backends/cxxrtl/cxxrtl_vcd.h

   1 /*
   2  *  yosys -- Yosys Open SYnthesis Suite
   3  *
   4  *  Copyright (C) 2020  whitequark <whitequark@whitequark.org>
   5  *
   6  *  Permission to use, copy, modify, and/or distribute this software for any
   7  *  purpose with or without fee is hereby granted.
   8  *
   9  *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  *
  17  */
  18
  19 #ifndef CXXRTL_VCD_H
  20 #define CXXRTL_VCD_H
  21
  22 #include <backends/cxxrtl/cxxrtl.h>
  23
  24 namespace cxxrtl {
  25
  26 class vcd_writer {
  27         struct variable {
  28                 size_t ident;
  29                 size_t width;
  30                 chunk_t *curr;
  31                 size_t prev_off;
  32         };
  33
  34         std::vector<std::string> current_scope;
  35         std::vector<variable> variables;
  36         std::vector<chunk_t> cache;
  37         std::map<chunk_t*, size_t> aliases;
  38         bool streaming = false;
  39
  40         void emit_timescale(unsigned number, const std::string &unit) {
  41                 assert(!streaming);
  42                 assert(number == 1 || number == 10 || number == 100);
  43                 assert(unit == "s" || unit == "ms" || unit == "us" ||
  44                        unit == "ns" || unit == "ps" || unit == "fs");
  45                 buffer += "$timescale " + std::to_string(number) + " " + unit + " $end\n";
  46         }
  47
  48         void emit_scope(const std::vector<std::string> &scope) {
  49                 assert(!streaming);
  50                 while (current_scope.size() > scope.size() ||
  51                        (current_scope.size() > 0 &&
  52                         current_scope[current_scope.size() - 1] != scope[current_scope.size() - 1])) {
  53                         buffer += "$upscope $end\n";
  54                         current_scope.pop_back();
  55                 }
  56                 while (current_scope.size() < scope.size()) {
  57                         buffer += "$scope module " + scope[current_scope.size()] + " $end\n";
  58                         current_scope.push_back(scope[current_scope.size()]);
  59                 }
  60         }
  61
  62         void emit_ident(size_t ident) {
  63                 do {
  64                         buffer += '!' + ident % 94; // "base94"
  65                         ident /= 94;
  66                 } while (ident != 0);
  67         }
  68
  69         void emit_var(const variable &var, const std::string &type, const std::string &name,
  70                       size_t lsb_at, bool multipart) {
  71                 assert(!streaming);
  72                 buffer += "$var " + type + " " + std::to_string(var.width) + " ";
  73                 emit_ident(var.ident);
  74                 buffer += " " + name;
  75                 if (multipart || name.back() == ']' || lsb_at != 0) {
  76                         if (var.width == 1)
  77                                 buffer += " [" + std::to_string(lsb_at) + "]";
  78                         else
  79                                 buffer += " [" + std::to_string(lsb_at + var.width - 1) + ":" + std::to_string(lsb_at) + "]";
  80                 }
  81                 buffer += " $end\n";
  82         }
  83
  84         void emit_enddefinitions() {
  85                 assert(!streaming);
  86                 buffer += "$enddefinitions $end\n";
  87                 streaming = true;
  88         }
  89
  90         void emit_time(uint64_t timestamp) {
  91                 assert(streaming);
  92                 buffer += "#" + std::to_string(timestamp) + "\n";
  93         }
  94
  95         void emit_scalar(const variable &var) {
  96                 assert(streaming);
  97                 assert(var.width == 1);
  98                 buffer += (*var.curr ? '1' : '0');
  99                 emit_ident(var.ident);
 100                 buffer += '\n';
 101         }
 102
 103         void emit_vector(const variable &var) {
 104                 assert(streaming);
 105                 buffer += 'b';
 106                 for (size_t bit = var.width - 1; bit != (size_t)-1; bit--) {
 107                         bool bit_curr = var.curr[bit / (8 * sizeof(chunk_t))] & (1 << (bit % (8 * sizeof(chunk_t))));
 108                         buffer += (bit_curr ? '1' : '0');
 109                 }
 110                 buffer += ' ';
 111                 emit_ident(var.ident);
 112                 buffer += '\n';
 113         }
 114
 115         const variable &register_variable(size_t width, chunk_t *curr, bool constant = false) {
 116                 if (aliases.count(curr)) {
 117                         return variables[aliases[curr]];
 118                 } else {
 119                         const size_t chunks = (width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 120                         aliases[curr] = variables.size();
 121                         if (constant) {
 122                                 variables.emplace_back(variable { variables.size(), width, curr, (size_t)-1 });
 123                         } else {
 124                                 variables.emplace_back(variable { variables.size(), width, curr, cache.size() });
 125                                 cache.insert(cache.end(), &curr[0], &curr[chunks]);
 126                         }
 127                         return variables.back();
 128                 }
 129         }
 130
 131         bool test_variable(const variable &var) {
 132                 if (var.prev_off == (size_t)-1)
 133                         return false; // constant
