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gave integer bits to D instead of adding manually everywhere

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This commit is contained in:
Cedar Turek 2023-04-18 15:41:04 -07:00
parent 054c8d638c
commit 871d495ca1
6 changed files with 17 additions and 25 deletions
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2
src/fpu/fdivsqrt/fdivsqrt.sv
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@ -57,7 +57,7 @@ module fdivsqrt(
logic [`DIVb+3:0] WS, WC; // Partial remainder components
logic [`DIVb+3:0] X; // Iterator Initial Value (from dividend)
logic [`DIVb-1:0] D; // Iterator Divisor
logic [`DIVb+3:0] D; // Iterator Divisor
logic [`DIVb:0] FirstU, FirstUM; // Intermediate result values
logic [`DIVb+1:0] FirstC; // Step tracker
logic Firstun; // Quotient selection

11
src/fpu/fdivsqrt/fdivsqrtiter.sv
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@ -33,8 +33,7 @@ module fdivsqrtiter(
input logic IFDivStartE,
input logic FDivBusyE,
input logic SqrtE,
input logic [`DIVb+3:0] X,
input logic [`DIVb-1:0] D,
input logic [`DIVb+3:0] X, D,
output logic [`DIVb:0] FirstU, FirstUM,
output logic [`DIVb+1:0] FirstC,
output logic Firstun,
@ -95,12 +94,10 @@ module fdivsqrtiter(
flopen #(`DIVb+2) creg(clk, FDivBusyE, NextC, C[0]);
// Divisor Selections
// - choose the negitive version of what's being selected
// - D is a 0.b mantissa
assign DBar = {3'b111, 1'b0, ~D};
assign DBar = ~D; // for -D
if(`RADIX == 4) begin : d2
assign DBar2 = {2'b11, 1'b0, ~D, 1'b1};
assign D2 = {2'b0, 1'b1, D, 1'b0};
assign D2 = D << 1; // for 2D, only used in R4
assign DBar2 = ~D2; // for -2D, only used in R4
end
// k=DIVCOPIES of the recurrence logic

9
src/fpu/fdivsqrt/fdivsqrtpostproc.sv
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@ -32,7 +32,7 @@ module fdivsqrtpostproc(
input logic clk, reset,
input logic StallM,
input logic [`DIVb+3:0] WS, WC,
input logic [`DIVb-1:0] D,
input logic [`DIVb+3:0] D,
input logic [`DIVb:0] FirstU, FirstUM,
input logic [`DIVb+1:0] FirstC,
input logic SqrtE,
@ -46,7 +46,7 @@ module fdivsqrtpostproc(
output logic [`XLEN-1:0] FIntDivResultM
);
logic [`DIVb+3:0] W, Sum, DM;
logic [`DIVb+3:0] W, Sum;
logic [`DIVb:0] PreQmM;
logic NegStickyM;
logic weq0E, WZeroM;
@ -67,7 +67,7 @@ module fdivsqrtpostproc(
assign FirstK = ({1'b1, FirstC} & ~({1'b1, FirstC} << 1));
assign FZeroSqrtE = {FirstUM[`DIVb], FirstUM, 2'b0} | {FirstK,1'b0}; // F for square root
assign FZeroDivE = {3'b001,D,1'b0}; // F for divide
assign FZeroDivE = D << 1; // F for divide
mux2 #(`DIVb+4) fzeromux(FZeroDivE, FZeroSqrtE, SqrtE, FZeroE);
csa #(`DIVb+4) fadd(WS, WC, FZeroE, 1'b0, WSF, WCF); // compute {WCF, WSF} = {WS + WC + FZero};
aplusbeq0 #(`DIVb+4) wcfpluswsfeq0(WCF, WSF, wfeq0E);
@ -102,11 +102,10 @@ module fdivsqrtpostproc(
logic signed [`DIVb+3:0] PreResultM, PreIntResultM;
assign W = $signed(Sum) >>> `LOGR;
assign DM = {4'b0001, D};
assign UnsignedQuotM = {3'b000, PreQmM};
// Integer remainder: sticky and sign correction muxes
mux2 #(`DIVb+4) normremdmux(W, W+DM, NegStickyM, NormRemDM);
mux2 #(`DIVb+4) normremdmux(W, W+D, NegStickyM, NormRemDM);
mux2 #(`DIVb+4) normremsmux(NormRemDM, -NormRemDM, AsM, NormRemM);
mux2 #(`DIVb+4) quotresmux(UnsignedQuotM, -UnsignedQuotM, NegQuotM, NormQuotM);

