From fd133e1570308d6121181c729fbaeaf45267eb63 Mon Sep 17 00:00:00 2001
From: Dirk Farin <dirk.farin@gmail.com>
Date: Tue, 30 Jul 2024 12:53:47 +0200
Subject: [PATCH] changes requested in review (#72)

---
 display.c |  2 +-
 file.c    | 33 ++++++++++++++++++++++++---------
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/display.c b/display.c
index a2a5675..06a2b31 100644
--- a/display.c
+++ b/display.c
@@ -164,7 +164,7 @@ void exitCurses(void)
 
 static void printaddr(uint64_t addr)
 {
-  char templ[7];
+  char templ[7]; // maximum string is "%016lX", which is 6 chars + 1 null byte
   sprintf(templ,"%%0%dlX", nAddrDigits);
   PRINTW((templ, addr));
 }
diff --git a/file.c b/file.c
index d53288b..3337f15 100644
--- a/file.c
+++ b/file.c
@@ -16,6 +16,26 @@
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.*/
 #include "hexedit.h"
 
+
+// Compute number of hex-digits needed to display an address.
+// We only increase this by full bytes (2 digits).
+// Because the input is uint64_t, the maximum result is 16 (64bit = 16*4bit).
+int compute_nDigits(uint64_t maxAddr)
+{
+  int digits = 0;
+  while (maxAddr) {
+    digits+=2;
+    maxAddr >>= 8;
+  }
+
+  if (digits==0) {
+    return 2;
+  }
+
+  return digits;
+}
+
+
 void openFile(void)
 {
   struct stat st;
@@ -54,16 +74,11 @@ void openFile(void)
   }
   biggestLoc = fileSize;
 
-  // compute number of digits for address
+  nAddrDigits = compute_nDigits(biggestLoc);
 
-  nAddrDigits=8;
-  off_t maxAddr = biggestLoc;
-  if (maxAddr > 0xFFFFFFFF) {
-    maxAddr >>= 32;
-    while (maxAddr) {
-      nAddrDigits+=2;
-      maxAddr >>= 8;
-    }
+  // use at least 8 digits (4 byte addresses)
+  if (nAddrDigits < 8) {
+    nAddrDigits = 8;
   }
 }