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/////////////////////////////////////////////////////////////////////
//// ////
//// EXCEPT ////
//// Floating Point Exception/Special Numbers Unit ////
//// ////
//// Author: Rudolf Usselmann ////
//// rudi@asics.ws ////
//// ////
/////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2000 Rudolf Usselmann ////
//// rudi@asics.ws ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
//// ////
//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////
//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////
//// POSSIBILITY OF SUCH DAMAGE. ////
//// ////
/////////////////////////////////////////////////////////////////////
`timescale 1ns / 100ps
module except( clk, opa, opb, inf, ind, qnan, snan, opa_nan, opb_nan,
opa_00, opb_00, opa_inf, opb_inf, opa_dn, opb_dn);
input clk;
input [31:0] opa, opb;
output inf, ind, qnan, snan, opa_nan, opb_nan;
output opa_00, opb_00;
output opa_inf, opb_inf;
output opa_dn;
output opb_dn;
////////////////////////////////////////////////////////////////////////
//
// Local Wires and registers
//
wire [7:0] expa, expb; // alias to opX exponent
wire [22:0] fracta, fractb; // alias to opX fraction
reg expa_ff, infa_f_r, qnan_r_a, snan_r_a;
reg expb_ff, infb_f_r, qnan_r_b, snan_r_b;
reg inf, ind, qnan, snan; // Output registers
reg opa_nan, opb_nan;
reg expa_00, expb_00, fracta_00, fractb_00;
reg opa_00, opb_00;
reg opa_inf, opb_inf;
reg opa_dn, opb_dn;
////////////////////////////////////////////////////////////////////////
//
// Aliases
//
assign expa = opa[30:23];
assign expb = opb[30:23];
assign fracta = opa[22:0];
assign fractb = opb[22:0];
////////////////////////////////////////////////////////////////////////
//
// Determine if any of the input operators is a INF or NAN or any other special number
//
always @(posedge clk)
expa_ff <= #1 &expa;
always @(posedge clk)
expb_ff <= #1 &expb;
always @(posedge clk)
infa_f_r <= #1 !(|fracta);
always @(posedge clk)
infb_f_r <= #1 !(|fractb);
always @(posedge clk)
qnan_r_a <= #1 fracta[22];
always @(posedge clk)
snan_r_a <= #1 !fracta[22] & |fracta[21:0];
always @(posedge clk)
qnan_r_b <= #1 fractb[22];
always @(posedge clk)
snan_r_b <= #1 !fractb[22] & |fractb[21:0];
always @(posedge clk)
ind <= #1 (expa_ff & infa_f_r) & (expb_ff & infb_f_r);
always @(posedge clk)
inf <= #1 (expa_ff & infa_f_r) | (expb_ff & infb_f_r);
always @(posedge clk)
qnan <= #1 (expa_ff & qnan_r_a) | (expb_ff & qnan_r_b);
always @(posedge clk)
snan <= #1 (expa_ff & snan_r_a) | (expb_ff & snan_r_b);
always @(posedge clk)
opa_nan <= #1 &expa & (|fracta[22:0]);
always @(posedge clk)
opb_nan <= #1 &expb & (|fractb[22:0]);
always @(posedge clk)
opa_inf <= #1 (expa_ff & infa_f_r);
always @(posedge clk)
opb_inf <= #1 (expb_ff & infb_f_r);
always @(posedge clk)
expa_00 <= #1 !(|expa);
always @(posedge clk)
expb_00 <= #1 !(|expb);
always @(posedge clk)
fracta_00 <= #1 !(|fracta);
always @(posedge clk)
fractb_00 <= #1 !(|fractb);
always @(posedge clk)
opa_00 <= #1 expa_00 & fracta_00;
always @(posedge clk)
opb_00 <= #1 expb_00 & fractb_00;
always @(posedge clk)
opa_dn <= #1 expa_00;
always @(posedge clk)
opb_dn <= #1 expb_00;
endmodule
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