1 files changed, 22 insertions, 0 deletions
diff --git a/ext/digest/sha1/sha1init.c b/ext/digest/sha1/sha1init.c
index 1f8b89e276..44dda3f9fa 100644
--- a/ext/digest/sha1/sha1init.c
+++ b/ext/digest/sha1/sha1init.c
@@ -22,9 +22,31 @@ static const rb_digest_metadata_t sha1 = {
 };
 
 /*
+ * Document-class: Digest::SHA1 < Digest::Base
  * A class for calculating message digests using the SHA-1 Secure Hash
  * Algorithm by NIST (the US' National Institute of Standards and
  * Technology), described in FIPS PUB 180-1.
+ *
+ * See Digest::Instance for digest API.
+ *
+ * SHA-1 calculates a digest of 160 bits (20 bytes).
+ *
+ * == Examples
+ *  require 'digest'
+ *  
+ *  # Compute a complete digest
+ *  Digest::SHA1.hexdigest 'abc'      #=> "a9993e36..."
+ *
+ *  # Compute digest by chunks
+ *  sha1 = Digest::SHA1.new               # =>#<Digest::SHA1>
+ *  sha1.update "ab"
+ *  sha1 << "c"                           # alias for #update
+ *  sha1.hexdigest                        # => "a9993e36..."
+ *
+ *  # Use the same object to compute another digest
+ *  sha1.reset
+ *  sha1 << "message"
+ *  sha1.hexdigest                        # => "6f9b9af3..."
  */
 void
 Init_sha1(void)