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()] + " $end\n";
  58                         current_scope.push_back(scope[current_scope.size()]);
  59                 }
  60         }
  61
  62         void emit_ident(size_t ident) {
  63                 do {
  64                         buffer += '!' + ident % 94; // "base94"
  65                         ident /= 94;
  66                 } while (ident != 0);
  67         }
  68
  69         void emit_var(const variable &var, const std::string &type, const std::string &name) {
  70                 assert(!streaming);
  71                 buffer += "$var " + type + " " + std::to_string(var.width) + " ";
  72                 emit_ident(var.ident);
  73                 buffer += " " + name + " $end\n";
  74         }
  75
  76         void emit_enddefinitions() {
  77                 assert(!streaming);
  78                 buffer += "$enddefinitions $end\n";
  79                 streaming = true;
  80         }
  81
  82         void emit_time(uint64_t timestamp) {
  83                 assert(streaming);
  84                 buffer += "#" + std::to_string(timestamp) + "\n";
  85         }
  86
  87         void emit_scalar(const variable &var) {
  88                 assert(streaming);
  89                 assert(var.width == 1);
  90                 buffer += (*var.curr ? '1' : '0');
  91                 emit_ident(var.ident);
  92                 buffer += '\n';
  93         }
  94
  95         void emit_vector(const variable &var) {
  96                 assert(streaming);
  97                 buffer += 'b';
  98                 for (size_t bit = var.width - 1; bit != (size_t)-1; bit--) {
  99                         bool bit_curr = var.curr[bit / (8 * sizeof(chunk_t))] & (1 << (bit % (8 * sizeof(chunk_t))));
 100                         buffer += (bit_curr ? '1' : '0');
 101                 }
 102                 buffer += ' ';
 103                 emit_ident(var.ident);
 104                 buffer += '\n';
 105         }
 106
 107         const variable &register_variable(size_t width, chunk_t *curr, bool constant = false) {
 108                 if (aliases.count(curr)) {
 109                         return variables[aliases[curr]];
 110                 } else {
 111                         const size_t chunks = (width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 112                         aliases[curr] = variables.size();
 113                         if (constant) {
 114                                 variables.emplace_back(variable { variables.size(), width, curr, (size_t)-1 });
 115                         } else {
 116                                 variables.emplace_back(variable { variables.size(), width, curr, cache.size() });
 117                                 cache.insert(cache.end(), &curr[0], &curr[chunks]);
 118                         }
 119                         return variables.back();
 120                 }
 121         }
 122
 123         bool test_variable(const variable &var) {
 124                 if (var.prev_off == (size_t)-1)
 125                         return false; // constant
 126                 const size_t chunks = (var.width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 127                 if (std::equal(&var.curr[0], &var.curr[chunks], &cache[var.prev_off])) {
 128                         return false;
 129                 } else {
 130                         std::copy(&var.curr[0], &var.curr[chunks], &cache[var.prev_off]);
 131                         return true;
 132                 }
 133         }
 134
 135         static std::vector<std::string> split_hierarchy(const std::string &hier_name) {
 136                 std::vector<std::string> hierarchy;
 137                 size_t prev = 0;
 138                 while (true) {
 139                         size_t curr = hier_name.find_first_of(' ', prev);
 140                         if (curr == std::string::npos) {
 141                                 hierarchy.push_back(hier_name.substr(prev));
 142                                 break;
 143                         } else {
 144                                 hierarchy.push_back(hier_name.substr(prev, curr - prev));
 145                                 prev = curr + 1;
 146                         }
 147                 }
 148                 return hierarchy;
 149         }
 150
 151 public:
 152         std::string buffer;
 153
 154         void timescale(unsigned number, const std::string &unit) {
 155                 emit_timescale(number, unit);
 156         }
 157
 158         void add(const std::string &hier_name, const debug_item &item) {
 159                 std::vector<std::string> scope = split_hierarchy(hier_name);
 160                 std::string name = scope.back();
 161                 scope.pop_back();
 162
 163                 emit_scope(scope);
 164                 switch (item.type) {
 165                         // Not the best naming but oh well...
 166                         case debug_item::VALUE:
 167                                 emit_var(register_variable(item.width, item.curr, /*constant=*/item.next == nullptr), "wire", name);
 168                                 break;
 169                         case debug_item::WIRE:
 170                                 emit_var(register_variable(item.width, item.curr), "reg", name);
 171                                 break;
 172                         case debug_item::MEMORY: {
 173                                 const size_t stride = (item.width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
 174                                 for (size_t index = 0; index < item.depth; index++) {
 175                                         chunk_t *nth_curr = &item.curr[stride * index];
 176                                         std::string nth_name = name + '[' + std::to_string(index) + ']';
 177                                         emit_var(register_variable(item.width, nth_curr), "reg", nth_name);
 178                                 }
 179                                 break;
 180                         }
 181                         case debug_item::ALIAS:
 182                                 // Like VALUE, but, even though `item.next == nullptr` always holds, the underlying value
 183                                 // can actually change, and must be tracked. In most cases the VCD identifier will be
 184                                 // unified with the aliased reg, but we should handle the case where only the alias is
 185                                 // added to the VCD writer, too.
 186                                 emit_var(register_variable(item.width, item.curr), "wire", name);
 187                                 break;
 188                 }
 189         }
 190
 191         template<class Filter>
 192         void add(const debug_items &items, const Filter &filter) {
 193                 // `debug_items` is a map, so the items are already sorted in an order optimal for emitting
 194                 // VCD scope sections.
 195                 for (auto &it : items)
 196                         if (filter(it.first, it.second))
 197                                 add(it.first, it.second);
 198         }
 199
 200         void add(const debug_items &items) {
 201                 this->template add(items, [](const std::string &, const debug_item &) {
 202                         return true;
 203                 });
 204         }
 205
 206         void add_without_memories(const debug_items &items) {
 207                 this->template add(items, [](const std::string &, const debug_item &item) {
 208                         return item.type != debug_item::MEMORY;
 209                 });
 210         }
 211
 212         void sample(uint64_t timestamp) {
 213                 bool first_sample = !streaming;
 214                 if (first_sample) {
 215                         emit_scope({});
 216                         emit_enddefinitions();
 217                 }
 218                 emit_time(timestamp);
 219                 for (auto var : variables)
 220                         if (test_variable(var) || first_sample) {
 221                                 if (var.width == 1)
 222                                         emit_scalar(var);
 223                                 else
 224                                         emit_vector(var);
 225                         }
 226         }
 227 };
 228
 229 }
 230
 231 #endif