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Started cleaning up shifting leading 1 in fdivsqrt

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This commit is contained in:
David Harris 2023-11-10 08:46:55 -08:00
parent 426aabbc1a
commit 4c106215f4
2 changed files with 18 additions and 18 deletions
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18
config/shared/config-shared.vh
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@ -94,15 +94,15 @@ localparam FMT2 = ((F_SUPPORTED & (LEN1 != S_LEN)) ? 2'd0 : 2'd2);
localparam BIAS2 = ((F_SUPPORTED & (LEN1 != S_LEN)) ? S_BIAS : H_BIAS);
// division constants
localparam DIVN = (((NF+2<XLEN) & IDIV_ON_FPU) ? XLEN : NF+2); // standard length of input
localparam LOGR = ($clog2(RADIX)); // r = log(R)
localparam RK = (LOGR*DIVCOPIES); // r*k used for intdiv preproc
localparam LOGRK = ($clog2(RK)); // log2(r*k)
localparam FPDUR = ((DIVN+1+(LOGR*DIVCOPIES))/(LOGR*DIVCOPIES)+(RADIX/4));
localparam DURLEN = ($clog2(FPDUR+1));
localparam DIVb = (FPDUR*LOGR*DIVCOPIES-1); // canonical fdiv size (b)
localparam DIVBLEN = ($clog2(DIVb+1)-1);
localparam DIVa = (DIVb+1-XLEN); // used for idiv on fpu: Shift residual right by b - (XLEN-1) to put remainder in lsbs of integer result
localparam DIVN = ((NF+2<XLEN) & IDIV_ON_FPU) ? XLEN : NF+2; // standard length of input
localparam LOGR = $clog2(RADIX); // r = log(R)
localparam RK = LOGR*DIVCOPIES; // r*k used for intdiv preproc
localparam LOGRK = $clog2(RK); // log2(r*k)
localparam FPDUR = (DIVN+1)/RK + 1 + (RADIX/4);
localparam DURLEN = $clog2(FPDUR+1);
localparam DIVb = FPDUR*RK - 1; // canonical fdiv size (b)
localparam DIVBLEN = $clog2(DIVb+1)-1;
localparam DIVa = DIVb+1-XLEN; // used for idiv on fpu: Shift residual right by b - (XLEN-1) to put remainder in lsbs of integer result
// largest length in IEU/FPU
localparam CVTLEN = ((NF<XLEN) ? (XLEN) : (NF)); // max(XLEN, NF)

18
src/fpu/fdivsqrt/fdivsqrtpreproc.sv
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@ -52,7 +52,7 @@ module fdivsqrtpreproc import cvw::*; #(parameter cvw_t P) (
logic [P.DIVb:0] PreSqrtX;
logic [P.DIVb+3:0] DivX, DivXShifted, SqrtX, PreShiftX; // Variations of dividend, to be muxed
logic [P.NE+1:0] QeE; // Quotient Exponent (FP only)
logic [P.DIVb-1:0] IFX, IFD; // Correctly-sized inputs for iterator, selected from int or fp input
logic [P.DIVb:0] IFX, IFD; // Correctly-sized inputs for iterator, selected from int or fp input
logic [P.DIVBLEN:0] mE, nE, ell; // Leading zeros of inputs
logic NumerZeroE; // Numerator is zero (X or A)
logic AZeroE, BZeroE; // A or B is Zero for integer division
@ -89,12 +89,12 @@ module fdivsqrtpreproc import cvw::*; #(parameter cvw_t P) (
mux2 #(P.XLEN) posbmux(BE, -BE, BsE, PosB);
// Select integer or floating point inputs
mux2 #(P.DIVb) ifxmux({Xm, {(P.DIVb-P.NF-1){1'b0}}}, {PosA, {(P.DIVb-P.XLEN){1'b0}}}, IntDivE, IFX);
mux2 #(P.DIVb) ifdmux({Ym, {(P.DIVb-P.NF-1){1'b0}}}, {PosB, {(P.DIVb-P.XLEN){1'b0}}}, IntDivE, IFD);
mux2 #(P.DIVb+1) ifxmux({Xm, {(P.DIVb-P.NF){1'b0}}}, {PosA, {(P.DIVb-P.XLEN+1){1'b0}}}, IntDivE, IFX);
mux2 #(P.DIVb+1) ifdmux({Ym, {(P.DIVb-P.NF){1'b0}}}, {PosB, {(P.DIVb-P.XLEN+1){1'b0}}}, IntDivE, IFD);
mux2 #(1) numzmux(XZeroE, AZeroE, IntDivE, NumerZeroE);
end else begin // Int not supported
assign IFX = {Xm, {(P.DIVb-P.NF-1){1'b0}}};
assign IFD = {Ym, {(P.DIVb-P.NF-1){1'b0}}};
assign IFX = {Xm, {(P.DIVb-P.NF){1'b0}}};
assign IFD = {Ym, {(P.DIVb-P.NF){1'b0}}};
assign NumerZeroE = XZeroE;
end
@ -103,12 +103,12 @@ module fdivsqrtpreproc import cvw::*; #(parameter cvw_t P) (
//////////////////////////////////////////////////////
// count leading zeros for Subnorm FP and to normalize integer inputs
lzc #(P.DIVb) lzcX (IFX, ell);
lzc #(P.DIVb) lzcY (IFD, mE);
lzc #(P.DIVb) lzcX (IFX[P.DIVb:1], ell);
lzc #(P.DIVb) lzcY (IFD[P.DIVb:1], mE);
// Normalization shift: shift off leading one
assign Xfract = (IFX << ell) << 1;
assign Dfract = (IFD << mE) << 1;
assign Xfract = (IFX[P.DIVb:1] << ell) << 1;
assign Dfract = (IFD[P.DIVb:1] << mE) << 1;
//////////////////////////////////////////////////////
// Integer Right Shift to digit boundary