Improved speed of float serialization (about twice faster)

CHANGELOG.md

@@ -1,6 +1,11 @@
 ArduinoJson: change log
 =======================
 
+HEAD
+----
+
+* Improved speed of float serialization (about twice faster)
+
 v5.6.2
 ------
 

include/ArduinoJson/Internals/JsonWriter.hpp

@@ -98,12 +98,6 @@ class JsonWriter {
       powersOf10 = 0;
     }
 
-    // Round correctly so that print(1.999, 2) prints as "2.00"
-    JsonFloat rounding = 0.5;
-    for (uint8_t i = 0; i < digits; ++i) rounding /= 10.0;
-
-    value += rounding;
-
     // Extract the integer part of the value and print it
     JsonUInt int_part = static_cast<JsonUInt>(value);
     JsonFloat remainder = value - static_cast<JsonFloat>(int_part);
@@ -116,10 +110,16 @@ class JsonWriter {
 
     // Extract digits from the remainder one at a time
     while (digits-- > 0) {
+      // Extract digit
       remainder *= 10.0;
-      JsonUInt toPrint = JsonUInt(remainder);
-      writeInteger(JsonUInt(remainder));
-      remainder -= static_cast<JsonFloat>(toPrint);
+      char currentDigit = char(remainder);
+      remainder -= static_cast<JsonFloat>(currentDigit);
+
+      // Round up last digit (so that print(1.999, 2) prints as "2.00")
+      if (digits == 0 && remainder >= 0.5) currentDigit++;
+
+      // Print
+      writeRaw(char('0' + currentDigit));
     }
 
     if (powersOf10 < 0) {