Document the new HAVE_CCTK_<datatype> macros.

git-svn-id: http://svn.cactuscode.org/flesh/trunk@3796 17b73243-c579-4c4c-a9d2-2d5706c11dac

1 files changed, 35 insertions, 20 deletions

diff --git a/doc/UsersGuide/ThornWriters.tex b/doc/UsersGuide/ThornWriters.tex
index e50ba409..8aa86bf5 100644
--- a/doc/UsersGuide/ThornWriters.tex
+++ b/doc/UsersGuide/ThornWriters.tex
@@ -4113,7 +4113,7 @@ allow for a homogeneous code.
 \label{sect-ThornWriting/DataTypes}
 \label{sec:datyansi}
 
-Cactus supports the following fixed size data types:
+Cactus knows about the following fixed size data types:
 
 \begin{center}
 \begin{tabular}{|l|l|l|l|}
@@ -4134,6 +4134,21 @@ Data Type & Size (bytes) & Variable Type & Fortran Equivalent\\
 \end{tabular}
 \end{center}
 
+The availability of these types, and the corresponding
+C data types are platform-dependent. For each fixed-size data type there exists
+a corresponding preprocessor macro {\t HAVE\_<data type>} which should be used
+to check whether the given CCTK data type is supported, eg.
+
+\begin{verbatim}
+  /* declare variable with extended-precision complex data type if available
+     otherwise with default CCTK precision */
+  #ifdef HAVE_CCTK_COMPLEX32
+  CCTK_COMPLEX32 var;
+  #else
+  CCTK_COMPLEX   var;
+  #endif
+\end{verbatim}
+
 In addition Cactus provides three generic numeric data types which map onto
 the compilers' native data types used to represent integer, real, and complex
 values. The size for these generic types can be chosen at configuration time
@@ -4161,23 +4176,6 @@ variables in the thorn routines. Note that variable declarations in
 thorns should obviously match with definitions in the interface files
 where appropriate.
 
-Cactus also provides generic data and function pointers, which can
-be used from either C or Fortran (these may not work yet for thorn interface
-files):
-
-\begin{center}
-\begin{tabular}{|l|l|l|}
-\hline
-Data Type               & Variable Type & C equivalent                  \\
-\hline
-{\t CCTK\_POINTER}      & {\t CCTK\_VARIABLE\_POINTER}
-                                        & {\t void *data\_ptr}          \\
-{\t CCTK\_FPOINTER}     & {\t CCTK\_VARIABLE\_FPOINTER}
-                                        & {\t void (*fn\_ptr)(void)}    \\
-\hline
-\end{tabular}
-\end{center}
-
 Also provided, are a set of macros which
 are interpreted by the preprocessor at compile time to signify which
 data size is being used:
@@ -4201,8 +4199,25 @@ Data Type & {\t \#define}\\
 \end{tabular}
 \end{center}
 
-Note that the availability of these types, and the corresponding
-C data types are platform dependent.
+Cactus also provides generic data and function pointers, which can
+be used from either C or Fortran (these may not work yet for thorn interface
+files):
+
+\begin{center}
+\begin{tabular}{|l|l|l|}
+\hline
+Data Type               & Variable Type & C equivalent                  \\
+\hline
+{\t CCTK\_POINTER}      & {\t CCTK\_VARIABLE\_POINTER}
+                                        & {\t void *data\_ptr}          \\
+{\t CCTK\_POINTER\_TO\_CONST}      & {\t CCTK\_VARIABLE\_POINTER}
+                                        & {\t const void *data\_ptr}          \\
+{\t CCTK\_FPOINTER}     & {\t CCTK\_VARIABLE\_FPOINTER}
+                                        & {\t void (*fn\_ptr)(void)}    \\
+\hline
+\end{tabular}
+\end{center}
+
 
 \subsection{Fortran Thorn Writers}