hash: use config.h settings for endian.
[ccan] / ccan / tally / tally.c
index 1433a3aa2650e45cf2bfc44c3bce646400f8dfba..0d0190795557b60ccfe8d73138dfda2baf99477d 100644 (file)
@@ -8,46 +8,36 @@
 #include <stdio.h>
 #include <assert.h>
 
-#define MAX_STEP_BITS (sizeof(size_t)*CHAR_BIT)
+#define SIZET_BITS (sizeof(size_t)*CHAR_BIT)
 
 /* We use power of 2 steps.  I tried being tricky, but it got buggy. */
 struct tally {
        ssize_t min, max;
        size_t total[2];
        /* This allows limited frequency analysis. */
-       size_t buckets;
-       size_t step_bits;
-       size_t counts[1 /* [buckets] */ ];
+       unsigned buckets, step_bits;
+       size_t counts[1 /* Actually: [buckets] */ ];
 };
 
-struct tally *tally_new(size_t buckets)
+struct tally *tally_new(unsigned buckets)
 {
        struct tally *tally;
 
+       /* There is always 1 bucket. */
+       if (buckets == 0)
+               buckets = 1;
+
        /* Check for overflow. */
        if (buckets && SIZE_MAX / buckets < sizeof(tally->counts[0]))
                return NULL;
-       tally = malloc(sizeof(*tally) + sizeof(tally->counts[0])*buckets);
+       tally = malloc(sizeof(*tally) + sizeof(tally->counts[0])*(buckets-1));
        if (tally) {
-               /* SSIZE_MAX isn't portable, so make it one of these types. */
-               BUILD_ASSERT(sizeof(tally->min) == sizeof(int)
-                            || sizeof(tally->min) == sizeof(long)
-                            || sizeof(tally->min) == sizeof(long long));
-               if (sizeof(tally->min) == sizeof(int)) {
-                       tally->min = INT_MAX;
-                       tally->max = INT_MIN;
-               } else if (sizeof(tally->min) == sizeof(long)) {
-                       tally->min = LONG_MAX;
-                       tally->max = LONG_MIN;
-               } else if (sizeof(tally->min) == sizeof(long long)) {
-                       tally->min = (ssize_t)LLONG_MAX;
-                       tally->max = (ssize_t)LLONG_MIN;
-               }
+               tally->max = ((size_t)1 << (SIZET_BITS - 1));
+               tally->min = ~tally->max;
                tally->total[0] = tally->total[1] = 0;
-               /* There is always 1 bucket. */
-               tally->buckets = buckets+1;
+               tally->buckets = buckets;
                tally->step_bits = 0;
-               memset(tally->counts, 0, sizeof(tally->counts[0])*(buckets+1));
+               memset(tally->counts, 0, sizeof(tally->counts[0])*buckets);
        }
        return tally;
 }
@@ -55,9 +45,9 @@ struct tally *tally_new(size_t buckets)
 static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
 {
        /* Don't over-shift. */
-       if (step_bits == MAX_STEP_BITS)
+       if (step_bits == SIZET_BITS)
                return 0;
-       assert(step_bits < MAX_STEP_BITS);
+       assert(step_bits < SIZET_BITS);
        return (size_t)(val - min) >> step_bits;
 }
 
@@ -65,9 +55,9 @@ static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
 static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b)
 {
        /* Don't over-shift. */
-       if (step_bits == MAX_STEP_BITS)
+       if (step_bits == SIZET_BITS)
                return min;
-       assert(step_bits < MAX_STEP_BITS);
+       assert(step_bits < SIZET_BITS);
        return min + ((ssize_t)b << step_bits);
 }
 
@@ -324,6 +314,33 @@ ssize_t tally_mean(const struct tally *tally)
        return divls64(tally->total[1], tally->total[0], count);
 }
 
+ssize_t tally_total(const struct tally *tally, ssize_t *overflow)
+{
+       if (overflow) {
+               *overflow = tally->total[1];
+               return tally->total[0];
+       }
+
+       /* If result is negative, make sure we can represent it. */
+       if (tally->total[1] & ((size_t)1 << (SIZET_BITS-1))) {
+               /* Must have only underflowed once, and must be able to
+                * represent result at ssize_t. */
+               if ((~tally->total[1])+1 != 0
+                   || (ssize_t)tally->total[0] >= 0) {
+                       /* Underflow, return minimum. */
+                       return (ssize_t)((size_t)1 << (SIZET_BITS - 1));
+               }
+       } else {
+               /* Result is positive, must not have overflowed, and must be
+                * able to represent as ssize_t. */
+               if (tally->total[1] || (ssize_t)tally->total[0] < 0) {
+                       /* Overflow.  Return maximum. */
+                       return (ssize_t)~((size_t)1 << (SIZET_BITS - 1));
+               }
+       }
+       return tally->total[0];
+}
+
 static ssize_t bucket_range(const struct tally *tally, unsigned b, size_t *err)
 {
        ssize_t min, max;
@@ -408,7 +425,7 @@ char *tally_histogram(const struct tally *tally,
        } else {
                /* We create a temporary then renormalize so < height. */
                /* FIXME: Antialias properly! */
-               tmp = tally_new(tally->buckets-1);
+               tmp = tally_new(tally->buckets);
                if (!tmp)
                        return NULL;
                tmp->min = tally->min;
@@ -417,7 +434,7 @@ char *tally_histogram(const struct tally *tally,
                memcpy(tmp->counts, tally->counts,
                       sizeof(tally->counts[0]) * tmp->buckets);
                while ((max_bucket = get_max_bucket(tmp)) >= height)
-                       renormalize(tmp, tmp->min, tmp->max *= 2);
+                       renormalize(tmp, tmp->min, tmp->max * 2);
                /* Restore max */
                tmp->max = tally->max;
                tally = tmp;
@@ -436,23 +453,32 @@ char *tally_histogram(const struct tally *tally,
                free(tmp);
                return NULL;
        }
+
        for (i = 0; i < height; i++) {
-               unsigned covered = 0;
-               count = (double)tally->counts[i] / largest_bucket * width;
+               unsigned covered = 1, row;
+
+               /* People expect minimum at the bottom. */
+               row = height - i - 1;
+               count = (double)tally->counts[row] / largest_bucket * (width-1)+1;
 
-               if (i == 0)
+               if (row == 0)
                        covered = snprintf(p, width, "%zi", tally->min);
-               else if (i == height - 1)
+               else if (row == height - 1)
                        covered = snprintf(p, width, "%zi", tally->max);
-               if (covered) {
-                       if (covered > width)
-                               covered = width;
-                       p += covered;
-                       if (count > covered)
-                               count -= covered;
-                       else
-                               count = 0;
-               }
+               else if (row == bucket_of(tally->min, tally->step_bits, 0))
+                       *p = '+';
+               else
+                       *p = '|';
+
+               if (covered > width)
+                       covered = width;
+               p += covered;
+
+               if (count > covered)
+                       count -= covered;
+               else
+                       count = 0;
+
                memset(p, '*', count);
                p += count;
                *p = '\n';