lut5.comp

来自「CNC 的开放码,EMC2 V2.2.8版」· COMP 代码 · 共 136 行

component lut5 """Arbitrary 5-input logic function based on a look-up table""";
pin in bit in_0;
pin in bit in_1;
pin in bit in_2;
pin in bit in_3;
pin in bit in_4;
pin out bit out;
param rw u32 function;
function _ nofp;
description """
.B lut5
constructs an arbitrary logic function with up to 5 inputs using a
\\fBl\\fRook-\\fBu\\fRp \\fBt\\fRable.  The function is specified by the HAL pin
\\fBfunction\\fR.  The necessary value for \\fBfunction\\fR can be determined
by writing the truth table, and computing the sum of the \\fBweights\\fR for
which the output value should be \\fRTRUE\\fR.
.PP
.SS Example Functions
A 5-input
\\fIand\\fR function is TRUE only when all the inputs are true, so the correct
value for \\fBfunction\\fR is \\fB0x80000000\\fR.
.PP
A 5-input \\fIor\\fR
function is TRUE whenever any of the inputs are true, so the correct value for
\\fBfunction\\fR is \\fB0xffffffffe\\fR.
.PP
A 2-input \\fIxor\\fR function is
TRUE whenever exactly one of the inputs is true, so the correct value for
\\fBfunction\\fR is \\fB0x6\\fR.  Only \\fBin-0\\fR and \\fBin-1\\fR should be
connected to signals, because if any other bit is \\fBTRUE\\fR then the output
will be \\fBFALSE\\fR.
.ie '\*[.T]'html' \\{\\
.HTML \\
<STYLE> \\
#weight TD { text-align: center; padding-left: .5ex; padding-right: .5ex } \\
#weight TH { text-align: center; padding-left: .5ex; padding-right: .5ex } \\
#weight TD.W { text-align: right; } \\
</STYLE> \\
<TABLE ID="weight" STYLE="border: 1px solid black; border-collapse: collapse"> \\
    <COL SPAN=5 STYLE="margin: .2ex"><COL SPAN=1 STYLE="border-left: 1px solid black"> \\
<TR STYLE="border-bottom: 1px solid black"> \\
    <TH COLSPAN=6>Weights for each line of truth table \\
<TR STYLE="border-bottom: 1px solid black"> \\
    <TH>Bit 4<TH>Bit 3<TH>Bit 2<TH>Bit 1<TH>Bit 0<TH> Weight \\
<TR><TD>0<TD>0<TD>0<TD>0<TD>0<TD CLASS="w">0x1 \\
<TR><TD>0<TD>0<TD>0<TD>0<TD>1<TD CLASS="w">0x2 \\
<TR><TD>0<TD>0<TD>0<TD>1<TD>0<TD CLASS="w">0x4 \\
<TR><TD>0<TD>0<TD>0<TD>1<TD>1<TD CLASS="w">0x8 \\
<TR><TD>0<TD>0<TD>1<TD>0<TD>0<TD CLASS="w">0x10 \\
<TR><TD>0<TD>0<TD>1<TD>0<TD>1<TD CLASS="w">0x20 \\
<TR><TD>0<TD>0<TD>1<TD>1<TD>0<TD CLASS="w">0x40 \\
<TR><TD>0<TD>0<TD>1<TD>1<TD>1<TD CLASS="w">0x80 \\
