fp1eu.vhd

sparc org, vhdl rtl code

----------------------------------------------------------------------------
--  This file is a part of the LEON VHDL model
--  Copyright (C) 1999  European Space Agency (ESA)
--
--  This library is free software; you can redistribute it and/or
--  modify it under the terms of the GNU Lesser General Public
--  License as published by the Free Software Foundation; either
--  version 2 of the License, or (at your option) any later version.
--
--  See the file COPYING.LGPL for the full details of the license.


-----------------------------------------------------------------------------
-- Entity: 	fp
-- File:	fp.vhd
-- Author:	Jiri Gaisler - ESA/ESTEC
-- Description:	Parallel floating-point and co-processor interface
-- The interface allows one execution unit
------------------------------------------------------------------------------

library IEEE;
use IEEE.std_logic_1164.all;
use work.leon_config.all;
use work.leon_iface.all;
use work.sparcv8.all;
use work.tech_map.all;
use work.fpulib.all;

-- pragma translate_off
use STD.TEXTIO.all;
use work.debug.all;
-- pragma translate_on

entity fp1eu is
port (
    rst    : in  std_logic;			-- Reset
    clk    : in  clk_type;
    holdn  : in  std_logic;			-- pipeline hold
    xholdn : in  std_logic;			-- pipeline hold
    cpi    : in  cp_in_type;
    cpo    : out cp_out_type
  );
end;

architecture rtl of fp1eu is

type cpins_type is (none, cpop, load, store);

type pl_ctrl is record		-- pipeline control record
  cpins    : cpins_type;	-- CP instruction
  rreg1    : std_logic;		-- using rs1
  rreg2    : std_logic;		-- using rs1
  rs1d     : std_logic;		-- rs1 is double (64-bit)
  rs2d     : std_logic;		-- rs2 is double (64-bit)
  wreg     : std_logic;		-- write CP regfile
  rdd      : std_logic;		-- rd is double (64-bit)
  wrcc     : std_logic;		-- write CP condition codes
  acsr     : std_logic;		-- access CP control register
end record;

type unit_status_type is (free, started, ready);
type unit_ctrl is record	-- execution unit control record
  status   : unit_status_type;		    -- unit status
  rs1      : std_logic_vector (4 downto 0); -- destination register
  rs2      : std_logic_vector (4 downto 0); -- destination register
  rd       : std_logic_vector (4 downto 0); -- destination register
  rreg1    : std_logic;		-- using rs1
  rreg2    : std_logic;		-- using rs1
  rs1d     : std_logic;		-- rs1 is double (64-bit)
  rs2d     : std_logic;		-- rs2 is double (64-bit)
  wreg     : std_logic;		-- will write CP regfile
  rdd      : std_logic;		-- rd is double (64-bit)
  wbok     : std_logic;		-- ok to write result
  wrcc     : std_logic;		-- will write CP condition codes
  rst      : std_logic;		-- reset register
  pc       : std_logic_vector (31 downto PCLOW); -- program counter
  inst     : std_logic_vector (31 downto 0); -- instruction
end record;

type csr_type is record	-- CP status register
  cc       : std_logic_vector (1 downto 0); -- condition codes
  aexc     : std_logic_vector (4 downto 0); -- exception codes
  cexc     : std_logic_vector (4 downto 0); -- exception codes
  tem      : std_logic_vector (4 downto 0); -- trap enable mask
  rd       : std_logic_vector (1 downto 0); -- rounding mode
  tt       : std_logic_vector (2 downto 0); -- trap type
end record;

type execstate is (nominal, excpend, exception);
type reg_type is record	-- registers clocked with pipeline
  start    : std_logic;		-- start EU
end record;

