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[/] [ft816float/] [trunk/] [rtl/] [verilog2/] [fpNextAfter.sv] - Rev 69
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// ============================================================================
// __
// \\__/ o\ (C) 2019 Robert Finch, Waterloo
// \ __ / All rights reserved.
// \/_// robfinch<remove>@finitron.ca
// ||
//
// fpNextAfter.v
// - floating point nextafter()
// - return next representable value
//
// This source file 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 3 of the License, or
// (at your option) any later version.
//
// This source file is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// ============================================================================
`include "fpConfig.sv"
module fpNextAfter(clk, ce, a, b, o);
parameter FPWID=80;
`include "fpSize.sv"
input clk;
input ce;
input [MSB:0] a;
input [MSB:0] b;
output reg [MSB:0] o;
wire [4:0] cmp_o;
wire nana, nanb;
wire xza, mza;
fpCompare #(FPWID) u1 (.a(a), .b(b), .o(cmp_o), .nanx(nanxab) );
fpDecomp #(FPWID) u2 (.i(a), .sgn(), .exp(), .man(), .fract(), .xz(xza), .mz(mza), .vz(), .inf(), .xinf(), .qnan(), .snan(), .nan(nana));
fpDecomp #(FPWID) u3 (.i(b), .sgn(), .exp(), .man(), .fract(), .xz(), .mz(), .vz(), .inf(), .xinf(), .qnan(), .snan(), .nan(nanb));
wire [MSB:0] ap1 = a + {2'd1,{`EXTRA_BITS{1'b0}}};
wire [MSB:0] am1 = a - {2'd1,{`EXTRA_BITS{1'b0}}};
wire [EMSB:0] infXp = {EMSB+1{1'b1}};
always @(posedge clk)
if (ce)
casez({a[MSB],cmp_o})
6'b?1????: o <= nana ? a : b; // Unordered
6'b????1?: o <= a; // a,b Equal
6'b0????1:
if (ap1[MSB-1:FMSB+1]==infXp)
o <= {a[MSB:FMSB+1],{FMSB+1{1'b0}}};
else
o <= ap1;
6'b0????0:
if (xza && mza)
;
else
o <= am1;
6'b1????0:
if (ap1[MSB-1:FMSB+1]==infXp)
o <= {a[MSB:FMSB+1],{FMSB+1{1'b0}}};
else
o <= ap1;
6'b1????1:
if (xza && mza)
;
else
o <= am1;
default: o <= a;
endcase
endmodule
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