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_tconvert from float64_t
long longfp64_int64_to_float64()fp64_to_int64()
long long
fp64_uint64_to_float64() fp64_to_uint64()
long fp64_int32_to_float64()
fp64_uint32_to_float64() fp64_to_uint32
int fp64_int32_to_float64() * fp64_to_int16()
fp64_uint32_to_float64() * fp64_to_uint16()
char fp64_int32_to_float64() *fp64_to_int8()
fp64_uint32_to_float64() *fp64_to_uint8()

*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.