diff options
Diffstat (limited to 'lib/ccan/tally/tally.c')
| -rw-r--r-- | lib/ccan/tally/tally.c | 490 |
1 files changed, 490 insertions, 0 deletions
diff --git a/lib/ccan/tally/tally.c b/lib/ccan/tally/tally.c new file mode 100644 index 00000000000..b1839befe3b --- /dev/null +++ b/lib/ccan/tally/tally.c @@ -0,0 +1,490 @@ +#include <ccan/tally/tally.h> +#include <ccan/build_assert/build_assert.h> +#include <ccan/likely/likely.h> +#include <stdint.h> +#include <limits.h> +#include <string.h> +#include <stdio.h> +#include <assert.h> +#include <stdlib.h> + +#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. */ + unsigned buckets, step_bits; + size_t counts[1 /* Actually: [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-1)); + if (tally) { + tally->max = ((size_t)1 << (SIZET_BITS - 1)); + tally->min = ~tally->max; + tally->total[0] = tally->total[1] = 0; + tally->buckets = buckets; + tally->step_bits = 0; + memset(tally->counts, 0, sizeof(tally->counts[0])*buckets); + } + return tally; +} + +static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val) +{ + /* Don't over-shift. */ + if (step_bits == SIZET_BITS) + return 0; + assert(step_bits < SIZET_BITS); + return (size_t)(val - min) >> step_bits; +} + +/* Return the min value in bucket b. */ +static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b) +{ + /* Don't over-shift. */ + if (step_bits == SIZET_BITS) + return min; + assert(step_bits < SIZET_BITS); + return min + ((ssize_t)b << step_bits); +} + +/* Does shifting by this many bits truncate the number? */ +static bool shift_overflows(size_t num, unsigned bits) +{ + if (bits == 0) + return false; + + return ((num << bits) >> 1) != (num << (bits - 1)); +} + +/* When min or max change, we may need to shuffle the frequency counts. */ +static void renormalize(struct tally *tally, + ssize_t new_min, ssize_t new_max) +{ + size_t range, spill; + unsigned int i, old_min; + + /* Uninitialized? Don't do anything... */ + if (tally->max < tally->min) + goto update; + + /* 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; + while (!shift_overflows(tally->buckets, tally->step_bits) + && range > ((size_t)tally->buckets << tally->step_bits)) { + /* Collapse down. */ + for (i = 1; i < tally->buckets; i++) { + tally->counts[i/2] += tally->counts[i]; + tally->counts[i] = 0; + } + tally->step_bits++; + } + + /* Now if minimum has dropped, move buckets up. */ + old_min = bucket_of(new_min, tally->step_bits, tally->min); + memmove(tally->counts + old_min, + tally->counts, + sizeof(tally->counts[0]) * (tally->buckets - old_min)); + 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; + } + +update: + tally->min = new_min; + tally->max = new_max; +} + +void tally_add(struct tally *tally, ssize_t val) +{ + ssize_t new_min = tally->min, new_max = tally->max; + bool need_renormalize = false; + + if (val < tally->min) { + new_min = val; + need_renormalize = true; + } + if (val > tally->max) { + new_max = val; + need_renormalize = true; + } + if (need_renormalize) + renormalize(tally, new_min, new_max); + + /* 128-bit arithmetic! If we didn't want exact mean, we could just + * pull it out of counts. */ + if (val > 0 && tally->total[0] + val < tally->total[0]) + tally->total[1]++; + else if (val < 0 && tally->total[0] + val > tally->total[0]) + tally->total[1]--; + tally->total[0] += val; + tally->counts[bucket_of(tally->min, tally->step_bits, val)]++; +} + +size_t tally_num(const