<TR><TD>0<TD>1<TD>0<TD>0<TD>0<TD CLASS="w">0x100 \\
<TR><TD>0<TD>1<TD>0<TD>0<TD>1<TD CLASS="w">0x200 \\
<TR><TD>0<TD>1<TD>0<TD>1<TD>0<TD CLASS="w">0x400 \\
<TR><TD>0<TD>1<TD>0<TD>1<TD>1<TD CLASS="w">0x800 \\
<TR><TD>0<TD>1<TD>1<TD>0<TD>0<TD CLASS="w">0x1000 \\
<TR><TD>0<TD>1<TD>1<TD>0<TD>1<TD CLASS="w">0x2000 \\
<TR><TD>0<TD>1<TD>1<TD>1<TD>0<TD CLASS="w">0x4000 \\
<TR><TD>0<TD>1<TD>1<TD>1<TD>1<TD CLASS="w">0x8000 \\
<TR><TD>1<TD>0<TD>0<TD>0<TD>0<TD CLASS="w">0x10000 \\
<TR><TD>1<TD>0<TD>0<TD>0<TD>1<TD CLASS="w">0x20000 \\
<TR><TD>1<TD>0<TD>0<TD>1<TD>0<TD CLASS="w">0x40000 \\
<TR><TD>1<TD>0<TD>0<TD>1<TD>1<TD CLASS="w">0x80000 \\
<TR><TD>1<TD>0<TD>1<TD>0<TD>0<TD CLASS="w">0x100000 \\
<TR><TD>1<TD>0<TD>1<TD>0<TD>1<TD CLASS="w">0x200000 \\
<TR><TD>1<TD>0<TD>1<TD>1<TD>0<TD CLASS="w">0x400000 \\
<TR><TD>1<TD>0<TD>1<TD>1<TD>1<TD CLASS="w">0x800000 \\
<TR><TD>1<TD>1<TD>0<TD>0<TD>0<TD CLASS="w">0x1000000 \\
<TR><TD>1<TD>1<TD>0<TD>0<TD>1<TD CLASS="w">0x2000000 \\
<TR><TD>1<TD>1<TD>0<TD>1<TD>0<TD CLASS="w">0x4000000 \\
<TR><TD>1<TD>1<TD>0<TD>1<TD>1<TD CLASS="w">0x8000000 \\
<TR><TD>1<TD>1<TD>1<TD>0<TD>0<TD CLASS="w">0x10000000 \\
<TR><TD>1<TD>1<TD>1<TD>0<TD>1<TD CLASS="w">0x20000000 \\
<TR><TD>1<TD>1<TD>1<TD>1<TD>0<TD CLASS="w">0x40000000 \\
<TR><TD>1<TD>1<TD>1<TD>1<TD>1<TD CLASS="w">0x80000000
\\}
.el \\{\\
.TS
box tab(;);
cb s s s s s
cb cb cb cb cb | cb
c  c  c  c  c  | r.
Weights for each line of truth table
_
Bit 4;Bit 3;Bit 2;Bit 1;Bit 0; Weight
_
0;0;0;0;0;0x1
0;0;0;0;1;0x2
0;0;0;1;0;0x4
0;0;0;1;1;0x8
0;0;1;0;0;0x10
0;0;1;0;1;0x20
0;0;1;1;0;0x40
0;0;1;1;1;0x80
0;1;0;0;0;0x100
0;1;0;0;1;0x200
0;1;0;1;0;0x400
0;1;0;1;1;0x800
0;1;1;0;0;0x1000
0;1;1;0;1;0x2000
0;1;1;1;0;0x4000
0;1;1;1;1;0x8000
1;0;0;0;0;0x10000
1;0;0;0;1;0x20000
1;0;0;1;0;0x40000
1;0;0;1;1;0x80000
1;0;1;0;0;0x100000
1;0;1;0;1;0x200000
1;0;1;1;0;0x400000
1;0;1;1;1;0x800000
1;1;0;0;0;0x1000000
1;1;0;0;1;0x2000000
1;1;0;1;0;0x4000000
1;1;0;1;1;0x8000000
1;1;1;0;0;0x10000000
1;1;1;0;1;0x20000000
1;1;1;1;0;0x40000000
1;1;1;1;1;0x80000000
.TE
\\}
""";
license "GPL";
;;

FUNCTION(_) {
    int shift = 0;
    if(in_0) shift += 1;
    if(in_1) shift += 2;
    if(in_2) shift += 4;
    if(in_3) shift += 8;
    if(in_4) shift += 16;

    out = (function & (1<<shift)) != 0;
}