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divsqrt comment cleanup

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This commit is contained in:
David Harris 2022-09-08 15:40:42 -07:00
parent e0a9b19008
commit 1c3064af08
2 changed files with 5 additions and 3 deletions
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2
pipelined/src/fpu/fdivsqrtfsm.sv
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@ -62,7 +62,7 @@ module fdivsqrtfsm(
if (reset) begin
state <= #1 IDLE;
end else if (DivStart&~StallE) begin
step <= (`DURLEN)'(`FPDUR); // *** this should be adjusted to depend on the precision
step <= (`DURLEN)'(`FPDUR); // *** this should be adjusted to depend on the precision; sqrt should use one fewer step becasue firststep=1
if (SpecialCase) state <= #1 DONE;
else state <= #1 BUSY;
end else if (DivDone) begin

6
pipelined/src/fpu/fdivsqrtiter.sv
View File

@ -94,7 +94,7 @@ module fdivsqrtiter(
assign NextWSN = {WSA[`DIVCOPIES-1][`DIVb+2:0], 1'b0};
assign NextWCN = {WCA[`DIVCOPIES-1][`DIVb+2:0], 1'b0};
assign NextC = {1'b1, C[`DIVCOPIES-1][`DIVb-1:1]};
end else begin
end else begin : nextw
assign NextWSN = {WSA[`DIVCOPIES-1][`DIVb+1:0], 2'b0};
assign NextWCN = {WCA[`DIVCOPIES-1][`DIVb+1:0], 2'b0};
assign NextC = {2'b11, C[`DIVCOPIES-1][`DIVb-1:2]};
@ -102,6 +102,7 @@ module fdivsqrtiter(
if (`RADIX == 2) assign initC = {1'b1, {(`DIVb-1){1'b0}}}; // *** note that these are preshifted right by r compared to book
else assign initC = {2'b11, {(`DIVb-2){1'b0}}};
// assign initC = 0;
// mux2 #(`DIVb+4) wsmux(NextWSN, {3'b0, X}, DivStart, WSN);
mux2 #(`DIVb+4) wsmux(NextWSN, {{3{SqrtE&~XZeroE}}, X}, DivStart, WSN);
@ -130,7 +131,7 @@ module fdivsqrtiter(
.C(C[i]), .S(S[i]), .SM(SM[i]), .SNext(SNext[i]), .SMNext(SMNext[i]), .qn(qn[i]));
end else begin: stage
logic j1;
assign j1 = (i == 0 & C[0][`DIVb-2] & ~C[0][`DIVb-3]); // not quite right ***
assign j1 = (i == 0 & C[0][`DIVb-2] & ~C[0][`DIVb-3]);
fdivsqrtstage4 fdivsqrtstage(.D, .DBar, .D2, .DBar2, .SqrtM, .j1,
.WS(WS[i]), .WC(WC[i]), .WSA(WSA[i]), .WCA(WCA[i]), .Q(Q[i]), .QM(QM[i]), .QNext(QNext[i]), .QMNext(QMNext[i]),
.C(C[i]), .S(S[i]), .SM(SM[i]), .SNext(SNext[i]), .SMNext(SMNext[i]), .qn(qn[i]));
@ -159,6 +160,7 @@ module fdivsqrtiter(
mux2 #(`DIVb+1) QMmux(QMNext[`DIVCOPIES-1], '1, DivStart, QMMux);
flopen #(`DIVb+1) QMreg(clk, DivStart|DivBusy, QMMux, QM[0]);
// if starting new square root, set S to 1 and SM to 0
flopenr #(`DIVb+1) SMreg(clk, DivStart, DivBusy, SMNext[`DIVCOPIES-1], SM[0]);
mux2 #(`DIVb+1) Smux(SNext[`DIVCOPIES-1], {1'b1, {(`DIVb){1'b0}}}, DivStart, SMux);
flopen #(`DIVb+1) Sreg(clk, DivStart|DivBusy, SMux, S[0]);