struct tally *tally) +{ + size_t i, num = 0; + for (i = 0; i < tally->buckets; i++) + num += tally->counts[i]; + return num; +} + +ssize_t tally_min(const struct tally *tally) +{ + return tally->min; +} + +ssize_t tally_max(const struct tally *tally) +{ + return tally->max; +} + +/* FIXME: Own ccan module please! */ +static unsigned fls64(uint64_t val) +{ +#if HAVE_BUILTIN_CLZL + if (val <= ULONG_MAX) { + /* This is significantly faster! */ + return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0; + } else { +#endif + uint64_t r = 64; + + if (!val) + return 0; + if (!(val & 0xffffffff00000000ull)) { + val <<= 32; + r -= 32; + } + if (!(val & 0xffff000000000000ull)) { + val <<= 16; + r -= 16; + } + if (!(val & 0xff00000000000000ull)) { + val <<= 8; + r -= 8; + } + if (!(val & 0xf000000000000000ull)) { + val <<= 4; + r -= 4; + } + if (!(val & 0xc000000000000000ull)) { + val <<= 2; + r -= 2; + } + if (!(val & 0x8000000000000000ull)) { + val <<= 1; + r -= 1; + } + return r; +#if HAVE_BUILTIN_CLZL + } +#endif +} + +/* This is stolen straight from Hacker's Delight. */ +static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v) +{ + const uint64_t b = 4294967296ULL; // Number base (32 bits). + uint32_t un[4], // Dividend and divisor + vn[2]; // normalized and broken + // up into halfwords. + uint32_t q[2]; // Quotient as halfwords. + uint64_t un1, un0, // Dividend and divisor + vn0; // as fullwords. + uint64_t qhat; // Estimated quotient digit. + uint64_t rhat; // A remainder. + uint64_t p; // Product of two digits. + int64_t s, i, j, t, k; + + if (u1 >= v) // If overflow, return the largest + return (uint64_t)-1; // possible quotient. + + s = 64 - fls64(v); // 0 <= s <= 63. + vn0 = v << s; // Normalize divisor. + vn[1] = vn0 >> 32; // Break divisor up into + vn[0] = vn0 & 0xFFFFFFFF; // two 32-bit halves. + + // Shift dividend left. + un1 = ((u1 << s) | (u0 >> (64 - s))) & (-s >> 63); + un0 = u0 << s; + un[3] = un1 >> 32; // Break dividend up into + un[2] = un1; // four 32-bit halfwords + un[1] = un0 >> 32; // Note: storing into + un[0] = un0; // halfwords truncates. + + for (j = 1; j >= 0; j--) { + // Compute estimate qhat of q[j]. + qhat = (un[j+2]*b + un[j+1])/vn[1]; + rhat = (un[j+2]*b + un[j+1]) - qhat*vn[1]; + again: + if (qhat >= b || qhat*vn[0] > b*rhat + un[j]) { + qhat = qhat - 1; + rhat = rhat + vn[1]; + if (rhat < b) goto again; + } + + // Multiply and subtract. + k = 0; + for (i = 0; i < 2; i++) { + p = qhat*vn[i]; + t = un[i+j] - k - (p & 0xFFFFFFFF); + un[i+j] = t; + k = (p >> 32) - (t >> 32); + } + t = un[j+2] - k; + un[j+2] = t; + + q[j] = qhat; // Store quotient digit. + if (t < 0) { // If we subtracted too + q[j] = q[j] - 1; // much, add back. + k = 0; + for (i = 0; i < 2; i++) { + t = un[i+j] + vn[i] + k; + un[i+j] = t; + k = t >> 32; + } + un[j+2] = un[j+2] + k; + } + } // End j. + + return q[1]*b + q[0]; +} + +static int64_t divls64(int64_t u1, uint64_t u0, int64_t v) +{ + int64_t q, uneg, vneg, diff, borrow; + + uneg = u1 >> 63; // -1 if u < 0. + if (uneg) { // Compute the absolute + u0 = -u0; // value of the dividend u. + borrow = (u0 != 0); + u1 = -u1 - borrow; + } + + vneg = v >> 63; // -1 if v < 0. + v = (v ^ vneg) - vneg; // Absolute value of v. + + if ((uint64_t)u1 >= (uint64_t)v) + goto overflow; + + q = divlu64(u1, u0, v); + + diff = uneg ^ vneg; // Negate q if signs of + q = (q ^ diff) - diff; // u and v differed. + + if ((diff ^ q) < 0 && q != 