> t -> t
   val digest_bigstring : bigstring -> int -> int -> t -> t
   val unsafe_digest_bigstring : bigstring -> int -> int -> t -> t
+  val to_int32 : t -> int32
+  val of_int32 : int32 -> t
 end
 
 module Adler32 : S =

src-ocaml/checkseum.ml

@@ -13,6 +13,8 @@ module type S = sig
   val unsafe_digest_string : String.t -> int -> int -> t -> t
   val digest_bigstring : bigstring -> int -> int -> t -> t
   val unsafe_digest_bigstring : bigstring -> int -> int -> t -> t
+  val to_int32 : t -> int32
+  val of_int32 : int32 -> t
 end
 
 module Adler32 : S = Gin_adler32

src-ocaml/gin_adler32.ml

@@ -133,3 +133,5 @@ let unsafe_digest_bigstring a o l v =
   digest ~get:Bigarray.Array1.unsafe_get a o l v
 
 let digest_bigstring a o l v = digest ~get:Bigarray.Array1.get a o l v
+let to_int32 = Optint.to_unsigned_int32
+let of_int32 = Optint.of_unsigned_int32

src-ocaml/gin_crc24.ml

@@ -35,3 +35,5 @@ let digest_string a o l v = crc24 ~get:String.get a o l v
 let unsafe_digest_string a o l v = crc24 ~get:String.unsafe_get a o l v
 let digest_bytes a o l v = crc24 ~get:Bytes.get a o l v
 let unsafe_digest_bytes a o l v = crc24 ~get:Bytes.unsafe_get a o l v
+let to_int32 = Optint.to_unsigned_int32
+let of_int32 = Optint.of_unsigned_int32

src-ocaml/gin_crc32.ml

@@ -303,3 +303,5 @@ let digest_string a o l v = crc32 ~get:String.get a o l v
 let unsafe_digest_string a o l v = crc32 ~get:String.unsafe_get a o l v
 let digest_bytes a o l v = crc32 ~get:Bytes.get a o l v
 let unsafe_digest_bytes a o l v = crc32 ~get:Bytes.unsafe_get a o l v
+let to_int32 = Optint.to_unsigned_int32
+let of_int32 = Optint.of_unsigned_int32

src-ocaml/gin_crc32c.ml

@@ -303,3 +303,5 @@ let digest_string a o l v = crc32c ~get:String.get a o l v
 let unsafe_digest_string a o l v = crc32c ~get:String.unsafe_get a o l v
 let digest_bytes a o l v = crc32c ~get:Bytes.get a o l v
 let unsafe_digest_bytes a o l v = crc32c ~get:Bytes.unsafe_get a o l v
+let to_int32 = Optint.to_unsigned_int32
+let of_int32 = Optint.of_unsigned_int32

src/checkseum.mli

@@ -35,6 +35,18 @@ module type S = sig
   val unsafe_digest_bigstring : bigstring -> int -> int -> t -> t
   (** [unsafe_digest_bigstring msg off len t] is the same as {!digest_bigstring}
       without bound-checking. *)
+
+  val to_int32 : t -> int32
+  (** [to_int32 crc] casts [crc] to an {b unsigned} [int32] value. We precise
+      {i unsigned} because every bits are significant for the checksum (even the
+      sign bit). We interpret the given [int32] as a value where the sign bit
+      does not have any signification (hence the {i unsigned}). *)
+
+  val of_int32 : int32 -> t
+  (** [of_int32 crc] casts the given unsigned [int32] value to {!t}. For a
+      checksum, every bits (including the sign bit) has a signification. The
+      user must interpret the given [int32] as an unsigned [int32] (eg.
+      regardless the sign bit which has another signification for the checksum). *)
 end
 
 module Adler32 : S

test/test.ml

@@ -7,72 +7,42 @@ let make ~name (module M : Checkseum.S) input expected =
     fun () ->
       Alcotest.check checkseum name
         M.(digest_string input 0 (String.length input) default)
-        expected )
+        M.(of_int32 expected) )
 
