feat: difftest framework

npc/csrc/Flow/main.cpp

@@ -1,7 +1,10 @@
 #include "components.hpp"
 #include "config.hpp"
 #include "vl_wrapper.hpp"
+#include "vpi_user.h"
 #include <VFlow.h>
+#include <cstdint>
+#include <difftest.hpp>
 
 using VlModule = VlModuleInterfaceCommon<VFlow>;
 using Registers = _RegistersVPI<uint32_t, 32>;
@@ -16,6 +19,8 @@ void *pmem_get() {
 int pmem_read(int raddr) {
   void *pmem = pmem_get();
   auto mem = static_cast<Memory<int, 128 * 1024> *>(pmem);
+  // TODO: Do memory difftest at memory read and write to diagnose at a finer
+  // granularity
   return mem->read(raddr);
 }
 
@@ -26,19 +31,55 @@ void pmem_write(int waddr, int wdata, char wmask) {
 }
 }
 
+VlModule *top;
+Registers *regs;
+using CPUState = CPUStateBase<uint32_t, 32>;
+vpiHandle pc = nullptr;
+void difftest_memcpy(paddr_t, void *, size_t, bool){};
+
+void difftest_regcpy(void *p, bool direction) {
+
+  if (direction == DIFFTEST_FROM_REF) {
+    ((CPUState *)p)->pc = regs->get_pc();
+    for (int i = 0; i < 32; i++) {
+      ((CPUState *)p)->reg[i] = (*regs)[i];
+    }
+  }
+}
+
+void difftest_exec(uint64_t n) {
+  while (n--) {
+    for (int i = 0; i < 2; i++) {
+      if (top->is_posedge()) {
+        // Posedge
+        regs->update();
+      }
+      top->eval();
+    }
+  }
+}
+void difftest_init(int port) {
+  //   top = std::make_unique<VlModule>(config.do_trace, config.wavefile);
+  top = new VlModule{config.do_trace, config.wavefile};
+  regs = new Registers("TOP.Flow.reg_0.regFile_", "TOP.Flow.pc.out");
+  top->reset_eval(10);
+}
+
 int main(int argc, char **argv, char **env) {
   config.cli_parse(argc, argv);
-  auto top = std::make_shared<VlModule>(config.do_trace, config.wavefile);
-  Registers regs("TOP.Flow.reg_0.regFile_");
 
-  top->reset_eval(10);
-  for (int i = 0; i < config.max_sim_time; i++) {
-    if (top->is_posedge()) {
-      // Posedge
-      regs.update();
-      regs.print_regs();
-    }
-    top->eval();
+  /* -- Difftest -- */
+  std::filesystem::path ref{config.lib_ref};
+  DifftestInterface dut_interface = DifftestInterface{
+      &difftest_memcpy, &difftest_regcpy, &difftest_exec, &difftest_init};
+  DifftestInterface ref_interface = DifftestInterface{ref};
+
+  Difftest<CPUStateBase<uint32_t, 32>> diff{dut_interface, ref_interface,
+                                            pmem_get(), 128};
+  int t = 8;
+  while (t--) {
+    diff.step(1);
   }
+
   return 0;
 }