diff --git a/src/test/csrc/emu.cpp b/src/test/csrc/emu.cpp
index 292bd82627442eace5bf859f2d1ee34ab3462100..396bc4757f5a4a39849d6362d726c430edc257d7 100644
--- a/src/test/csrc/emu.cpp
+++ b/src/test/csrc/emu.cpp
@@ -430,7 +430,7 @@ void Emulator::snapshot_save(const char *filename) {
 }
 
 void Emulator::snapshot_load(const char *filename) {
-  VerilatedRestore stream;
+  VerilatedRestoreMem stream;
   stream.open(filename);
   stream >> *dut_ptr;
 
diff --git a/src/test/csrc/ram.cpp b/src/test/csrc/ram.cpp
index b3026fc941e39f85e26c6f61cf0fa0ccdfc2899f..40cb3e26ec6a04d0982365f1008d05c70ef51d10 100644
--- a/src/test/csrc/ram.cpp
+++ b/src/test/csrc/ram.cpp
@@ -4,7 +4,7 @@
 #include "common.h"
 #include "ram.h"
 
-#define RAMSIZE (64 * 1024 * 1024 * 1024UL)
+#define RAMSIZE (256 * 1024 * 1024UL)
 
 #ifdef WITH_DRAMSIM3
 #include "cosimulation.h"
@@ -104,9 +104,9 @@ void addpageSv39() {
 #endif
 
 // Return whether the file is a gz file
-int isGzFile(const char *img) {
-  assert(img != NULL && strlen(img) >= 4);
-  return !strcmp(img + (strlen(img) - 3), ".gz");
+int isGzFile(const char *filename) {
+  assert(filename != NULL && strlen(filename) >= 4);
+  return !strcmp(filename + (strlen(filename) - 3), ".gz");
 }
 
 // Read binary from .gz file
diff --git a/src/test/csrc/snapshot.cpp b/src/test/csrc/snapshot.cpp
index 15aafafbfbfeaae769cd445a8f75330d4823c289..e4bbdcb708635be4414d098aa174fcfd63780b21 100644
--- a/src/test/csrc/snapshot.cpp
+++ b/src/test/csrc/snapshot.cpp
@@ -1,6 +1,88 @@
 #include "snapshot.h"
+#include <zlib.h>
 
