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yosys/tests/iwls2005/fpu/fpu.v

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/////////////////////////////////////////////////////////////////////
//// ////
//// FPU ////
//// Floating Point Unit (Single precision) ////
//// ////
//// 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
/*
FPU Operations (fpu_op):
========================
0 = add
1 = sub
2 = mul
3 = div
4 =
5 =
6 =
7 =
Rounding Modes (rmode):
=======================
0 = round_nearest_even
1 = round_to_zero
2 = round_up
3 = round_down
*/
module fpu( clk, rmode, fpu_op, opa, opb, out, inf, snan, qnan, ine, overflow, underflow, zero, div_by_zero);
input clk;
input [1:0] rmode;
input [2:0] fpu_op;
input [31:0] opa, opb;
output [31:0] out;
output inf, snan, qnan;
output ine;
output overflow, underflow;
output zero;
output div_by_zero;
parameter INF = 31'h7f800000,
QNAN = 31'h7fc00001,
SNAN = 31'h7f800001;
////////////////////////////////////////////////////////////////////////
//
// Local Wires
//
reg zero;
reg [31:0] opa_r, opb_r; // Input operand registers
reg [31:0] out; // Output register
reg div_by_zero; // Divide by zero output register
wire signa, signb; // alias to opX sign
wire sign_fasu; // sign output
wire [26:0] fracta, fractb; // Fraction Outputs from EQU block
wire [7:0] exp_fasu; // Exponent output from EQU block
reg [7:0] exp_r; // Exponent output (registerd)
wire [26:0] fract_out_d; // fraction output
wire co; // carry output
reg [27:0] fract_out_q; // fraction output (registerd)
wire [30:0] out_d; // Intermediate final result output
wire overflow_d, underflow_d;// Overflow/Underflow Indicators
reg overflow, underflow; // Output registers for Overflow & Underflow
reg inf, snan, qnan; // Output Registers for INF, SNAN and QNAN
reg ine; // Output Registers for INE
reg [1:0] rmode_r1, rmode_r2, // Pipeline registers for rounding mode
rmode_r3;
reg [2:0] fpu_op_r1, fpu_op_r2, // Pipeline registers for fp opration
fpu_op_r3;
wire mul_inf, div_inf;
wire mul_00, div_00;
////////////////////////////////////////////////////////////////////////
//
// Input Registers
//
always @(posedge clk)
opa_r <= #1 opa;
always @(posedge clk)
opb_r <= #1 opb;
always @(posedge clk)
rmode_r1 <= #1 rmode;
always @(posedge clk)
rmode_r2 <= #1 rmode_r1;
always @(posedge clk)
rmode_r3 <= #1 rmode_r2;
always @(posedge clk)
fpu_op_r1 <= #1 fpu_op;
always @(posedge clk)
fpu_op_r2 <= #1 fpu_op_r1;
always @(posedge clk)
fpu_op_r3 <= #1 fpu_op_r2;
////////////////////////////////////////////////////////////////////////
//
// Exceptions block
//
wire inf_d, ind_d, qnan_d, snan_d, opa_nan, opb_nan;
wire opa_00, opb_00;
wire opa_inf, opb_inf;
wire opa_dn, opb_dn;
except u0( .clk(clk),
.opa(opa_r), .opb(opb_r),
.inf(inf_d), .ind(ind_d),
.qnan(qnan_d), .snan(snan_d),
.opa_nan(opa_nan), .opb_nan(opb_nan),
.opa_00(opa_00), .opb_00(opb_00),
.opa_inf(opa_inf), .opb_inf(opb_inf),
.opa_dn(opa_dn), .opb_dn(opb_dn)
);
////////////////////////////////////////////////////////////////////////
