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Fix run-time formatting of variable wider than 1023 bits (#2261)

This commit is contained in:
Geza Lore 2020-04-15 22:26:15 +01:00 committed by GitHub
parent f3308d236b
commit 1a64c7d232
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3 changed files with 30 additions and 10 deletions
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7
src/V3EmitC.cpp
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@ -2042,9 +2042,10 @@ void EmitCStmts::displayArg(AstNode* dispp, AstNode** elistp, bool isScan, const
string pfmt;
if ((fmtLetter == '#' || fmtLetter == 'd' || fmtLetter == 't') && !isScan
&& vfmt == "") { // Size decimal output. Spec says leading spaces, not zeros
double mantissabits = argp->widthMin() - ((fmtLetter == 'd') ? 1 : 0);
double maxval = pow(2.0, mantissabits);
double dchars = log10(maxval) + 1.0;
const double mantissabits = argp->widthMin() - ((fmtLetter == 'd') ? 1 : 0);
// This is log10(2**mantissabits) as log2(2**mantissabits)/log2(10),
// + 1.0 rounding bias.
double dchars = mantissabits / 3.321928094887362 + 1.0;
if (fmtLetter == 'd') dchars++; // space for sign
int nchars = int(dchars);
pfmt = string("%") + cvtToStr(nchars) + fmtLetter;

2
test_regress/t/t_format_wide_decimal.out
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@ -1,2 +1,4 @@
179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137215
89884656743115795386465259539451236680898848947115328636715040578866337902750481566354238661203768010560056939935696678829394884407208311246423715319737062188883946712432742638151109800623047059726541476042502884419075341171231440736956555270413618581675255342293149119973622969239858152417678164812112068607
44942328371557897693232629769725618340449424473557664318357520289433168951375240783177119330601884005280028469967848339414697442203604155623211857659868531094441973356216371319075554900311523529863270738021251442209537670585615720368478277635206809290837627671146574559986811484619929076208839082406056034303
*-* All Finished *-*

31
test_regress/t/t_format_wide_decimal.v
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@ -6,15 +6,32 @@
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
module t_format_wide_decimal;
module t_format_wide_decimal(/*AUTOARG*/
// Inputs
clk
);
input clk;
initial begin
// Format very wide constant number (which has more bits than can
// be counted in exponent of a double precision float), with %d.
$display("%d", 1024'hffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
int cycle = 0;
bit [1023:0] x = '1;
$write("*-* All Finished *-*\n");
$finish;
always @(posedge clk) begin
if (cycle == 0) begin
// Format very wide constant number (which has more bits than can
// be counted in exponent of a double precision float), with %d.
$display("%d", 1024'hffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
end else begin
// Same, but for a variable with value only known at run-time
$display("%d", x);
end
cycle <= cycle + 1;
x <= x >> 1;
if (cycle == 2) begin
$write("*-* All Finished *-*\n");
$finish;
end
end
endmodule