1 /* Licensed under LGPLv3+ - see LICENSE file for details */
2 #include <ccan/tally/tally.h>
3 #include <ccan/build_assert/build_assert.h>
4 #include <ccan/likely/likely.h>
12 #define SIZET_BITS (sizeof(size_t)*CHAR_BIT)
14 /* We use power of 2 steps. I tried being tricky, but it got buggy. */
18 /* This allows limited frequency analysis. */
19 unsigned buckets, step_bits;
20 size_t counts[1 /* Actually: [buckets] */ ];
23 struct tally *tally_new(unsigned buckets)
27 /* There is always 1 bucket. */
31 /* Overly cautious check for overflow. */
32 if (sizeof(*tally) * buckets / sizeof(*tally) != buckets)
34 tally = (struct tally *)malloc(
35 sizeof(*tally) + sizeof(tally->counts[0])*(buckets-1));
37 tally->max = ((size_t)1 << (SIZET_BITS - 1));
38 tally->min = ~tally->max;
39 tally->total[0] = tally->total[1] = 0;
40 tally->buckets = buckets;
42 memset(tally->counts, 0, sizeof(tally->counts[0])*buckets);
47 static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
49 /* Don't over-shift. */
50 if (step_bits == SIZET_BITS)
52 assert(step_bits < SIZET_BITS);
53 return (size_t)(val - min) >> step_bits;
56 /* Return the min value in bucket b. */
57 static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b)
59 /* Don't over-shift. */
60 if (step_bits == SIZET_BITS)
62 assert(step_bits < SIZET_BITS);
63 return min + ((ssize_t)b << step_bits);
66 /* Does shifting by this many bits truncate the number? */
67 static bool shift_overflows(size_t num, unsigned bits)
72 return ((num << bits) >> 1) != (num << (bits - 1));
75 /* When min or max change, we may need to shuffle the frequency counts. */
76 static void renormalize(struct tally *tally,
77 ssize_t new_min, ssize_t new_max)
80 unsigned int i, old_min;
82 /* Uninitialized? Don't do anything... */
83 if (tally->max < tally->min)
86 /* If we don't have sufficient range, increase step bits until
87 * buckets cover entire range of ssize_t anyway. */
88 range = (new_max - new_min) + 1;
89 while (!shift_overflows(tally->buckets, tally->step_bits)
90 && range > ((size_t)tally->buckets << tally->step_bits)) {
92 for (i = 1; i < tally->buckets; i++) {
93 tally->counts[i/2] += tally->counts[i];
99 /* Now if minimum has dropped, move buckets up. */
100 old_min = bucket_of(new_min, tally->step_bits, tally->min);
101 memmove(tally->counts + old_min,
103 sizeof(tally->counts[0]) * (tally->buckets - old_min));
104 memset(tally->counts, 0, sizeof(tally->counts[0]) * old_min);
106 /* If we moved boundaries, adjust buckets to that ratio. */
107 spill = (tally->min - new_min) % (1 << tally->step_bits);
108 for (i = 0; i < tally->buckets-1; i++) {
109 size_t adjust = (tally->counts[i] >> tally->step_bits) * spill;
110 tally->counts[i] -= adjust;
111 tally->counts[i+1] += adjust;
115 tally->min = new_min;
116 tally->max = new_max;
119 void tally_add(struct tally *tally, ssize_t val)
121 ssize_t new_min = tally->min, new_max = tally->max;
122 bool need_renormalize = false;
124 if (val < tally->min) {
126 need_renormalize = true;
128 if (val > tally->max) {
130 need_renormalize = true;
132 if (need_renormalize)
133 renormalize(tally, new_min, new_max);
135 /* 128-bit arithmetic! If we didn't want exact mean, we could just
136 * pull it out of counts. */
137 if (val > 0 && tally->total[0] + val < tally->total[0])
139 else if (val < 0 && tally->total[0] + val > tally->total[0])
141 tally->total[0] += val;
142 tally->counts[bucket_of(tally->min, tally->step_bits, val)]++;
145 size_t tally_num(const struct tally *tally)
148 for (i = 0; i < tally->buckets; i++)
149 num += tally->counts[i];
153 ssize_t tally_min(const struct tally *tally)
158 ssize_t tally_max(const struct tally *tally)
163 /* FIXME: Own ccan module please! */
164 static unsigned fls64(uint64_t val)
166 #if HAVE_BUILTIN_CLZL
167 if (val <= ULONG_MAX) {
168 /* This is significantly faster! */
169 return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
176 if (!(val & 0xffffffff00000000ull)) {
180 if (!(val & 0xffff000000000000ull)) {
184 if (!(val & 0xff00000000000000ull)) {
188 if (!(val & 0xf000000000000000ull)) {
192 if (!(val & 0xc000000000000000ull)) {
196 if (!(val & 0x8000000000000000ull)) {
201 #if HAVE_BUILTIN_CLZL
206 /* This is stolen straight from Hacker's Delight. */
207 static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v)
209 const uint64_t b = 4294967296ULL; // Number base (32 bits).
