Lionel Lacassagne
Laboratoire d'Informatique de Paris 6 (LIP6) - Universite Pierre et Marie Curie (UPMC)
System on Chip Department (SoC)
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F16 Format
sometimes size matters...
Advantages
F16 format has several advantages:
  • automatic vectorisation like 32-bit FP
  • smaller cache footprints than 32-bit FP
  • better precision than 16-bit integer
two kinds of format are possible:
IEEE 754 Format
for 16-bit wide, IEEE format is
  • 1-bit sign
  • 5-bit exponent with a bias of 15
  • 10-bit mantissa
Dynamic range is 65000 to 2^-8
custom Format
parameters can be tuned:
  • still a 1-bit sign
  • mantissa could be smaller than 10 bits
  • exponent bias can be smaller to take into account "big numbers" (close to 2^32)
Dynamic range now depends on exponent, and precision depends on mantissa size
Big Brother is watching you
just smile ;-)