Cleanup emulator.cc, use getopt, add help text (#487)

This changes the emulator to conform to POSIX-style options (e.g.,
short/'-' and long/'--') while preserving legacy option parsing (i.e.,
'+'). Options are read from the user until the first
non-option (either POSIX or legacy) is encountered. This and
everything following is assumed to be the binary and any arguments the
user wants to run on the emulator. All non-options are passed directly
to the DTM. This allows for the same option to be passed, safely, to
both the emulator and the binary, e.g., "+verbose".

This introduces a dependency on <getopt.h>.

Closes #484.

csrc/emulator.cc

@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <getopt.h>
 
 extern dtm_t* dtm;
 static uint64_t trace_count = 0;
@@ -33,33 +34,123 @@ extern "C" int vpi_get_vlog_info(void* arg)
   return 0;
 }
 
+static void usage(const char * program_name) {
+  printf("Usage: %s [OPTION]... BINARY [BINARY ARGS]\n", program_name);
+  fputs("\
+Run a BINARY on the Rocket Chip emulator.\n\
+\n\
+Mandatory arguments to long options are mandatory for short options too.\n\
+  -c, --cycle-count          print the cycle count before exiting\n\
+       +cycle-count\n\
+  -h, --help                 display this help and exit\n\
+  -m, --max-cycles=CYCLES    kill the emulation after CYCLES\n\
+       +max-cycles=CYCLES\n\
+  -s, --seed=SEED            use random number seed SEED\n\
+  -V, --verbose              enable all Chisel printfs\n\
+       +verbose\n\
+", stdout);
+#if VM_TRACE
+  fputs("\
+  -v, --vcd=FILE,            write vcd trace to FILE (or '-' for stdout)\n\
+  -x, --start=CYCLE          start VCD tracing at CYCLE\n\
+      +start\n\
+", stdout);
+#else
+  fputs("\
+VCD options (e.g., -v, +start) require a debug-enabled emulator.\n\
+Try `make debug`.\n\
+", stdout);
+#endif
+}
+
 int main(int argc, char** argv)
 {
   unsigned random_seed = (unsigned)time(NULL) ^ (unsigned)getpid();
   uint64_t max_cycles = -1;
-  uint64_t start = 0;
   int ret = 0;
-  FILE *vcdfile = NULL;
   bool print_cycles = false;
+#if VM_TRACE
+  FILE * vcdfile = NULL;
+  uint64_t start = 0;
+#endif
 
-  for (int i = 1; i < argc; i++)
-  {
-    std::string arg = argv[i];
-    if (arg.substr(0, 2) == "-v") {
-      const char* filename = argv[i]+2;
-      vcdfile = strcmp(filename, "-") == 0 ? stdout : fopen(filename, "w");
-      if (!vcdfile)
-        abort();
-    } else if (arg.substr(0, 2) == "-s")
-      random_seed = atoi(argv[i]+2);
-    else if (arg == "+verbose")
-      verbose = true;
-    else if (arg.substr(0, 12) == "+max-cycles=")
-      max_cycles = atoll(argv[i]+12);
-    else if (arg.substr(0, 7) == "+start=")
-      start = atoll(argv[i]+7);
-    else if (arg.substr(0, 12) == "+cycle-count")
-      print_cycles = true;
+  std::vector<std::string> to_dtm;
+  while (1) {
+    static struct option long_options[] = {
+      {"cycle-count", no_argument,       0, 'c' },
+      {"help",        no_argument,       0, 'h' },
+      {"max-cycles",  required_argument, 0, 'm' },
+      {"seed",        required_argument, 0, 's' },
+      {"verbose",     no_argument,       0, 'V' },
+#if VM_TRACE
+      {"vcd",         required_argument, 0, 'v' },
+      {"start",       required_argument, 0, 'x' },
+#endif
+      {0, 0, 0, 0}
+    };
+    int option_index = 0;
+#if VM_TRACE
+    int c = getopt_long(argc, argv, "-chm:s:v:Vx:", long_options, &option_index);
+#else
+    int c = getopt_long(argc, argv, "-chm:s:V", long_options, &option_index);
+#endif
+    if (c == -1) break;
+    switch (c) {
+      // Process "normal" options with '--' long options or '-' short options
+      case '?': usage(argv[0]);             return 1;
+      case 'c': print_cycles = true;        break;
+      case 'h': usage(argv[0]);             return 0;
+      case 'm': max_cycles = atoll(optarg); break;
+      case 's': random_seed = atoi(optarg); break;
+      case 'V': verbose = true;             break;
+#if VM_TRACE
+      case 'v': {
+        vcdfile = strcmp(optarg, "-") == 0 ? stdout : fopen(optarg, "w");
+        if (!vcdfile) {
+          std::cerr << "Unable to open " << optarg << " for VCD write\n";
+          return 1;
+        }
+        break;
+      }
+      case 'x': start = atoll(optarg);      break;
+#endif
+      // Processing of legacy '+' options and recognition of when
+      // we've hit the binary. The binary is expected to be a
+      // non-option and not start with '-' or '+'.
+      case 1: {
+        if (optarg[0] != '+') {
+          to_dtm.push_back(optarg);
+          goto done_processing;
+        }
+        std::string arg = optarg;
+        if (arg == "+verbose")
+          verbose = true;
+        else if (arg.substr(0, 12) == "+max-cycles=")
+          max_cycles = atoll(optarg+12);
+#if VM_TRACE
+        else if (arg.substr(0, 7) == "+start=")
+          start = atoll(optarg+7);
+#endif
+        else if (arg.substr(0, 12) == "+cycle-count")
+          print_cycles = true;
+        else {
+          fprintf(stderr, "%s: unrecognized option '%s'\n", argv[0], optarg);
+          usage(argv[0]);
+          return 1;
+        }
+        break;
+      }
+    }
+  }
+
+done_processing:
+  if (optind < argc)
+    while (optind < argc)
+      to_dtm.push_back(argv[optind++]);
+  if (!to_dtm.size()) {
+    std::cerr << "No binary specified for emulator\n";
+    usage(argv[0]);
+    return 1;
   }
 
   if (verbose)
@@ -81,7 +172,7 @@ int main(int argc, char** argv)
   }
 #endif
 
-  dtm = new dtm_t(std::vector<std::string>(argv + 1, argv + argc));
+  dtm = new dtm_t(to_dtm);
 
   signal(SIGTERM, handle_sigterm);
 
@@ -117,10 +208,9 @@ int main(int argc, char** argv)
 #if VM_TRACE
   if (tfp)
     tfp->close();
-#endif
-
   if (vcdfile)
     fclose(vcdfile);
+#endif
 
   if (dtm->exit_code())
   {
@@ -137,8 +227,7 @@ int main(int argc, char** argv)
     fprintf(stderr, "Completed after %ld cycles\n", trace_count);
   }
 
-  delete dtm;
-  delete tile;
-
+  if (dtm) delete dtm;
+  if (tile) delete tile;
   return ret;
 }