Imported from libpng-1.0.4d2.tar

KNOWNBUG

@@ -38,13 +38,21 @@ Known bugs and suggested enhancements in libpng-1.0.4
    for the png_set_gAMA(), png_set_cHRM(), and corresponding png_get_()
    functions will be needed.
 
-4. September 1999 -- BUG --
+4. September 1999 -- BUG [FIXED] --
 
-   Portions of the new MMX code in pngvcrd.c are defined out because the
-   did not work properly.  When PNGVCRD_INTERLACE_BUG_IS_FIXED is defined,
-   to enable the code, pngtest pngtest.png pngout.png results in a
-   "Debug error! Damage before normal block # 57 at 0x007e19f0" on
-   a Pentium II with MMX system.  This seems to be caused by the heap
-   being trashed before a free() in png_read_destroy().
+   Portions of the new MMX code in pngvcrd.c were ifdef'd out because they
+   didn't work properly, but the bug appears to have been found and fixed.
+   As a result, all parts of the code are once again enabled.  If you think
+   there's still a problem, you can recompile with one of the following two
+   macros defined and see if the problem goes away:
 
-   When PNGVCRD_COMBINE_BUG_IS_FIXED is defined (what?)
+	DISABLE_PNGVCRD_COMBINE
+	DISABLE_PNGVCRD_INTERLACE
+
+   The second one is in the function where the bug was; as far as we are
+   aware, there was never any bug in the other function.  Please notify us
+   if you find any problems in libpng, regardless of whether the two macros
+   make any difference:  png-implement@ccrc.wustl.edu
+
+   Again, we believe the MMX code in pngvcrd.c is 100% correct, but it has
+   not yet been tested extensively.