 #ifdef VM_SAVABLE
+
+int compressToFile(uint8_t *buf, const char *filename, long size) {
+  gzFile gzfp = gzopen(filename, "wb");
+  assert(gzfp != NULL);
+
+  assert(gzwrite(gzfp, buf, size) > 0);
+
+  gzclose(gzfp);
+  return 0;
+
+  // gzFile compressed_mem = gzopen(filename, "wb");
+
+  // if(compressed_mem == NULL) {
+  //   printf("Can't open compressed binary file '%s'", filename);
+  //   return -1;
+  // }
+
+  // uint64_t curr_size = 0;
+  // const uint32_t chunk_size = 16384;
+  // long *temp_page = new long[chunk_size];
+  // long *pmem_current = (long*)ptr;
+
+  // while (curr_size < buf_size) {
+  //   uint32_t bytes_write = gzwrite(compressed_mem, temp_page, chunk_size);
+  //   if (bytes_write == 0) { break; }
+  //   for (uint32_t x = 0; x < bytes_write / sizeof(long) + 1; x++) {
+  //     if (*(temp_page + x) != 0) {
+  //       pmem_current = (long*)((uint8_t*)ptr + curr_size + x * sizeof(long));
+  //       *pmem_current = *(temp_page + x);
+  //     }
+  //   }
+  //   curr_size += bytes_write;
+  // }
+  // printf("Write %lu bytes from gz stream in total\n", curr_size);
+
+  // delete [] temp_page;
+
+  // if(gzclose(compressed_mem)) {
+  //   printf("Error closing '%s'\n", filename);
+  //   return -1;
+  // }
+  // return curr_size;
+}
+
+// Read binary from .gz file
+int readFromGz(void* ptr, const char *file_name, long buf_size) {
+  gzFile compressed_mem = gzopen(file_name, "rb");
+
+  if(compressed_mem == NULL) {
+    printf("Can't open compressed binary file '%s'", file_name);
+    return -1;
+  }
+
+  uint64_t curr_size = 0;
+  const uint32_t chunk_size = 16384;
+  long *temp_page = new long[chunk_size];
+  long *pmem_current = (long*)ptr;
+
+  while (curr_size < buf_size) {
+    uint32_t bytes_read = gzread(compressed_mem, temp_page, chunk_size);
+    if (bytes_read == 0) { break; }
+    // assert(bytes_read % sizeof(long) == 0);
+    for (uint32_t x = 0; x < bytes_read / sizeof(long) + 1; x++) {
+      if (*(temp_page + x) != 0) {
+        pmem_current = (long*)((uint8_t*)ptr + curr_size + x * sizeof(long));
+        *pmem_current = *(temp_page + x);
+      }
+    }
+    curr_size += bytes_read;
+  }
+  printf("Read %lu bytes from gz stream in total\n", curr_size);
+
+  delete [] temp_page;
+
+  if(gzclose(compressed_mem)) {
+    printf("Error closing '%s'\n", file_name);
+    return -1;
+  }
+  return curr_size;
+}
+
 void VerilatedSaveMem::flush() {
   long flush_size = m_cp - m_bufp;
   assert(buf_size - size > flush_size);
@@ -13,11 +95,86 @@ void VerilatedSaveMem::save() {
   if (size == 0) return;
   trailer();
   flush();
-  FILE *fp = fopen(m_filename.c_str(), "w");
-  assert(fp != NULL);
-  fwrite(buf, size, 1, fp);
-  fclose(fp);
+  if(size <= (512 * 1024 * 1024UL)){
+    FILE *fp = fopen(m_filename.c_str(), "w");
+    assert(fp != NULL);
+    fwrite(buf, size, 1, fp);
+    fclose(fp);
+  } else {
+    compressToFile(buf, (m_filename + ".gz").c_str(), size);
+  }
   size = 0;
   printf("save snapshot to %s...\n", m_filename.c_str());
 }
+
+void VerilatedRestoreMem::fill() {
+  m_assertOne.check();
+  if (VL_UNLIKELY(!isOpen())) return;
+  // Move remaining characters down to start of buffer.  (No memcpy, overlaps allowed)
+  vluint8_t* rp = m_bufp;
+  for (vluint8_t* sp = m_cp; sp < m_endp; *rp++ = *sp++) {}  // Overlaps
+  m_endp = m_bufp + (m_endp - m_cp);
+  m_cp = m_bufp;  // Reset buffer
+  // Read into buffer starting at m_endp
+  while (true) {
+      ssize_t remaining = (m_bufp + bufferSize() - m_endp);
+      if (remaining == 0) break;
+      errno = 0;
+      ssize_t got = unbuf_read(m_endp, remaining);
+      if (got > 0) {
+          m_endp += got;
+      } else if (VL_UNCOVERABLE(got < 0)) {
+          if (VL_UNCOVERABLE(errno != EAGAIN && errno != EINTR)) {
+              // LCOV_EXCL_START
+              // write failed, presume error (perhaps out of disk space)
+              std::string msg = std::string(__FUNCTION__) + ": " + strerror(errno);
+              VL_FATAL_MT("", 0, "", msg.c_str());
+              close();
+              break;
+              // LCOV_EXCL_STOP
+          }
+      } else {  // got==0, EOF
+          // Fill buffer from here to end with NULLs so reader's don't
+          // need to check eof each character.
+          while (m_endp < m_bufp + bufferSize()) *m_endp++ = '\0';
+          break;
+      }
+  }
+}
+
+void VerilatedRestoreMem::open(const char* filename) {
+  m_assertOne.check();
+  if (isOpen()) return;
+  VL_DEBUG_IF(VL_DBG_MSGF("- restore: opening restore file %s\n", filenamep););
+
+  if (VL_UNCOVERABLE(filename[0] == '|')) {
+      assert(0);  // LCOV_EXCL_LINE // Not supported yet.
+  } else {
+      size = readFromGz(buf, filename, buf_size);
+  }
+  m_isOpen = true;
+  m_filename = filename;
+  m_cp = m_bufp;
+  m_endp = m_bufp;
+  header();
+}
+
+void VerilatedRestoreMem::close() {
+  if (!isOpen()) return;
+    trailer();
+    flush();
+    m_isOpen = false;
+}
+
+int VerilatedRestoreMem::unbuf_read(uint8_t* dest, long rsize) {
+  if(buf_ptr + rsize > size) {
+    rsize = size - buf_ptr;
+  }
+  for(int i = 0; i < rsize; i++) {
+    dest[i] = buf[buf_ptr + i];
+  }
+  buf_ptr += rsize;
+
+  return rsize;
+}
 #endif
diff --git a/src/test/csrc/snapshot.h b/src/test/csrc/snapshot.h
index 5bebdceda71a0f9f15a5d954277acbaa44a4ce10..5e039ab650de4c7bddde12d914e9c06ccec897f0 100644
--- a/src/test/csrc/snapshot.h
+++ b/src/test/csrc/snapshot.h
@@ -32,6 +32,29 @@ public:
   void flush();
   void save();
 };
+
+class VerilatedRestoreMem : public VerilatedDeserialize {
+  const static long buf_size = (1024 * 1024 * 1024UL);
+  uint8_t *buf;
+  long size, buf_ptr;
+  // gzFile compressed_mem;
+
+public:
+  VerilatedRestoreMem() {
+    buf = new uint8_t[buf_size];
+    size = 0;
+  }
+  ~VerilatedRestoreMem() { close(); delete buf; }
+
+  void open(const char* filenamep) VL_MT_UNSAFE_ONE;
+  void open(const std::string& filename) VL_MT_UNSAFE_ONE { open(filename.c_str()); }
+
+  int unbuf_read(uint8_t* dest, long rsize);
+
+  void close();
+  void flush() {}
+  void fill();
+};
 #endif
 
 #endif