dd: use correct multiplication factor and simplify code

function                                             old     new   delta
dd_output_status                                     332     364     +32

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 7 insertions, 19 deletions

diff --git a/coreutils/dd.c b/coreutils/dd.c
index f2e1a1683..8bba62ce1 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -49,9 +49,9 @@ struct globals {
 static void dd_output_status(int UNUSED_PARAM cur_signal)
 {
 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
-        unsigned long long total;
-        unsigned long long diff_scaled;
-        unsigned long long diff_us = monotonic_us(); /* before fprintf */
+        double seconds;
+        unsigned long long bytes_sec;
+        unsigned long long now_us = monotonic_us(); /* before fprintf */
 #endif
 
         /* Deliberately using %u, not %d */
@@ -72,24 +72,12 @@ static void dd_output_status(int UNUSED_PARAM cur_signal)
          * (echo DONE) | ./busybox dd >/dev/null
          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
          */
-        diff_us -= G.begin_time_us;
-        /* We need to calculate "(total * 1000000) / usec" without overflow.
-         * this would work too, but is bigger than integer code below.
-         * total = G.total_bytes * (double)1000000 / (diff_us ? diff_us : 1);
-         */
-        diff_scaled = diff_us;
-        total = G.total_bytes;
-        while (total > MAXINT(unsigned long long) / (1024 * 1024)) {
-                total >>= 1;
-                diff_scaled >>= 1;
-        }
-        total *= (1024 * 1024); /* should be 1000000, but it's +45 bytes */
-        if (diff_scaled > 1)
-                total /= diff_scaled;
+        seconds = (now_us - G.begin_time_us) / 1000000.0;
+        bytes_sec = G.total_bytes / seconds;
         fprintf(stderr, "%f seconds, %sB/s\n",
-                        diff_us / 1000000.0,
+                        seconds,
                         /* show fractional digit, use suffixes */
-                        make_human_readable_str(total, 1, 0)
+                        make_human_readable_str(bytes_sec, 1, 0)
         );
 #endif
 }