Eliminate hwacha <-> riscv circular dependence

We now split out the spike executable into another subproject,
which depends on both rocket and hwacha

1 files changed, 102 insertions, 0 deletions

diff --git a/spike/xspike.cc b/spike/xspike.cc
new file mode 100644
index 0000000..4331dbe
--- /dev/null
+++ b/spike/xspike.cc
@@ -0,0 +1,102 @@
+// See LICENSE for license details.
+
+// xspike forks an xterm for spike's target machine console,
+// preserving the current terminal for debugging.
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <cstdio>
+#include <climits>
+#include <cstring>
+#include <stdexcept>
+
+static pid_t fork_spike(int tty_fd, int argc, char** argv);
+static pid_t fork_xterm(int* tty_fd);
+
+int main(int argc, char** argv)
+{
+  int tty_fd, wait_status, ret = -1;
+  pid_t xterm, spike;
+
+  static bool signal_exit = false;
+  auto handle_signal = [](int) { signal_exit = true; };
+
+  if ((xterm = fork_xterm(&tty_fd)) < 0)
+  {
+    fprintf(stderr, "could not open xterm\n");
+    goto out;
+  }
+
+  signal(SIGINT, handle_signal);
+
+  if ((spike = fork_spike(tty_fd, argc, argv)) < 0)
+  {
+    fprintf(stderr, "could not open spike\n");
+    goto close_xterm;
+  }
+
+  while ((ret = waitpid(spike, &wait_status, 0)) < 0)
+    if (signal_exit)
+      break;
+
+  if (ret < 0) // signal_exit
+    kill(spike, SIGTERM);
+  else
+    ret = WIFEXITED(wait_status) ? WEXITSTATUS(wait_status) : -1;
+
+close_xterm:
+  kill(-xterm, SIGTERM);
+out:
+  return ret;
+}
+
+static pid_t fork_spike(int tty_fd, int argc, char** argv)
+{
+  pid_t pid = fork();
+  if (pid < 0)
+    return -1;
+
+  if (pid == 0)
+  {
+    if (dup2(tty_fd, STDIN_FILENO) < 0 || dup2(tty_fd, STDOUT_FILENO) < 0)
+      return -1;
+    execvp("spike", argv);
+    return -1;
+  }
+
+  return pid;
+}
+
+static pid_t fork_xterm(int* tty_fd)
+{
+  static const char cmd[] = "3>&1 xterm -title xspike -e sh -c 'tty 1>&3; termios-xspike'";
+
+  int fds[2];
+  if (pipe(fds) < 0)
+    return -1;
+
+  pid_t pid = fork();
+  if (pid < 0)
+    return -1;
+
+  if (pid == 0)
+  {
+    setpgid(0, 0);
+    if (dup2(fds[1], STDOUT_FILENO) < 0)
+      return -1;
+    execl("/bin/sh", "sh", "-c", cmd, NULL);
+    return -1;
+  }
+
+  char tty[NAME_MAX];
+  ssize_t ttylen = read(fds[0], tty, sizeof(tty));
+  if (ttylen <= 1 || tty[ttylen-1] != '\n')
+    return -1;
+  tty[ttylen-1] = '\0';
+  if ((*tty_fd = open(tty, O_RDWR)) < 0)
+    return -1;
+
+  return pid;
+}