210 uint32_t un[4], // Dividend and divisor
211 vn[2]; // normalized and broken
212 // up into halfwords.
213 uint32_t q[2]; // Quotient as halfwords.
214 uint64_t un1, un0, // Dividend and divisor
215 vn0; // as fullwords.
216 uint64_t qhat; // Estimated quotient digit.
217 uint64_t rhat; // A remainder.
218 uint64_t p; // Product of two digits.
219 int64_t s, i, j, t, k;
221 if (u1 >= v) // If overflow, return the largest
222 return (uint64_t)-1; // possible quotient.
224 s = 64 - fls64(v); // 0 <= s <= 63.
225 vn0 = v << s; // Normalize divisor.
226 vn[1] = vn0 >> 32; // Break divisor up into
227 vn[0] = vn0 & 0xFFFFFFFF; // two 32-bit halves.
229 // Shift dividend left.
230 un1 = ((u1 << s) | (u0 >> (64 - s))) & (-s >> 63);
232 un[3] = un1 >> 32; // Break dividend up into
233 un[2] = un1; // four 32-bit halfwords
234 un[1] = un0 >> 32; // Note: storing into
235 un[0] = un0; // halfwords truncates.
237 for (j = 1; j >= 0; j--) {
238 // Compute estimate qhat of q[j].
239 qhat = (un[j+2]*b + un[j+1])/vn[1];
240 rhat = (un[j+2]*b + un[j+1]) - qhat*vn[1];
242 if (qhat >= b || qhat*vn[0] > b*rhat + un[j]) {
245 if (rhat < b) goto again;
248 // Multiply and subtract.
250 for (i = 0; i < 2; i++) {
252 t = un[i+j] - k - (p & 0xFFFFFFFF);
254 k = (p >> 32) - (t >> 32);
259 q[j] = qhat; // Store quotient digit.
260 if (t < 0) { // If we subtracted too
261 q[j] = q[j] - 1; // much, add back.
263 for (i = 0; i < 2; i++) {
264 t = un[i+j] + vn[i] + k;
268 un[j+2] = un[j+2] + k;
272 return q[1]*b + q[0];
275 static int64_t divls64(int64_t u1, uint64_t u0, int64_t v)
277 int64_t q, uneg, vneg, diff, borrow;
279 uneg = u1 >> 63; // -1 if u < 0.
280 if (uneg) { // Compute the absolute
281 u0 = -u0; // value of the dividend u.
286 vneg = v >> 63; // -1 if v < 0.
287 v = (v ^ vneg) - vneg; // Absolute value of v.
289 if ((uint64_t)u1 >= (uint64_t)v)
292 q = divlu64(u1, u0, v);
294 diff = uneg ^ vneg; // Negate q if signs of
295 q = (q ^ diff) - diff; // u and v differed.
297 if ((diff ^ q) < 0 && q != 0) { // If overflow, return the largest
298 overflow: // possible neg. quotient.
