Changeset 1251 for cpp/common

Timestamp:

06/22/23 03:21:19 (17 months ago)

Author:

Maciej Komosinski

Message:

• unified Visual C++ and Borland setting of floating point exception flags
• more flags for *nixes to really catch division by zero (FE_DIVBYZERO was not sufficient) and overflow

File:

• cpp/common/nonstd_math.cpp (modified) (6 diffs)

cpp/common/nonstd_math.cpp

@@ -1 +1 @@
 // This file is a part of Framsticks SDK.  http://www.framsticks.com/
-// Copyright (C) 1999-2020  Maciej Komosinski and Szymon Ulatowski.
+// Copyright (C) 1999-2023  Maciej Komosinski and Szymon Ulatowski.
 // See LICENSE.txt for details.
 
@@ -30 +30 @@
                 (char*)
 #endif
-                str.data(); //now we will be operating directly on the internal std::string buffer
-                for (int i = str.length() - 1, end = str.length(); i >= 0; i--) //remove trailing zeros, and maybe also '.'
+                        str.data(); //now we will be operating directly on the internal std::string buffer
+                for (int i = int(str.length()) - 1, end = int(str.length()); i >= 0; i--) //remove trailing zeros, and maybe also '.'
                 {
                         if (s[i] == '0')
@@ -76 +76 @@
                 strncpy(buffer, s.c_str(), std::min(bufferlen, (int)s.length() + 1));
                 buffer[bufferlen - 1] = 0; //ensure the string is truncated
-                return s.length();
+                return int(s.length());
         }
 }
@@ -91 +91 @@
 
 
+// Idea: enable selected floating point exceptions when the app starts and disable them temporarily when dividing values in ExtValue, so that we can directly handle problematic cases there.
+// This allows to catch problematic situations when the program performs calculations using NaN, INF etc.
+
 #ifdef IPHONE
 //TODO! -> ? http://stackoverflow.com/questions/12762418/how-to-enable-sigfpe-signal-on-division-by-zero-in-ios-app
@@ -121 +124 @@
 #include <fenv.h>
 
-void fpExceptInit()
-{}
-
-void fpExceptEnable()
-{
-        feclearexcept(FE_DIVBYZERO);
-        feenableexcept(FE_DIVBYZERO);
-}
-
-void fpExceptDisable()
-{
-        fedisableexcept(FE_DIVBYZERO);
-}
-
-#endif
-
-
-
-#ifdef __BORLANDC__
-// there was once a problem like this:
+static constexpr int WANTED_FP_EXCEPTIONS = FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW;
+
+void fpExceptInit()
+{}
+
+void fpExceptEnable()
+{
+        feclearexcept(WANTED_FP_EXCEPTIONS);
+        feenableexcept(WANTED_FP_EXCEPTIONS);
+}
+
+void fpExceptDisable()
+{
+        fedisableexcept(WANTED_FP_EXCEPTIONS);
+}
+
+#endif
+
+
+
+#if defined(__BORLANDC__) || defined(_MSC_VER)
+
+// in Borland, there was once a problem like this:
 // http://qc.embarcadero.com/wc/qcmain.aspx?d=5128
 // http://www.delorie.com/djgpp/doc/libc/libc_112.html
@@ -150 +156 @@
 // But it was resolved by restarting windows and cleaning all intermediate compilation files :o (restarting windows was the key element! restarting BC++Builder and deleting files would not help)
 
-#include "log.h"
+
+#if defined(__BORLANDC__) // adding a missing constant and a function
+#define _MCW_EM         0x0008001f              // Interrupt Exception Masks - from Visual C++'s float.h
+
+void _controlfp_s(unsigned int* _CurrentState, unsigned int  _NewValue, unsigned int  _Mask) //pretends to be the real _controlfp_s() function
+{
+        *_CurrentState = _control87(_NewValue, _Mask);
+}
+#endif
+
+#if defined(_MSC_VER) 
+#pragma fenv_access (on)
+#endif
+
+// http://stackoverflow.com/questions/2769814/how-do-i-use-try-catch-to-catch-floating-point-errors
+
+//#include "log.h"
 
 unsigned int fp_control_word_std;
 unsigned int fp_control_word_muted;
 