//
// Pre-Normalize block
// - Adjusts the numbers to equal exponents and sorts them
// - determine result sign
// - determine actual operation to perform (add or sub)
//
wire nan_sign_d, result_zero_sign_d;
reg sign_fasu_r;
wire [7:0] exp_mul;
wire sign_mul;
reg sign_mul_r;
wire [23:0] fracta_mul, fractb_mul;
wire inf_mul;
reg inf_mul_r;
wire [1:0] exp_ovf;
reg [1:0] exp_ovf_r;
wire sign_exe;
reg sign_exe_r;
wire [2:0] underflow_fmul_d;
pre_norm u1(.clk(clk), // System Clock
.rmode(rmode_r2), // Roundin Mode
.add(!fpu_op_r1[0]), // Add/Sub Input
.opa(opa_r), .opb(opb_r), // Registered OP Inputs
.opa_nan(opa_nan), // OpA is a NAN indicator
.opb_nan(opb_nan), // OpB is a NAN indicator
.fracta_out(fracta), // Equalized and sorted fraction
.fractb_out(fractb), // outputs (Registered)
.exp_dn_out(exp_fasu), // Selected exponent output (registered);
.sign(sign_fasu), // Encoded output Sign (registered)
.nan_sign(nan_sign_d), // Output Sign for NANs (registered)
.result_zero_sign(result_zero_sign_d), // Output Sign for zero result (registered)
.fasu_op(fasu_op) // Actual fasu operation output (registered)
);
always @(posedge clk)
sign_fasu_r <= #1 sign_fasu;
pre_norm_fmul u2(
.clk(clk),
.fpu_op(fpu_op_r1),
.opa(opa_r), .opb(opb_r),
.fracta(fracta_mul),
.fractb(fractb_mul),
.exp_out(exp_mul), // FMUL exponent output (registered)
.sign(sign_mul), // FMUL sign output (registered)
.sign_exe(sign_exe), // FMUL exception sign output (registered)
.inf(inf_mul), // FMUL inf output (registered)
.exp_ovf(exp_ovf), // FMUL exponnent overflow output (registered)
.underflow(underflow_fmul_d)
);
always @(posedge clk)
sign_mul_r <= #1 sign_mul;
always @(posedge clk)
sign_exe_r <= #1 sign_exe;
always @(posedge clk)
inf_mul_r <= #1 inf_mul;
always @(posedge clk)
exp_ovf_r <= #1 exp_ovf;
////////////////////////////////////////////////////////////////////////
//
// Add/Sub
//
add_sub27 u3(
.add(fasu_op), // Add/Sub
.opa(fracta), // Fraction A input
.opb(fractb), // Fraction B Input
.sum(fract_out_d), // SUM output
.co(co_d) ); // Carry Output
always @(posedge clk)
fract_out_q <= #1 {co_d, fract_out_d};
////////////////////////////////////////////////////////////////////////
//
// Mul
//
wire [47:0] prod;
mul_r2 u5(.clk(clk), .opa(fracta_mul), .opb(fractb_mul), .prod(prod));
////////////////////////////////////////////////////////////////////////
//
// Divide
//
wire [49:0] quo;
wire [49:0] fdiv_opa;
wire [49:0] remainder;
wire remainder_00;
reg [4:0] div_opa_ldz_d, div_opa_ldz_r1, div_opa_ldz_r2;
always @(fracta_mul)
casex(fracta_mul[22:0])
23'b1??????????????????????: div_opa_ldz_d = 1;
23'b01?????????????????????: div_opa_ldz_d = 2;
23'b001????????????????????: div_opa_ldz_d = 3;
23'b0001???????????????????: div_opa_ldz_d = 4;
23'b00001??????????????????: div_opa_ldz_d = 5;
23'b000001?????????????????: div_opa_ldz_d = 6;
23'b0000001????????????????: div_opa_ldz_d = 7;
23'b00000001???????????????: div_opa_ldz_d = 8;
23'b000000001??????????????: div_opa_ldz_d = 9;
23'b0000000001?????????????: div_opa_ldz_d = 10;
