(ls-lisp-format): Fix last change.

2 files changed, 23 insertions, 6 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d0c371b19b9..da619ce06a3 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2008-04-25  Eli Zaretskii  <eliz@gnu.org>
+
+        * ls-lisp.el (ls-lisp-format): Fix last change.
+
 2008-04-24  Nick Roberts  <nickrob@snap.net.nz>
 
         * progmodes/gdb-ui.el (gdb-invalidate-assembler): Compare numeric
diff --git a/lisp/ls-lisp.el b/lisp/ls-lisp.el
index 2ce3c9dfd6b..e1e10531880 100644
--- a/lisp/ls-lisp.el
+++ b/lisp/ls-lisp.el
@@ -532,14 +532,27 @@ SWITCHES, TIME-INDEX and NOW give the full switch list and time data."
                 (let ((inode (nth 10 file-attr)))
                   (if (consp inode)
                       (if (consp (cdr inode))
-                          (format " %17.0f "
-                                  (+ (* (car inode) 1099511627776.0)
-                                     (* (cadr inode) 65536.0)
-                                     (cddr inode)))
-                        (format " %17.0f "
+                          ;; 2^(24+16) = 1099511627776.0, but
+                          ;; multiplying by it and then adding the
+                          ;; other members of the cons cell in one go
+                          ;; loses precision, since a double does not
+                          ;; have enough significant digits to hold a
+                          ;; full 64-bit value.  So below we split
+                          ;; 1099511627776 into high 13 and low 5
+                          ;; digits and compute in two parts.
+                          (let ((p1 (* (car inode) 10995116.0))
+                                (p2 (+ (* (car inode) 27776.0)
+                                       (* (cadr inode) 65536.0)
+                                       (cddr inode))))
+                            (format " %13.0f%05.0f "
+                                    ;; Use floor to emulate integer
+                                    ;; division.
+                                    (+ p1 (floor p2 100000.0))
+                                    (mod p2 100000.0)))
+                        (format " %18.0f "
                                 (+ (* (car inode) 65536.0)
                                    (cdr inode))))
-                    (format " %17d " inode))))
+                    (format " %18d " inode))))
             ;; nil is treated like "" in concat
             (if (memq ?s switches)      ; size in K
                 (format " %4.0f" (fceiling (/ file-size 1024.0))))