Make difficulty 128 bit instead of 64 bit

Based on Boolberry work by:
  jahrsg <jahr@jahr.me>
  cr.zoidberg <crypto.zoidberg@gmail.com>

tests/difficulty/CMakeLists.txt

@@ -45,3 +45,6 @@ set_property(TARGET difficulty-tests
 add_test(
   NAME    difficulty
   COMMAND difficulty-tests "${CMAKE_CURRENT_SOURCE_DIR}/data.txt")
+add_test(
+  NAME    wide_difficulty
+  COMMAND ${PYTHON_EXECUTABLE} "${CMAKE_CURRENT_SOURCE_DIR}/wide_difficulty.py" "${PYTHON_EXECUTABLE}" "${CMAKE_CURRENT_SOURCE_DIR}/gen_wide_data.py" "${CMAKE_CURRENT_BINARY_DIR}/difficulty-tests" "${CMAKE_CURRENT_BINARY_DIR}/wide_data.txt")

tests/difficulty/difficulty.cpp

@@ -43,16 +43,15 @@ using namespace std;
 
 #define DEFAULT_TEST_DIFFICULTY_TARGET        120
 
-int main(int argc, char *argv[]) {
-    if (argc != 2) {
-        cerr << "Wrong arguments" << endl;
-        return 1;
-    }
-    vector<uint64_t> timestamps, cumulative_difficulties;
-    fstream data(argv[1], fstream::in);
+static int test_wide_difficulty(const char *filename)
+{
+    std::vector<uint64_t> timestamps;
+    std::vector<cryptonote::difficulty_type> cumulative_difficulties;
+    fstream data(filename, fstream::in);
     data.exceptions(fstream::badbit);
     data.clear(data.rdstate());
-    uint64_t timestamp, difficulty, cumulative_difficulty = 0;
+    uint64_t timestamp;
+    cryptonote::difficulty_type difficulty, cumulative_difficulty = 0;
     size_t n = 0;
     while (data >> timestamp >> difficulty) {
         size_t begin, end;
@@ -63,11 +62,11 @@ int main(int argc, char *argv[]) {
             end = n - DIFFICULTY_LAG;
             begin = end - DIFFICULTY_WINDOW;
         }
-        uint64_t res = cryptonote::next_difficulty(
-            vector<uint64_t>(timestamps.begin() + begin, timestamps.begin() + end),
-            vector<uint64_t>(cumulative_difficulties.begin() + begin, cumulative_difficulties.begin() + end), DEFAULT_TEST_DIFFICULTY_TARGET);
+        cryptonote::difficulty_type res = cryptonote::next_difficulty(
+            std::vector<uint64_t>(timestamps.begin() + begin, timestamps.begin() + end),
+            std::vector<cryptonote::difficulty_type>(cumulative_difficulties.begin() + begin, cumulative_difficulties.begin() + end), DEFAULT_TEST_DIFFICULTY_TARGET);
         if (res != difficulty) {
-            cerr << "Wrong difficulty for block " << n << endl
+            cerr << "Wrong wide difficulty for block " << n << endl
                 << "Expected: " << difficulty << endl
                 << "Found: " << res << endl;
             return 1;
@@ -81,3 +80,60 @@ int main(int argc, char *argv[]) {
     }
     return 0;
 }
+
+int main(int argc, char *argv[]) {
+    if (argc < 2) {
+        cerr << "Wrong arguments" << endl;
+        return 1;
+    }
+    if (argc == 3 && strcmp(argv[1], "--wide") == 0)
+    {
+        return test_wide_difficulty(argv[2]);
+    }
+
+    vector<uint64_t> timestamps, cumulative_difficulties;
+    std::vector<cryptonote::difficulty_type> wide_cumulative_difficulties;
+    fstream data(argv[1], fstream::in);
+    data.exceptions(fstream::badbit);
+    data.clear(data.rdstate());
+    uint64_t timestamp;
+    uint64_t difficulty, cumulative_difficulty = 0;
+    cryptonote::difficulty_type wide_cumulative_difficulty = 0;
+    size_t n = 0;
+    while (data >> timestamp >> difficulty) {
+        size_t begin, end;
+        if (n < DIFFICULTY_WINDOW + DIFFICULTY_LAG) {
+            begin = 0;
+            end = min(n, (size_t) DIFFICULTY_WINDOW);
+        } else {
+            end = n - DIFFICULTY_LAG;
+            begin = end - DIFFICULTY_WINDOW;
+        }
+        uint64_t res = cryptonote::next_difficulty_64(
+            vector<uint64_t>(timestamps.begin() + begin, timestamps.begin() + end),
+            std::vector<uint64_t>(cumulative_difficulties.begin() + begin, cumulative_difficulties.begin() + end), DEFAULT_TEST_DIFFICULTY_TARGET);
+        if (res != difficulty) {
+            cerr << "Wrong difficulty for block " << n << endl
+                << "Expected: " << difficulty << endl
+                << "Found: " << res << endl;
+            return 1;
+        }
+        cryptonote::difficulty_type wide_res = cryptonote::next_difficulty(
+            std::vector<uint64_t>(timestamps.begin() + begin, timestamps.begin() + end),
+            std::vector<cryptonote::difficulty_type>(wide_cumulative_difficulties.begin() + begin, wide_cumulative_difficulties.begin() + end), DEFAULT_TEST_DIFFICULTY_TARGET);
+        if (wide_res.convert_to<uint64_t>() != res) {
+            cerr << "Wrong wide difficulty for block " << n << endl
+                << "Expected: " << res << endl
+                << "Found: " << wide_res << endl;
+            return 1;
+        }
+        timestamps.push_back(timestamp);
+        cumulative_difficulties.push_back(cumulative_difficulty += difficulty);
+        wide_cumulative_difficulties.push_back(wide_cumulative_difficulty += difficulty);
+        ++n;
+    }
+    if (!data.eof()) {
+        data.clear(fstream::badbit);
+    }
+    return 0;
+}

