blif code generator support for arbitrary MUX devices.

tgt-blif/lpm_mux.cc

@@ -20,9 +20,17 @@
 
 # include  "priv.h"
 # include  "nex_data.h"
+# include  <vector>
 # include  <cassert>
 
-int print_lpm_mux(FILE*fd, ivl_lpm_t net)
+using namespace std;
+
+/*
+ * This handles the special case that the select port to the MUX is a
+ * single bit. In other words, a binary mux. This may have an
+ * arbitrary data width, but it selects from input A or input B.
+ */
+static int print_lpm_mux_s1(FILE*fd, ivl_lpm_t net)
 {
       ivl_nexus_t nex_out = ivl_lpm_q(net);
       blif_nex_data_t*ned_out = blif_nex_data_t::get_nex_data(nex_out);
@@ -55,3 +63,66 @@ int print_lpm_mux(FILE*fd, ivl_lpm_t net)
 
       return 0;
 }
+
+static int print_lpm_mux_sN(FILE*fd, ivl_lpm_t net)
+{
+      ivl_nexus_t nex_out = ivl_lpm_q(net);
+      blif_nex_data_t*ned_out = blif_nex_data_t::get_nex_data(nex_out);
+
+      ivl_nexus_t nex_sel = ivl_lpm_select(net);
+      blif_nex_data_t*ned_sel = blif_nex_data_t::get_nex_data(nex_sel);
+
+      vector<blif_nex_data_t*> ned_d (ivl_lpm_size(net));
+      for (size_t idx = 0 ; idx < ned_d.size() ; idx += 1) {
+	    ivl_nexus_t tmp = ivl_lpm_data(net,idx);
+	    ned_d[idx] = blif_nex_data_t::get_nex_data(tmp);
+      }
+
+      for (unsigned wid = 0 ; wid < ivl_lpm_width(net) ; wid += 1) {
+	      // First, print the names record with all the ports...
+	    fprintf(fd, ".names");
+	    for (size_t idx = 0 ; idx < ned_sel->get_width() ; idx += 1) {
+		  fprintf(fd, " %s%s", ned_sel->get_name(), ned_sel->get_name_index(idx));
+	    }
+
+	    for (size_t idx = 0 ; idx < ned_d.size() ; idx += 1) {
+		  fprintf(fd, " %s%s", ned_d[idx]->get_name(),
+			  ned_d[idx]->get_name_index(wid));
+	    }
+
+	    fprintf(fd, " %s%s\n", ned_out->get_name(), ned_out->get_name_index(wid));
+
+	      // Print the logic table. We need one line for each
+	      // select address. The select pins must exactly match
+	      // the select address. The output depends only on the
+	      // select D input.
+	    for (size_t didx = 0 ; didx < ned_d.size() ; didx += 1) {
+
+		  for (size_t idx = 0 ; idx < ned_sel->get_width() ; idx += 1) {
+			if (didx & (1<<idx))
+			      fputc('1', fd);
+			else
+			      fputc('0', fd);
+		  }
+
+		  for (size_t idx = 0 ; idx < ned_d.size() ; idx += 1) {
+			if (didx == idx)
+			      fputc('1', fd);
+			else
+			      fputc('-', fd);
+		  }
+
+		  fprintf(fd, " 1\n");
+	    }
+      }
+
+      return 0;
+}
+
+int print_lpm_mux(FILE*fd, ivl_lpm_t net)
+{
+      if (ivl_lpm_selects(net) == 1)
+	    return print_lpm_mux_s1(fd, net);
+      else
+	    return print_lpm_mux_sN(fd, net);
+}