SpaceMask_GetStateBits() returns -1 on error.

git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/SpaceMask/trunk@30 a491c6a4-70bf-4b89-8b36-d6c0cb1f094e

2 files changed, 8 insertions, 4 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 349de9b..d6adc5d 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -199,9 +199,12 @@ bitmask corresponding to the given type or state. For example, if a
 given type uses three bits of the mask, the returned value could be
 the integer corresponding to the bitfield $001110000$\ldots, where the
 location of $1$s indicates the bits which have been allocated to the
-given type. A return value of $0$ indicates that the bitmask could
+given type. A return value of $-1$ indicates that the bitmask could
 not be determined for some reason (for example, the requested state
-was not previously registered).
+was not previously registered)\footnote{Note that a potential
+ambiguity arises here, in that if the full mask is allocated to a
+single type, then $-1$ is a valid state. It is assumed that this
+eventuality won't arise in practice.}.
 
 The following macros have been defined for fast setting and checking
 of the mask by direct bitwise operations:
diff --git a/src/MaskUtils.c b/src/MaskUtils.c
index ad9e5e6..784f5b0 100644
--- a/src/MaskUtils.c
+++ b/src/MaskUtils.c
@@ -422,7 +422,8 @@ SpaceMask_GetTypeBits(const char* type_name)
   @author     Denis Pollney
   @date       15 October 2002
   @desc 
-              Returns the bitmask corresponding to the given state.
+              Returns the bitmask corresponding to the given state, or
+	      -1 if the state does not exist.
   @enddesc 
 @@*/
 
@@ -449,7 +450,7 @@ SpaceMask_GetStateBits(const char* type_name, const char* state_name)
 	      "Requested state \"%s\" could not be found in type \"%s\"\n",
 	      state_name, type_name);
 
-  return 0;
+  return -1;
 }
 
 /*@@