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. */
32 /* Overly cautious check for overflow. */
33 if (sizeof(*tally) * buckets / sizeof(*tally) != buckets) {
37 tally = (struct tally *)malloc(
38 sizeof(*tally) + sizeof(tally->counts[0])*(buckets-1));
43 tally->max = ((size_t)1 << (SIZET_BITS - 1));
44 tally->min = ~tally->max;
45 tally->total[0] = tally->total[1] = 0;
46 tally->buckets = buckets;
48 memset(tally->counts, 0, sizeof(tally->counts[0])*buckets);
52 static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
54 /* Don't over-shift. */
55 if (step_bits == SIZET_BITS) {
58 assert(step_bits < SIZET_BITS);
59 return (size_t)(val - min) >> step_bits;
62 /* Return the min value in bucket b. */
63 static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b)
65 /* Don't over-shift. */
66 if (step_bits == SIZET_BITS) {
69 assert(step_bits < SIZET_BITS);
70 return min + ((ssize_t)b << step_bits);
73 /* Does shifting by this many bits truncate the number? */
74 static bool shift_overflows(size_t num, unsigned bits)
80 return ((num << bits) >> 1) != (num << (bits - 1));
83 /* When min or max change, we may need to shuffle the frequency counts. */
84 static void renormalize(struct tally *tally,
85 ssize_t new_min, ssize_t new_max)
88 unsigned int i, old_min;
90 /* Uninitialized? Don't do anything... */
91 if (tally->max < tally->min) {
95 /* If we don't have sufficient range, increase step bits until
96 * buckets cover entire range of ssize_t anyway. */
97 range = (new_max - new_min) + 1;
98 while (!shift_overflows(tally->buckets, tally->step_bits)
99 && range > ((size_t)tally->buckets << tally->step_bits)) {
101 for (i = 1; i < tally->buckets; i++) {
102 tally->counts[i/2] += tally->counts[i];
103 tally->counts[i] = 0;
108 /* Now if minimum has dropped, move buckets up. */
109 old_min = bucket_of(new_min, tally->step_bits, tally->min);
110 memmove(tally->counts + old_min,
112 sizeof(tally->counts[0]) * (tally->buckets - old_min));
113 memset(tally->counts, 0, sizeof(tally->counts[0]) * old_min);
115 /* If we moved boundaries, adjust buckets to that ratio. */
116 spill = (tally->min - new_min) % (1 << tally->step_bits);
117 for (i = 0; i < tally->buckets-1; i++) {
118 size_t adjust = (tally->counts[i] >> tally->step_bits) * spill;
119 tally->counts[i] -= adjust;
120 tally->counts[i+1] += adjust;
124 tally->min = new_min;
125 tally->max = new_max;
128 void tally_add(struct tally *tally, ssize_t val)
130 ssize_t new_min = tally->min, new_max = tally->max;
131 bool need_renormalize = false;
133 if (val < tally->min) {
135 need_renormalize = true;
137 if (val > tally->max) {
139 need_renormalize = true;
141 if (need_renormalize) {
142 renormalize(tally, new_min, new_max);
145 /* 128-bit arithmetic! If we didn't want exact mean, we could just
146 * pull it out of counts. */
147 if (val > 0 && tally->total[0] + val < tally->total[0]) {
149 } else if (val < 0 && tally->total[0] + val > tally->total[0]) {
152 tally->total[0] += val;
153 tally->counts[bucket_of(tally->min, tally->step_bits, val)]++;
156 size_t tally_num(const struct tally *tally)
159 for (i = 0; i < tally->buckets; i++)
160 num += tally->counts[i];
164 ssize_t tally_min(const struct tally *tally)
169 ssize_t tally_max(const struct tally *tally)
174 /* FIXME: Own ccan module please! */
175 static unsigned fls64(uint64_t val)
177 #if HAVE_BUILTIN_CLZL
178 if (val <= ULONG_MAX) {
179 /* This is significantly faster! */
180 return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
187 if (!(val & 0xffffffff00000000ull)) {
191 if (!(val & 0xffff000000000000ull)) {
195 if (!(val & 0xff00000000000000ull)) {
199 if (!(val & 0xf000000000000000ull)) {
203 if (!(val & 0xc000000000000000ull)) {
207 if (!(val & 0x8000000000000000ull)) {
212 #if HAVE_BUILTIN_CLZL
217 /* This is stolen straight from Hacker's Delight. */
218 static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v)
220 const uint64_t b = 4294967296ULL; // Number base (32 bits).
