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));
40 tally->max = ((size_t)1 << (SIZET_BITS - 1));
41 tally->min = ~tally->max;
42 tally->total[0] = tally->total[1] = 0;
43 tally->buckets = buckets;
45 memset(tally->counts, 0, sizeof(tally->counts[0])*buckets);
49 static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val)
51 /* Don't over-shift. */
52 if (step_bits == SIZET_BITS)
54 assert(step_bits < SIZET_BITS);
55 return (size_t)(val - min) >> step_bits;
58 /* Return the min value in bucket b. */
59 static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b)
61 /* Don't over-shift. */
62 if (step_bits == SIZET_BITS)
64 assert(step_bits < SIZET_BITS);
65 return min + ((ssize_t)b << step_bits);
68 /* Does shifting by this many bits truncate the number? */
69 static bool shift_overflows(size_t num, unsigned bits)
74 return ((num << bits) >> 1) != (num << (bits - 1));
77 /* When min or max change, we may need to shuffle the frequency counts. */
78 static void renormalize(struct tally *tally,
79 ssize_t new_min, ssize_t new_max)
82 unsigned int i, old_min;
84 /* Uninitialized? Don't do anything... */
85 if (tally->max < tally->min)
88 /* If we don't have sufficient range, increase step bits until
89 * buckets cover entire range of ssize_t anyway. */
90 range = (new_max - new_min) + 1;
91 while (!shift_overflows(tally->buckets, tally->step_bits)
92 && range > ((size_t)tally->buckets << tally->step_bits)) {
94 for (i = 1; i < tally->buckets; i++) {
95 tally->counts[i/2] += tally->counts[i];
101 /* Now if minimum has dropped, move buckets up. */
102 old_min = bucket_of(new_min, tally->step_bits, tally->min);
103 memmove(tally->counts + old_min,
105 sizeof(tally->counts[0]) * (tally->buckets - old_min));
106 memset(tally->counts, 0, sizeof(tally->counts[0]) * old_min);
108 /* If we moved boundaries, adjust buckets to that ratio. */
109 spill = (tally->min - new_min) % (1 << tally->step_bits);
110 for (i = 0; i < tally->buckets-1; i++) {
111 size_t adjust = (tally->counts[i] >> tally->step_bits) * spill;
112 tally->counts[i] -= adjust;
113 tally->counts[i+1] += adjust;
117 tally->min = new_min;
118 tally->max = new_max;
121 void tally_add(struct tally *tally, ssize_t val)
123 ssize_t new_min = tally->min, new_max = tally->max;
124 bool need_renormalize = false;
126 if (val < tally->min) {
128 need_renormalize = true;
130 if (val > tally->max) {
132 need_renormalize = true;
134 if (need_renormalize)
135 renormalize(tally, new_min, new_max);
137 /* 128-bit arithmetic! If we didn't want exact mean, we could just
138 * pull it out of counts. */
139 if (val > 0 && tally->total[0] + val < tally->total[0])
141 else if (val < 0 && tally->total[0] + val > tally->total[0])
143 tally->total[0] += val;
144 tally->counts[bucket_of(tally->min, tally->step_bits, val)]++;
147 size_t tally_num(const struct tally *tally)
150 for (i = 0; i < tally->buckets; i++)
151 num += tally->counts[i];
155 ssize_t tally_min(const struct tally *tally)
160 ssize_t tally_max(const struct tally *tally)
165 /* FIXME: Own ccan module please! */
166 static unsigned fls64(uint64_t val)
168 #if HAVE_BUILTIN_CLZL
169 if (val <= ULONG_MAX) {
170 /* This is significantly faster! */
171 return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
178 if (!(val & 0xffffffff00000000ull)) {
182 if (!(val & 0xffff000000000000ull)) {
186 if (!(val & 0xff00000000000000ull)) {
190 if (!(val & 0xf000000000000000ull)) {
194 if (!(val & 0xc000000000000000ull)) {
198 if (!(val & 0x8000000000000000ull)) {
203 #if HAVE_BUILTIN_CLZL
208 /* This is stolen straight from Hacker's Delight. */
209 static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v)
211 const uint64_t b = 4294967296ULL; // Number base (32 bits).
