iverilog/vvp/bufif.cc

98 lines
2.4 KiB
C++

/*
* Copyright (c) 2001-2010 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
# include "bufif.h"
# include "functor.h"
# include "schedule.h"
# include "statistics.h"
vvp_bufif_s::vvp_bufif_s(bool en_invert, bool out_invert,
unsigned str0, unsigned str1)
: pol_(en_invert? 1 : 0), inv_(out_invert? 1 : 0)
{
odrive0 = str0;
odrive1 = str1;
count_functors_bufif += 1;
}
void vvp_bufif_s::set(vvp_ipoint_t ptr, bool push, unsigned v, unsigned)
{
put(ptr, v);
unsigned in0 = ival & 0x03;
unsigned in1 = (ival >> 2) & 0x03;
unsigned char out0 = 0x00 | (odrive0<<0) | (odrive0<<4);
unsigned char out1 = 0x88 | (odrive1<<0) | (odrive1<<4);
unsigned char outX = 0x80 | (odrive0<<0) | (odrive1<<4);
unsigned char outH = 0x80 | (0) | (odrive1<<4);
unsigned char outL = 0x80 | (odrive0<<0) | (0);
unsigned val;
unsigned str;
switch (in1 ^ pol_) {
case 1:
switch (in0 ^ inv_) {
case 0:
val = 0;
str = out0;
break;
case 1:
val = 1;
str = out1;
break;
default:
val = 2;
str = outX;
break;
}
break;
case 0:
val = 3;
str = HiZ;
break;
/* The control input is x or z, so the output is H or
L, depending on the (possibly inverted) input. This
is not the same as X, as it is a combination of the
drive strength of the output and HiZ. */
default:
switch (in0 ^ inv_) {
case 0:
val = 2;
str = outL;
break;
case 1:
val = 2;
str = outH;
break;
default:
val = 2;
str = outX;
break;
}
break;
}
put_ostr(val, str, push);
}