 let () =
   Alcotest.run "checkseum"
     [
       ( "crc32c",
         [
-          make ~name:"0" (module Checkseum.Crc32c) "" Optint.zero;
-          make ~name:"1"
-            (module Checkseum.Crc32c)
-            "\x00"
-            (Optint.of_unsigned_int32 0x527d5351l);
+          make ~name:"0" (module Checkseum.Crc32c) "" 0l;
+          make ~name:"1" (module Checkseum.Crc32c) "\x00" 0x527d5351l;
           make ~name:"2"
             (module Checkseum.Crc32c)
-            "\xff\xff\xff\xff"
-            (Optint.of_unsigned_int32 0xffffffffl);
-          make ~name:"3"
-            (module Checkseum.Crc32c)
-            "123456789"
-            (Optint.of_unsigned_int32 0xe3069283l);
+            "\xff\xff\xff\xff" 0xffffffffl;
+          make ~name:"3" (module Checkseum.Crc32c) "123456789" 0xe3069283l;
           make ~name:"4"
             (module Checkseum.Crc32c)
-            "Thou hast made me, and shall thy work decay?"
-            (Optint.of_unsigned_int32 0x866374c0l);
+            "Thou hast made me, and shall thy work decay?" 0x866374c0l;
         ] );
       ( "crc32",
         [
-          make ~name:"0" (module Checkseum.Crc32) "" Optint.zero;
-          make ~name:"1"
-            (module Checkseum.Crc32)
-            "\x00"
-            (Optint.of_unsigned_int32 0xd202ef8dl);
-          make ~name:"2"
-            (module Checkseum.Crc32)
-            "\xff\xff\xff\xff"
-            (Optint.of_unsigned_int32 0xffffffffl);
-          make ~name:"3"
-            (module Checkseum.Crc32)
-            "123456789"
-            (Optint.of_unsigned_int32 0xcbf43926l);
+          make ~name:"0" (module Checkseum.Crc32) "" 0l;
+          make ~name:"1" (module Checkseum.Crc32) "\x00" 0xd202ef8dl;
+          make ~name:"2" (module Checkseum.Crc32) "\xff\xff\xff\xff" 0xffffffffl;
+          make ~name:"3" (module Checkseum.Crc32) "123456789" 0xcbf43926l;
           make ~name:"4"
             (module Checkseum.Crc32)
-            "Thou hast made me, and shall thy work decay?"
-            (Optint.of_unsigned_int32 0xf1fabe1dl);
+            "Thou hast made me, and shall thy work decay?" 0xf1fabe1dl;
           make ~name:"5"
             (module Checkseum.Crc32)
             (String.concat "%" (List.init 1000 (const "abcdef")))
-            (Optint.of_unsigned_int32 0xadc436fl);
+            0xadc436fl;
         ] );
       ( "crc24",
         [
-          make ~name:"0"
-            (module Checkseum.Crc24)
-            ""
-            (Optint.of_unsigned_int32 0xb704cel);
-          make ~name:"1"
-            (module Checkseum.Crc24)
-            "a"
-            (Optint.of_unsigned_int32 0xf25713l);
-          make ~name:"2"
-            (module Checkseum.Crc24)
-            "abc"
-            (Optint.of_unsigned_int32 0xba1c7bl);
-          make ~name:"3"
-            (module Checkseum.Crc24)
-            "message digest"
-            (Optint.of_unsigned_int32 0xdbf0b6l);
+          make ~name:"0" (module Checkseum.Crc24) "" 0xb704cel;
+          make ~name:"1" (module Checkseum.Crc24) "a" 0xf25713l;
+          make ~name:"2" (module Checkseum.Crc24) "abc" 0xba1c7bl;
+          make ~name:"3" (module Checkseum.Crc24) "message digest" 0xdbf0b6l;
         ] );
     ]