Fix 256 color mapping in rxvt.el

* term/rxvt.el (rxvt-rgb-convert-to-16bit): Standardize with
xterm-rgb-convert-to-16bit.
(rxvt-register-default-colors): Standardize with
xterm-register-default-colors.

Fixes: debbugs:14078

2 files changed, 11 insertions, 4 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 8d67a12e3d6..a55cf9c180d 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2013-12-17  oblique  <psyberbits@gmail.com>  (tiny change)
+
+        * term/rxvt.el (rxvt-rgb-convert-to-16bit): Standardize with
+        xterm-rgb-convert-to-16bit.
+        (rxvt-register-default-colors): Standardize with
+        xterm-register-default-colors (Bug#14078).
+
 2013-12-17  Dima Kogan  <dima@secretsauce.net>  (tiny change)
 
         * simple.el (kill-region): Pass mark first, then point, so that
diff --git a/lisp/term/rxvt.el b/lisp/term/rxvt.el
index 0e026a8e4be..4dbbc12786c 100644
--- a/lisp/term/rxvt.el
+++ b/lisp/term/rxvt.el
@@ -201,7 +201,7 @@
 
 (defun rxvt-rgb-convert-to-16bit (prim)
   "Convert an 8-bit primary color value PRIM to a corresponding 16-bit value."
-  (min 65535 (round (* (/ prim 255.0) 65535.0))))
+  (logior prim (lsh prim 8)))
 
 (defun rxvt-register-default-colors ()
   "Register the default set of colors for rxvt or compatible emulator.
@@ -233,9 +233,9 @@ for the currently selected frame."
             (tty-color-define (format "color-%d" (- 256 ncolors))
                               (- 256 ncolors)
                               (mapcar 'rxvt-rgb-convert-to-16bit
-                                      (list (round (* r 42.5))
-                                            (round (* g 42.5))
-                                            (round (* b 42.5)))))
+                                      (list (if (zerop r) 0 (+ (* r 40) 55))
+                                            (if (zerop g) 0 (+ (* g 40) 55))
+                                            (if (zerop b) 0 (+ (* b 40) 55)))))
             (setq b (1+ b))
             (if (> b 5)
                 (setq g (1+ g)