type regx_type is record	-- registers clocked continuously
  res      : std_logic_vector (63 downto 0); -- write stage result
  waddr    : std_logic_vector (3 downto 0); -- write stage dest
  wren     : std_logic_vector (1 downto 0); -- write stage regfile write enable
  csr      : csr_type;                       -- co-processor status register
  start    : std_logic;		-- start EU
  starty   : std_logic;		-- start EU
  startx   : std_logic;		-- start EU
  holdn    : std_logic;
  wbok     : std_logic;		-- ok to write result
  state    : execstate;		-- FP/CP state
end record;

signal vcc, gnd, wb, snnotdb, fp_ctl_scan_out : std_logic;
signal rfi1, rfi2 : rf_cp_in_type;
signal rfo1, rfo2 : rf_cp_out_type;
signal ex, exin, me, mein, wr, wrin : pl_ctrl;
signal r, rin  : reg_type;
signal rx, rxin  : regx_type;
signal eui : cp_unit_in_type;
signal euo : cp_unit_out_type;
signal eu, euin : unit_ctrl;

function ldcheck (rdin : std_logic_vector; ldd : std_logic; eu : unit_ctrl) 
  return std_logic is
variable lock : std_logic;
variable rd : std_logic_vector(4 downto 0);
begin
  lock := '0'; rd := rdin;
  if (eu.status > free) then
    if (eu.rdd = '0') then
      if ((eu.wreg = '1') and (rd = eu.rd)) or
	 ((eu.rreg1 = '1') and (rd = eu.rs1)) or
	 ((eu.rreg2 = '1') and (rd = eu.rs2))
      then lock := '1'; end if;
      if (ldd = '1') then
	if ((eu.wreg = '1')  and ((rd(4 downto 1) & '1') = eu.rd)) or
	   ((eu.rreg1 = '1') and ((rd(4 downto 1) & '1') = eu.rs1)) or
	   ((eu.rreg2 = '1') and ((rd(4 downto 1) & '1') = eu.rs2))
	then lock := '1'; end if;
      end if;
    else
      if ((eu.wreg = '1')  and (rd(4 downto 1) = eu.rd(4 downto 1))) or
	 ((eu.rreg1 = '1') and (rd(4 downto 1) = eu.rs1(4 downto 1))) or
	 ((eu.rreg2 = '1') and (rd(4 downto 1) = eu.rs2(4 downto 1)))
      then lock := '1'; end if;
    end if;
  end if;
  return(lock);
end;
function stcheck (rdin : std_logic_vector; std : std_logic; eu : unit_ctrl) 
  return std_logic is
variable lock : std_logic;
variable rd : std_logic_vector(4 downto 0);
begin
  lock := '0'; rd := rdin;
  if (eu.status > free) then
    if (eu.rdd = '0') then
      if ((eu.wreg = '1') and (rd = eu.rd)) then lock := '1'; end if;
      if (std = '1') then
	if ((eu.wreg = '1')  and ((rd(4 downto 1) & '1') = eu.rd))
	then lock := '1'; end if;
      end if;
    else
      if ((eu.wreg = '1')  and (rd(4 downto 1) = eu.rd(4 downto 1))) or
	 ((eu.rreg1 = '1') and (rd(4 downto 1) = eu.rs1(4 downto 1))) or
	 ((eu.rreg2 = '1') and (rd(4 downto 1) = eu.rs2(4 downto 1)))
      then lock := '1'; end if;
    end if;
  end if;
  return(lock);
end;

function srccheck (rsin : std_logic_vector; dbl : std_logic; eu : unit_ctrl) 
  return std_logic is
variable lock : std_logic;
variable rs : std_logic_vector(4 downto 0);
begin
  lock := '0'; rs := rsin;
  if (eu.wreg = '1')  and (rs(4 downto 1) = eu.rd(4 downto 1)) then
    if ((dbl or eu.rdd) = '1') or (rs(0) = eu.rd(0)) then lock := '1'; end if;
  end if;
  return(lock);
end;

begin

  vcc <= '1'; gnd <= '1';

