Index: zzuf/trunk/src/debug.c
===================================================================
--- zzuf/trunk/src/debug.c	(revision 2326)
+++ zzuf/trunk/src/debug.c	(revision 2336)
@@ -39,4 +39,8 @@
 extern int _zz_debugfd;
 
+/**
+ * Helper macro to write an integer value to a given file descriptor,
+ * either in base 10 or in hexadecimal.
+ */
 #define WRITE_INT(fd, i, base) \
     do \
@@ -53,4 +57,15 @@
     } while(0)
 
+/**
+ * Format a string, printf-like, and write the resulting data to zzuf's
+ * debug file descriptor _zz_debugfd. If the debug file descriptor is
+ * still -1, this function does nothing.
+ *
+ * This function's code is roughly equivalent to the following *printf
+ * calls, except it only uses signal-safe functions:
+ *  - fprintf(stderr, "** zzuf debug ** ");
+ *  - vfprintf(stderr, format, args);
+ *  - fprintf(stderr, "\n");
+ */
 void _zz_debug(char const *format, ...)
 {
@@ -65,12 +80,4 @@
     saved_errno = errno;
     va_start(args, format);
-
-#if 0
-    /* This function's code is equivalent to the following *printf calls,
-     * except it only uses signal-safe functions */
-    fprintf(stderr, "** zzuf debug ** ");
-    vfprintf(stderr, format, args);
-    fprintf(stderr, "\n");
-#endif
 
     write(_zz_debugfd, "** zzuf debug ** ", 17);