23'b00000000001????????????: div_opa_ldz_d = 11;
23'b000000000001???????????: div_opa_ldz_d = 12;
23'b0000000000001??????????: div_opa_ldz_d = 13;
23'b00000000000001?????????: div_opa_ldz_d = 14;
23'b000000000000001????????: div_opa_ldz_d = 15;
23'b0000000000000001???????: div_opa_ldz_d = 16;
23'b00000000000000001??????: div_opa_ldz_d = 17;
23'b000000000000000001?????: div_opa_ldz_d = 18;
23'b0000000000000000001????: div_opa_ldz_d = 19;
23'b00000000000000000001???: div_opa_ldz_d = 20;
23'b000000000000000000001??: div_opa_ldz_d = 21;
23'b0000000000000000000001?: div_opa_ldz_d = 22;
23'b0000000000000000000000?: div_opa_ldz_d = 23;
endcase
assign fdiv_opa = !(|opa_r[30:23]) ? {(fracta_mul<<div_opa_ldz_d), 26'h0} : {fracta_mul, 26'h0};
div_r2 u6(.clk(clk), .opa(fdiv_opa), .opb(fractb_mul), .quo(quo), .rem(remainder));
assign remainder_00 = !(|remainder);
always @(posedge clk)
div_opa_ldz_r1 <= #1 div_opa_ldz_d;
always @(posedge clk)
div_opa_ldz_r2 <= #1 div_opa_ldz_r1;
////////////////////////////////////////////////////////////////////////
//
// Normalize Result
//
wire ine_d;
reg [47:0] fract_denorm;
wire [47:0] fract_div;
wire sign_d;
reg sign;
reg [30:0] opa_r1;
reg [47:0] fract_i2f;
reg opas_r1, opas_r2;
wire f2i_out_sign;
always @(posedge clk) // Exponent must be once cycle delayed
case(fpu_op_r2)
0,1: exp_r <= #1 exp_fasu;
2,3: exp_r <= #1 exp_mul;
4: exp_r <= #1 0;
5: exp_r <= #1 opa_r1[30:23];
endcase
assign fract_div = (opb_dn ? quo[49:2] : {quo[26:0], 21'h0});
always @(posedge clk)
opa_r1 <= #1 opa_r[30:0];
always @(posedge clk)
fract_i2f <= #1 (fpu_op_r2==5) ?
(sign_d ? 1-{24'h00, (|opa_r1[30:23]), opa_r1[22:0]}-1 : {24'h0, (|opa_r1[30:23]), opa_r1[22:0]}) :
(sign_d ? 1 - {opa_r1, 17'h01} : {opa_r1, 17'h0});
always @(fpu_op_r3 or fract_out_q or prod or fract_div or fract_i2f)
case(fpu_op_r3)
0,1: fract_denorm = {fract_out_q, 20'h0};
2: fract_denorm = prod;
3: fract_denorm = fract_div;
4,5: fract_denorm = fract_i2f;
endcase
always @(posedge clk)
opas_r1 <= #1 opa_r[31];
always @(posedge clk)
opas_r2 <= #1 opas_r1;
assign sign_d = fpu_op_r2[1] ? sign_mul : sign_fasu;
always @(posedge clk)
sign <= #1 (rmode_r2==2'h3) ? !sign_d : sign_d;
post_norm u4(.clk(clk), // System Clock
.fpu_op(fpu_op_r3), // Floating Point Operation
.opas(opas_r2), // OPA Sign
.sign(sign), // Sign of the result
.rmode(rmode_r3), // Rounding mode
.fract_in(fract_denorm), // Fraction Input
.exp_ovf(exp_ovf_r), // Exponent Overflow
.exp_in(exp_r), // Exponent Input
.opa_dn(opa_dn), // Operand A Denormalized
.opb_dn(opb_dn), // Operand A Denormalized
.rem_00(remainder_00), // Diveide Remainder is zero
.div_opa_ldz(div_opa_ldz_r2), // Divide opa leading zeros count
.output_zero(mul_00 | div_00), // Force output to Zero
.out(out_d), // Normalized output (un-registered)
.ine(ine_d), // Result Inexact output (un-registered)
.overflow(overflow_d), // Overflow output (un-registered)
.underflow(underflow_d), // Underflow output (un-registered)
.f2i_out_sign(f2i_out_sign) // F2I Output Sign
);
