Add IEEE 754 single/double precision support to wxDataStream classes.

Allow to optionally raed/write float/double values in IEEE 754 single/double
precision formats, respectively, instead of always using the extended
precision format for both of them.

This makes the code more flexible, allowing for better interoperability with
the other programs, and also allows to implement floating point functions in
these classes even when wxUSE_APPLE_IEEE is turned off (as can be the case
because of the licencing concerns for the code in extended.c).

Closes #10625.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73938 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/datstrm.cpp

@@ -24,6 +24,24 @@
     #include "wx/math.h"
 #endif //WX_PRECOMP
 
+namespace
+{
+
+// helper unions used to swap bytes of floats and doubles
+union Float32Data
+{
+    wxFloat32 f;
+    wxUint32 i;
+};
+
+union Float64Data
+{
+    wxFloat64 f;
+    wxUint32 i[2];
+};
+
+} // anonymous namespace
+
 // ----------------------------------------------------------------------------
 // wxDataStreamBase
 // ----------------------------------------------------------------------------
@@ -37,6 +55,12 @@ wxDataStreamBase::wxDataStreamBase(const wxMBConv& conv)
     wxUnusedVar(conv);
 
     m_be_order = false;
+
+    // For compatibility with the existing data files, we use extended
+    // precision if it is available, i.e. if wxUSE_APPLE_IEEE is on.
+#if wxUSE_APPLE_IEEE
+    m_useExtendedPrecision = true;
+#endif // wxUSE_APPLE_IEEE
 }
 
 #if wxUSE_UNICODE
@@ -108,13 +132,48 @@ wxUint8 wxDataInputStream::Read8()
 double wxDataInputStream::ReadDouble()
 {
 #if wxUSE_APPLE_IEEE
-  char buf[10];
+    if ( m_useExtendedPrecision )
+    {
+        char buf[10];
 
-  m_input->Read(buf, 10);
-  return wxConvertFromIeeeExtended((const wxInt8 *)buf);
-#else
-  return 0.0;
-#endif
+        m_input->Read(buf, 10);
+        return wxConvertFromIeeeExtended((const wxInt8 *)buf);
+    }
+    else
+#endif // wxUSE_APPLE_IEEE
+    {
+        Float64Data floatData;
+
+        if ( m_be_order == (wxBYTE_ORDER == wxBIG_ENDIAN) )
+        {
+            floatData.i[0] = Read32();
+            floatData.i[1] = Read32();
+        }
+        else
+        {
+            floatData.i[1] = Read32();
+            floatData.i[0] = Read32();
+        }
+
+        return static_cast<double>(floatData.f);
+    }
+}
+
+float wxDataInputStream::ReadFloat()
+{
+#if wxUSE_APPLE_IEEE
+    if ( m_useExtendedPrecision )
+    {
+        return (float)ReadDouble();
+    }
+    else
+#endif // wxUSE_APPLE_IEEE
+    {
+        Float32Data floatData;
+
+        floatData.i = Read32();
+        return static_cast<float>(floatData.f);
+    }
 }
 
 wxString wxDataInputStream::ReadString()
@@ -388,6 +447,14 @@ void wxDataInputStream::ReadDouble(double *buffer, size_t size)
   }
 }
 
+void wxDataInputStream::ReadFloat(float *buffer, size_t size)
+{
+  for (wxUint32 i=0; i<size; i++)
+  {
+    *(buffer++) = ReadFloat();
+  }
+}
+
 wxDataInputStream& wxDataInputStream::operator>>(wxString& s)
 {
   s = ReadString();
@@ -466,7 +533,7 @@ wxDataInputStream& wxDataInputStream::operator>>(double& d)
 
 wxDataInputStream& wxDataInputStream::operator>>(float& f)
 {
-  f = (float)ReadDouble();
+  f = ReadFloat();
   return *this;
 }
 
@@ -535,22 +602,49 @@ void wxDataOutputStream::WriteString(const wxString& string)
 
 void wxDataOutputStream::WriteDouble(double d)
 {
-  char buf[10];
-
 #if wxUSE_APPLE_IEEE
-  wxConvertToIeeeExtended(d, (wxInt8 *)buf);
-#else
-  wxUnusedVar(d);
-#if !defined(__VMS__) && !defined(__GNUG__)
-#ifdef _MSC_VER
-# pragma message("wxDataOutputStream::WriteDouble() not using IeeeExtended - will not work!")
-#else
-# pragma warning "wxDataOutputStream::WriteDouble() not using IeeeExtended - will not work!"
-#endif
-#endif
-   buf[0] = '\0';
-#endif
-  m_output->Write(buf, 10);
+    if ( m_useExtendedPrecision )
+    {
+        char buf[10];
+
+        wxConvertToIeeeExtended(d, (wxInt8 *)buf);
+        m_output->Write(buf, 10);
+    }
+    else
+#endif // wxUSE_APPLE_IEEE
+    {
+        Float64Data floatData;
+
+        floatData.f = (wxFloat64)d;
+
+        if ( m_be_order == (wxBYTE_ORDER == wxBIG_ENDIAN) )
+        {
+            Write32(floatData.i[0]);
+            Write32(floatData.i[1]);
+        }
+        else
+        {
+            Write32(floatData.i[1]);
+            Write32(floatData.i[0]);
+        }
+    }
+}
+
+void wxDataOutputStream::WriteFloat(float f)
+{
+#if wxUSE_APPLE_IEEE
+    if ( m_useExtendedPrecision )
+    {
+        WriteDouble((double)f);
+    }
+    else
+#endif // wxUSE_APPLE_IEEE
+    {
+        Float32Data floatData;
+
+        floatData.f = (wxFloat32)f;
+        Write32(floatData.i);
+    }
 }
 
 #if wxHAS_INT64
@@ -664,6 +758,14 @@ void wxDataOutputStream::WriteDouble(const double *buffer, size_t size)
   }
 }
 
+void wxDataOutputStream::WriteFloat(const float *buffer, size_t size)
+{
+  for (wxUint32 i=0; i<size; i++)
+  {
+    WriteFloat(*(buffer++));
+  }
+}
+
 wxDataOutputStream& wxDataOutputStream::operator<<(const wxString& string)
 {
   WriteString(string);
@@ -742,7 +844,7 @@ wxDataOutputStream& wxDataOutputStream::operator<<(double d)
 
 wxDataOutputStream& wxDataOutputStream::operator<<(float f)
 {
-  WriteDouble((double)f);
+  WriteFloat(f);
   return *this;
 }