Avoid unnecessary string copies

[stockfish] / src / uci.cpp

diff --git a/src/uci.cpp b/src/uci.cpp
index c0bacfafefea2a56ea032674db28c3d11e2e951b..30c1fa0cce0cfc448dc4cf96ae78684c324f4a0e 100644 (file)
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 #include <sstream>
 #include <string>
 
+#include "benchmark.h"
 #include "evaluate.h"
 #include "movegen.h"
 #include "position.h"
@@ -36,8 +37,6 @@ using namespace std;
 
 namespace Stockfish {
 
-extern vector<string> setup_bench(const Position&, istream&);
-
 namespace {
 
   // FEN string for the initial position in standard chess
@@ -161,7 +160,7 @@ namespace {
     uint64_t num, nodes = 0, cnt = 1;
 
     vector<string> list = setup_bench(pos, args);
-    num = count_if(list.begin(), list.end(), [](string s) { return s.find("go ") == 0 || s.find("eval") == 0; });
+    num = count_if(list.begin(), list.end(), [](const string& s) { return s.find("go ") == 0 || s.find("eval") == 0; });
 
     TimePoint elapsed = now();
 
@@ -207,13 +206,17 @@ namespace {
      // The coefficients of a third-order polynomial fit is based on the fishtest data
      // for two parameters that need to transform eval to the argument of a logistic
      // function.
-     double as[] = {-1.17202460e-01, 5.94729104e-01, 1.12065546e+01, 1.22606222e+02};
-     double bs[] = {-1.79066759,  11.30759193, -17.43677612,  36.47147479};
+     constexpr double as[] = {  -0.58270499,    2.68512549,   15.24638015,  344.49745382};
+     constexpr double bs[] = {  -2.65734562,   15.96509799,  -20.69040836,   73.61029937 };
+
+     // Enforce that NormalizeToPawnValue corresponds to a 50% win rate at ply 64
+     static_assert(UCI::NormalizeToPawnValue == int(as[0] + as[1] + as[2] + as[3]));
+
      double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
      double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];
 
      // Transform the eval to centipawns with limited range
-     double x = std::clamp(double(100 * v) / PawnValueEg, -2000.0, 2000.0);
+     double x = std::clamp(double(v), -4000.0, 4000.0);
 
      // Return the win rate in per mille units rounded to the nearest value
      return int(0.5 + 1000 / (1 + std::exp((a - x) / b)));
@@ -224,7 +227,7 @@ namespace {
 
 /// UCI::loop() waits for a command from the stdin, parses it and then calls the appropriate
 /// function. It also intercepts an end-of-file (EOF) indication from the stdin to ensure a
-/// graceful exit if the GUI dies unexpectedly. When called with some command-line arguments, 
+/// graceful exit if the GUI dies unexpectedly. When called with some command-line arguments,
 /// like running 'bench', the function returns immediately after the command is executed.
 /// In addition to the UCI ones, some additional debug commands are also supported.
 
@@ -240,7 +243,7 @@ void UCI::loop(int argc, char* argv[]) {
       cmd += std::string(argv[i]) + " ";
 
   do {
-      if (argc == 1 && !getline(cin, cmd)) // Wait for an input or an end-of-file (EOF) indication 
+      if (argc == 1 && !getline(cin, cmd)) // Wait for an input or an end-of-file (EOF) indication
           cmd = "quit";
 
       istringstream is(cmd);
@@ -312,7 +315,7 @@ string UCI::value(Value v) {
   stringstream ss;
 
   if (abs(v) < VALUE_MATE_IN_MAX_PLY)
-      ss << "cp " << v * 100 / PawnValueEg;
+      ss << "cp " << v * 100 / NormalizeToPawnValue;
   else
       ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;