From 7840ef16e9fae8341efea5a882f484262d50d7e6 Mon Sep 17 00:00:00 2001
From: Daniel Larimer <dan@bitshares.org>
Date: Thu, 4 Feb 2016 16:32:13 -0500
Subject: [PATCH] adding rshift

---
 include/fc/crypto/sha256.hpp  |  1 +
 src/crypto/_digest_common.cpp | 26 +++++++++++++++++++++++++-
 src/crypto/_digest_common.hpp |  1 +
 src/crypto/sha256.cpp         |  5 +++++
 4 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/include/fc/crypto/sha256.hpp b/include/fc/crypto/sha256.hpp
index 387a1d0..87fffa2 100644
--- a/include/fc/crypto/sha256.hpp
+++ b/include/fc/crypto/sha256.hpp
@@ -60,6 +60,7 @@ class sha256
       return ds;
     }
     friend sha256 operator << ( const sha256& h1, uint32_t i       );
+    friend sha256 operator >> ( const sha256& h1, uint32_t i       );
     friend bool   operator == ( const sha256& h1, const sha256& h2 );
     friend bool   operator != ( const sha256& h1, const sha256& h2 );
     friend sha256 operator ^  ( const sha256& h1, const sha256& h2 );
diff --git a/src/crypto/_digest_common.cpp b/src/crypto/_digest_common.cpp
index 2c5c652..67a015b 100644
--- a/src/crypto/_digest_common.cpp
+++ b/src/crypto/_digest_common.cpp
@@ -16,7 +16,7 @@ namespace fc { namespace detail {
         uint8_t* out8 = (uint8_t*) out;
 
         if (i >= 8) {
-            shift_l( in8, out8, n, i >> 3 );
+            shift_l( in8, out8, n, i / 8 );
             i &= 7;
             in8 = out8;
         }
@@ -26,4 +26,28 @@ namespace fc { namespace detail {
             out8[p] = (in8[p] << i) | (in8[p+1]>>(8-i));
         out8[p] = in8[p] << i;
     }
+    static void shift_r( const uint8_t* in, uint8_t* out, std::size_t n, unsigned int i) {
+        if (i < n) {
+            memcpy( out+i, in, n-i );
+        } else {
+            i = n;
+        }
+        memset( out, 0, i );
+    }
+
+    void shift_r( const char* in, char* out, std::size_t n, unsigned int i) {
+        const uint8_t* in8 = (uint8_t*) in;
+        uint8_t* out8 = (uint8_t*) out;
+
+        if (i >= 8) {
+            shift_r( in8, out8, n, i / 8 );
+            i &= 7;
+            in8 = out8;
+        }
+
+        std::size_t p;
+        for( p = n-1; p > 0; --p )
+            out8[p] = (in8[p] >> i) | (in8[p-1]<<(8-i));
+        out8[p] = in8[p] >> i;
+    }
 }}
diff --git a/src/crypto/_digest_common.hpp b/src/crypto/_digest_common.hpp
index 8aa21b3..8582309 100644
--- a/src/crypto/_digest_common.hpp
+++ b/src/crypto/_digest_common.hpp
@@ -4,4 +4,5 @@
  */
 namespace fc { namespace detail {
     void shift_l( const char* in, char* out, std::size_t n, unsigned int i);
+    void shift_r( const char* in, char* out, std::size_t n, unsigned int i);
 }}
diff --git a/src/crypto/sha256.cpp b/src/crypto/sha256.cpp
index b043c2c..9c3b9e6 100644
--- a/src/crypto/sha256.cpp
+++ b/src/crypto/sha256.cpp
@@ -69,6 +69,11 @@ namespace fc {
       fc::detail::shift_l( h1.data(), result.data(), result.data_size(), i );
       return result;
     }
+    sha256 operator >> ( const sha256& h1, uint32_t i ) {
+      sha256 result;
+      fc::detail::shift_r( h1.data(), result.data(), result.data_size(), i );
+      return result;
+    }
     sha256 operator ^ ( const sha256& h1, const sha256& h2 ) {
       sha256 result;
       result._hash[0] = h1._hash[0] ^ h2._hash[0];