212 uint32_t un[4], // Dividend and divisor
213 vn[2]; // normalized and broken
214 // up into halfwords.
215 uint32_t q[2]; // Quotient as halfwords.
216 uint64_t un1, un0, // Dividend and divisor
217 vn0; // as fullwords.
218 uint64_t qhat; // Estimated quotient digit.
219 uint64_t rhat; // A remainder.
220 uint64_t p; // Product of two digits.
221 int64_t s, i, j, t, k;
223 if (u1 >= v) // If overflow, return the largest
224 return (uint64_t)-1; // possible quotient.
226 s = 64 - fls64(v); // 0 <= s <= 63.
227 vn0 = v << s; // Normalize divisor.
228 vn[1] = vn0 >> 32; // Break divisor up into
229 vn[0] = vn0 & 0xFFFFFFFF; // two 32-bit halves.
231 // Shift dividend left.
232 un1 = ((u1 << s) | (u0 >> (64 - s))) & (-s >> 63);
234 un[3] = un1 >> 32; // Break dividend up into
235 un[2] = un1; // four 32-bit halfwords
236 un[1] = un0 >> 32; // Note: storing into
237 un[0] = un0; // halfwords truncates.
239 for (j = 1; j >= 0; j--) {
240 // Compute estimate qhat of q[j].
241 qhat = (un[j+2]*b + un[j+1])/vn[1];
242 rhat = (un[j+2]*b + un[j+1]) - qhat*vn[1];
244 if (qhat >= b || qhat*vn[0] > b*rhat + un[j]) {
247 if (rhat < b) goto again;
250 // Multiply and subtract.
252 for (i = 0; i < 2; i++) {
254 t = un[i+j] - k - (p & 0xFFFFFFFF);
256 k = (p >> 32) - (t >> 32);
261 q[j] = qhat; // Store quotient digit.
262 if (t < 0) { // If we subtracted too
263 q[j] = q[j] - 1; // much, add back.
265 for (i = 0; i < 2; i++) {
266 t = un[i+j] + vn[i] + k;
270 un[j+2] = un[j+2] + k;
274 return q[1]*b + q[0];
277 static int64_t divls64(int64_t u1, uint64_t u0, int64_t v)
279 int64_t q, uneg, vneg, diff, borrow;
281 uneg = u1 >> 63; // -1 if u < 0.
282 if (uneg) { // Compute the absolute
283 u0 = -u0; // value of the dividend u.
288 vneg = v >> 63; // -1 if v < 0.
289 v = (v ^ vneg) - vneg; // Absolute value of v.
291 if ((uint64_t)u1 >= (uint64_t)v)
294 q = divlu64(u1, u0, v);
296 diff = uneg ^ vneg; // Negate q if signs of
297 q = (q ^ diff) - diff; // u and v differed.
299 if ((diff ^ q) < 0 && q != 0) { // If overflow, return the largest
300 overflow: // possible neg. quotient.
