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Fixed too many decimals places in float serialization (issue #543)

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bblanchon committed Jul 14, 2017
1 parent abfd399 commit d41f7a816593af4d182c05d445f1792cbf4a0421
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@@ -8,6 +8,7 @@ HEAD
* Fixed warning "dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]"
* Fixed warning "floating constant exceeds range of 'float' [-Woverflow]" (issue #544)
* Removed `ARDUINOJSON_DOUBLE_IS_64BITS` as it became useless.
* Fixed too many decimals places in float serialization (issue #543)
v5.11.0
-------
@@ -1,46 +0,0 @@
// Copyright Benoit Blanchon 2014-2017
// MIT License
//
// Arduino JSON library
// https://bblanchon.github.io/ArduinoJson/
// If you like this project, please add a star!
#pragma once
#include "../Configuration.hpp"
#include "../TypeTraits/FloatTraits.hpp"
namespace ArduinoJson {
namespace Polyfills {
template <typename T>
int16_t normalize(T& value) {
using namespace TypeTraits;
int16_t powersOf10 = 0;
int8_t index = sizeof(T) == 8 ? 8 : 5;
int bit = 1 << index;
if (value >= ARDUINOJSON_POSITIVE_EXPONENTIATION_THRESHOLD) {
for (; index >= 0; index--) {
if (value >= FloatTraits<T>::positiveBinaryPowerOfTen(index)) {
value *= FloatTraits<T>::negativeBinaryPowerOfTen(index);
powersOf10 = int16_t(powersOf10 + bit);
}
bit >>= 1;
}
}
if (value > 0 && value <= ARDUINOJSON_NEGATIVE_EXPONENTIATION_THRESHOLD) {
for (; index >= 0; index--) {
if (value < FloatTraits<T>::negativeBinaryPowerOfTenPlusOne(index)) {
value *= FloatTraits<T>::positiveBinaryPowerOfTen(index);
powersOf10 = int16_t(powersOf10 - bit);
}
bit >>= 1;
}
}
return powersOf10;
}
}
}
@@ -0,0 +1,94 @@
// Copyright Benoit Blanchon 2014-2017
// MIT License
//
// Arduino JSON library
// https://bblanchon.github.io/ArduinoJson/
// If you like this project, please add a star!
#pragma once
#include "../Configuration.hpp"
#include "../Polyfills/math.hpp"
#include "../TypeTraits/FloatTraits.hpp"
namespace ArduinoJson {
namespace Internals {
template <typename TFloat>
struct FloatParts {
uint32_t integral;
uint32_t decimal;
int16_t exponent;
int8_t decimalPlaces;
FloatParts(TFloat value) {
const uint32_t maxDecimalPart = sizeof(TFloat) >= 8 ? 1000000000 : 1000000;
exponent = normalize(value);
integral = uint32_t(value);
TFloat remainder = value - TFloat(integral);
remainder *= maxDecimalPart;
decimal = uint32_t(remainder);
remainder = remainder - TFloat(decimal);
// rounding:
// increment by 1 if remainder >= 0.5
decimal += uint32_t(remainder * 2);
if (decimal >= maxDecimalPart) {
decimal = 0;
integral++;
if (exponent && integral >= 10) {
exponent++;
integral = 1;
}
}
decimalPlaces = sizeof(TFloat) >= 8 ? 9 : 6;
// recude number of decimal places by the number of integral places
for (uint32_t tmp = integral; tmp >= 10; tmp /= 10) {
decimal /= 10;
decimalPlaces--;
}
// remove trailing zeros
while (decimal % 10 == 0 && decimalPlaces > 0) {
decimal /= 10;
decimalPlaces--;
}
}
static int16_t normalize(TFloat& value) {
typedef TypeTraits::FloatTraits<TFloat> traits;
int16_t powersOf10 = 0;
int8_t index = sizeof(TFloat) == 8 ? 8 : 5;
int bit = 1 << index;
if (value >= ARDUINOJSON_POSITIVE_EXPONENTIATION_THRESHOLD) {
for (; index >= 0; index--) {
if (value >= traits::positiveBinaryPowerOfTen(index)) {
value *= traits::negativeBinaryPowerOfTen(index);
powersOf10 = int16_t(powersOf10 + bit);
}
bit >>= 1;
}
}
if (value > 0 && value <= ARDUINOJSON_NEGATIVE_EXPONENTIATION_THRESHOLD) {
for (; index >= 0; index--) {
if (value < traits::negativeBinaryPowerOfTenPlusOne(index)) {
value *= traits::positiveBinaryPowerOfTen(index);
powersOf10 = int16_t(powersOf10 - bit);
}
bit >>= 1;
}
}
return powersOf10;
}
};
}
}
@@ -9,12 +9,9 @@
#include <stdint.h>
#include "../Data/Encoding.hpp"
#include "../Data/JsonFloat.hpp"
#include "../Data/JsonInteger.hpp"
#include "../Polyfills/attributes.hpp"
#include "../Polyfills/math.hpp"
#include "../Polyfills/normalize.hpp"
#include "../TypeTraits/FloatTraits.hpp"
#include "../Serialization/FloatParts.hpp"
namespace ArduinoJson {
namespace Internals {
@@ -28,10 +25,6 @@ namespace Internals {
// indentation.
