Added test for meaning of tcl_platform(wordSize) dkf_64bit_support_branch

2 files changed, 16 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index b3b1b45..1300d0f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2002-01-24  Donal K. Fellows  <fellowsd@cs.man.ac.uk>
+
+	* tests/platform.test (platform-2.1): Added test to make sure that
+	the meaning of tcl_platform(wordSize) is what I think it is.
+
 2001-12-02  Donal K. Fellows  <fellowsd@cs.man.ac.uk>
 
 	* tests/platform.test (platform-1.1): 
diff --git a/tests/platform.test b/tests/platform.test
index 288cc72..19001ee 100644
--- a/tests/platform.test
+++ b/tests/platform.test
@@ -25,6 +25,17 @@ test platform-1.1 {TclpSetVariables: tcl_platform} {
     set result
 } {byteOrder machine os osVersion platform user wordSize}
 
+# Test assumes twos-complement arithmetic, which is true of virtually
+# everything these days.  Note that this does *not* use wide(), and
+# this is intentional since that could make Tcl's numbers wider than
+# the machine-integer on some platforms...
+test platform-2.1 {tcl_platform(wordSize) indicates size of native word} {
+    set result [expr {1 << (8 * $tcl_platform(wordSize) - 1)}]
+    # Result must be the largest bit in a machine word, which this checks
+    # without assuming how wide the word really is
+    list [expr {$result < 0}] [expr {$result ^ ($result - 1)}]
+} {1 -1}
+
 # cleanup
 ::tcltest::cleanupTests
 return