diff options
Diffstat (limited to 'src/libnetdata/storage_number/storage_number.c')
| -rw-r--r-- | src/libnetdata/storage_number/storage_number.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/src/libnetdata/storage_number/storage_number.c b/src/libnetdata/storage_number/storage_number.c new file mode 100644 index 000000000..89a67a532 --- /dev/null +++ b/src/libnetdata/storage_number/storage_number.c @@ -0,0 +1,170 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "../libnetdata.h" + +bool is_system_ieee754_double(void) { + static bool logged = false; + + struct { + NETDATA_DOUBLE original; + + union { + uint64_t i; + NETDATA_DOUBLE d; + }; + } tests[] = { + { .original = 1.25, .i = 0x3FF4000000000000 }, + { .original = 1.0, .i = 0x3FF0000000000000 }, + { .original = 2.0, .i = 0x4000000000000000 }, + { .original = 4.0, .i = 0x4010000000000000 }, + { .original = 8.8, .i = 0x402199999999999A }, + { .original = 16.16, .i = 0x403028F5C28F5C29 }, + { .original = 32.32, .i = 0x404028F5C28F5C29 }, + { .original = 64.64, .i = 0x405028F5C28F5C29 }, + { .original = 128.128, .i = 0x406004189374BC6A }, + { .original = 32768.32768, .i = 0x40E0000A7C5AC472 }, + { .original = 65536.65536, .i = 0x40F0000A7C5AC472 }, + { .original = -65536.65536, .i = 0xC0F0000A7C5AC472 }, + { .original = 65535.65535, .i = 0x40EFFFF4F8A0902E }, + { .original = -65535.65535, .i = 0xC0EFFFF4F8A0902E }, + { .original = 4.503599627e15, .i = 0x432FFFFFFFF4B180 }, + { .original = -4.503599627e15, .i = 0xC32FFFFFFFF4B180 }, + { .original = 1.25e25, .i = 0x4524ADF4B7320335 }, + { .original = 1.25e307, .i = 0x7FB1CCF385EBC8A0 }, + { .original = 1.25e-25, .i = 0x3AC357C299A88EA7 }, + { .original = 1.25e-100, .i = 0x2B317F7D4ED8C33E }, + { .original = NAN, .i = 0x7FF8000000000000 }, + { .original = -INFINITY, .i = 0xFFF0000000000000 }, + { .original = INFINITY, .i = 0x7FF0000000000000 }, + { .original = 1.25e-132, .i = 0x248C6463225AB7EC }, + { .original = 0.0, .i = 0x0000000000000000 }, + { .original = -0.0, .i = 0x8000000000000000 }, + { .original = DBL_MIN, .i = 0x0010000000000000 }, + { .original = DBL_MAX, .i = 0x7FEFFFFFFFFFFFFF }, + { .original = -DBL_MIN, .i = 0x8010000000000000 }, + { .original = -DBL_MAX, .i = 0xFFEFFFFFFFFFFFFF }, + }; + + size_t errors = 0; + size_t elements = sizeof(tests) / sizeof(tests[0]); + for(size_t i = 0; i < elements ; i++) { + uint64_t *ptr = (uint64_t *)&tests[i].original; + + if(*ptr != tests[i].i && (tests[i].original == tests[i].d || (isnan(tests[i].original) && isnan(tests[i].d)))) { + if(!logged) + netdata_log_info("IEEE754: test #%zu, value " NETDATA_DOUBLE_FORMAT_G " is represented in this system as %lX, but it was expected as %lX", + i+1, tests[i].original, *ptr, tests[i].i); + errors++; + } + } + + if(!errors && sizeof(NETDATA_DOUBLE) == sizeof(uint64_t)) { + if(!logged) + netdata_log_info("IEEE754: system is using IEEE754 DOUBLE PRECISION values"); + + logged = true; + return true; + } + else { + if(!logged) + netdata_log_info("IEEE754: system is NOT compatible with IEEE754 DOUBLE PRECISION values"); + + logged = true; + return false; + } +} + +storage_number pack_storage_number(NETDATA_DOUBLE value, SN_FLAGS flags) { + // bit 32 = sign 0:positive, 1:negative + // bit 31 = 0:divide, 1:multiply + // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total) + // bit 27 SN_EXISTS_100 + // bit 26 SN_EXISTS_RESET + // bit 25 SN_ANOMALY_BIT = 0: anomalous, 1: not anomalous + // bit 24 to bit 1 = the value + + if(unlikely(fpclassify(value) == FP_NAN || fpclassify(value) == FP_INFINITE)) + return SN_EMPTY_SLOT; + + storage_number r = flags & SN_USER_FLAGS; + + if(unlikely(fpclassify(value) == FP_ZERO || fpclassify(value) == FP_SUBNORMAL)) + return r; + + int m = 0; + NETDATA_DOUBLE n = value, factor = 10; + + // if the value is negative + // add the sign bit and make it positive + if(n < 0) { + r += SN_FLAG_NEGATIVE; // the sign bit 32 + n = -n; + } + + if(n / 10000000.0 > 0x00ffffff) { + factor = 100; + r |= SN_FLAG_NOT_EXISTS_MUL100; + } + + // make its integer part fit in 0x00ffffff + // by dividing it by 10 up to 7 times + // and increasing the multiplier + while(m < 7 && n > (NETDATA_DOUBLE)0x00ffffff) { + n /= factor; + m++; + } + + if(m) { + // the value was too big, and we divided it + // so, we add a multiplier to unpack it + r += SN_FLAG_MULTIPLY + (m << 27); // the multiplier m + + if(n > (NETDATA_DOUBLE)0x00ffffff) { + #ifdef NETDATA_INTERNAL_CHECKS + netdata_log_error("Number " NETDATA_DOUBLE_FORMAT " is too big.", value); + #endif + r += 0x00ffffff; + return r; + } + } + else { + // 0x0019999e is the number that can be multiplied + // by 10 to give 0x00ffffff + // while the value is below 0x0019999e we can + // multiply it by 10, up to 7 times, increasing + // the multiplier + while(m < 7 && n < (NETDATA_DOUBLE)0x0019999e) { + n *= 10; + m++; + } + + if (unlikely(n > (NETDATA_DOUBLE)0x00ffffff)) { + n /= 10; + m--; + } + // the value was small enough, and we multiplied it + // so, we add a divider to unpack it + r += (m << 27); // the divider m + } + + r += lrint((double) n); + + return r; +} + +// Lookup table to make storage number unpacking efficient. +NETDATA_DOUBLE unpack_storage_number_lut10x[4 * 8]; + +__attribute__((constructor)) void initialize_lut(void) { + // The lookup table is partitioned in 4 subtables based on the + // values of the factor and exp bits. + for (int i = 0; i < 8; i++) { + // factor = 0 + unpack_storage_number_lut10x[0 * 8 + i] = 1 / pow(10, i); // exp = 0 + unpack_storage_number_lut10x[1 * 8 + i] = pow(10, i); // exp = 1 + + // factor = 1 + unpack_storage_number_lut10x[2 * 8 + i] = 1 / pow(100, i); // exp = 0 + unpack_storage_number_lut10x[3 * 8 + i] = pow(100, i); // exp = 1 + } +} |