-- instruction decoding

  pipeline : process(cpi, ex, me, wr, eu, euin, r, rx, rfi1, rfi2, rfo1, rfo2,
		     holdn, xholdn,
			euo, rst, wb)
  variable op     : std_logic_vector(1 downto 0);
  variable op3    : std_logic_vector(5 downto 0);
  variable opc    : std_logic_vector(8 downto 0);
  variable stdata : std_logic_vector(31 downto 0);
  variable rs1, rs2, rd : std_logic_vector(4 downto 0);
  variable ctrl   : pl_ctrl;
  variable ldlock : std_logic;
  variable wren   : std_logic_vector(1 downto 0);
  variable waddr  : std_logic_vector(3 downto 0);
  variable rtaddr : std_logic_vector(3 downto 0);
  variable wrdata : std_logic_vector(63 downto 0);
  variable rtdata : std_logic_vector(63 downto 0);
  variable rv : reg_type;
  variable rxv : regx_type;
  variable euv : unit_ctrl;
  variable euiv : cp_unit_in_type;
  variable ddep     : std_logic;
  variable cpexc    : std_logic;
  variable fpill    : std_logic;
  variable ccv      : std_logic;
  variable qne      : std_logic;
  variable wbv      : std_logic;
  variable op1      : std_logic_vector (63 downto 0); -- operand1
  variable op2      : std_logic_vector (63 downto 0); -- operand2
  variable opcode   : std_logic_vector (9 downto 0); -- FP opcode
  begin

-------------------------------------------------------------
-- decode stage
-------------------------------------------------------------
    op    := cpi.dinst(31 downto 30);
    op3   := cpi.dinst(24 downto 19);
    opc   := cpi.dinst(13 downto 5);
    rs1   := cpi.dinst(18 downto 14);
    rs2   := cpi.dinst(4 downto 0);
    rd    := cpi.dinst(29 downto 25);

    rv := r; rxv := rx;
    ctrl.cpins := none; ctrl.wreg := '0'; ctrl.rdd := '0';
    ctrl.wrcc := '0'; ctrl.acsr := '0'; ldlock := '0';
    ctrl.rreg1 := '0'; ctrl.rreg2 := '0';
    ctrl.rs1d := '0'; ctrl.rs2d := '0'; fpill := '0';
    stdata := (others => '-'); wren := "00"; cpexc := '0';
    ccv := '0'; rv.start := '0'; rxv.wbok := '0';
    rxv.start := '0';
    euv := eu;
    if eu.status /= free then qne := '1'; else qne := '0'; end if;

    euiv.opcode := cpi.ex.inst(19) & cpi.ex.inst(13 downto 5);
    euiv.start := '0'; euiv.load := '0';
    euiv.flush := eu.rst or euin.rst;
    wbv := '0';
    euv.rst := not rst;
    if (eu.status = started) and (euo.busy = '0') then 
      euv.status := ready;
    end if;
    if (eu.status > free) then ccv := ccv or eu.wrcc; end if;