template <typename Print>
class JsonWriter {
static const uint8_t maxDecimalPlaces = sizeof(JsonFloat) >= 8 ? 9 : 6;
static const uint32_t maxDecimalPart =
sizeof(JsonFloat) >= 8 ? 1000000000 : 1000000;
public:
explicit JsonWriter(Print &sink) : _sink(sink), _length(0) {}
@@ -87,7 +80,8 @@ class JsonWriter {
}
}
void writeFloat(JsonFloat value) {
template <typename TFloat>
void writeFloat(TFloat value) {
if (Polyfills::isNaN(value)) return writeRaw("NaN");
if (value < 0.0) {
@@ -97,28 +91,27 @@ class JsonWriter {
if (Polyfills::isInfinity(value)) return writeRaw("Infinity");
uint32_t integralPart, decimalPart;
int16_t powersOf10;
splitFloat(value, integralPart, decimalPart, powersOf10);
FloatParts<TFloat> parts(value);
writeInteger(integralPart);
if (decimalPart) writeDecimals(decimalPart, maxDecimalPlaces);
writeInteger(parts.integral);
if (parts.decimalPlaces) writeDecimals(parts.decimal, parts.decimalPlaces);
if (powersOf10 < 0) {
if (parts.exponent < 0) {
writeRaw("e-");
writeInteger(-powersOf10);
writeInteger(-parts.exponent);
}
if (powersOf10 > 0) {
if (parts.exponent > 0) {
writeRaw('e');
writeInteger(powersOf10);
writeInteger(parts.exponent);
}
}
template <typename UInt>
void writeInteger(UInt value) {
char buffer[22];
char *ptr = buffer + sizeof(buffer) - 1;
char *end = buffer + sizeof(buffer) - 1;
char *ptr = end;
*ptr = 0;
do {
@@ -130,15 +123,9 @@ class JsonWriter {
}
void writeDecimals(uint32_t value, int8_t width) {
// remove trailing zeros
while (value % 10 == 0 && width > 0) {
value /= 10;
width--;
}
// buffer should be big enough for all digits, the dot and the null
// terminator
char buffer[maxDecimalPlaces + 2];
char buffer[16];
char *ptr = buffer + sizeof(buffer) - 1;
// write the string in reverse order
@@ -166,30 +153,6 @@ class JsonWriter {
private:
JsonWriter &operator=(const JsonWriter &); // cannot be assigned
void splitFloat(JsonFloat value, uint32_t &integralPart,
uint32_t &decimalPart, int16_t &powersOf10) {
powersOf10 = Polyfills::normalize(value);
integralPart = uint32_t(value);
JsonFloat remainder = value - JsonFloat(integralPart);
remainder *= maxDecimalPart;
decimalPart = uint32_t(remainder);
remainder = remainder - JsonFloat(decimalPart);
// rounding:
// increment by 1 if remainder >= 0.5
decimalPart += uint32_t(remainder * 2);
if (decimalPart >= maxDecimalPart) {
decimalPart = 0;
integralPart++;
if (powersOf10 && integralPart >= 10) {
powersOf10++;
integralPart = 1;
}
}
}
};
}
}
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