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authortobigun <tobigun@b956fd51-792f-4845-bead-9b4dfca2ff2c>2008-04-22 16:24:39 +0000
committertobigun <tobigun@b956fd51-792f-4845-bead-9b4dfca2ff2c>2008-04-22 16:24:39 +0000
commit7be51db0f1853f2a9c4c403f4552826a3dcc8544 (patch)
tree51ca4af82a4c0e13061eb73b8275357cfbda82c3
parent0bf82c1d17814e6190033e79984801846be27b6c (diff)
downloadusdx-7be51db0f1853f2a9c4c403f4552826a3dcc8544.tar.gz
usdx-7be51db0f1853f2a9c4c403f4552826a3dcc8544.tar.xz
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SSE floating-point-exception (FPE) fix. Occured when playing ogg-files or with projectM. See UCommon.pas for more information.
git-svn-id: svn://svn.code.sf.net/p/ultrastardx/svn/trunk@1034 b956fd51-792f-4845-bead-9b4dfca2ff2c
-rw-r--r--Game/Code/Classes/UCommon.pas125
-rw-r--r--Game/Code/Classes/UMain.pas8
2 files changed, 128 insertions, 5 deletions
diff --git a/Game/Code/Classes/UCommon.pas b/Game/Code/Classes/UCommon.pas
index 5582c59b..7539a958 100644
--- a/Game/Code/Classes/UCommon.pas
+++ b/Game/Code/Classes/UCommon.pas
@@ -11,10 +11,10 @@ interface
uses
SysUtils,
Classes,
-{$IFDEF MSWINDOWS}
+ {$IFDEF MSWINDOWS}
Windows,
Messages,
-{$ENDIF}
+ {$ENDIF}
ULog;
{$IFNDEF DARWIN}
@@ -42,6 +42,9 @@ procedure DeallocateHWnd(hWnd: HWND);
function StringReplaceW(text : WideString; search, rep: WideChar):WideString;
function AdaptFilePaths( const aPath : widestring ): widestring;
+procedure DisableFloatingPointExceptions();
+procedure SetDefaultNumericLocale();
+procedure RestoreNumericLocale();
{$IFNDEF win32}
procedure ZeroMemory( Destination: Pointer; Length: DWORD );
@@ -63,12 +66,126 @@ function IsControlChar(ch: WideChar): boolean;
implementation
uses
-{$IFDEF Delphi}
+ Math,
+ {$IFDEF Delphi}
Dialogs,
-{$ENDIF}
+ {$ENDIF}
+ {$IFDEF LINUX}
+ libc,
+ {$ENDIF}
UMain,
UConfig;
+var
+ PrevNumLocale: string;
+
+// In Linux and maybe MacOSX some units (like cwstring) call setlocale(LC_ALL, '')
+// to set the language/country specific locale (e.g. charset) for this application.
+// Unfortunately, LC_NUMERIC is set by this call too.
+// It defines the decimal-separator and other country-specific numeric settings.
+// This parameter is used by the C string-to-float parsing functions atof() and strtod().
+// After changing LC_NUMERIC some external C-based libs (like projectM) are not
+// able to parse strings correctly
+// (e.g. in Germany "0.9" is not recognized as a valid number anymore but "0,9" is).
+// So we reset the numeric settings to the default ('C').
+// Note: The behaviour of Pascal parsing functions (e.g. strtofloat()) is not
+// changed by this because it doesn't use the locale-settings.
+// TODO:
+// - Check if this is needed in MacOSX (at least the locale is set in cwstring)
+// - Find out which libs are concerned by this problem.
+// If only projectM is concerned by this problem set and restore the numeric locale
+// for each call to projectM instead of changing it globally.
+procedure SetDefaultNumericLocale();
+begin
+ {$ifdef LINUX}
+ PrevNumLocale := setlocale(LC_NUMERIC, nil);
+ setlocale(LC_NUMERIC, 'C');
+ {$endif}
+end;
+
+procedure RestoreNumericLocale();
+begin
+ {$ifdef LINUX}
+ setlocale(LC_NUMERIC, PChar(PrevNumLocale));
+ {$endif}
+end;
+
+(*
+ * If an invalid floating point operation was performed the Floating-point unit (FPU)
+ * generates a Floating-point exception (FPE). Dependending on the settings in
+ * the FPU's control-register (interrupt mask) the FPE is handled by the FPU itself
+ * (we will call this as "FPE disabled" later on) or is passed to the application
+ * (FPE enabled).
+ * If FPEs are enabled a floating-point division by zero (e.g. 10.0 / 0.0) is
+ * considered an error and an exception is thrown. Otherwise the FPU will handle
+ * the error and return the result infinity (INF) (10.0 / 0.0 = INF) without
+ * throwing an error to the application.
+ * The same applies to a division by INF that either raises an exception
+ * (FPE enabled) or returns 0.0 (FPE disabled).
+ * Normally (as with C-programs), Floating-point exceptions (FPE) are DISABLED
+ * on program startup (at least with Intel CPUs), but for some strange reasons
+ * they are ENABLED in pascal (both delphi and FPC) by default.
