Define Qntan_Hasher

1 files changed, 52 insertions, 0 deletions

diff --git a/include/qntan/Qntan.h b/include/qntan/Qntan.h
index 09c0ed5..1848984 100644
--- a/include/qntan/Qntan.h
+++ b/include/qntan/Qntan.h
@@ -75,6 +75,7 @@ struct Qntan_FileSystem_Dirent;
 struct Qntan_FileSystem;
 struct Qntan_FourierTransform;
 struct Qntan_Process;
+struct Qntan_Hasher;
 struct Qntan_HshIdx;
 struct Qntan_HshTbl;
 struct Qntan_HshTbl_Cursor;
@@ -975,6 +976,57 @@ struct Qntan_Process {
 
 
 
+struct Qntan_Hasher {
+	/* Genetic hash abstraction. Could be SHA1, SHA256, MD5, whatever
+	 * your UseCase needs. Usually the one requesting an implementation
+	 * of this interface specifies what hash should be given.
+	 */
+	void (*reset)( struct Qntan_Hasher**,
+		void(*onDone)(int err,Qntan_Cls arg), Qntan_Cls arg );
+	/* Resets the internal hashing state so the next call to `add()`
+	 * will be as the 1st chunk of data of the data-to-be hashed.
+	 * `err` is zero if OK, or negative on error. Positive values are
+	 * reserved.
+	 */
+	void (*add)( struct Qntan_Hasher**, char const*buf, int buf_len,
+		void(*onDone)(int err,Qntan_Cls arg), Qntan_Cls arg );
+	/* Append (some also say "update") more data to the current hash
+	 * calculation.
+	 * Caller MUST ensure `buf` stays valid until `onDone()` gets called.
+	 * `err` is zero if OK, or negative on error. Positive values are
+	 * reserved.
+	 * The implementation is free when to call `onDone`. For very
+	 * lightweight hashes this could be even from the same thread
+	 * directly. For more CPU intensive hashes, an impl should offload
+	 * the work to a worker thread. But still it can decide to call
+	 * `onDone` early, that means if the buffer got copied away and
+	 * queued to a worker thead somewhere else. Or it also could
+	 * callbacl only as soon the worker thead already did process the
+	 * given input. The only thing is (as always) that `onDone()`
+	 * should be called on the EventLoop, NOT from some other worker
+	 * thread!
+	 */
+	void (*finalize)( struct Qntan_Hasher**,
+		void(*onDone)(int err, char const*result, Qntan_Cls arg),
+		Qntan_Cls arg );
+	/* Finalize (for example process remaining/buffered data etc) and then get
+	 * the result hash back.
+	 * `err` is negative on error. Positive values indicate how many
+	 * octets the `result` is in length (num octets).
+	 * `result` is the !!BINARY-REPRESENTATION!! of the hash result! (NOT
+	 * STRING, NOT HEX, or any shit like that!).
+	 */
+};
+
+
+
+
+
+
+
+
+
+
 struct Qntan_HshIdx {
 	/* An n-dimensional HashTable. Where as many properties as wanted
 	 * can be used to index into the table.