Quartus Forth Manual

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Floating Point Format

The built-in floating point values in Quartus Forth are in Motorola Fast Floating Point (FFP) format.  Each float is 4 bytes (32 bits) long, defined as follows:

3 2        1
10987654321098765432109876543210
MMMMMMMMMMMMMMMMMMMMMMMMSEEEEEEE

M..M is the mantissa, forming an unsigned 24-bit integer of value m.

E..E is the binary exponent, forming an unsigned 7-bit integer of value e.

S is the sign, 0 or 1.

The value of an FFP number is either 0 if all bits are 0, or computed as follows:

(-1)S * m * 2e-88

Floating Point Range

Quartus Forth supports zero and non-zero floating point values within the following bounds:

Base 10:

9.22337177 x 1019 > +number > 5.42101070 x 10-20
-9.22337177 x 1019 > -number > -2.71050535 x 10-20

Base 2:

.FFFFFF x 263 > +number > .FFFFFF x 2-63
-.FFFFFF x 263 > -number > -.FFFFFF x 2-63


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