////////////////////////////////////////////////////////////////////////
//
// FPU Outputs
//
reg fasu_op_r1, fasu_op_r2;
wire [30:0] out_fixed;
wire output_zero_fasu;
wire output_zero_fdiv;
wire output_zero_fmul;
reg inf_mul2;
wire overflow_fasu;
wire overflow_fmul;
wire overflow_fdiv;
wire inf_fmul;
wire sign_mul_final;
wire out_d_00;
wire sign_div_final;
wire ine_mul, ine_mula, ine_div, ine_fasu;
wire underflow_fasu, underflow_fmul, underflow_fdiv;
wire underflow_fmul1;
reg [2:0] underflow_fmul_r;
reg opa_nan_r;
always @(posedge clk)
fasu_op_r1 <= #1 fasu_op;
always @(posedge clk)
fasu_op_r2 <= #1 fasu_op_r1;
always @(posedge clk)
inf_mul2 <= #1 exp_mul == 8'hff;
// Force pre-set values for non numerical output
assign mul_inf = (fpu_op_r3==3'b010) & (inf_mul_r | inf_mul2) & (rmode_r3==2'h0);
assign div_inf = (fpu_op_r3==3'b011) & (opb_00 | opa_inf);
assign mul_00 = (fpu_op_r3==3'b010) & (opa_00 | opb_00);
assign div_00 = (fpu_op_r3==3'b011) & (opa_00 | opb_inf);
assign out_fixed = ( (qnan_d | snan_d) |
(ind_d & !fasu_op_r2) |
((fpu_op_r3==3'b011) & opb_00 & opa_00) |
(((opa_inf & opb_00) | (opb_inf & opa_00 )) & fpu_op_r3==3'b010)
) ? QNAN : INF;
always @(posedge clk)
out[30:0] <= #1 (mul_inf | div_inf | (inf_d & (fpu_op_r3!=3'b011) & (fpu_op_r3!=3'b101)) | snan_d | qnan_d) & fpu_op_r3!=3'b100 ? out_fixed :
out_d;
assign out_d_00 = !(|out_d);
assign sign_mul_final = (sign_exe_r & ((opa_00 & opb_inf) | (opb_00 & opa_inf))) ? !sign_mul_r : sign_mul_r;
assign sign_div_final = (sign_exe_r & (opa_inf & opb_inf)) ? !sign_mul_r : sign_mul_r | (opa_00 & opb_00);
always @(posedge clk)
out[31] <= #1 ((fpu_op_r3==3'b101) & out_d_00) ? (f2i_out_sign & !(qnan_d | snan_d) ) :
((fpu_op_r3==3'b010) & !(snan_d | qnan_d)) ? sign_mul_final :
((fpu_op_r3==3'b011) & !(snan_d | qnan_d)) ? sign_div_final :
(snan_d | qnan_d | ind_d) ? nan_sign_d :
output_zero_fasu ? result_zero_sign_d :
sign_fasu_r;
// Exception Outputs
assign ine_mula = ((inf_mul_r | inf_mul2 | opa_inf | opb_inf) & (rmode_r3==2'h1) &
!((opa_inf & opb_00) | (opb_inf & opa_00 )) & fpu_op_r3[1]);
assign ine_mul = (ine_mula | ine_d | inf_fmul | out_d_00 | overflow_d | underflow_d) &
!opa_00 & !opb_00 & !(snan_d | qnan_d | inf_d);
assign ine_div = (ine_d | overflow_d | underflow_d) & !(opb_00 | snan_d | qnan_d | inf_d);
assign ine_fasu = (ine_d | overflow_d | underflow_d) & !(snan_d | qnan_d | inf_d);
always @(posedge clk)
ine <= #1 fpu_op_r3[2] ? ine_d :
!fpu_op_r3[1] ? ine_fasu :
fpu_op_r3[0] ? ine_div : ine_mul;
assign overflow_fasu = overflow_d & !(snan_d | qnan_d | inf_d);
assign overflow_fmul = !inf_d & (inf_mul_r | inf_mul2 | overflow_d) & !(snan_d | qnan_d);
assign overflow_fdiv = (overflow_d & !(opb_00 | inf_d | snan_d | qnan_d));
always @(posedge clk)
overflow <= #1 fpu_op_r3[2] ? 0 :
!fpu_op_r3[1] ? overflow_fasu :
fpu_op_r3[0] ? overflow_fdiv : overflow_fmul;
always @(posedge clk)
underflow_fmul_r <= #1 underflow_fmul_d;
assign underflow_fmul1 = underflow_fmul_r[0] |
(underflow_fmul_r[1] & underflow_d ) |
((opa_dn | opb_dn) & out_d_00 & (prod!=0) & sign) |