tests/difficulty/gen_wide_data.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+import random
+
+DIFFICULTY_TARGET = 120
+DIFFICULTY_WINDOW = 720
+DIFFICULTY_LAG = 15
+DIFFICULTY_CUT = 60
+
+def difficulty():
+    times = []
+    diffs = []
+    while True:
+        if len(times) <= 1:
+            diff = 1
+        else:
+            begin = max(len(times) - DIFFICULTY_WINDOW - DIFFICULTY_LAG, 0)
+            end = min(begin + DIFFICULTY_WINDOW, len(times))
+            length = end - begin
+            assert length >= 2
+            if length <= DIFFICULTY_WINDOW - 2 * DIFFICULTY_CUT:
+                cut_begin = 0
+                cut_end = length
+            else:
+                excess = length - (DIFFICULTY_WINDOW - 2 * DIFFICULTY_CUT)
+                cut_begin = (excess + 1) // 2
+                cut_end = length - excess // 2
+            assert cut_begin + 2 <= cut_end
+            wnd = times[begin:end]
+            wnd.sort()
+            dtime = wnd[cut_end - 1] - wnd[cut_begin]
+            dtime = max(dtime, 1)
+            ddiff = sum(diffs[begin + cut_begin + 1:begin + cut_end])
+            diff = (ddiff * DIFFICULTY_TARGET + dtime - 1) // dtime
+        times.append((yield diff))
+        diffs.append(diff)
+
+random.seed(1)
+time = 1000
+gen = difficulty()
+diff = next(gen)
+for i in range(100000):
+    power = 100 if i < 10000 else 100000000 if i < 500 else 1000000000000 if i < 1000 else 1000000000000000 if i < 2000 else 10000000000000000000 if i < 4000 else 1000000000000000000000000 
+    time += random.randint(-diff // power - 10, 3 * diff // power + 10)
+    print(time, diff)
+    diff = gen.send(time)

tests/difficulty/wide_difficulty.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+import sys
+import subprocess
+
+python = sys.argv[1]
+py = sys.argv[2]
+c = sys.argv[3]
+data = sys.argv[4]
+
+first = python + " " + py + " > " + data
+second = [c, '--wide', data]
+
+try:
+  print('running: ', first)
+  subprocess.check_call(first, shell=True)
+  print('running: ', second)
+  subprocess.check_call(second)
+except:
+  sys.exit(1)
+