10
src/fpu/fdivsqrt/fdivsqrtpreproc.sv
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@ -38,8 +38,7 @@ module fdivsqrtpreproc (
input logic XZeroE,
input logic [2:0] Funct3E,
output logic [`NE+1:0] QeM,
output logic [`DIVb+3:0] X,
output logic [`DIVb-1:0] D,
output logic [`DIVb+3:0] X, D,
// Int-specific
input logic [`XLEN-1:0] ForwardedSrcAE, ForwardedSrcBE, // *** these are the src outputs before the mux choosing between them and PCE to put in srcA/B
input logic IntDivE, W64E,
@ -111,7 +110,9 @@ module fdivsqrtpreproc (
// Denormalized numbers have Xe = 0 and an unbiased exponent of 1-BIAS. They are shifted right if the number of leading zeros is odd.
mux2 #(`DIVb+1) sqrtxmux({~XZeroE, XPreproc}, {1'b0, ~XZeroE, XPreproc[`DIVb-1:1]}, (Xe[0] ^ ell[0]), PreSqrtX);
assign DivX = {3'b000, ~NumerZeroE, XPreproc};
// *** CT 4/13/23 Create D output here with leading 1 appended as well, use in the other modules
// Divisior register
flopen #(`DIVb+4) dreg(clk, IFDivStartE, {4'b0001, DPreproc}, D);
// ***CT: factor out fdivsqrtcycles
if (`IDIV_ON_FPU) begin:intrightshift // Int Supported
@ -173,8 +174,5 @@ module fdivsqrtpreproc (
// Floating-point exponent
fdivsqrtexpcalc expcalc(.Fmt, .Xe, .Ye, .Sqrt, .XZero(XZeroE), .ell, .m(mE), .Qe(QeE));
flopen #(`NE+2) expreg(clk, IFDivStartE, QeE, QeM);
// Divisior register
flopen #(`DIVb) dreg(clk, IFDivStartE, DPreproc, D);
endmodule

5
src/fpu/fdivsqrt/fdivsqrtstage2.sv
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@ -30,8 +30,7 @@
/* verilator lint_off UNOPTFLAT */
module fdivsqrtstage2 (
input logic [`DIVb-1:0] D,
input logic [`DIVb+3:0] DBar,
input logic [`DIVb+3:0] D, DBar,
input logic [`DIVb:0] U, UM,
input logic [`DIVb+3:0] WS, WC,
input logic [`DIVb+1:0] C,
@ -66,7 +65,7 @@ module fdivsqrtstage2 (
always_comb
if (up) Dsel = DBar;
else if (uz) Dsel = '0;
else Dsel = {4'b0001, D}; // un
else Dsel = D; // un
// Partial Product Generation
// WSA, WCA = WS + WC - qD

5
src/fpu/fdivsqrt/fdivsqrtstage4.sv
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@ -29,8 +29,7 @@
`include "wally-config.vh"
module fdivsqrtstage4 (
input logic [`DIVb-1:0] D,
input logic [`DIVb+3:0] DBar, D2, DBar2,
input logic [`DIVb+3:0] D, DBar, D2, DBar2,
input logic [`DIVb:0] U,UM,
input logic [`DIVb+3:0] WS, WC,
input logic [`DIVb+1:0] C,
@ -75,7 +74,7 @@ module fdivsqrtstage4 (
4'b1000: Dsel = DBar2;
4'b0100: Dsel = DBar;
4'b0000: Dsel = '0;
4'b0010: Dsel = {3'b0, 1'b1, D};
4'b0010: Dsel = D;
4'b0001: Dsel = D2;
default: Dsel = 'x;
endcase