X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftally%2Ftally.c;h=29f055588015f5e38f02513c6dcce39b4657ff20;hp=1433a3aa2650e45cf2bfc44c3bce646400f8dfba;hb=5628cd2c21655a84dfcf5cc693c8c0d5701fe75d;hpb=7a36f69eea4ee572bdf191d6048350751cd2ab5b diff --git a/ccan/tally/tally.c b/ccan/tally/tally.c index 1433a3aa..29f05558 100644 --- a/ccan/tally/tally.c +++ b/ccan/tally/tally.c @@ -1,4 +1,4 @@ -#include "config.h" +/* Licensed under LGPLv3+ - see LICENSE file for details */ #include #include #include @@ -7,57 +7,55 @@ #include #include #include +#include -#define MAX_STEP_BITS (sizeof(size_t)*CHAR_BIT) +#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. */ - size_t buckets; - size_t step_bits; - size_t counts[1 /* [buckets] */ ]; + unsigned buckets, step_bits; + size_t counts[1 /* Actually: [buckets] */ ]; }; -struct tally *tally_new(size_t buckets) +struct tally *tally_new(unsigned buckets) { struct tally *tally; - /* Check for overflow. */ - if (buckets && SIZE_MAX / buckets < sizeof(tally->counts[0])) + /* There is always 1 bucket. */ + if (buckets == 0) { + buckets = 1; + } + + /* Overly cautious check for overflow. */ + if (sizeof(*tally) * buckets / sizeof(*tally) != buckets) { + return NULL; + } + + tally = (struct tally *)malloc( + sizeof(*tally) + sizeof(tally->counts[0])*(buckets-1)); + if (tally == NULL) { return NULL; - tally = malloc(sizeof(*tally) + sizeof(tally->counts[0])*buckets); - if (tally) { - /* SSIZE_MAX isn't portable, so make it one of these types. */ - BUILD_ASSERT(sizeof(tally->min) == sizeof(int) - || sizeof(tally->min) == sizeof(long) - || sizeof(tally->min) == sizeof(long long)); - if (sizeof(tally->min) == sizeof(int)) { - tally->min = INT_MAX; - tally->max = INT_MIN; - } else if (sizeof(tally->min) == sizeof(long)) { - tally->min = LONG_MAX; - tally->max = LONG_MIN; - } else if (sizeof(tally->min) == sizeof(long long)) { - tally->min = (ssize_t)LLONG_MAX; - tally->max = (ssize_t)LLONG_MIN; - } - tally->total[0] = tally->total[1] = 0; - /* There is always 1 bucket. */ - tally->buckets = buckets+1; - tally->step_bits = 0; - memset(tally->counts, 0, sizeof(tally->counts[0])*(buckets+1)); } + + 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 == MAX_STEP_BITS) + if (step_bits == SIZET_BITS) { return 0; - assert(step_bits < MAX_STEP_BITS); + } + assert(step_bits < SIZET_BITS); return (size_t)(val - min) >> step_bits; } @@ -65,17 +63,19 @@ static unsigned bucket_of(ssize_t min, unsigned step_bits, ssize_t val) static ssize_t bucket_min(ssize_t min, unsigned step_bits, unsigned b) { /* Don't over-shift. */ - if (step_bits == MAX_STEP_BITS) + if (step_bits == SIZET_BITS) { return min; - assert(step_bits < MAX_STEP_BITS); + } + 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) + if (bits == 0) { return false; + } return ((num << bits) >> 1) != (num << (bits - 1)); } @@ -88,8 +88,9 @@ static void renormalize(struct tally *tally, unsigned int i, old_min; /* Uninitialized? Don't do anything... */ - if (tally->max < tally->min) + 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. */ @@ -137,15 +138,17 @@ void tally_add(struct tally *tally, ssize_t val) new_max = val; need_renormalize = true; } - if (need_renormalize) + 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]) + if (val > 0 && tally->total[0] + val < tally->total[0]) { tally->total[1]++; - else if (val < 0 && tally->total[0] + val > tally->total[0]) + } 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)]++; } @@ -153,8 +156,9 @@ void tally_add(struct tally *tally, ssize_t val) size_t tally_num(const struct tally *tally) { size_t i, num = 0; - for (i = 0; i < tally->buckets; i++) + for (i = 0; i < tally->buckets; i++) { num += tally->counts[i]; + } return num; } @@ -179,8 +183,9 @@ static unsigned fls64(uint64_t val) #endif uint64_t r = 64; - if (!val) + if (!val) { return 0; + } if (!