FPnew - New Floating-Point Unit with Transprecision Capabilities

Parametric floating-point unit with support for standard RISC-V formats and operations as well as transprecision formats.

IMPORTANT

This project is currently under development. It is not considered stable and there is no support.

Getting Started

Dependencies

Consider using Bender for managing dependencies in your projects. FPnew comes with Bender support!

FPnew currently depends on the following:

• find_first_one from the common_cells repository (https://iis-git.ee.ethz.ch/sasa/common_cells)
• The divider and square-root unit (if needed) from the fpu-div-sqrt-mvp repository (https://iis-git.ee.ethz.ch/pulp-open/fpu-div-sqrt-mvp)

Usage - VHDL Users

VHDL users should make use of the FPnew package in the instantiating architecture in order to have access to all types used within FPnew.

library work;
use work.fpnew_pkg.all;

Then, fpnew can be directly instantiated in your design.

i_fpnew: fpnew
generic map (
  FORMATS    => FORMATS,
  INTFORMATS => INTFORMATS,
  UNITTYPES  => UNITTYPES,
  LATENCIES  => LATENCIES,
  GENVECTORS => GENVECTORS,
  TAG_WIDTH  => TAG_WIDTH,
  IN_NANBOX  => IN_NANBOX)
port map (
  Clk_CI         => Clk_CI,
  Reset_RBI      => Reset_RBI,
  A_DI           => A_D,
  B_DI           => B_D,
  C_DI           => C_D,
  RoundMode_SI   => RoundMode_S,
  Op_SI          => Op_S,
  OpMod_SI       => OpMod_S,
  VectorialOp_SI => VectorialOp_S,
  FpFmt_SI       => FpFmt_S,
  FpFmt2_SI      => FpFmt2_S,
  IntFmt_SI      => IntFmt_S,
  Tag_DI         => Tag_D,
  InValid_SI     => InValid_S,
  InReady_SO     => InReady_S,
  Flush_SI       => Flush_S,
  Z_DO           => Z_D,
  Status_DO      => Status_D,
  Tag_DO         => Tag_D,
  OutValid_SO    => OutValid_S,
  OutReady_SI    => OutReady_S);

Usage - SystemVerilog Users

Unfortunately, VHDL packages cannot be imported in SystemVerilog. Thus, fpnew_top, a wrapper that converts all ports of fpnew to std_logic_1164 types is provided. Furthermore, it parallelizes array-type generics into scalar ones so instantiation is more convenient in SystemVerilog. Note not all generics are acessible as parameters of fpnew_top. If you want to change another generic, it's best to remap it in fpnew_top directly or adding a new parameter fpnew_top.

Instantiate fpnew_top directly in your module.

fpnew_top #(
    .WIDTH                ( WIDTH                ),
    .TAG_WIDTH            ( TAG_WIDTH            ),

    .RV64                 ( RV64                 ),
    .RVF                  ( RVF                  ),
    .RVD                  ( RVD                  ),
    .Xf16                 ( Xf16                 ),
    .Xf16alt              ( Xf16alt              ),
    .Xf8                  ( Xf8                  ),
    .Xfvec                ( Xfvec                ),

    .TYPE_ADDMUL          ( TYPE_ADDMUL          ),
    .TYPE_DIVSQRT         ( TYPE_DIVSQRT         ),
    .TYPE_NONCOMP         ( TYPE_NONCOMP         ),
    .TYPE_CONV            ( TYPE_CONV            ),

    .LATENCY_COMP_F       ( LATENCY_COMP_F       ),
    .LATENCY_COMP_D       ( LATENCY_COMP_D       ),
    .LATENCY_COMP_Xf16    ( LATENCY_COMP_Xf16    ),
    .LATENCY_COMP_Xf16alt ( LATENCY_COMP_Xf16alt ),
    .LATENCY_COMP_Xf8     ( LATENCY_COMP_Xf8     ),
    .LATENCY_DIVSQRT      ( LATENCY_DIVSQRT      ),
    .LATENCY_NONCOMP      ( LATENCY_NONCOMP      ),
    .LATENCY_CONV         ( LATENCY_CONV         )
) i_fpnew_top (
    .Clk_CI         ( clk_i          ),
    .Reset_RBI      ( rst_ni         ),
    .A_DI           ( operand_a      ),
    .B_DI           ( operand_b      ),
    .C_DI           ( operand_c      ),
    .RoundMode_SI   ( rm             ),
    .Op_SI          ( op             ),
    .OpMod_SI       ( op_mod         ),
    .VectorialOp_SI ( vec_op         ),
    .FpFmt_SI       ( fmt            ),
    .FpFmt2_SI      ( fmt2           ),
    .IntFmt_SI      ( ifmt           ),
    .Tag_DI         ( in_tag         ),
    .InValid_SI     ( in_valid       ),
    .InReady_SO     ( in_ready       ),
    .Flush_SI       ( flush          ),
    .Z_DO           ( result         ),
    .Status_DO      ( status         ),
    .Tag_DO         ( out_tag        ),
    .OutValid_SO    ( out_valid      ),
    .OutReady_SI    ( out_ready      )
);

In order to access the enumerated types from the fpnew_pkg package, a module fpnew_pkg_constants is provided that statically drives all values of relevant enumerated types. Using these signals to drive input ports of FPnew ensures that changes to the encoding of enumerators from fpnew_pkg take effect in your design too.

fpnew_pkg_constants can also be directly instantiated and will be optimized during sythesis.

fpnew_pkg_constants i_fpnew_constants (
    .OP_NUMBITS   ( OP_NUMBITS   ),
    .OP_FMADD     ( OP_FMADD     ),
    .OP_FNMSUB    ( OP_FNMSUB    ),
    .OP_ADD       ( OP_ADD       ),
    .OP_MUL       ( OP_MUL       ),
    .OP_DIV       ( OP_DIV       ),
    .OP_SQRT      ( OP_SQRT      ),
    .OP_SGNJ      ( OP_SGNJ      ),
    .OP_MINMAX    ( OP_MINMAX    ),
    .OP_CMP       ( OP_CMP       ),
    .OP_CLASS     ( OP_CLASS     ),
    .OP_F2I       ( OP_F2I       ),
    .OP_I2F       ( OP_I2F       ),
    .OP_F2F       ( OP_F2F       ),
    .OP_CPK       ( OP_CPK       ),
    .FMT_NUMBITS  ( FMT_NUMBITS  ),
    .FMT_FP32     ( FMT_FP32     ),
    .FMT_FP64     ( FMT_FP64     ),
    .FMT_FP16     ( FMT_FP16     ),
    .FMT_FP8      ( FMT_FP8      ),
    .FMT_FP16ALT  ( FMT_FP16ALT  ),
    .FMT_CUST1    ( FMT_CUST1    ),
    .FMT_CUST2    ( FMT_CUST2    ),
    .FMT_CUST3    ( FMT_CUST3    ),
    .IFMT_NUMBITS ( IFMT_NUMBITS ),
    .IFMT_INT8    ( IFMT_INT8    ),
    .IFMT_INT16   ( IFMT_INT16   ),
    .IFMT_INT32   ( IFMT_INT32   ),
    .IFMT_INT64   ( IFMT_INT64   )
);

Documentation

Documentation on the FPnew is provided in doc/README.md.

FPnew source code documentation can be generated with doxygen and is especially useful as reference for fpnew_pkg types and functions:

cd doc
doxygen doxyfile

The documentation will be generated at doc/html/index.html and can be viewed with your favorite browser.