Add sha256 and sha512 checksums

That should suffice...

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/sha256.h b/sha256.h
new file mode 100644
index 0000000..a3ca0e6
--- /dev/null
+++ b/sha256.h
@@ -0,0 +1,13 @@
+#ifndef FIO_SHA256_H
+#define FIO_SHA256_H
+
+struct sha256_ctx {
+	uint32_t count[2];
+	uint32_t state[8];
+	uint8_t *buf;
+};
+
+void sha256_init(struct sha256_ctx *);
+void sha256_update(struct sha256_ctx *, const uint8_t *, unsigned int);
+
+#endif