+ * Many libs operating with floating-point values rely heavily on the C-specific
+ * behaviour. So using them in delphi is a ticking time-bomb because sooner or
+ * later they will crash because of an FPE (this problem occurs massively
+ * in OpenGL-based libs like projectM). In contrast to this no error will occur
+ * if the lib is linked to a C-program.
+ *
+ * Further info on FPUs:
+ * For x86 and x86_64 CPUs we have to consider two FPU instruction sets.
+ * The math co-processor i387 (aka 8087 or x87) set introduced with the i386
+ * and SSE (Streaming SIMD Extensions) introduced with the Pentium3.
+ * Both of them have separate control-registers (x87: FPUControlWord, SSE: MXCSR)
+ * to control FPEs. Either has (among others) 6bits to enable/disable several
+ * exception types (Invalid,Denormalized,Zero,Overflow,Underflow,Precision).
+ * Those exception-types must all be masked (=1) to get the default C behaviour.
+ * The control-registers can be set with the asm-ops FLDCW (x87) and LDMXCSR (SSE).
+ * Instead of using assembler code, we can use Set8087CW() provided by delphi and
+ * FPC to set the x87 control-word. FPC also provides SetSSECSR() for SSE's MXCSR.
+ * Note that both Delphi and FPC enable FPEs (e.g. for div-by-zero) on program
+ * startup but only FPC enables FPEs (especially div-by-zero) for SSE too.
+ * So we have to mask FPEs for x87 in Delphi and FPC and for SSE in FPC only.
+ * FPC and Delphi both provide a SetExceptionMask() for control of the FPE
+ * mask. SetExceptionMask() sets the masks for x87 in Delphi and for x87 and SSE
+ * in FPC (seems as if Delphi [2005] is not SSE aware). So SetExceptionMask()
+ * is what we need and it even is plattform and CPU independent.
+ *
+ * Pascal OpenGL headers (like the Delphi standard ones or JEDI-SDL headers)
+ * already call Set8087CW() to disable FPEs but due to some bugs in the JEDI-SDL
+ * headers they do not work properly with FPC. I already patched them, so they
+ * work at least until they are updated the next time. In addition Set8086CW()
+ * does not suffice to disable FPEs because the SSE FPEs are not disabled by this.
+ * FPEs with SSE are a big problem with some libs because many linux distributions
+ * optimize code for SSE or Pentium3 (for example: int(INF) which convert the
+ * double value "infinity" to an integer might be automatically optimized by
+ * using SSE's CVTSD2SI instruction). So SSE FPEs must be turned off in any case
+ * to make USDX portable.
+ *
+ * Summary:
+ * Call this function on initialization to make sure FPEs are turned off.
+ * It will solve a lot of errors with FPEs in external libs.
+ *)
+procedure DisableFloatingPointExceptions();
+begin
+ (*
+ // We will use SetExceptionMask() instead of Set8087CW()/SetSSECSR().
+ // Note: Leave these lines for documentation purposes just in case
+ // SetExceptionMask() does not work anymore (due to bugs in FPC etc.).
+ {$IF Defined(CPU386) or Defined(CPUI386) or Defined(CPUX86_64)}
+ Set8087CW($133F);
+ {$IFEND}
+ {$IF Defined(FPC)}
+ if (has_sse_support) then
+ SetSSECSR($1F80);
+ {$IFEND}
+ *)
+
+ // disable all of the six FPEs (x87 and SSE) to be compatible with C/C++ and
+ // other libs which rely on the standard FPU behaviour (no div-by-zero FPE anymore).
+ SetExceptionMask([exInvalidOp, exDenormalized, exZeroDivide,
+ exOverflow, exUnderflow, exPrecision]);
+end;
+
function StringReplaceW(text : WideString; search, rep: WideChar):WideString;
var
iPos : integer;
diff --git a/Game/Code/Classes/UMain.pas b/Game/Code/Classes/UMain.pas
index fef2ff31..2e49ac8d 100644
--- a/Game/Code/Classes/UMain.pas
+++ b/Game/Code/Classes/UMain.pas
@@ -131,6 +131,7 @@ uses
UParty,
UConfig,
UCore,
+ UCommon,
UGraphicClasses,
UPluginDefs,
UPlatform;
@@ -148,6 +149,11 @@ begin
if Platform.TerminateIfAlreadyRunning( {var} WndTitle) then
Exit;
+ // fix floating-point exceptions (FPE)
+ DisableFloatingPointExceptions();
+ // fix the locale for string-to-float parsing in C-libs
+ SetDefaultNumericLocale();
+
//------------------------------
//StartUp - Create Classes and Load Files
//------------------------------
@@ -177,7 +183,7 @@ begin
// SDL
Log.BenchmarkStart(1);
Log.LogStatus('Initialize SDL', 'Initialization');
- SDL_Init(SDL_INIT_VIDEO);
+ SDL_Init(SDL_INIT_VIDEO or SDL_INIT_TIMER);
Log.BenchmarkEnd(1);
Log.LogBenchmark('Initializing SDL', 1);