iverilog/tgt-blif/lpm_cmp_gt.cc

155 lines
5.3 KiB
C++

/*
* Copyright (c) 2013 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
# include "priv.h"
# include "nex_data.h"
# include <cassert>
static int print_lpm_cmp_gt_s(FILE*fd, ivl_lpm_t net)
{
ivl_nexus_t q_nex = ivl_lpm_q(net);
ivl_nexus_t a_nex = ivl_lpm_data(net,0);
ivl_nexus_t b_nex = ivl_lpm_data(net,1);
blif_nex_data_t*q_ned = blif_nex_data_t::get_nex_data(q_nex);
blif_nex_data_t*a_ned = blif_nex_data_t::get_nex_data(a_nex);
blif_nex_data_t*b_ned = blif_nex_data_t::get_nex_data(b_nex);
assert(1 == q_ned->get_width());
assert(ivl_lpm_width(net) == a_ned->get_width());
assert(ivl_lpm_width(net) == b_ned->get_width());
// This is true if the operator is GE instead of just GT.
bool ge_flag = ivl_lpm_type(net)==IVL_LPM_CMP_GE;
// Special case: if the input vector is a single bit, then the
// operation is trivial. Note that since this is signed, the
// "1" bit represents -1 and is <0.
if (ivl_lpm_width(net) == 1) {
fprintf(fd, ".names %s%s %s%s %s%s\n"
"01 1\n",
a_ned->get_name(), a_ned->get_name_index(0),
b_ned->get_name(), b_ned->get_name_index(0),
q_ned->get_name(), q_ned->get_name_index(0));
if (ge_flag) fprintf(fd, "00 1\n11 1\n");
return 0;
}
fprintf(stderr, "%s:%u: sorry: blif: Signed magnitude compare not implemented yet\n",
ivl_lpm_file(net), ivl_lpm_lineno(net));
return 1;
}
static int print_lpm_cmp_gt_u(FILE*fd, ivl_lpm_t net)
{
ivl_nexus_t q_nex = ivl_lpm_q(net);
ivl_nexus_t a_nex = ivl_lpm_data(net,0);
ivl_nexus_t b_nex = ivl_lpm_data(net,1);
blif_nex_data_t*q_ned = blif_nex_data_t::get_nex_data(q_nex);
blif_nex_data_t*a_ned = blif_nex_data_t::get_nex_data(a_nex);
blif_nex_data_t*b_ned = blif_nex_data_t::get_nex_data(b_nex);
assert(1 == q_ned->get_width());
assert(ivl_lpm_width(net) == a_ned->get_width());
assert(ivl_lpm_width(net) == b_ned->get_width());
// This is true if the operator is GE instead of just GT.
bool ge_flag = ivl_lpm_type(net)==IVL_LPM_CMP_GE;
// Special case: if the input vector is a single bit, then the
// operation is trivial.
if (ivl_lpm_width(net) == 1) {
fprintf(fd, ".names %s%s %s%s %s%s\n"
"10 1\n",
a_ned->get_name(), a_ned->get_name_index(0),
b_ned->get_name(), b_ned->get_name_index(0),
q_ned->get_name(), q_ned->get_name_index(0));
if (ge_flag) fprintf(fd, "00 1\n11 1\n");
return 0;
}
// Calculate GT and EQ for each bit.
for (unsigned idx = 0 ; idx < ivl_lpm_width(net) ; idx += 1) {
fprintf(fd, ".names %s%s %s%s %s%s/G%u\n"
"10 1\n",
a_ned->get_name(), a_ned->get_name_index(idx),
b_ned->get_name(), b_ned->get_name_index(idx),
q_ned->get_name(), q_ned->get_name_index(0), idx);
}
for (unsigned idx = ge_flag?0 : 1 ; idx < ivl_lpm_width(net) ; idx += 1) {
fprintf(fd, ".names %s%s %s%s %s%s/E%u\n"
"11 1\n"
"00 1\n",
a_ned->get_name(), a_ned->get_name_index(idx),
b_ned->get_name(), b_ned->get_name_index(idx),
q_ned->get_name(), q_ned->get_name_index(0), idx);
}
// Generate a wide function to blend the per-bit comparisons.
fprintf(fd, ".names");
for (unsigned idx = 0 ; idx < ivl_lpm_width(net) ; idx += 1) {
fprintf(fd, " %s%s/G%u",
q_ned->get_name(), q_ned->get_name_index(0), idx);
}
for (unsigned idx = ge_flag?0:1 ; idx < ivl_lpm_width(net) ; idx += 1) {
fprintf(fd, " %s%s/E%u",
q_ned->get_name(), q_ned->get_name_index(0), idx);
}
fprintf(fd, " %s%s\n", q_ned->get_name(), q_ned->get_name_index(0));
for (unsigned idx = 0 ; idx < ivl_lpm_width(net) ; idx += 1) {
for (unsigned jdx = 0 ; jdx < ivl_lpm_width(net) ; jdx += 1) {
if (jdx != idx)
fprintf(fd, "-");
else
fprintf(fd, "1");
}
for (unsigned jdx = ge_flag?0:1 ; jdx < ivl_lpm_width(net) ; jdx += 1) {
if (jdx <= idx)
fprintf(fd, "-");
else
fprintf(fd, "1");
}
fprintf(fd, " 1\n");
}
if (ge_flag) {
for (unsigned idx = 0 ; idx < ivl_lpm_width(net) ; idx += 1)
fputc('-', fd);
for (unsigned idx = 0 ; idx < ivl_lpm_width(net) ; idx += 1)
fputc('1', fd);
fprintf(fd, " 1\n");
}
return 0;
}
int print_lpm_cmp_gt(FILE*fd, ivl_lpm_t net)
{
fprintf(fd, "# %s:%u: LPM_LPM_CMP_GT: width=%u\n",
ivl_lpm_file(net), ivl_lpm_lineno(net), ivl_lpm_width(net));
if (ivl_lpm_signed(net))
return print_lpm_cmp_gt_s(fd, net);
else
return print_lpm_cmp_gt_u(fd, net);
}