8000 Fixed too many decimals places in float serialization (issue #543) · trinhduc/ArduinoJson@d41f7a8 · GitHub
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Fixed too many decimals places in float serialization (issue bblanchon#543)
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‎CHANGELOG.md

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* Fixed warning "dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]"
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* Fixed warning "floating constant exceeds range of 'float' [-Woverflow]" (issue #544)
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* Removed `ARDUINOJSON_DOUBLE_IS_64BITS` as it became useless.
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* Fixed too many decimals places in float serialization (issue #543)
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v5.11.0
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‎src/ArduinoJson/Polyfills/normalize.hpp

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This file was deleted.

‎src/ArduinoJson/Serialization/FloatParts.hpp

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// Copyright Benoit Blanchon 2014-2017
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// MIT License
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//
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// Arduino JSON library
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// https://bblanchon.github.io/ArduinoJson/
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// If you like this project, please add a star!
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#pragma once
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#include "../Configuration.hpp"
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#include "../Polyfills/math.hpp"
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#include "../TypeTraits/FloatTraits.hpp"
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namespace ArduinoJson {
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namespace Internals {
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template <typename TFloat>
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struct FloatParts {
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uint32_t integral;
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uint32_t decimal;
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int16_t exponent;
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int8_t decimalPlaces;
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FloatParts(TFloat value) {
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const uint32_t maxDecimalPart = sizeof(TFloat) >= 8 ? 1000000000 : 1000000;
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exponent = normalize(value);
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integral = uint32_t(value);
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TFloat remainder = value - TFloat(integral);
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remainder *= maxDecimalPart;
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decimal = uint32_t(remainder);
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remainder = remainder - TFloat(decimal);
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// rounding:
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// increment by 1 if remainder >= 0.5
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decimal += uint32_t(remainder * 2);
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if (decimal >= maxDecimalPart) {
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decimal = 0;
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integral++;
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if (exponent && integral >= 10) {
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exponent++;
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integral = 1;
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}
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}
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decimalPlaces = sizeof(TFloat) >= 8 ? 9 : 6;
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// recude number of decimal places by the number of integral places
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for (uint32_t tmp = integral; tmp >= 10; tmp /= 10) {
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decimal /= 10;
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decimalPlaces--;
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}
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// remove trailing zeros
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while (decimal % 10 == 0 && decimalPlaces > 0) {
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decimal /= 10;
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decimalPlaces--;
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}
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}
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static int16_t normalize(TFloat& value) {
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typedef TypeTraits::FloatTraits<TFloat> traits;
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int16_t powersOf10 = 0;
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int8_t index = sizeof(TFloat) == 8 ? 8 : 5;
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int bit = 1 << index;
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if (value >= ARDUINOJSON_POSITIVE_EXPONENTIATION_THRESHOLD) {
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for (; index >= 0; index--) {
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if (value >= traits::positiveBinaryPowerOfTen(index)) {
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value *= traits::negativeBinaryPowerOfTen(index);
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powersOf10 = int16_t(powersOf10 + bit);
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}
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bit >>= 1;
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}
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}
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if (value > 0 && value <= ARDUINOJSON_NEGATIVE_EXPONENTIATION_THRESHOLD) {
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for (; index >= 0; index--) {
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if (value < traits::negativeBinaryPowerOfTenPlusOne(index)) {
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value *= traits::positiveBinaryPowerOfTen(index);
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powersOf10 = int16_t(powersOf10 - bit);
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}
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bit >>= 1;
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}
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}
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return powersOf10;
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}
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};
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}
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}

‎src/ArduinoJson/Serialization/JsonWriter.hpp

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#include <stdint.h>
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#include "../Data/Encoding.hpp"
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#include "../Data/JsonFloat.hpp"
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#include "../Data/JsonInteger.hpp"
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#include "../Polyfills/attributes.hpp"
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#include "../Polyfills/math.hpp"
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#include "../Polyfills/normalize.hpp"
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#include "../TypeTraits/FloatTraits.hpp"
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#include "../Serialization/FloatParts.hpp"
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namespace ArduinoJson {
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namespace Internals {
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// indentation.
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template <typename Print>
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class JsonWriter {
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static const uint8_t maxDecimalPlaces = sizeof(JsonFloat) >= 8 ? 9 : 6;
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static const uint32_t maxDecimalPart =
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sizeof(JsonFloat) >= 8 ? 1000000000 : 1000000;
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public:
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explicit JsonWriter(Print &sink) : _sink(sink), _length(0) {}
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}
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}
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void writeFloat(JsonFloat value) {
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template <typename TFloat>
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void writeFloat(TFloat value) {
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if (Polyfills::isNaN(value)) return writeRaw("NaN");
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if (value < 0.0) {
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if (Polyfills::isInfinity(value)) return writeRaw("Infinity");
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uint32_t integralPart, decimalPart;
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int16_t powersOf10;
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splitFloat(value, integralPart, decimalPart, powersOf10);
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FloatParts<TFloat> parts(value);
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writeInteger(integralPart);
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if (decimalPart) writeDecimals(decimalPart, maxDecimalPlaces);
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writeInteger(parts.integral);
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if (parts.decimalPlaces) writeDecimals(parts.decimal, parts.decimalPlaces);
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if (powersOf10 < 0) {
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if (parts.exponent < 0) {
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writeRaw("e-");
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writeInteger(-powersOf10);
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writeInteger(-parts.exponent);
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}
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if (powersOf10 > 0) {
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if (parts.exponent > 0) {
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writeRaw('e');
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writeInteger(powersOf10);
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writeInteger(parts.exponent);
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}
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}
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template <typename UInt>
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void writeInteger(UInt value) {
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char buffer[22];
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char *ptr = buffer + sizeof(buffer) - 1;
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char *end = buffer + sizeof(buffer) - 1;
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char *ptr = end;
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*ptr = 0;
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do {
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}
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void writeDecimals(uint32_t value, int8_t width) {
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// remove trailing zeros
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while (value % 10 == 0 && width > 0) {
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value /= 10;
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width--;
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}
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// buffer should be big enough for all digits, the dot and the null
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// terminator
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char buffer[maxDecimalPlaces + 2];
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char buffer[16];
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char *ptr = buffer + sizeof(buffer) - 1;
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// write the string in reverse order
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private:
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JsonWriter &operator=(const JsonWriter &); // cannot be assigned
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void splitFloat(JsonFloat value, uint32_t &integralPart,
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uint32_t &decimalPart, int16_t &powersOf10) {
172-
powersOf10 = Polyfills::normalize(value);
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174-
integralPart = uint32_t(value);
175-
JsonFloat remainder = value - JsonFloat(integralPart);
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177-
remainder *= maxDecimalPart;
178-
decimalPart = uint32_t(remainder);
179-
remainder = remainder - JsonFloat(decimalPart);
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// rounding:
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// increment by 1 if remainder >= 0.5
183-
decimalPart += uint32_t(remainder * 2);
184-
if (decimalPart >= maxDecimalPart) {
185-
decimalPart = 0;
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integralPart++;
187-
if (powersOf10 && integralPart >= 10) {
188-
powersOf10++;
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integralPart = 1;
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}
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}
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}
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};
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}
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}

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