    -- decode CP instructions
      case op is
      when FMT3 =>
        case op3 is
        when FPOP1 => 
	  if rx.state = exception then rxv.state := excpend; rxv.csr.tt := "100";
          elsif rx.state = nominal then
	    ctrl.cpins := cpop; ctrl.wreg := '1';
            case opc is
            when FMOVS | FABSS | FNEGS => ctrl.rreg2 := '1';
            when FITOS | FSTOI => ctrl.rreg2 := '1';
            when FITOD | FSTOD => ctrl.rreg2 := '1'; ctrl.rdd := '1';
            when FDTOI | FDTOS => ctrl.rreg2 := '1'; ctrl.rs2d  := '1';
            when FSQRTS => ctrl.rreg2 := '1';
            when FSQRTD => ctrl.rreg2 := '1'; ctrl.rs2d  := '1'; ctrl.rdd := '1';
            when FADDS | FSUBS | FMULS | FDIVS => 
	      ctrl.rreg1 := '1'; ctrl.rreg2 := '1';
            when FADDD | FSUBD | FMULD | FDIVD => 
	      ctrl.rreg1 := '1'; ctrl.rreg2 := '1'; ctrl.rs1d  := '1'; 
	      ctrl.rs2d  := '1'; ctrl.rdd := '1';
            when others => fpill := '1'; -- illegal instuction
            end case;
	  end if;
        when FPOP2 => 
	  if rx.state = exception then rxv.state := excpend; rxv.csr.tt := "100";
          elsif rx.state = nominal then
	    ctrl.cpins := cpop; ctrl.wrcc := '1';
	    ctrl.rreg1 := '1'; ctrl.rreg2 := '1';
            case opc is
            when FCMPD | FCMPED => 
	      ctrl.rs1d := '1'; ctrl.rs2d := '1';
            when others => fpill := '1'; -- illegal instuction
            end case;
	  end if;
        when others => null;
        end case;
        if (ex.cpins = load) and ((cpi.ex.annul or cpi.ex.trap) = '0') and
	  (ex.wreg = '1')
        then
	  if (ctrl.rreg1 = '1') and
	   (rs1(4 downto 1) = cpi.ex.inst(29 downto 26)) and
	   (((ctrl.rs1d or ex.rdd) = '1') or (rs1(0) = cpi.ex.inst(25)))
	  then ldlock := '1'; end if;
	  if (ctrl.rreg2 = '1') and
	   (rs2(4 downto 1) = cpi.ex.inst(29 downto 26)) and
	   (((ctrl.rs2d or ex.rdd) = '1') or (rs2(0) = cpi.ex.inst(25)))
	  then ldlock := '1'; end if;
        end if;
      when LDST =>
        case op3 is
        when LDF | LDDF =>
	  if rx.state = exception then rxv.state := excpend; rxv.csr.tt := "100";
          elsif rx.state = nominal then
	    ctrl.rdd := op3(1) and op3(0);
	    ctrl.cpins := load; ctrl.wreg := '1';
            -- dst interlock
	    ldlock := ldlock or ldcheck(rd, ctrl.rdd, euin);
 	  end if;
        when STF | STDF =>
	  -- check for CP register dependencies
	  if (ex.cpins = load) and ((cpi.ex.annul or cpi.ex.trap) = '0') and
	     (cpi.ex.cnt = "00") and 
	       ((rd = cpi.ex.inst(29 downto 25)) or
	       ((rd(4 downto 1) = cpi.ex.inst(29 downto 26)) and 
		  (ex.rdd = '1')))
	  then ldlock := '1'; end if;
          if rx.state = nominal then
	    ldlock := ldlock or stcheck(rd, (op3(1) and op3(0)), euin);
	  end if;
	  if (ldlock = '0') then ctrl.cpins := store; end if;
        when STFSR | LDFSR =>
	  if (rx.state = exception) and (op3 = LDFSR) then 
	    rxv.state := excpend;  rxv.csr.tt := "100";
          else
	    if (ex.cpins = load) and ((cpi.ex.annul or cpi.ex.trap) = '0') and
	     (cpi.ex.cnt = "00") and (op3 = STFSR) and (ex.acsr = '1')
	    then ldlock := '1'; end if;
	    if (rx.state = nominal) then 
	      if (((cpi.ex.annul or cpi.ex.trap) = '0') and (ex.cpins = cpop)) 
		or (eu.status > free) 
	      then ldlock := '1'; end if;
	    end if;
	  end if;
	  if (ldlock = '0') then
	    ctrl.acsr := '1';
	    if op3 = STFSR then ctrl.cpins := store; 
	    else ctrl.cpins := load; end if;
	  end if;
        when STDFQ => 
	  if (rx.state = nominal) then 
	    rxv.state := excpend; rxv.csr.tt := "100";
	  else ctrl.cpins := store; end if;
        when others => null;
        end case;
      when others => null;
      end case;
    if ((cpi.flush or cpi.dtrap or cpi.dannul or ldlock) = '1') then
      ctrl.cpins := none; ctrl.acsr := '0';