 134                 const size_t chunks = (var.width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 135                 if (std::equal(&var.curr[0], &var.curr[chunks], &cache[var.prev_off])) {
 136                         return false;
 137                 } else {
 138                         std::copy(&var.curr[0], &var.curr[chunks], &cache[var.prev_off]);
 139                         return true;
 140                 }
 141         }
 142
 143         static std::vector<std::string> split_hierarchy(const std::string &hier_name) {
 144                 std::vector<std::string> hierarchy;
 145                 size_t prev = 0;
 146                 while (true) {
 147                         size_t curr = hier_name.find_first_of(' ', prev);
 148                         if (curr == std::string::npos) {
 149                                 hierarchy.push_back(hier_name.substr(prev));
 150                                 break;
 151                         } else {
 152                                 hierarchy.push_back(hier_name.substr(prev, curr - prev));
 153                                 prev = curr + 1;
 154                         }
 155                 }
 156                 return hierarchy;
 157         }
 158
 159 public:
 160         std::string buffer;
 161
 162         void timescale(unsigned number, const std::string &unit) {
 163                 emit_timescale(number, unit);
 164         }
 165
 166         void add(const std::string &hier_name, const debug_item &item, bool multipart = false) {
 167                 std::vector<std::string> scope = split_hierarchy(hier_name);
 168                 std::string name = scope.back();
 169                 scope.pop_back();
 170
 171                 emit_scope(scope);
 172                 switch (item.type) {
 173                         // Not the best naming but oh well...
 174                         case debug_item::VALUE:
 175                                 emit_var(register_variable(item.width, item.curr, /*constant=*/item.next == nullptr),
 176                                          "wire", name, item.lsb_at, multipart);
 177                                 break;
 178                         case debug_item::WIRE:
 179                                 emit_var(register_variable(item.width, item.curr),
 180                                          "reg", name, item.lsb_at, multipart);
 181                                 break;
 182                         case debug_item::MEMORY: {
 183                                 const size_t stride = (item.width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 184                                 for (size_t index = 0; index < item.depth; index++) {
 185                                         chunk_t *nth_curr = &item.curr[stride * index];
 186                                         std::string nth_name = name + '[' + std::to_string(index) + ']';
 187                                         emit_var(register_variable(item.width, nth_curr),
 188                                                  "reg", nth_name, item.lsb_at, multipart);
 189                                 }
 190                                 break;
 191                         }
 192                         case debug_item::ALIAS:
 193                                 // Like VALUE, but, even though `item.next == nullptr` always holds, the underlying value
 194                                 // can actually change, and must be tracked. In most cases the VCD identifier will be
 195                                 // unified with the aliased reg, but we should handle the case where only the alias is
 196                                 // added to the VCD writer, too.
 197                                 emit_var(register_variable(item.width, item.curr),
 198                                          "wire", name, item.lsb_at, multipart);
 199                                 break;
 200                 }
 201         }
 202
 203         template<class Filter>
 204         void add(const debug_items &items, const Filter &filter) {
 205                 // `debug_items` is a map, so the items are already sorted in an order optimal for emitting
 206                 // VCD scope sections.
 207                 for (auto &it : items.table)
 208                         for (auto &part : it.second)
 209                                 if (filter(it.first, part))
 210                                         add(it.first, part, it.second.size() > 1);
 211         }
 212
 213         void add(const debug_items &items) {
 214                 this->template add(items, [](const std::string &, const debug_item &) {
 215                         return true;
 216                 });
 217         }
 218
 219         void add_without_memories(const debug_items &items) {
 220                 this->template add(items, [](const std::string &, const debug_item &item) {
 221                         return item.type != debug_item::MEMORY;
 222                 });
 223         }
 224
 225         void sample(uint64_t timestamp) {
 226                 bool first_sample = !streaming;
 227                 if (first_sample) {
 228                         emit_scope({});
 229                         emit_enddefinitions();
 230                 }
 231                 emit_time(timestamp);
 232                 for (auto var : variables)
 233                         if (test_variable(var) || first_sample) {
 234                                 if (var.width == 1)
 235                                         emit_scalar(var);
 236                                 else
 237                                         emit_vector(var);
 238                         }
 239         }
 240 };
 241
 242 }
 243
 244 #endif