- * This provides a layer of functions and macros to ensure extensions will
- * get to use the same RTL functions as the core.
+ * <rich@phekda.freeserve.co.uk>: The DJGPP port has code that converts
+ * the return code of system() into the form that Unixy wait usually
+ * returns:
+ *
+ * - signal number in bits 0-6;
+ * - core dump flag in bit 7;
+ * - exit code in bits 8-15.
+ *
+ * Bits 0-7 are always zero for DJGPP, because it uses system().
+ * See djgpp.c.
+ *
+ * POSIX::W* use the W* macros from <sys/wait.h> to decode
+ * the return code. Unfortunately the W* macros for DJGPP use
+ * a different format than Unixy wait does. So there's a mismatch
+ * and, say, WEXITSTATUS($?) will return bogus values.
+ *
+ * So here we add hack to redefine the W* macros from DJGPP's <sys/wait.h>
+ * to work with our return-code conversion.