I fixed a bug that caused incorrect rounding when there was a carry over across all digits, including the one before the decimal point. Check out the latest version via the Arduino library manager.
History of fp64lib
It took quite some time from the first implmentation of a 64-bit multiplication to the full blown library. I have documented some of the history of why and how fp64lib was created, including some design decisions. Find out more under Documentation / History.
V1.0.4 available
I fixed some bugs, converted fp64_atof from macro to a function and included some small examples. Check out the latest version, via the Arduino library manager.
Initial release V1.0 available
After 2 years of development, reading several 100 pages of algorithms, after typing more than half a million lines of code, after creating, testing and verifying more that 19000 test cases, after endless hours/nights/weekends of hunting down nasty bugs, after documenting more than 60 top level functions, it’s finally good enough to be released as a V1.0.
The initial release of fp64lib for Atmel AVR 328 microprocessors is available here as a downloadable library for the Arduino IDE.
Have fun using it and I am pleased to receive any feedback via mail (at) fp64lib (dot) org.
Conversion functions
As fp64lib is an add-on library, getting data into the float64_t datatype and out of it is a key. The following will not work:
float64_t x = 1.0;
float64_t y = (float64_t) 3.141;
float64_t z = 10;
The above statements will all load some data into x, y, and z – but it will definitely not be 1.0, 3.141 or 10! Instead, use the following code that will work correctly:
float64_t x = fp64_sd(1.0);
float64_t y = fp64_sd(3.141);
float64_t z = fp64_uint32_to_float64(10);
fp64lib provides quite a number of functions to convert data to all native C data types: more...
| convert to float64_t | convert from float64_t | |
| long long | fp64_int64_to_float64() | fp64_to_int64() |
| unsigned long long | fp64_uint64_to_float64() | fp64_to_uint64() |
| long | fp64_int32_to_float64() fp64_long_to_float64() | fp64_to_int32() |
| unsigned long | fp64_uint32_to_float64() | fp64_to_uint32 |
| int | fp64_int32_to_float64() * | fp64_to_int16() |
| unsigned int | fp64_uint32_to_float64() * | fp64_to_uint16() |
| char | fp64_int32_to_float64() * | fp64_to_int8() |
| unsigned char | fp64_uint32_to_float64() * | fp64_to_uint8() |
| float | fp64_sd() | fp64_ds() |
| char* | fp64_strtod() | fp64_to_decimalExp() fp64_to_string() |
*For these data types, no special routine was needed to implement, as the compiler automatically extends (“coerces”) the smaller data type into a signed/unsigned long. So basically the following two lines are identical:
float64_t x = fp64_int32_to_float64( 17 );
float64_t x = fp64_int32_to_float64( (long) 17 );
So you can go with the short version.
More to come soon…
Soon, the initial version of a full 64-bit floating point library for the Atmel AVR 328 microprocessors, which are used for example in the popular Arduino boards, will be released.
Beside the basic mathematical operations (+, -, *, / ), the library implements all the necessary standard functions of math.h, like sin(), sqrt() or log() and most of IEEE 754 features like NaN, Inf, signed zero and subnormal numbers.
All routines are optimized for minimal size, leaving enough flash space for your application.