lcov-1.7 into third_party for code coverage on POSIX systems.

Non-lcov-1.7 files are 
  lcov/LICENCE
  lcov/README.chromium
  lcov/bin/mcov

Review URL: http://codereview.chromium.org/57083

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@13066 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 48 insertions, 0 deletions

diff --git a/third_party/lcov/example/methods/gauss.c b/third_party/lcov/example/methods/gauss.c
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+++ b/third_party/lcov/example/methods/gauss.c
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+/*
+ *  methods/gauss.c
+ *
+ *  Calculate the sum of a given range of integer numbers.
+ *
+ *  Somewhat of a more subtle way of calculation - and it even has a story
+ *  behind it:
+ *
+ *  Supposedly during math classes in elementary school, the teacher of
+ *  young mathematician Gauss gave the class an assignment to calculate the
+ *  sum of all natural numbers between 1 and 100, hoping that this task would
+ *  keep the kids occupied for some time. The story goes that Gauss had the
+ *  result ready after only a few minutes. What he had written on his black
+ *  board was something like this:
+ *
+ *    1 + 100 = 101
+ *    2 + 99  = 101
+ *    3 + 98  = 101
+ *    .
+ *    .
+ *    100 + 1 = 101
+ *
+ *    s = (1/2) * 100 * 101 = 5050
+ *
+ *  A more general form of this formula would be
+ *  
+ *    s = (1/2) * (max + min) * (max - min + 1)
+ *
+ *  which is used in the piece of code below to implement the requested
+ *  function in constant time, i.e. without dependencies on the size of the
+ *  input parameters.
+ *
+ */
+
+#include "gauss.h"
+
+
+int gauss_get_sum (int min, int max)
+{
+	/* This algorithm doesn't work well with invalid range specifications
+	   so we're intercepting them here. */
+	if (max < min)
+	{
+		return 0;
+	}
+
+	return (int) ((max + min) * (double) (max - min + 1) / 2);
+}