This repository contains hardware floating-point units written in Chisel. This library contains parameterized floating-point units for fused multiply-add operations, conversions between integer and floating-point numbers, and conversions between floating-point conversions with different precision.
WARNING: These units are works in progress. They may not be yet completely free of bugs, nor are they fully optimized.
The floating-point units in this repository work on an internal recoded format (exponent has an additional bit) to handle subnormal numbers more efficiently in a microprocessor. A more detailed explanation will come soon, but in the mean time here are some example mappings for single-precision numbers.
IEEE format Recoded format
---------------------------------- -----------------------------------
s 00000000 00000000000000000000000 s 000------ 00000000000000000000000
s 00000000 00000000000000000000001 s 001101011 00000000000000000000000
s 00000000 0000000000000000000001f s 001101100 f0000000000000000000000
s 00000000 000000000000000000001ff s 001101101 ff000000000000000000000
... ... ... ...
s 00000000 001ffffffffffffffffffff s 001111111 ffffffffffffffffffff000
s 00000000 01fffffffffffffffffffff s 010000000 fffffffffffffffffffff00
s 00000000 1ffffffffffffffffffffff s 010000001 ffffffffffffffffffffff0
s 00000001 fffffffffffffffffffffff s 010000010 fffffffffffffffffffffff
s 00000010 fffffffffffffffffffffff s 010000011 fffffffffffffffffffffff
... ... ... ...
s 11111101 fffffffffffffffffffffff s 101111110 fffffffffffffffffffffff
s 11111110 fffffffffffffffffffffff s 101111111 fffffffffffffffffffffff
s 11111111 00000000000000000000000 s 110------ -----------------------
s 11111111 fffffffffffffffffffffff s 111------ fffffffffffffffffffffff
To unit-test these floating-point units, you need the berkeley-testfloat-3 package.
To test floating-point units with the C simulator:
$ make
