[Assorted-commits] SF.net SVN: assorted: [381] cpp-commons/trunk/src/commons/strings.h

[<yan...@us...>]

Revision: 381
          http://assorted.svn.sourceforge.net/assorted/?rev=381&view=rev
Author:   yangzhang
Date:     2008-02-11 15:23:44 -0800 (Mon, 11 Feb 2008)

Log Message:
-----------
added scan

Modified Paths:
--------------
    cpp-commons/trunk/src/commons/strings.h

Modified: cpp-commons/trunk/src/commons/strings.h
===================================================================
--- cpp-commons/trunk/src/commons/strings.h	2008-02-11 23:23:00 UTC (rev 380)
+++ cpp-commons/trunk/src/commons/strings.h	2008-02-11 23:23:44 UTC (rev 381)
@@ -6,6 +6,7 @@
 #include <strings.h>
 
 #include <commons/check.h>
+#include <commons/pointers.h>
 
 namespace commons
 {
@@ -77,6 +78,60 @@
     return unsafe_strstr((char*) p, q, lim);
   }
 
+  /**
+   * "Touch" the entire memory region. Useful for ensuring that some piece of
+   * memory is "warmed up." Visits each character. Note that this might be
+   * optimized out if the caller doesn't meaningfully use the (mostly
+   * meaningless) return value.
+   */
+  inline char
+  scan(const void* buf, size_t len)
+  {
+    char sum = 0;
+    const char* start = (const char*) buf;
+    for (const char* p = start; p < start + len; p++) {
+      sum += *p;
+    }
+    return sum;
+  }
+
+  /**
+   * "Touch" the entire memory region. Useful for ensuring that some piece of
+   * memory is "warmed up." Uses memcpy on 1024-byte chunks. Note that this
+   * might be optimized out if the caller doesn't meaningfully use the (mostly
+   * meaningless) return value.
+   */
+  inline char
+  scan_big_step(const void* buf, size_t len)
+  {
+    const size_t sz = 1024;
+    char tmp[sz];
+    const char* p = (const char*) buf;
+    const char* end = p + len;
+    for (; p + sz < end; p += 1024) {
+      memcpy(tmp, p, sz);
+    }
+    memcpy(tmp, p, end - p);
+    return sz == 0 ? 0 : tmp[0];
+  }
+
+//  /**
+//   * Find an int in the buffer. Return pointer to the first occurrence on
+//   * success, NULL on failure.
+//   */
+//  inline const void*
+//  findint(const void* buf, size_t len, int x)
+//  {
+//    const void* pend = (buf + len);
+//    // Word-align the start and end pointers.
+//    const int* end = (const int*) round_up(p, sizeof(int));
+//    const int* start = (const int*) round_down(buf, sizeof(int));
+//    for (const int* p = buf; p < end; ++p) {
+//      if (*p == x) return p;
+//    }
+//    return NULL;
+//  }
+
 }
 
 #endif


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