Add support for calculating hashes with watchdog triggering

Implement watchodg-aware variants of hash calculation functions:
- crc32_wd()
- md5_wd()
- sha1_csum_wd()
The above functions calculate the hash of the input buffer in chunks,
triggering the watchdog after processing each chunk. The chunk size
is given as a function call parameter.

Signed-off-by: Bartlomiej Sieka <tur@semihalf.com>
diff --git a/include/sha1.h b/include/sha1.h
index 15ea13c..734d1fb 100644
--- a/include/sha1.h
+++ b/include/sha1.h
@@ -80,6 +80,17 @@
 		unsigned char output[20] );
 
 /**
+ * \brief	   Output = SHA-1( input buffer ), with watchdog triggering
+ *
+ * \param input    buffer holding the  data
+ * \param ilen	   length of the input data
+ * \param output   SHA-1 checksum result
+ * \param chunk_sz watchdog triggering period (in bytes of input processed)
+ */
+void sha1_csum_wd (unsigned char *input, int ilen,
+		unsigned char output[20], unsigned int chunk_sz);
+
+/**
  * \brief	   Output = SHA-1( file contents )
  *
  * \param path	   input file name