299 q = 0x8000000000000000ULL;
304 ssize_t tally_mean(const struct tally *tally)
306 size_t count = tally_num(tally);
310 if (sizeof(tally->total[0]) == sizeof(uint32_t)) {
311 /* Use standard 64-bit arithmetic. */
312 int64_t total = tally->total[0]
313 | (((uint64_t)tally->total[1]) << 32);
314 return total / count;
316 return divls64(tally->total[1], tally->total[0], count);
319 ssize_t tally_total(const struct tally *tally, ssize_t *overflow)
322 *overflow = tally->total[1];
323 return tally->total[0];
326 /* If result is negative, make sure we can represent it. */
327 if (tally->total[1] & ((size_t)1 << (SIZET_BITS-1))) {
328 /* Must have only underflowed once, and must be able to
329 * represent result at ssize_t. */
330 if ((~tally->total[1])+1 != 0
331 || (ssize_t)tally->total[0] >= 0) {
332 /* Underflow, return minimum. */
333 return (ssize_t)((size_t)1 << (SIZET_BITS - 1));
336 /* Result is positive, must not have overflowed, and must be
337 * able to represent as ssize_t. */
338 if (tally->total[1] || (ssize_t)tally->total[0] < 0) {
339 /* Overflow. Return maximum. */
340 return (ssize_t)~((size_t)1 << (SIZET_BITS - 1));
343 return tally->total[0];
346 static ssize_t bucket_range(const struct tally *tally, unsigned b, size_t *err)
350 min = bucket_min(tally->min, tally->step_bits, b);
351 if (b == tally->buckets - 1)
354 max = bucket_min(tally->min, tally->step_bits, b+1) - 1;
356 /* FIXME: Think harder about cumulative error; is this enough?. */
357 *err = (max - min + 1) / 2;
358 /* Avoid overflow. */
359 return min + (max - min) / 2;
362 ssize_t tally_approx_median(const struct tally *tally, size_t *err)
364 size_t count = tally_num(tally), total = 0;
367 for (i = 0; i < tally->buckets; i++) {
368 total += tally->counts[i];
369 if (total * 2 >= count)
372 return bucket_range(tally, i, err);
375 ssize_t tally_approx_mode(const struct tally *tally, size_t *err)
377 unsigned int i, min_best = 0, max_best = 0;
379 for (i = 0; i < tally->buckets; i++) {
380 if (tally->counts[i] > tally->counts[min_best]) {
381 min_best = max_best = i;
382 } else if (tally->counts[i] == tally->counts[min_best]) {
387 /* We can have more than one best, making our error huge. */
388 if (min_best != max_best) {
390 min = bucket_range(tally, min_best, err);
391 max = bucket_range(tally, max_best, err);
393 *err += (size_t)(max - min);
394 return min + (max - min) / 2;
397 return bucket_range(tally, min_best, err);
400 static unsigned get_max_bucket(const struct tally *tally)
404 for (i = tally->buckets; i > 0; i--)
405 if (tally->counts[i-1])
410 char *tally_histogram(const struct tally *tally,
411 unsigned width, unsigned height)
413 unsigned int i, count, max_bucket, largest_bucket;
417 assert(width >= TALLY_MIN_HISTO_WIDTH);
418 assert(height >= TALLY_MIN_HISTO_HEIGHT);
420 /* Ignore unused buckets. */
421 max_bucket = get_max_bucket(tally);
423 /* FIXME: It'd be nice to smooth here... */
424 if (height >= max_bucket) {
428 /* We create a temporary then renormalize so < height. */
429 /* FIXME: Antialias properly! */
430 tmp = tally_new(tally->buckets);
433 tmp->min = tally->min;
434 tmp->max = tally->max;
435 tmp->step_bits = tally->step_bits;
436 memcpy(tmp->counts, tally->counts,
437 sizeof(tally->counts[0]) * tmp->buckets);
438 while ((max_bucket = get_max_bucket(tmp)) >= height)
439 renormalize(tmp, tmp->min, tmp->max * 2);
441 tmp->max = tally->max;
446 /* Figure out longest line, for scale. */
448 for (i = 0; i < tally->buckets; i++) {
449 if (tally->counts[i] > largest_bucket)
450 largest_bucket = tally->counts[i];
453 p = graph = malloc(height * (width + 1) + 1);
459 for (i = 0; i < height; i++) {
460 unsigned covered = 1, row;
462 /* People expect minimum at the bottom. */
463 row = height - i - 1;
464 count = (double)tally->counts[row] / largest_bucket * (width-1)+1;
467 covered = snprintf(p, width, "%zi", tally->min);
468 else if (row == height - 1)
469 covered = snprintf(p, width, "%zi", tally->max);
470 else if (row == bucket_of(tally->min, tally->step_bits, 0))
484 memset(p, '*', count);