From bf194646e7a4bd348fd6033b183a1fd78a0aaef1 Mon Sep 17 00:00:00 2001
From: James Slocum <j.m.slocum@gmail.com>
Date: Thu, 3 Oct 2013 21:16:39 -0400
Subject: Fixed 2 bugs. Fixed a segfault, and read error. 1) the for(t=0;
 t<array_size; t+=block_size) loop could write past the end of the buffer and
 segfault 2) The 'a' buffer was not being advanced, causing the same memory to
 be read over and over,  this caused heavy cache hits and unrealistically high
 results.

---
 README | 1 +
 mbw.c  | 9 ++++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/README b/README
index 0c6f722..218fd8b 100644
--- a/README
+++ b/README
@@ -1,6 +1,7 @@
 MBW determines the "copy" memory bandwidth available to userspace programs. Its simplistic approach models that of real applications. It is not tuned to extremes and it is not aware of hardware architecture, just like your average software package.
 
 2006, 2012 Andras.Horvath atnospam gmail.com
+2013 j.m.slocum atnospam gmail.com
 
 http://github.com/raas/mbw
 
diff --git a/mbw.c b/mbw.c
index 3a02826..1c6fe63 100644
--- a/mbw.c
+++ b/mbw.c
@@ -27,6 +27,8 @@
  * MBW memory bandwidth benchmark
  *
  * 2006, 2012 Andras.Horvath@gmail.com
+ * 2013 j.m.slocum@gmail.com 
+ * (Special thanks to Stephen Pasich)
  *
  * http://github.com/raas/mbw
  *
@@ -97,6 +99,7 @@ double worker(unsigned long long asize, long *a, long *b, int type, unsigned lon
     unsigned int long_size=sizeof(long);
     /* array size in bytes */
     unsigned long long array_bytes=asize*long_size;
+    unsigned int advance=block_size/long_size;
 
     if(type==1) { /* memcpy test */
         /* timer starts */
@@ -106,11 +109,11 @@ double worker(unsigned long long asize, long *a, long *b, int type, unsigned lon
         gettimeofday(&endtime, NULL);
     } else if(type==2) { /* memcpy block test */
         gettimeofday(&starttime, NULL);
-        for(t=0; t<array_bytes; t+=block_size) {
+        for (t=array_bytes; t >= block_size; t-=block_size, a+=advance){
             b=mempcpy(b, a, block_size);
         }
-        if(t>array_bytes) {
-            b=mempcpy(b, a, t-array_bytes);
+        if(t) {
+            b=mempcpy(b, a, t);
         }
         gettimeofday(&endtime, NULL);
     } else { /* dumb test */
-- 
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