Improved self-test routine.

diff --git a/frontend/src/self_test.cpp b/frontend/src/self_test.cpp
index 7d4f33f..f872cae 100644 (file)
--- a/frontend/src/self_test.cpp
+++ b/frontend/src/self_test.cpp
@@ -178,15 +178,19 @@ static bool append_string(UnorderedHashSet &hash_set, std::vector<std::array<uin
  */
 bool self_test(const bool keep_going, const bool lower_case)
 {
-       bool success = true;
-       for(size_t i = 0U; SELFTEST_INPUT[i].count > 0U; ++i)
+       bool success = mhash384_selftest();
+
+       if(success)
        {
-               if(!test_string(SELFTEST_INPUT[i].count, SELFTEST_INPUT[i].string, SELFTEST_EXPECTED[i], lower_case))
+               for(size_t i = 0U; SELFTEST_INPUT[i].count > 0U; ++i)
                {
-                       success = false;
-                       if(!keep_going)
+                       if(!test_string(SELFTEST_INPUT[i].count, SELFTEST_INPUT[i].string, SELFTEST_EXPECTED[i], lower_case))
                        {
-                               break; /*failure*/
+                               success = false;
+                               if(!keep_going)
+                               {
+                                       break; /*failure*/
+                               }
                        }
                }
        }

diff --git a/libmhash384/include/mhash384.h b/libmhash384/include/mhash384.h
index 4db88be..947be77 100644 (file)
--- a/libmhash384/include/mhash384.h
+++ b/libmhash384/include/mhash384.h
@@ -60,11 +60,14 @@ mhash384_t;
 /*
  * MHash-384 public functions
  */
-MHASH384_API void mhash384_init   (mhash384_t *const ctx);
-MHASH384_API void mhash384_update (mhash384_t *const ctx, const uint8_t *const data_in, const size_t len);
-MHASH384_API void mhash384_final  (mhash384_t *const ctx, uint8_t *const digest_out);
-MHASH384_API void mhash384_get    (uint8_t *const digest_out, const uint8_t *const data_in, const size_t len);
-MHASH384_API void mhash384_version(uint16_t *const major, uint16_t *const minor, uint16_t *const patch);
+MHASH384_API void mhash384_init    (mhash384_t *const ctx);
+MHASH384_API void mhash384_update  (mhash384_t *const ctx, const uint8_t *const data_in, const size_t len);
+MHASH384_API void mhash384_final   (mhash384_t *const ctx, uint8_t *const digest_out);
+MHASH384_API void mhash384_get     (uint8_t *const digest_out, const uint8_t *const data_in, const size_t len);
+MHASH384_API void mhash384_version (uint16_t *const major, uint16_t *const minor, uint16_t *const patch);
+#ifndef MHASH384_NOSELFTEST
+MHASH384_API bool mhash384_selftest(void);
+#endif //MHASH384_NOSELFTEST
 
 /*
  * MHash384 wrapper class for C++

diff --git a/libmhash384/src/mhash384.cpp b/libmhash384/src/mhash384.cpp
index b824b78..1785482 100644 (file)
--- a/libmhash384/src/mhash384.cpp
+++ b/libmhash384/src/mhash384.cpp
@@ -47,6 +47,10 @@ typedef uint32_t ui32_t;
 typedef uint16_t ui16_t;
 typedef uint8_t  byte_t;
 
+/* ======================================================================== */
+/* CONSTANT TABLES                                                          */
+/* ======================================================================== */
+
 /*
  * Const
  */
@@ -862,6 +866,10 @@ static const byte_t MHASH384_FIN[MHASH384_SIZE] =
        0x0F, 0x1E, 0x25, 0x10, 0x0B, 0x2F, 0x1B, 0x0E, 0x15, 0x2C, 0x1D, 0x27, 0x08, 0x03, 0x24, 0x18
 };
 
+/* ======================================================================== */
+/* INTERNAL FUNCTIONS                                                       */
+/* ======================================================================== */
+
 /*
  * CityHash 128-Bit to 64-Bit mixing function (Murmur-inspired)
  */
@@ -897,6 +905,10 @@ static byte_t ALWAYS_INLINE get_byte(const ui64_t *const hash, const ui32_t idx)
 } \
 while(0)
 
+/* ======================================================================== */
+/* PUBLIC FUNCTIONS                                                         */
+/* ======================================================================== */
+
 /*
  * Initialize hash computation
  */
@@ -957,3 +969,62 @@ void mhash384_version(ui16_t *const major, ui16_t *const minor, ui16_t *const pa
        *minor = MHASH384_VERSION_MINOR;
        *patch = MHASH384_VERSION_PATCH;
 }
+
+/* ======================================================================== */
+/* SELF-TEST FUNCTIONS                                                      */
+/* ======================================================================== */
+
+#ifndef MHASH384_NOSELFTEST
+
+/*
+ * Population count of 64-Bit word
+ */
+static ALWAYS_INLINE ui32_t popcnt64(ui64_t u)
+{
+       u -= (u >> 1U) & 0x5555555555555555;
+       u = (u & 0x3333333333333333) + ((u >> 2U) & 0x3333333333333333);
+       u = (u + (u >> 4U)) & 0x0f0f0f0f0f0f0f0f;
+       return (ui32_t)((u * 0x0101010101010101) >> 56U);
+}
+
+/*
+ * Hamming distance of 384-Bit table row
+ */
+static ALWAYS_INLINE ui32_t hamming_distance(const ui64_t *const x, const ui64_t *const y)
+{
+       ui32_t distance = 0U;
+       for(size_t i = 0; i < MHASH384_WORDS; ++i)
+       {
+               distance += popcnt64(x[i] ^ y[i]);
+       }
+       return distance;
+}
+
+/*
+ * MHash384 self-test
+ */
+bool mhash384_selftest(void)
+{
+       for(size_t i = 0; i <= 256U; ++i)
+       {
+               ui32_t min_distance = UINT32_MAX;
+               for(size_t j = 0; j <= 256U; ++j)
+               {
+                       if(i != j)
+                       {
+                               const ui32_t distance = hamming_distance(MHASH384_XOR[i], MHASH384_XOR[j]);
+                               if(distance < min_distance)
+                               {
+                                       min_distance = distance;
+                               }
+                       }
+               }
+               if(min_distance < 182U)
+               {
+                       return false; //self-test has failed!
+               }
+       }
+       return true;
+}
+
+#endif //MHASH384_NOSELFTEST