221 uint32_t un[4], // Dividend and divisor
222 vn[2]; // normalized and broken
223 // up into halfwords.
224 uint32_t q[2]; // Quotient as halfwords.
225 uint64_t un1, un0, // Dividend and divisor
226 vn0; // as fullwords.
227 uint64_t qhat; // Estimated quotient digit.
228 uint64_t rhat; // A remainder.
229 uint64_t p; // Product of two digits.
230 int64_t s, i, j, t, k;
232 if (u1 >= v) // If overflow, return the largest
233 return (uint64_t)-1; // possible quotient.
235 s = 64 - fls64(v); // 0 <= s <= 63.
236 vn0 = v << s; // Normalize divisor.
237 vn[1] = vn0 >> 32; // Break divisor up into
238 vn[0] = vn0 & 0xFFFFFFFF; // two 32-bit halves.
240 // Shift dividend left.
241 un1 = ((u1 << s) | (u0 >> (64 - s))) & (-s >> 63);
243 un[3] = un1 >> 32; // Break dividend up into
244 un[2] = un1; // four 32-bit halfwords
245 un[1] = un0 >> 32; // Note: storing into
246 un[0] = un0; // halfwords truncates.
248 for (j = 1; j >= 0; j--) {
249 // Compute estimate qhat of q[j].
250 qhat = (un[j+2]*b + un[j+1])/vn[1];
251 rhat = (un[j+2]*b + un[j+1]) - qhat*vn[1];
253 if (qhat >= b || qhat*vn[0] > b*rhat + un[j]) {
256 if (rhat < b) goto again;
259 // Multiply and subtract.
261 for (i = 0; i < 2; i++) {
263 t = un[i+j] - k - (p & 0xFFFFFFFF);
265 k = (p >> 32) - (t >> 32);
270 q[j] = qhat; // Store quotient digit.
271 if (t < 0) { // If we subtracted too
272 q[j] = q[j] - 1; // much, add back.
274 for (i = 0; i < 2; i++) {
275 t = un[i+j] + vn[i] + k;
279 un[j+2] = un[j+2] + k;
283 return q[1]*b + q[0];
286 static int64_t divls64(int64_t u1, uint64_t u0, int64_t v)
288 int64_t q, uneg, vneg, diff, borrow;
290 uneg = u1 >> 63; // -1 if u < 0.
291 if (uneg) { // Compute the absolute
292 u0 = -u0; // value of the dividend u.
297 vneg = v >> 63; // -1 if v < 0.
298 v = (v ^ vneg) - vneg; // Absolute value of v.
300 if ((uint64_t)u1 >= (uint64_t)v)
303 q = divlu64(u1, u0, v);
305 diff = uneg ^ vneg; // Negate q if signs of
306 q = (q ^ diff) - diff; // u and v differed.
308 if ((diff ^ q) < 0 && q != 0) { // If overflow, return the largest
309 overflow: // possible neg. quotient.
