Jira-575, Jira-506: Bug fixes to print float and double correctly, i…

[SidLeung]

…n a string or std output.

With latest toolChain, the printing of float and double would result in an overfloat condition if the value is bigger than 8 digits. The String construction would hang the code. The fix put it will print out a large float/double in the exponent format of, x.xxe+yyy, if the value has more than 8 digits.

@calvinatintel @bigdinotech @kmsywula Please review my changes.

[SidLeung]

@bigdinotech Please check out my changes. The Flex team wants this code change so that they can check out the compiler/toolchain changes. Thanks!

[bigdinotech]

@calvinatintel code looks good to me. Please merge

[SidLeung]

@bigdinotech Thanks, Dino.
@calvinatintel This are the bug fixes that are needed to release with the Floating Point Toolchain changes. These changes work with the old toolchain, it's backward compatible.

[facchinm]

Hi @SidLeung ,
I'm sorry but this patch in fact reverts #122 and breaks the following sketch

float latitude = 45.20202;
float longitude = 8.656595;
char latBuffer[12];
char longBuffer[12];
char link[60];

void setup() {
  Serial.begin(115200);

  dtostrf(latitude, 0, 8, latBuffer);
  dtostrf(longitude, 0, 8, longBuffer);
  sprintf_P(link, PSTR("www.google.it/maps/place/%s,%s"), latBuffer, longBuffer);
}

void loop() {
  Serial.println(link);
  delay(100);
}

Maybe the new toolchain is needed for this to work correctly?
Ref: http://forum.arduino.cc/index.php?topic=380422.0

[SidLeung]

I will check out the appended Sketch. Thanks.

[SidLeung]

Would you please provide the expected result of the Sketch? What is the expected output if, say, latitude has a value of 2^32 = 4294967296? Thanks.

[facchinm]

Hi @SidLeung ,
the expercted output of the sketch is

www.google.it/maps/place/45.20201900,8.65659520

Using 2^32 = 4294967296 as latitude on AVR we get

www.google.it/maps/place/4294967300.00000000,8.65659520

[SidLeung]

Thanks for the quick answer. However, as stated in the sketch, latBuffer is 12 char long. For, a string of, "4294967300.00000000", will overflow the buffer when it is used by dtostrf(). Can, sprintf_P, still construct the entire string so nicely?