(underflow_fmul_r[2] & ((out_d[30:23]==0) | (out_d[22:0]==0)));
assign underflow_fasu = underflow_d & !(inf_d | snan_d | qnan_d);
assign underflow_fmul = underflow_fmul1 & !(snan_d | qnan_d | inf_mul_r);
assign underflow_fdiv = underflow_fasu & !opb_00;
always @(posedge clk)
underflow <= #1 fpu_op_r3[2] ? 0 :
!fpu_op_r3[1] ? underflow_fasu :
fpu_op_r3[0] ? underflow_fdiv : underflow_fmul;
always @(posedge clk)
snan <= #1 snan_d;
// synopsys translate_off
wire mul_uf_del;
wire uf2_del, ufb2_del, ufc2_del, underflow_d_del;
wire co_del;
wire [30:0] out_d_del;
wire ov_fasu_del, ov_fmul_del;
wire [2:0] fop;
wire [4:0] ldza_del;
wire [49:0] quo_del;
delay1 #0 ud000(clk, underflow_fmul1, mul_uf_del);
delay1 #0 ud001(clk, underflow_fmul_r[0], uf2_del);
delay1 #0 ud002(clk, underflow_fmul_r[1], ufb2_del);
delay1 #0 ud003(clk, underflow_d, underflow_d_del);
delay1 #0 ud004(clk, test.u0.u4.exp_out1_co, co_del);
delay1 #0 ud005(clk, underflow_fmul_r[2], ufc2_del);
delay1 #30 ud006(clk, out_d, out_d_del);
delay1 #0 ud007(clk, overflow_fasu, ov_fasu_del);
delay1 #0 ud008(clk, overflow_fmul, ov_fmul_del);
delay1 #2 ud009(clk, fpu_op_r3, fop);
delay3 #4 ud010(clk, div_opa_ldz_d, ldza_del);
delay1 #49 ud012(clk, quo, quo_del);
always @(test.error_event)
begin
#0.2
$display("muf: %b uf0: %b uf1: %b uf2: %b, tx0: %b, co: %b, out_d: %h (%h %h), ov_fasu: %b, ov_fmul: %b, fop: %h",
mul_uf_del, uf2_del, ufb2_del, ufc2_del, underflow_d_del, co_del, out_d_del, out_d_del[30:23], out_d_del[22:0],
ov_fasu_del, ov_fmul_del, fop );
$display("ldza: %h, quo: %b",
ldza_del, quo_del);
end
// synopsys translate_on
// Status Outputs
always @(posedge clk)
qnan <= #1 fpu_op_r3[2] ? 0 : (
snan_d | qnan_d | (ind_d & !fasu_op_r2) |
(opa_00 & opb_00 & fpu_op_r3==3'b011) |
(((opa_inf & opb_00) | (opb_inf & opa_00 )) & fpu_op_r3==3'b010)
);
assign inf_fmul = (((inf_mul_r | inf_mul2) & (rmode_r3==2'h0)) | opa_inf | opb_inf) &
!((opa_inf & opb_00) | (opb_inf & opa_00 )) &
fpu_op_r3==3'b010;
always @(posedge clk)
inf <= #1 fpu_op_r3[2] ? 0 :
(!(qnan_d | snan_d) & (
((&out_d[30:23]) & !(|out_d[22:0]) & !(opb_00 & fpu_op_r3==3'b011)) |
(inf_d & !(ind_d & !fasu_op_r2) & !fpu_op_r3[1]) |
inf_fmul |
(!opa_00 & opb_00 & fpu_op_r3==3'b011) |
(fpu_op_r3==3'b011 & opa_inf & !opb_inf)
)
);
assign output_zero_fasu = out_d_00 & !(inf_d | snan_d | qnan_d);
assign output_zero_fdiv = (div_00 | (out_d_00 & !opb_00)) & !(opa_inf & opb_inf) &
!(opa_00 & opb_00) & !(qnan_d | snan_d);
assign output_zero_fmul = (out_d_00 | opa_00 | opb_00) &
!(inf_mul_r | inf_mul2 | opa_inf | opb_inf | snan_d | qnan_d) &
!(opa_inf & opb_00) & !(opb_inf & opa_00);
always @(posedge clk)
zero <= #1 fpu_op_r3==3'b101 ? out_d_00 & !(snan_d | qnan_d):
fpu_op_r3==3'b011 ? output_zero_fdiv :
fpu_op_r3==3'b010 ? output_zero_fmul :
output_zero_fasu ;
always @(posedge clk)
opa_nan_r <= #1 !opa_nan & fpu_op_r2==3'b011;
always @(posedge clk)
div_by_zero <= #1 opa_nan_r & !opa_00 & !opa_inf & opb_00;
endmodule
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