(val & 0xffffffff00000000ull)) { val <<= 32; r -= 32; @@ -214,46 +219,49 @@ static unsigned fls64(uint64_t val) /* 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. + 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. + 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. + 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. + 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]. + /* 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; + if (rhat < b) { + goto again; + } } - // Multiply and subtract. + /* Multiply and subtract. */ k = 0; for (i = 0; i < 2; i++) { p = qhat*vn[i]; @@ -264,9 +272,9 @@ static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v) 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. + 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; @@ -275,7 +283,7 @@ static uint64_t divlu64(uint64_t u1, uint64_t u0, uint64_t v) } un[j+2] = un[j+2] + k; } - } // End j. + } /* End j. */ return q[1]*b + q[0]; } @@ -284,26 +292,28 @@ 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. + 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. + vneg = v >> 63; /* -1 if v < 0. */ + v = (v ^ vneg) - vneg; /* Absolute value of v. */ - if ((uint64_t)u1 >= (uint64_t)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. + 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. + if ((diff ^ q) < 0 && q != 0) { /* If overflow, return the + largest */ + overflow: /* possible neg. quotient. */ q = 0x8000000000000000ULL; } return q; @@ -312,8 +322,9 @@ static int64_t divls64(int64_t u1, uint64_t u0, int64_t v) ssize_t tally_mean(const struct tally *tally) { size_t count = tally_num(tally); - if (!count) + if (!count) { return 0; + } if (sizeof(tally->total[0]) == sizeof(uint32_t)) { /* Use standard 64-bit arithmetic. */ @@ -324,15 +335,43 @@ ssize_t tally_mean(const struct tally *tally) 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) + if (b == tally->buckets - 1) { max = tally->max; - else + } 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; @@ -347,8 +386,9 @@ ssize_t tally_approx_median(const struct tally *tally, size_t *err) for (i = 0; i < tally->buckets; i++) { total += tally->counts[i]; - if (total * 2 >= count) + if (total * 2 >= count) { break; + } } return bucket_range(tally, i, err); } @@ -382,9 +422,11 @@ static unsigned get_max_bucket(const struct tally *tally) { unsigned int i; - for (i = tally->buckets; i > 0; i--) - if (tally->counts[i-1]) + for (i = tally->buckets; i > 0; i--) { + if (tally->counts[i-1]) { break; + } + } return i; } @@ -408,16 +450,18 @@ char *tally_histogram(const struct tally *tally, } else { /* We create a temporary then renormalize so < height. */ /* FIXME: Antialias properly! */ - tmp = tally_new(tally->buckets-1); - if (!tmp) + 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); + while ((max_bucket = get_max_bucket(tmp)) >= height) { + renormalize(tmp, tmp->min, tmp->max * 2); + } /* Restore max */ tmp->max = tally->max; tally = tmp; @@ -427,33 +471,46 @@ char *tally_histogram(const struct tally *tally, /* Figure out longest line, for scale. */ largest_bucket = 0; for (i = 0; i < tally->buckets; i++) { - if (tally->counts[i] > largest_bucket) + if (tally->counts[i] > largest_bucket) { largest_bucket = tally->counts[i]; + } } - p = graph = malloc(height * (width + 1) + 1); + p = graph = (char *)malloc(height * (width + 1) + 1); if (!graph) { free(tmp); return NULL; } + for (i = 0; i < height; i++) { - unsigned covered = 0; - count = (double)tally->counts[i] / largest_bucket * width; + 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 (i == 0) + if (row == 0) { covered = snprintf(p, width, "%zi", tally->min); - else if (i == height - 1) + } else if (row == height - 1) { covered = snprintf(p, width, "%zi", tally->max); - if (covered) { - if (covered > width) - covered = width; - p += covered; - if (count > covered) - count -= covered; - else - count = 0; + } else if (row == bucket_of(tally->min, tally->step_bits, 0)) { + *p = '+'; + } else { + *p = '|'; } - memset(p, '*', count); + + if (covered > width) { + covered = width; + } + p += covered; + + if (count > covered) { + count -= covered; + memset(p, '*', count); + } else { + count = 0; + } + p += count; *p = '\n'; p++;