tgt-vvp/draw_mux.c

   1 /*
   2  * Copyright (c) 2002 Stephen Williams (steve@icarus.com)
   3  *
   4  *    This source code is free software; you can redistribute it
   5  *    and/or modify it in source code form under the terms of the GNU
   6  *    General Public License as published by the Free Software
   7  *    Foundation; either version 2 of the License, or (at your option)
   8  *    any later version.
   9  *
  10  *    This program is distributed in the hope that it will be useful,
  11  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *    GNU General Public License for more details.
  14  *
  15  *    You should have received a copy of the GNU General Public License
  16  *    along with this program; if not, write to the Free Software
  17  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  18  */
  19 #ifdef HAVE_CVS_IDENT
  20 #ident "$Id: draw_mux.c,v 1.14 2007/01/16 05:44:16 steve Exp $"
  21 #endif
  22
  23 # include  "vvp_priv.h"
  24 # include  <assert.h>
  25 #ifdef HAVE_MALLOC_H
  26 # include  <malloc.h>
  27 #endif
  28 # include  <stdlib.h>
  29 # include  <string.h>
  30
  31
  32 /*
  33  * This draws a simple A/B mux. The mux can have any width, enough
  34  * MUXZ nodes are created to support the vector.
  35  */
  36 static void draw_lpm_mux_ab(ivl_lpm_t net, const char*muxz)
  37 {
  38       unsigned width = ivl_lpm_width(net);
  39
  40         /* Only support A-B muxes in this function. */
  41       assert(ivl_lpm_size(net) == 2);
  42       assert(ivl_lpm_selects(net) == 1);
  43
  44       fprintf(vvp_out, "L_%p .functor %s %u", net, muxz, width);
  45       fprintf(vvp_out, ", %s", draw_input_from_net(ivl_lpm_data(net,0)));
  46       fprintf(vvp_out, ", %s", draw_input_from_net(ivl_lpm_data(net,1)));
  47       fprintf(vvp_out, ", %s", draw_input_from_net(ivl_lpm_select(net)));
  48       fprintf(vvp_out, ", C4<>;\n");
  49 }
  50
  51 static void draw_lpm_mux_nest(ivl_lpm_t net, const char*muxz)
  52 {
  53       int idx, level;
  54       unsigned width = ivl_lpm_width(net);
  55       unsigned swidth = ivl_lpm_selects(net);
  56       char*select_input;
  57
  58       assert(ivl_lpm_size(net) == (1 << swidth));
  59
  60       select_input = strdup(draw_net_input(ivl_lpm_select(net)));
  61
  62       fprintf(vvp_out, "L_%p/0s .part %s, 0, 1; Bit 0 of the select\n",
  63               net, select_input);
  64
  65       for (idx = 0 ;  idx < ivl_lpm_size(net) ;  idx += 2) {
  66             fprintf(vvp_out, "L_%p/0/%d .functor %s %u",
  67                     net, idx/2, muxz, width);
  68             fprintf(vvp_out, ", %s", draw_net_input(ivl_lpm_data(net,idx+0)));
  69             fprintf(vvp_out, ", %s", draw_net_input(ivl_lpm_data(net,idx+1)));
  70             fprintf(vvp_out, ", L_%p/0s, C4<>;\n", net);
  71       }
  72
  73       for (level = 1 ;  level < swidth-1 ;  level += 1) {
  74             fprintf(vvp_out, "L_%p/%ds .part %s, %d, 1;\n",
  75                     net, level, select_input, level);
  76
  77             for (idx = 0 ;  idx < (ivl_lpm_size(net) >> level); idx += 2) {
  78                   fprintf(vvp_out, "L_%p/%d/%d .functor %s %u",
  79                           net, level, idx/2, muxz, width);
  80                   fprintf(vvp_out, ", L_%p/%d/%d", net, level-1, idx+0);