310 q = 0x8000000000000000ULL;
315 ssize_t tally_mean(const struct tally *tally)
317 size_t count = tally_num(tally);
321 if (sizeof(tally->total[0]) == sizeof(uint32_t)) {
322 /* Use standard 64-bit arithmetic. */
323 int64_t total = tally->total[0]
324 | (((uint64_t)tally->total[1]) << 32);
325 return total / count;
327 return divls64(tally->total[1], tally->total[0], count);
330 ssize_t tally_total(const struct tally *tally, ssize_t *overflow)
333 *overflow = tally->total[1];
334 return tally->total[0];
337 /* If result is negative, make sure we can represent it. */
338 if (tally->total[1] & ((size_t)1 << (SIZET_BITS-1))) {
339 /* Must have only underflowed once, and must be able to
340 * represent result at ssize_t. */
341 if ((~tally->total[1])+1 != 0
342 || (ssize_t)tally->total[0] >= 0) {
343 /* Underflow, return minimum. */
344 return (ssize_t)((size_t)1 << (SIZET_BITS - 1));
347 /* Result is positive, must not have overflowed, and must be
348 * able to represent as ssize_t. */
349 if (tally->total[1] || (ssize_t)tally->total[0] < 0) {
350 /* Overflow. Return maximum. */
351 return (ssize_t)~((size_t)1 << (SIZET_BITS - 1));
354 return tally->total[0];
357 static ssize_t bucket_range(const struct tally *tally, unsigned b, size_t *err)
361 min = bucket_min(tally->min, tally->step_bits, b);
362 if (b == tally->buckets - 1)
365 max = bucket_min(tally->min, tally->step_bits, b+1) - 1;
367 /* FIXME: Think harder about cumulative error; is this enough?. */
368 *err = (max - min + 1) / 2;
369 /* Avoid overflow. */
370 return min + (max - min) / 2;
373 ssize_t tally_approx_median(const struct tally *tally, size_t *err)
375 size_t count = tally_num(tally), total = 0;
378 for (i = 0; i < tally->buckets; i++) {
379 total += tally->counts[i];
380 if (total * 2 >= count)
383 return bucket_range(tally, i, err);
386 ssize_t tally_approx_mode(const struct tally *tally, size_t *err)
388 unsigned int i, min_best = 0, max_best = 0;
390 for (i = 0; i < tally->buckets; i++) {
391 if (tally->counts[i] > tally->counts[min_best]) {
392 min_best = max_best = i;
393 } else if (tally->counts[i] == tally->counts[min_best]) {
398 /* We can have more than one best, making our error huge. */
399 if (min_best != max_best) {
401 min = bucket_range(tally, min_best, err);
402 max = bucket_range(tally, max_best, err);
404 *err += (size_t)(max - min);
405 return min + (max - min) / 2;
408 return bucket_range(tally, min_best, err);
411 static unsigned get_max_bucket(const struct tally *tally)
415 for (i = tally->buckets; i > 0; i--)
416 if (tally->counts[i-1])
421 char *tally_histogram(const struct tally *tally,
422 unsigned width, unsigned height)
424 unsigned int i, count, max_bucket, largest_bucket;
428 assert(width >= TALLY_MIN_HISTO_WIDTH);
429 assert(height >= TALLY_MIN_HISTO_HEIGHT);
431 /* Ignore unused buckets. */
432 max_bucket = get_max_bucket(tally);
434 /* FIXME: It'd be nice to smooth here... */
435 if (height >= max_bucket) {
439 /* We create a temporary then renormalize so < height. */
440 /* FIXME: Antialias properly! */
441 tmp = tally_new(tally->buckets);
444 tmp->min = tally->min;
445 tmp->max = tally->max;
446 tmp->step_bits = tally->step_bits;
447 memcpy(tmp->counts, tally->counts,
448 sizeof(tally->counts[0]) * tmp->buckets);
449 while ((max_bucket = get_max_bucket(tmp)) >= height)
450 renormalize(tmp, tmp->min, tmp->max * 2);
452 tmp->max = tally->max;
457 /* Figure out longest line, for scale. */
459 for (i = 0; i < tally->buckets; i++) {
460 if (tally->counts[i] > largest_bucket)
461 largest_bucket = tally->counts[i];
464 p = graph = (char *)malloc(height * (width + 1) + 1);
470 for (i = 0; i < height; i++) {
471 unsigned covered = 1, row;
473 /* People expect minimum at the bottom. */
474 row = height - i - 1;
475 count = (double)tally->counts[row] / largest_bucket * (width-1)+1;
478 covered = snprintf(p, width, "%zi", tally->min);
479 else if (row == height - 1)
480 covered = snprintf(p, width, "%zi", tally->max);
481 else if (row == bucket_of(tally->min, tally->step_bits, 0))
495 memset(p, '*', count);