1 files changed, 66 insertions, 0 deletions
diff --git a/extra/libkeccak_state_unmarshal.c b/extra/libkeccak_state_unmarshal.c
new file mode 100644
index 0000000..4714566
--- /dev/null
+++ b/extra/libkeccak_state_unmarshal.c
@@ -0,0 +1,66 @@
+/* See LICENSE file for copyright and license details. */
+#include "../common.h"
+
+
+#if defined(__clang__)
+# pragma clang diagnostic ignored "-Wcast-align"
+#endif
+
+
+/**
+ * Unmarshal a `struct libkeccak_state` from a buffer
+ * 
+ * @param   state  The slot for the unmarshalled state, must not be
+ *                 initialised (memory leak otherwise), can be `NULL`
+ * @param   data_  The input buffer
+ * @return         The number of bytes read from `data`, 0 on error
+ */
+size_t
+libkeccak_state_unmarshal(struct libkeccak_state *restrict state, const void *restrict data_)
+{
+#define get(VAR) \
+	do {\
+		__builtin_memcpy(&state->VAR, data, sizeof(state->VAR));\
+		data += sizeof(state->VAR);\
+	} while (0)
+
+	const unsigned char *restrict start = data_;
+	const unsigned char *restrict data = start;
+	size_t mptr;
+
+	if (!state) {
+		data += 7U * sizeof(long int);
+		data += 1U * sizeof(int64_t);
+		data += sizeof(state->S);
+		mptr = *(const size_t *)data;
+		data += 2U * sizeof(size_t);
+		data += mptr;
+		return (size_t)(data - start);
+	}
+
+	get(r);
+	get(c);
+	get(n);
+	get(b);
+	get(w);
+	get(wmod);
+	get(l);
+	get(nr);
+	memcpy(state->S, data, sizeof(state->S));
+	data += sizeof(state->S);
+	get(mptr);
+	get(mlen);
+	if (state->mptr) {
+		state->M = malloc(state->mptr * sizeof(char));
+		if (!state->M)
+			return 0;
+		memcpy(state->M, data, state->mptr * sizeof(char));
+		data += state->mptr;
+	} else {
+		state->M = NULL;
+	}
+
+	return (size_t)(data - start);
+
+#undef get
+}