301 q = 0x8000000000000000ULL;
306 ssize_t tally_mean(const struct tally *tally)
308 size_t count = tally_num(tally);
312 if (sizeof(tally->total[0]) == sizeof(uint32_t)) {
313 /* Use standard 64-bit arithmetic. */
314 int64_t total = tally->total[0]
315 | (((uint64_t)tally->total[1]) << 32);
316 return total / count;
318 return divls64(tally->total[1], tally->total[0], count);
321 ssize_t tally_total(const struct tally *tally, ssize_t *overflow)
324 *overflow = tally->total[1];
325 return tally->total[0];
328 /* If result is negative, make sure we can represent it. */
329 if (tally->total[1] & ((size_t)1 << (SIZET_BITS-1))) {
330 /* Must have only underflowed once, and must be able to
331 * represent result at ssize_t. */
332 if ((~tally->total[1])+1 != 0
333 || (ssize_t)tally->total[0] >= 0) {
334 /* Underflow, return minimum. */
335 return (ssize_t)((size_t)1 << (SIZET_BITS - 1));
338 /* Result is positive, must not have overflowed, and must be
339 * able to represent as ssize_t. */
340 if (tally->total[1] || (ssize_t)tally->total[0] < 0) {
341 /* Overflow. Return maximum. */
342 return (ssize_t)~((size_t)1 << (SIZET_BITS - 1));
345 return tally->total[0];
348 static ssize_t bucket_range(const struct tally *tally, unsigned b, size_t *err)
352 min = bucket_min(tally->min, tally->step_bits, b);
353 if (b == tally->buckets - 1)
356 max = bucket_min(tally->min, tally->step_bits, b+1) - 1;
358 /* FIXME: Think harder about cumulative error; is this enough?. */
359 *err = (max - min + 1) / 2;
360 /* Avoid overflow. */
361 return min + (max - min) / 2;
364 ssize_t tally_approx_median(const struct tally *tally, size_t *err)
366 size_t count = tally_num(tally), total = 0;
369 for (i = 0; i < tally->buckets; i++) {
370 total += tally->counts[i];
371 if (total * 2 >= count)
374 return bucket_range(tally, i, err);
377 ssize_t tally_approx_mode(const struct tally *tally, size_t *err)
379 unsigned int i, min_best = 0, max_best = 0;
381 for (i = 0; i < tally->buckets; i++) {
382 if (tally->counts[i] > tally->counts[min_best]) {
383 min_best = max_best = i;
384 } else if (tally->counts[i] == tally->counts[min_best]) {
389 /* We can have more than one best, making our error huge. */
390 if (min_best != max_best) {
392 min = bucket_range(tally, min_best, err);
393 max = bucket_range(tally, max_best, err);
395 *err += (size_t)(max - min);
396 return min + (max - min) / 2;
399 return bucket_range(tally, min_best, err);
402 static unsigned get_max_bucket(const struct tally *tally)
406 for (i = tally->buckets; i > 0; i--)
407 if (tally->counts[i-1])
412 char *tally_histogram(const struct tally *tally,
413 unsigned width, unsigned height)
415 unsigned int i, count, max_bucket, largest_bucket;
419 assert(width >= TALLY_MIN_HISTO_WIDTH);
420 assert(height >= TALLY_MIN_HISTO_HEIGHT);
422 /* Ignore unused buckets. */
423 max_bucket = get_max_bucket(tally);
425 /* FIXME: It'd be nice to smooth here... */
426 if (height >= max_bucket) {
430 /* We create a temporary then renormalize so < height. */
431 /* FIXME: Antialias properly! */
432 tmp = tally_new(tally->buckets);
435 tmp->min = tally->min;
436 tmp->max = tally->max;
437 tmp->step_bits = tally->step_bits;
438 memcpy(tmp->counts, tally->counts,
439 sizeof(tally->counts[0]) * tmp->buckets);
440 while ((max_bucket = get_max_bucket(tmp)) >= height)
441 renormalize(tmp, tmp->min, tmp->max * 2);
443 tmp->max = tally->max;
448 /* Figure out longest line, for scale. */
450 for (i = 0; i < tally->buckets; i++) {
451 if (tally->counts[i] > largest_bucket)
452 largest_bucket = tally->counts[i];
455 p = graph = (char *)malloc(height * (width + 1) + 1);
461 for (i = 0; i < height; i++) {
462 unsigned covered = 1, row;
464 /* People expect minimum at the bottom. */
465 row = height - i - 1;
466 count = (double)tally->counts[row] / largest_bucket * (width-1)+1;
469 covered = snprintf(p, width, "%zi", tally->min);
470 else if (row == height - 1)
471 covered = snprintf(p, width, "%zi", tally->max);
472 else if (row == bucket_of(tally->min, tally->step_bits, 0))
486 memset(p, '*', count);