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[/] [ft816float/] [trunk/] [rtl/] [verilog2/] [fpDiv.v] - Rev 57
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// ============================================================================ // __ // \\__/ o\ (C) 2006-2020 Robert Finch, Waterloo // \ __ / All rights reserved. // \/_// robfinch<remove>@finitron.ca // || // // fpDiv.v // - floating point divider // - parameterized FPWIDth // - IEEE 754 representation // // // 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/>. // // Floating Point Multiplier / Divider // //Properties: //+-inf * +-inf = -+inf (this is handled by exOver) //+-inf * 0 = QNaN //+-0 / +-0 = QNaN // ============================================================================ `include "fpConfig.sv" `include "fpDefines.v" //`define GOLDSCHMIDT 1'b1 module fpDiv(rst, clk, clk4x, ce, ld, op, a, b, o, done, sign_exe, overflow, underflow); parameter FPWID = 64; `include "fpSize.sv" // FADD is a constant that makes the divider width a multiple of four and includes eight extra bits. localparam FADD = FPWID==128 ? 9 : FPWID==96 ? 9 : FPWID==84 ? 9 : FPWID==80 ? 9 : FPWID==64 ? 13 : FPWID==52 ? 13 : FPWID==48 ? 10 : FPWID==44 ? 9 : FPWID==42 ? 11 : FPWID==40 ? 8 : FPWID==32 ? 10 : FPWID==24 ? 9 : 11; input rst; input clk; input clk4x; input ce; input ld; input op; input [MSB:0] a, b; output [EX:0] o; output done; output sign_exe; output overflow; output underflow; // registered outputs reg sign_exe=0; reg inf=0; reg overflow=0; reg underflow=0; reg so; reg [EMSB:0] xo; reg [FX:0] mo; assign o = {so,xo,mo}; // constants wire [EMSB:0] infXp = {EMSB+1{1'b1}}; // infinite / NaN - all ones // The following is the value for an exponent of zero, with the offset // eg. 8'h7f for eight bit exponent, 11'h7ff for eleven bit exponent, etc. wire [EMSB:0] bias = {1'b0,{EMSB{1'b1}}}; //2^0 exponent // The following is a template for a quiet nan. (MSB=1) wire [FMSB:0] qNaN = {1'b1,{FMSB{1'b0}}}; // variables reg [EMSB+2:0] ex1; // sum of exponents `ifndef GOLDSCHMIDT wire [(FMSB+FADD)*2-1:0] divo; `else wire [(FMSB+5)*2-1:0] divo; `endif // Operands wire sa, sb; // sign bit wire [EMSB:0] xa, xb; // exponent bits wire [FMSB+1:0] fracta, fractb; wire a_dn, b_dn; // a/b is denormalized wire az, bz; wire aInf, bInf; wire aNan,bNan; wire done1; wire signed [7:0] lzcnt; // ----------------------------------------------------------- // - decode the input operands // - derive basic information // - calculate exponent // - calculate fraction // ----------------------------------------------------------- wire ld1; fpDecompReg #(FPWID) u1a (.clk(clk), .ce(ce), .i(a), .sgn(sa), .exp(xa), .fract(fracta), .xz(a_dn), .vz(az), .inf(aInf), .nan(aNan) ); fpDecompReg #(FPWID) u1b (.clk(clk), .ce(ce), .i(b), .sgn(sb), .exp(xb), .fract(fractb), .xz(b_dn), .vz(bz), .inf(bInf), .nan(bNan) ); delay1 #(1) u5 (.clk(clk), .ce(ce), .i(ld), .o(ld1)); // Compute the exponent. // - correct the exponent for denormalized operands // - adjust the difference by the bias (add 127) // - also factor in the different decimal position for division reg [EMSB+2:0] ex1a; always @(posedge clk) if (ce) ex1a = (xa|a_dn) - (xb|b_dn) + bias; `ifndef GOLDSCHMIDT always @(posedge clk) if (ce) ex1 = ex1a + FMSB + (FADD-1) - lzcnt - 8'd1; `else if (ce) ex1 = ex1a + FMSB - lzcnt + 8'd4; `endif // check for exponent underflow/overflow wire under = ex1[EMSB+2]; // MSB set = negative exponent wire over = (&ex1[EMSB:0] | ex1[EMSB+1]) & !ex1[EMSB+2]; // Perform divide // Divider width must be a multiple of four `ifndef GOLDSCHMIDT `ifdef DIV_RADIX4 fpdivr4 #(FMSB+FADD) u2 (.clk(clk), .ld(ld1), .a({3'b0,fracta,8'b0}), .b({3'b0,fractb,8'b0}), .q(divo), .r(), .done(done1), .lzcnt(lzcnt)); `endif `ifdef DIV_RADIX16 fpdivr16 #(FMSB+FADD) u2 (.clk(clk), .ld(ld1), .a({3'b0,fracta,8'b0}), .b({3'b0,fractb,8'b0}), .q(divo), .r(), .done(done1), .lzcnt(lzcnt)); `endif //fpdivr2 #(FMSB+FADD) u2 (.clk4x(clk4x), .ld(ld), .a({3'b0,fracta,8'b0}), .b({3'b0,fractb,8'b0}), .q(divo), .r(), .done(done1), .lzcnt(lzcnt)); reg [(FMSB+FADD)*2-1:0] divo1, divo2; reg [7:0] lzcnts; always @(posedge clk) if (ce) lzcnts = lzcnt - 2; always @(posedge clk) if (ce) divo2 = divo[(FMSB+FADD)*2-1:0]; always @(posedge clk) if (ce) divo1 = divo2 << lzcnts; `else DivGoldschmidt #(.FPWID(FMSB+6),.WHOLE(1),.POINTS(FMSB+5)) u2 (.rst(rst), .clk(clk), .ld(ld1), .a({fracta,4'b0}), .b({fractb,4'b0}), .q(divo), .done(done1), .lzcnt(lzcnt)); reg [(FMSB+6)*2+1:0] divo1, divo2; always @(posedge clk) if (ce) divo2 = divo; always @(posedge clk) if (ce) divo1 = lzcnt > 8'd5 ? divo2 << (lzcnt-8'd6) : divo2 >> (8'd6-lzcnt); ; `endif delay2 #(1) u3 (.clk(clk), .ce(ce), .i(done1), .o(done2)); delay3 #(1) u4 (.clk(clk), .ce(ce), .i(done1), .o(done)); // determine when a NaN is output wire qNaNOut = (az&bz)|(aInf&bInf); always @(posedge clk) // Simulation likes to see these values reset to zero on reset. Otherwise the // values propagate in sim as X's. if (rst) begin xo <= 1'd0; mo <= 1'd0; so <= 1'd0; sign_exe <= 1'd0; overflow <= 1'd0; underflow <= 1'd0; end else if (ce) begin if (done2) begin casez({qNaNOut|aNan|bNan,bInf,bz,over,under}) 5'b1????: xo <= infXp; // NaN exponent value 5'b01???: xo <= 1'd0; // divide by inf 5'b001??: xo <= infXp; // divide by zero 5'b0001?: xo <= infXp; // overflow 5'b00001: xo <= 1'd0; // underflow default: xo <= ex1; // normal or underflow: passthru neg. exp. for normalization endcase casez({aNan,bNan,qNaNOut,bInf,bz,over,aInf&bInf,az&bz}) 8'b1???????: mo <= {1'b1,1'b1,a[FMSB-1:0],{FMSB+1{1'b0}}}; 8'b01??????: mo <= {1'b1,1'b1,b[FMSB-1:0],{FMSB+1{1'b0}}}; 8'b001?????: mo <= {1'b1,qNaN[FMSB:0]|{aInf,1'b0}|{az,bz},{FMSB+1{1'b0}}}; 8'b0001????: mo <= 1'd0; // div by inf 8'b00001???: mo <= 1'd0; // div by zero 8'b000001??: mo <= 1'd0; // Inf exponent 8'b0000001?: mo <= {1'b1,qNaN|`QINFDIV,{FMSB+1{1'b0}}}; // infinity / infinity 8'b00000001: mo <= {1'b1,qNaN|`QZEROZERO,{FMSB+1{1'b0}}}; // zero / zero `ifndef GOLDSCHMIDT default: mo <= divo1[(FMSB+FADD)*2-1:(FADD-2)*2-2]; // plain div `else default: mo <= divo1[(FMSB+6)*2+1:2]; // plain div `endif endcase so <= sa ^ sb; sign_exe <= sa & sb; overflow <= over; underflow <= under; end end endmodule module fpDivnr(rst, clk, clk4x, ce, ld, op, a, b, o, rm, done, sign_exe, inf, overflow, underflow); parameter FPWID=64; `include "fpSize.sv" input rst; input clk; input clk4x; input ce; input ld; input op; input [MSB:0] a, b; output [MSB:0] o; input [2:0] rm; output sign_exe; output done; output inf; output overflow; output underflow; wire [EX:0] o1; wire sign_exe1, inf1, overflow1, underflow1; wire [MSB+3:0] fpn0; wire done1; fpDiv #(FPWID) u1 (rst, clk, clk4x, ce, ld, op, a, b, o1, done1, sign_exe1, overflow1, underflow1); fpNormalize #(FPWID) u2(.clk(clk), .ce(ce), .under_i(underflow1), .i(o1), .o(fpn0) ); fpRound #(FPWID) u3(.clk(clk), .ce(ce), .rm(rm), .i(fpn0), .o(o) ); delay2 #(1) u4(.clk(clk), .ce(ce), .i(sign_exe1), .o(sign_exe)); delay2 #(1) u5(.clk(clk), .ce(ce), .i(inf1), .o(inf)); delay2 #(1) u6(.clk(clk), .ce(ce), .i(overflow1), .o(overflow)); delay2 #(1) u7(.clk(clk), .ce(ce), .i(underflow1), .o(underflow)); delay2 #(1) u8(.clk(clk), .ce(ce), .i(done1), .o(done)); endmodule
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