tally: avoid complaints about bitshifts on giant bucket sizes.

[ccan] / ccan / tally / tally.c

diff --git a/ccan/tally/tally.c b/ccan/tally/tally.c
index 29f055588015f5e38f02513c6dcce39b4657ff20..5cc3352a4a90df99362ac74ea0e9a6635ccafec4 100644 (file)
--- a/ccan/tally/tally.c
+++ b/ccan/tally/tally.c
@@ -56,7 +56,7 @@ static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
                return 0;
        }
        assert(step_bits < SIZET_BITS);
-       return (size_t)(val - min) >> step_bits;
+       return ((size_t)val - (size_t)min) >> step_bits;
 }
 
 /* Return the min value in bucket b. */
@@ -67,7 +67,7 @@ static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b)
                return min;
        }
        assert(step_bits < SIZET_BITS);
-       return min + ((ssize_t)b << step_bits);
+       return min + ((size_t)b << step_bits);
 }
 
 /* Does shifting by this many bits truncate the number? */
@@ -76,6 +76,9 @@ static bool shift_overflows(size_t num, unsigned bits)
        if (bits == 0) {
                return false;
        }
+       if (bits >= SIZET_BITS) {
+               return true;
+       }
 
        return ((num << bits) >> 1) != (num << (bits - 1));
 }
@@ -94,7 +97,7 @@ static void renormalize(struct tally *tally,
 
        /* If we don't have sufficient range, increase step bits until
         * buckets cover entire range of ssize_t anyway. */
-       range = (new_max - new_min) + 1;
+       range = ((size_t)new_max - (size_t)new_min) + 1;
        while (!shift_overflows(tally->buckets, tally->step_bits)
               && range > ((size_t)tally->buckets << tally->step_bits)) {
                /* Collapse down. */
@@ -113,11 +116,13 @@ static void renormalize(struct tally *tally,
        memset(tally->counts, 0, sizeof(tally->counts[0]) * old_min);
 
        /* If we moved boundaries, adjust buckets to that ratio. */
-       spill = (tally->min - new_min) % (1 << tally->step_bits);
-       for (i = 0; i < tally->buckets-1; i++) {
-               size_t adjust = (tally->counts[i] >> tally->step_bits) * spill;
-               tally->counts[i] -= adjust;
-               tally->counts[i+1] += adjust;
+       if (tally->step_bits < SIZET_BITS) {
+               spill = (tally->min - new_min) % ((size_t)1 << tally->step_bits);
+               for (i = 0; i < tally->buckets-1; i++) {
+                       size_t adjust = (tally->counts[i] >> tally->step_bits) * spill;
+                       tally->counts[i] -= adjust;
+                       tally->counts[i+1] += adjust;
+               }
        }
 
 update: