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-rw-r--r--backends/cxxrtl/cxxrtl_vcd.h14
1 files changed, 10 insertions, 4 deletions
diff --git a/backends/cxxrtl/cxxrtl_vcd.h b/backends/cxxrtl/cxxrtl_vcd.h
index 8ba94ea77..5f5f612b5 100644
--- a/backends/cxxrtl/cxxrtl_vcd.h
+++ b/backends/cxxrtl/cxxrtl_vcd.h
@@ -104,19 +104,25 @@ class vcd_writer {
buffer += '\n';
}
- const variable &register_variable(size_t width, chunk_t *curr) {
+ const variable &register_variable(size_t width, chunk_t *curr, bool immutable = false) {
if (aliases.count(curr)) {
return variables[aliases[curr]];
} else {
const size_t chunks = (width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
aliases[curr] = variables.size();
- variables.emplace_back(variable { variables.size(), width, curr, cache.size() });
- cache.insert(cache.end(), &curr[0], &curr[chunks]);
+ if (immutable) {
+ variables.emplace_back(variable { variables.size(), width, curr, (size_t)-1 });
+ } else {
+ variables.emplace_back(variable { variables.size(), width, curr, cache.size() });
+ cache.insert(cache.end(), &curr[0], &curr[chunks]);
+ }
return variables.back();
}
}
bool test_variable(const variable &var) {
+ if (var.prev_off == (size_t)-1)
+ return false; // immutable
const size_t chunks = (var.width + (sizeof(chunk_t) * 8 - 1)) / (sizeof(chunk_t) * 8);
if (std::equal(&var.curr[0], &var.curr[chunks], &cache[var.prev_off])) {
return false;
@@ -158,7 +164,7 @@ public:
switch (item.type) {
// Not the best naming but oh well...
case debug_item::VALUE:
- emit_var(register_variable(item.width, item.curr), "wire", name);
+ emit_var(register_variable(item.width, item.curr, /*immutable=*/item.next == nullptr), "wire", name);
break;
case debug_item::WIRE:
emit_var(register_variable(item.width, item.curr), "reg", name);