-void fpExceptInit()
-{
-        //unsigned int was=_clear87();
-        //logPrintf("","fpExceptInit",LOG_INFO,"control87 status before clear was %08x", was);
-        fp_control_word_std = _control87(0, 0);             //4978 = 1001101110010
+
+void fpExceptInit()
+{
+        _controlfp_s(&fp_control_word_std, 0, 0); //in Visual C++, the default value is exactly the masks listed below, and we have to turn them off to enable exceptions
         // Make the new fp env same as the old one, except for the changes we're going to make
-        fp_control_word_muted = fp_control_word_std | EM_INVALID | EM_DENORMAL | EM_ZERODIVIDE | EM_OVERFLOW | EM_UNDERFLOW | EM_INEXACT;  //4991 = 1001101111111
-}
-
-void fpExceptEnable()
-{
-        unsigned int was = _clear87(); //trzeba czyscic zeby nie bylo exception...
-        //logPrintf("","fpExceptEnable ",LOG_INFO,"control87 status before clear was %08x", was);
-        _control87(fp_control_word_std, 0xffffffff);
-        //logPrintf("","fpExceptEnable ",LOG_INFO,"control87 flags are %08x", _control87(0, 0)); //kontrola co sie ustawilo
-}
-
-void fpExceptDisable()
-{
-        unsigned int was = _clear87(); //trzeba czyscic zeby nie bylo exception...
+        fp_control_word_muted = fp_control_word_std & ~(EM_INVALID | /*EM_DENORMAL |*/ EM_ZERODIVIDE | EM_OVERFLOW /* | EM_UNDERFLOW | EM_INEXACT */); //commented out exceptions that occur during proper operation
+}
+
+void fpExceptEnable()
+{
+        //_fpreset(); //not needed since we just _clearfp()... mentioned in https://stackoverflow.com/questions/4282217/visual-c-weird-behavior-after-enabling-floating-point-exceptions-compiler-b
+        unsigned int was = _clearfp(); //need to clean so that there is no exception...
+        //logPrintf("","fpExceptEnable",LOG_INFO,"control87 status before clear was %08x", was);
+        _controlfp_s(&was, fp_control_word_muted, _MCW_EM);
+}
+
+void fpExceptDisable()
+{
+        //_fpreset(); //not needed since we just _clearfp()... mentioned in https://stackoverflow.com/questions/4282217/visual-c-weird-behavior-after-enabling-floating-point-exceptions-compiler-b
+        unsigned int was = _clearfp(); //need to clean so that there is no exception...
         //logPrintf("","fpExceptDisable",LOG_INFO,"control87 status before clear was %08x", was);
-        _control87(fp_control_word_muted, 0xffffffff);
-        //logPrintf("","fpExceptDisable",LOG_INFO,"control87 flags are %08x", _control87(0, 0)); //kontrola co sie ustawilo
-}
-
-#endif
-
-
-
-#ifdef _MSC_VER
-//Moznaby zrobic tak jak pod linuxem czyli wlaczyc exceptiony na poczatku i wylaczac na chwile przy dzieleniu w extvalue.
-//To by pozwoli³o na wy³apanie pod visualem z³ych sytuacji kiedy framsy licz¹ na NaN, INF itp.
-//http://stackoverflow.com/questions/2769814/how-do-i-use-try-catch-to-catch-floating-point-errors
-void fpExceptInit() {}
-void fpExceptEnable() {}
-void fpExceptDisable() {}
-#endif
+        _controlfp_s(&was, fp_control_word_std, _MCW_EM);
+}
+#endif