1 files changed, 103 insertions, 0 deletions
diff --git a/lib/ccan/tally/tally.h b/lib/ccan/tally/tally.h
new file mode 100644
index 0000000000..e715717507
--- /dev/null
+++ b/lib/ccan/tally/tally.h
@@ -0,0 +1,103 @@
+#ifndef CCAN_TALLY_H
+#define CCAN_TALLY_H
+#include <stdlib.h>
+
+struct tally;
+
+/**
+ * tally_new - allocate the tally structure.
+ * @buckets: the number of frequency buckets.
+ *
+ * This allocates a tally structure using malloc().  The greater the value
+ * of @buckets, the more accurate tally_approx_median() and tally_approx_mode()
+ * and tally_histogram() will be, but more memory is consumed.  If you want
+ * to use tally_histogram(), the optimal bucket value is the same as that
+ * @height argument.
+ */
+struct tally *tally_new(unsigned int buckets);
+
+/**
+ * tally_add - add a value.
+ * @tally: the tally structure.
+ * @val: the value to add.
+ */
+void tally_add(struct tally *tally, ssize_t val);
+
+/**
+ * tally_num - how many times as tally_add been called?
+ * @tally: the tally structure.
+ */
+size_t tally_num(const struct tally *tally);
+
+/**
+ * tally_min - the minimum value passed to tally_add.
+ * @tally: the tally structure.
+ *
+ * Undefined if tally_num() == 0.
+ */
+ssize_t tally_min(const struct tally *tally);
+
+/**
+ * tally_max - the maximum value passed to tally_add.
+ * @tally: the tally structure.
+ *
+ * Undefined if tally_num() == 0.
+ */
+ssize_t tally_max(const struct tally *tally);
+
+/**
+ * tally_mean - the mean value passed to tally_add.
+ * @tally: the tally structure.
+ *
+ * Undefined if tally_num() == 0, but will not crash.
+ */
+ssize_t tally_mean(const struct tally *tally);
+
+/**
+ * tally_total - the total value passed to tally_add.
+ * @tally: the tally structure.
+ * @overflow: the overflow value (or NULL).
+ *
+ * If your total can't overflow a ssize_t, you don't need @overflow.
+ * Otherwise, @overflow is the upper ssize_t, and the return value should
+ * be treated as the lower size_t (ie. the sign bit is in @overflow).
+ */
+ssize_t tally_total(const struct tally *tally, ssize_t *overflow);
+
+/**
+ * tally_approx_median - the approximate median value passed to tally_add.
+ * @tally: the tally structure.
+ * @err: the error in the returned value (ie. real median is +/- @err).
+ *
+ * Undefined if tally_num() == 0, but will not crash.  Because we
+ * don't reallocate, we don't store all values, so this median cannot be
+ * exact.
+ */
+ssize_t tally_approx_median(const struct tally *tally, size_t *err);
+
+/**
+ * tally_approx_mode - the approximate mode value passed to tally_add.
+ * @tally: the tally structure.
+ * @err: the error in the returned value (ie. real mode is +/- @err).
+ *
+ * Undefined if tally_num() == 0, but will not crash.  Because we
+ * don't reallocate, we don't store all values, so this mode cannot be
+ * exact.  It could well be a value which was never passed to tally_add!
+ */
+ssize_t tally_approx_mode(const struct tally *tally, size_t *err);
+
+#define TALLY_MIN_HISTO_WIDTH 8
+#define TALLY_MIN_HISTO_HEIGHT 3
+
+/**
+ * tally_graph - return an ASCII image of the tally_add distribution
+ * @tally: the tally structure.
+ * @width: the maximum string width to use (>= TALLY_MIN_HISTO_WIDTH)
+ * @height: the maximum string height to use (>= TALLY_MIN_HISTO_HEIGHT)
+ *
+ * Returns a malloc()ed string which draws a multi-line graph of the
+ * distribution of values.  On out of memory returns NULL.
+ */
+char *tally_histogram(const struct tally *tally,
+		      unsigned width, unsigned height);
+#endif /* CCAN_TALLY_H */