1 files changed, 128 insertions, 0 deletions
diff --git a/src/stats.c b/src/stats.c
new file mode 100644
index 0000000..7e51c9e
--- /dev/null
+++ b/src/stats.c
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright © 2010, Zed A. Shaw.
+ * Copyright © 2020 rsiddharth <s@ricketyspace.net>
+ */
+
+#include <math.h>
+#include <stats.h>
+
+Stats *Stats_recreate(double sum, double sumsq, unsigned long n,
+                      double min, double max)
+{
+    Stats *st  = malloc(sizeof(Stats));
+    check_mem(st);
+
+    st->sum =  sum;
+    st->sumsq = sumsq;
+    st->n  = n;
+    st->min = min;
+    st->max = max;
+
+    return st;
+
+ error:
+    return NULL;
+}
+
+Stats *Stats_create()
+{
+    return Stats_recreate(0.0, 0.0, 0L, 0.0, 0.0);
+}
+
+void Stats_sample(Stats *st, double s)
+{
+    st->sum  += s;
+    st->sumsq += s * s;
+
+    if (st->n == 0) {
+        st->min = s;
+        st->max = s;
+    } else {
+        if (st->min > s)
+            st->min = s;
+        if (st->max < s)
+            st->max = s;
+    }
+
+    st->n += 1;
+}
+
+char *Stats_dump(Stats *st)
+{
+    size_t char_sz = sizeof(char);
+    size_t dstr_len = 280 * char_sz;
+
+    // allocate space for dump string.
+    char *dstr = calloc(dstr_len, char_sz);
+    check_mem(dstr);
+
+    // dump into dump str.
+    int rc = snprintf(dstr, dstr_len,
+                      "sum: %f, sumsq: %f, n: %ld, "
+                      "min: %f, max: %f, mean: %f, stddev: %f\n",
+                      st->sum, st->sumsq, st->n, st->min, st->max,
+                      Stats_mean(st), Stats_stddev(st));
+    check(rc > 0, "stats dump failed");
+
+    return dstr;
+ error:
+    return NULL;
+}
+
+char *Stats_stringify(Stats *st)
+{
+    size_t stats_str_len = 80;
+
+    // allocate space for stringified stats.
+    char *stats_str = calloc(stats_str_len, sizeof(char));
+    check_mem(stats_str);
+
+    // stringify the stats
+    int rc = snprintf(stats_str, stats_str_len,
+                      "%.2f:%.2f:%ld:%.2f:%.2f",
+                      st->sum, st->sumsq, st->n, st->min, st->max);
+    check(rc > 0, "stringify stats failed");
+
+    return stats_str;
+ error:
+    if (stats_str) {
+        free(stats_str);
+    }
+    return NULL;
+}
+
+
+Stats *Stats_unstringify(char *st_str)
+{
+    Stats *st = NULL;
+
+    check(st_str != NULL, "st_str invalid");
+
+    bstring st_bstr = bfromcstr(st_str);
+    check(st_bstr != NULL, "st_str bstring convert failed");
+
+    struct bstrList *st_list = bsplit(st_bstr, ':');
+    check(st_list != NULL, "st_bstr split failed");
+    check(st_list->qty == 5, "wrong number of st parts");
+
+    st = Stats_create();
+    check(st != NULL, "stats creation failed");
+
+    st->sum = atof(bdata(st_list->entry[0]));
+    st->sumsq = atof(bdata(st_list->entry[1]));
+    st->n = atoi(bdata(st_list->entry[2]));
+    st->min = atof(bdata(st_list->entry[3]));
+    st->max = atof(bdata(st_list->entry[4]));
+
+    // clean up.
+    int rc = bstrListDestroy(st_list);
+    check(rc == BSTR_OK, "st_list destroy failed");
+
+    return st;
+ error:
+    if (st) {
+        free(st);
+    }
+    return NULL;
+}