0) { // If overflow, return the largest + overflow: // possible neg. quotient. + q = 0x8000000000000000ULL; + } + return q; +} + +ssize_t tally_mean(const struct tally *tally) +{ + size_t count = tally_num(tally); + if (!count) + return 0; + + if (sizeof(tally->total[0]) == sizeof(uint32_t)) { + /* Use standard 64-bit arithmetic. */ + int64_t total = tally->total[0] + | (((uint64_t)tally->total[1]) << 32); + return total / count; + } + 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; + + min = bucket_min(tally->min, tally->step_bits, b); + if (b == tally->buckets - 1) + max = tally->max; + else + max = bucket_min(tally->min, tally->step_bits, b+1) - 1; + + /* FIXME: Think harder about cumulative error; is this enough?. */ + *err = (max - min + 1) / 2; + /* Avoid overflow. */ + return min + (max - min) / 2; +} + +ssize_t tally_approx_median(const struct tally *tally, size_t *err) +{ + size_t count = tally_num(tally), total = 0; + unsigned int i; + + for (i = 0; i < tally->buckets; i++) { + total += tally->counts[i]; + if (total * 2 >= count) + break; + } + return bucket_range(tally, i, err); +} + +ssize_t tally_approx_mode(const struct tally *tally, size_t *err) +{ + unsigned int i, min_best = 0, max_best = 0; + + for (i = 0; i < tally->buckets; i++) { + if (tally->counts[i] > tally->counts[min_best]) { + min_best = max_best = i; + } else if (tally->counts[i] == tally->counts[min_best]) { + max_best = i; + } + } + + /* We can have more than one best, making our error huge. */ + if (min_best != max_best) { + ssize_t min, max; + min = bucket_range(tally, min_best, err); + max = bucket_range(tally, max_best, err); + max += *err; + *err += (size_t)(max - min); + return min + (max - min) / 2; + } + + return bucket_range(tally, min_best, err); +} + +static unsigned get_max_bucket(const struct tally *tally) +{ + unsigned int i; + + for (i = tally->buckets; i > 0; i--) + if (tally->counts[i-1]) + break; + return i; +} + +char *tally_histogram(const struct tally *tally, + unsigned width, unsigned height) +{ + unsigned int i, count, max_bucket, largest_bucket; + struct tally *tmp; + char *graph, *p; + + assert(width >= TALLY_MIN_HISTO_WIDTH); + assert(height >= TALLY_MIN_HISTO_HEIGHT); + + /* Ignore unused buckets. */ + max_bucket = get_max_bucket(tally); + + /* FIXME: It'd be nice to smooth here... */ + if (height >= max_bucket) { + height = max_bucket; + tmp = NULL; + } else { + /* We create a temporary then renormalize so < height. */ + /* FIXME: Antialias properly! */ + tmp = tally_new(tally->buckets); + if (!tmp) + return NULL; + tmp->min = tally->min; + tmp->max = tally->max; + tmp->step_bits = tally->step_bits; + 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); + /* Restore max */ + tmp->max = tally->max; + tally = tmp; + height = max_bucket; + } + + /* Figure out longest line, for scale. */ + largest_bucket = 0; + for (i = 0; i < tally->buckets; i++) { + if (tally->counts[i] > largest_bucket) + largest_bucket = tally->counts[i]; + } + + p = graph = malloc(height * (width + 1) + 1); + if (!graph) { + free(tmp); + return NULL; + } + + for (i = 0; i < height; i++) { + 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 (row == 0) + covered = snprintf(p, width, "%zi", tally->min); + else if (row == height - 1) + covered = snprintf(p, width, "%zi", tally->max); + 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'; + p++; + } + *p = '\0'; + free(tmp); + return graph; +} |