  81                   fprintf(vvp_out, ", L_%p/%d/%d", net, level-1, idx+1);
  82                   fprintf(vvp_out, ", L_%p/%ds",   net, level);
  83                   fprintf(vvp_out, ", C4<>;\n");
  84             }
  85
  86       }
  87
  88
  89       fprintf(vvp_out, "L_%p/%ds .part %s, %d, 1; Bit %d of the select\n",
  90               net, swidth-1, select_input, swidth-1, swidth-1);
  91
  92
  93       fprintf(vvp_out, "L_%p .functor %s %u", net, muxz, width);
  94       fprintf(vvp_out, ", L_%p/%d/0", net, swidth-2);
  95       fprintf(vvp_out, ", L_%p/%d/1", net, swidth-2);
  96       fprintf(vvp_out, ", L_%p/%ds",  net, swidth-1);
  97       fprintf(vvp_out, ", C4<>;\n");
  98
  99       free(select_input);
 100 }
 101
 102 void draw_lpm_mux(ivl_lpm_t net)
 103 {
 104       const char*muxz = "MUXZ";
 105
 106         /* The output of the mux defines the type of the mux. the
 107            ivl_target should guarantee that all the inputs are the
 108            same type as the output. */
 109       switch (data_type_of_nexus(ivl_lpm_q(net,0))) {
 110           case IVL_VT_REAL:
 111             muxz = "MUXR";
 112             break;
 113           default:
 114             muxz = "MUXZ";
 115             break;
 116       }
 117
 118       if ((ivl_lpm_size(net) == 2) && (ivl_lpm_selects(net) == 1)) {
 119             draw_lpm_mux_ab(net, muxz);
 120             return;
 121       }
 122
 123         /* Here we are at the worst case, we generate a tree of MUXZ
 124            devices to handle the arbitrary size. */
 125       draw_lpm_mux_nest(net, muxz);
 126 }
 127
 128 /*
 129  * $Log: draw_mux.c,v $
 130  * Revision 1.14  2007/01/16 05:44:16  steve
 131  *  Major rework of array handling. Memories are replaced with the
 132  *  more general concept of arrays. The NetMemory and NetEMemory
 133  *  classes are removed from the ivl core program, and the IVL_LPM_RAM
 134  *  lpm type is removed from the ivl_target API.
 135  *
 136  * Revision 1.13  2005/10/12 17:26:17  steve
 137  *  MUX nodes get inputs from nets, not from net inputs,
 138  *  Detect and draw alias nodes to reduce net size and
 139  *  handle force confusion.
 140  *
 141  * Revision 1.12  2005/09/01 04:11:37  steve
 142  *  Generate code to handle real valued muxes.
 143  *
 144  * Revision 1.11  2005/08/27 04:32:08  steve
 145  *  Handle synthesis of fully packed case statements.
 146  *
 147  * Revision 1.10  2005/06/17 03:46:52  steve
 148  *  Make functors know their own width.
 149  *
 150  * Revision 1.9  2005/04/06 05:29:09  steve
 151  *  Rework NetRamDq and IVL_LPM_RAM nodes.
 152  *
 153  * Revision 1.8  2005/02/12 22:54:29  steve
 154  *  Implement a-b muxes as vector devices
 155  *
 156  * Revision 1.7  2003/12/19 01:27:10  steve
 157  *  Fix various unsigned compare warnings.
 158  *
 159  * Revision 1.6  2003/02/25 03:40:45  steve
 160  *  Eliminate use of ivl_lpm_name function.
 161  *
 162  * Revision 1.5  2002/08/29 03:04:01  steve
 163  *  Generate x out for x select on wide muxes.
 164  *
 165  * Revision 1.4  2002/08/12 01:35:03  steve
 166  *  conditional ident string using autoconfig.
 167  *
 168  * Revision 1.3  2002/08/11 23:47:04  steve
 169  *  Add missing Log and Ident strings.
 170  *
 171  */