From 447444ae7a3ed4e13bfb09e0c15d458070e9b904 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 1 Jun 2016 23:15:04 +1200
Subject: [PATCH] Fix nits after review

---
 src/crypto/equihash.cpp | 22 ++++++++++-------
 src/crypto/equihash.h   | 52 ++++++++++++++++++++---------------------
 2 files changed, 40 insertions(+), 34 deletions(-)

diff --git a/src/crypto/equihash.cpp b/src/crypto/equihash.cpp
index 4694d2240..b31cf0461 100644
--- a/src/crypto/equihash.cpp
+++ b/src/crypto/equihash.cpp
@@ -120,10 +120,12 @@ FullStepRow<WIDTH>& FullStepRow<WIDTH>::operator=(const FullStepRow<WIDTH>& a)
 template<size_t WIDTH>
 bool StepRow<WIDTH>::IsZero(size_t len)
 {
-    char res = 0;
-    for (int i = 0; i < len; i++)
-        res |= hash[i];
-    return res == 0;
+    // This doesn't need to be constant time.
+    for (int i = 0; i < len; i++) {
+        if (hash[i] != 0)
+            return false;
+    }
+    return true;
 }
 
 template<size_t WIDTH>
@@ -139,10 +141,12 @@ std::vector<eh_index> FullStepRow<WIDTH>::GetIndices(size_t len, size_t lenIndic
 template<size_t WIDTH>
 bool HasCollision(StepRow<WIDTH>& a, StepRow<WIDTH>& b, int l)
 {
-    bool res = true;
-    for (int j = 0; j < l; j++)
-        res &= a.hash[j] == b.hash[j];
-    return res;
+    // This doesn't need to be constant time.
+    for (int j = 0; j < l; j++) {
+        if (a.hash[j] != b.hash[j])
+            return false;
+    }
+    return true;
 }
 
 template<size_t WIDTH>
@@ -334,6 +338,8 @@ std::set<std::vector<eh_index>> Equihash<N,K>::OptimisedSolve(const eh_HashState
     // First run the algorithm with truncated indices
 
     eh_index soln_size { 1 << K };
+    // Each element of partialSolns is dynamically allocated in a call to
+    // GetTruncatedIndices(), and freed at the end of this function.
     std::vector<eh_trunc*> partialSolns;
     {
 
diff --git a/src/crypto/equihash.h b/src/crypto/equihash.h
index 20952cb6a..373daf46a 100644
--- a/src/crypto/equihash.h
+++ b/src/crypto/equihash.h
@@ -135,42 +135,42 @@ public:
 
 #include "equihash.tcc"
 
-static Equihash<96,5> Eh965;
-static Equihash<48,5> Eh485;
+static Equihash<96,5> Eh96_5;
+static Equihash<48,5> Eh48_5;
 
-#define EhInitialiseState(n, k, base_state) \
-    if (n == 96 && k == 5) {                \
-        Eh965.InitialiseState(base_state);  \
-    } else if (n == 48 && k == 5) {         \
-        Eh485.InitialiseState(base_state);  \
-    } else {                                \
+#define EhInitialiseState(n, k, base_state)  \
+    if (n == 96 && k == 5) {                 \
+        Eh96_5.InitialiseState(base_state);  \
+    } else if (n == 48 && k == 5) {          \
+        Eh48_5.InitialiseState(base_state);  \
+    } else {                                 \
         throw std::invalid_argument("Unsupported Equihash parameters"); \
     }
 
-#define EhBasicSolve(n, k, base_state, solns) \
-    if (n == 96 && k == 5) {                  \
-        solns = Eh965.BasicSolve(base_state); \
-    } else if (n == 48 && k == 5) {           \
-        solns = Eh485.BasicSolve(base_state); \
-    } else {                                  \
+#define EhBasicSolve(n, k, base_state, solns)   \
+    if (n == 96 && k == 5) {                    \
+        solns = Eh96_5.BasicSolve(base_state);  \
+    } else if (n == 48 && k == 5) {             \
+        solns = Eh48_5.BasicSolve(base_state);  \
+    } else {                                    \
         throw std::invalid_argument("Unsupported Equihash parameters"); \
     }
 
-#define EhOptimisedSolve(n, k, base_state, solns) \
-    if (n == 96 && k == 5) {                      \
-        solns = Eh965.OptimisedSolve(base_state); \
-    } else if (n == 48 && k == 5) {               \
-        solns = Eh485.OptimisedSolve(base_state); \
-    } else {                                      \
+#define EhOptimisedSolve(n, k, base_state, solns)   \
+    if (n == 96 && k == 5) {                        \
+        solns = Eh96_5.OptimisedSolve(base_state);  \
+    } else if (n == 48 && k == 5) {                 \
+        solns = Eh48_5.OptimisedSolve(base_state);  \
+    } else {                                        \
         throw std::invalid_argument("Unsupported Equihash parameters"); \
     }
 
-#define EhIsValidSolution(n, k, base_state, soln, ret) \
-    if (n == 96 && k == 5) {                           \
-        ret = Eh965.IsValidSolution(base_state, soln); \
-    } else if (n == 48 && k == 5) {                    \
-        ret = Eh485.IsValidSolution(base_state, soln); \
-    } else {                                           \
+#define EhIsValidSolution(n, k, base_state, soln, ret)   \
+    if (n == 96 && k == 5) {                             \
+        ret = Eh96_5.IsValidSolution(base_state, soln);  \
+    } else if (n == 48 && k == 5) {                      \
+        ret = Eh48_5.IsValidSolution(base_state, soln);  \
+    } else {                                             \
         throw std::invalid_argument("Unsupported Equihash parameters"); \
     }