srt fixes

This commit is contained in:
David Harris 2022-02-14 18:40:27 +00:00
commit dee2822359
3 changed files with 89 additions and 16 deletions

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@ -17,7 +17,7 @@ if [file exists work] {
}
vlib work
vlog +incdir+../config/rv64gc +incdir+../config/shared srt.sv testbench.sv ../src/generic/flop/flop*.sv ../src/generic/mux.sv
vlog +incdir+../config/rv64gc +incdir+../config/shared srt.sv testbench.sv ../src/generic/flop/flop*.sv ../src/generic/mux.sv ../src/fpu/unpacking.sv
vopt +acc work.testbench -o workopt
vsim workopt

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@ -11,7 +11,52 @@
// This Verilog file models a radix 2 SRT divider which
// produces one quotient digit per cycle. The divider
// keeps the partial remainder in carry-save form.
`include "wally-config.vh"
// will also be used for integer division so keep in mind when naming modules/signals
/////////////////
// srt_divide //
////////////////
module srt_divide(input logic clk,
input logic req,
input logic sqrt, // 1 to compute sqrt(a), 0 to compute a/b
input logic [63:0] a, b, // input numbers
output logic [54:0] rp, rm,
output logic [10:0] expE);
// output logic from Unpackers
logic XSgnE, YSgnE, ZSgnE;
logic [10:0] XExpE, YExpE, ZExpE; // exponent
logic [52:0] XManE, YManE, ZManE;
logic XNormE;
logic XNaNE, YNaNE, ZNaNE;
logic XSNaNE, YSNaNE, ZSNaNE;
logic XDenormE, YDenormE, ZDenormE; // denormals
logic XZeroE, YZeroE, ZZeroE;
logic [10:0] BiasE; // currrently hardcoded, will probs be removed
logic XInfE, YInfE, ZInfE;
logic XExpMaxE; // says exponent is all ones, can ignore
// have Unpackers
// have mantissa divider
// exponent divider
// hopefully having the .* here works for unpacker --- nope it doesn't
unpack unpacking(a, b, 0, 1'b1, 0, XSgnE, YSgnE, ZSgnE, XExpE, YExpE, ZExpE, XManE, YManE, ZManE, XNormE,XNaNE, YNaNE, ZNaNE,XSNaNE, YSNaNE, ZSNaNE,XDenormE, YDenormE, ZDenormE,XZeroE, YZeroE, ZZeroE,BiasE,XInfE, YInfE, ZInfE,XExpMaxE);
srt srt(clk, req, XManE[51:0], YManE[51:0], rp, rm);
exp exp(XexpE, YExpE, expE);
endmodule
// exponent module
// first iteration
module exp(input [10:0] e1, e2,
output [10:0] e); // for a 64 bit number, exponent section is 11 bits
assign e = (e1 - e2) + 11'd1023; // bias is hardcoded
endmodule
/////////
// srt //
/////////
@ -39,12 +84,12 @@ module srt(input logic clk,
// When start is asserted, the inputs are loaded into the divider.
// Otherwise, the divisor is retained and the partial remainder
// is fed back for the next iteration.
mux2 psmux({psa[54:0], 1'b0}, {4'b0001, a}, req, psn);
flop psflop(clk, psn, ps);
mux2 pcmux({pca[54:0], 1'b0}, 56'b0, req, pcn);
flop pcflop(clk, pcn, pc);
mux2 dmux(d, {4'b0001, b}, req, dn);
flop dflop(clk, dn, d);
mux2_special psmux({psa[54:0], 1'b0}, {4'b0001, a}, req, psn);
flop_special psflop(clk, psn, ps);
mux2_special pcmux({pca[54:0], 1'b0}, 56'b0, req, pcn);
flop_special pcflop(clk, pcn, pc);
mux2_special dmux(d, {4'b0001, b}, req, dn);
flop_special dflop(clk, dn, d);
// Quotient Selection logic
// Given partial remainder, select quotient of +1, 0, or -1 (qp, qz, pm)
