5.48 Half-precision floating-point number format

The half-precision floating-point formats available are ieee and alternative. In both formats, the basic layout of the 16-bit number is the same.

The half-precision floating-point format is as follows:

Figure 5-1 Half-precision floating-point format
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Where:

   S (bit[15]):      Sign bit
   E (bits[14:10]):  Biased exponent
   T (bits[9:0]):    Mantissa.

The meanings of these fields depend on the format that is selected.

The IEEE half-precision format is as follows:

IF E==31:
   IF T==0: Value = Signed infinity
   IF T!=0: Value = Nan
             T[9] determines Quiet or Signalling:
                  0: Quiet NaN
                  1: Signalling NaN
IF 0<E<31:
   Value = (-1)^S x 2^(E-15) x (1 + (2^(-10) x T))
IF E==0:
   IF T==0: Value = Signed zero
   IF T!=0: Value = (-1)^S x 2^(-14) x (0 + (2^(-10) x T))

The alternative half-precision format is as follows:

IF 0<E<32:
   Value = (-1)^S x 2^(E-15) x (1 + (2^(-10) x T))
IF E==0:
   IF T==0: Value = Signed zero
   IF T!=0: Value = (-1)^S x 2^(-14) x (0 + (2^(-10) x T))
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