@ -54,7 +99,7 @@ module srt(input logic clk,
// Divisor Selection logic
inv dinv(d, d_b);
mux3 divisorsel(d_b, 56'b0, d, qp, qz, qm, dsel);
mux3_special divisorsel(d_b, 56'b0, d, qp, qz, qm, dsel);
// Partial Product Generation
csa csa(ps, pc, dsel, qp, psa, pca);
@ -63,7 +108,7 @@ endmodule
//////////
// mux2 //
//////////
module mux2(input logic [55:0] in0, in1,
module mux2_special(input logic [55:0] in0, in1,
input logic sel,
output logic [55:0] out);
@ -73,7 +118,7 @@ endmodule
//////////
// flop //
//////////
module flop(clk, in, out);
module flop_special(clk, in, out);
input clk;
input [55:0] in;
output [55:0] out;
@ -159,9 +204,9 @@ module inv(input logic [55:0] in,
endmodule
//////////
// mux3 //
// mux3_special //
//////////
module mux3(in0, in1, in2, sel0, sel1, sel2, out);
module mux3_special(in0, in1, in2, sel0, sel1, sel2, out);
input [55:0] in0;
input [55:0] in1;
input [55:0] in2;
@ -271,6 +316,24 @@ module testbench;
logic [51:0] b;
logic [51:0] r;
logic [54:0] rp, rm; // positive quotient digits
//input logic [63:0] X, Y, Z, - numbers
//input logic FmtE, ---- format, 1 is for double precision, 0 is single
//input logic [2:0] FOpCtrlE, ---- controling operations for FPU, 1 is sqrt, 0 is divide
// all variables are commented in fpu.sv
// output logic from Unpackers
logic XSgnE, YSgnE, ZSgnE;
logic [10:0] XExpE, YExpE, ZExpE; // exponent
logic [52:0] XManE, YManE, ZManE;
logic XNormE;
logic XNaNE, YNaNE, ZNaNE;
logic XSNaNE, YSNaNE, ZSNaNE;
logic XDenormE, YDenormE, ZDenormE; // denormals
logic XZeroE, YZeroE, ZZeroE;
logic [10:0] BiasE; // currrently hardcoded, will probs be removed
logic XInfE, YInfE, ZInfE;
logic XExpMaxE; // says exponent is all ones, can ignore
// Test parameters
parameter MEM_SIZE = 40000;
@ -287,8 +350,15 @@ module testbench;
logic [51:0] correctr, nextr;
integer testnum, errors;
// Unpackers
unpacking unpack(.X({12'b100010000010,a}), .Y({12'b100010000001,b}), .Z(0), .FmtE(1'b1), .FOpCtrlE(0), .*);
// Divider
srt srt(clk, req, a, b, rp, rm);
srt srt(.clk(clk), .req(req), .sqrt(1'b0), .a(XManE[51:0]), .b(YManE[51:0]), .rp(rp),.rm(rm));
//srt srt(.clk(clk), .req(req), .sqrt(1'b0), .a(a), .b(b), .rp(rp),.rm(rm));
// Divider + unpacker
// Final adder converts quotient digits to 2's complement & normalizes
finaladd finaladd(rp, rm, r);
@ -326,7 +396,9 @@ module testbench;
begin
req <= #5 1;
$display("result was %h, should be %h\n", r, correctr);
if ((correctr - r) > 1) // check if accurate to 1 ulp
//if (abs(correctr - r) > 1) // check if accurate to 1 ulp
// giving error "srt_stanford.sv(395): (vopt-7063) Failed to find 'abs' in hierarchical name 'abs'."
if (correctr - r > 1) // check if accurate to 1 ulp
begin
errors = errors+1;
$display("failed\n");

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@ -28,7 +28,7 @@ double random_input(void);
void main(void)
{
FILE *fptr;
double a, b, r;
double x1, x2, a, b, r;
double list[ENTRIES] = {1, 1.5, 1.25, 1.125, 1.0625,
1.75, 1.875, 1.99999,
1.1, 1.2, 1.01, 1.001, 1.0001,
@ -63,6 +63,7 @@ void main(void)
void output(FILE *fptr, double a, double b, double r)
{
printhex(fptr, a);
fprintf(fptr, "_");
printhex(fptr, b);