Add vvp "quiet" flag (issue #1193)

This adds a "-q" option on the vvp command line and a vvp_set_quiet_flag()
function in the VVP library API. Setting this flag will cause all output
to standard output via MCD bit 0 to be suppressed. It will not prevent the
output being sent to a log file if the vvp "-l" option has been used, and
it will not affect output to the STDOUT file descriptor.

vvp/lib_main.cc

@@ -68,6 +68,11 @@ void vvp_set_stop_is_finish(bool flag, int exit_code)
       stop_is_finish_exit_code = exit_code;
 }
 
+void vvp_set_quiet_flag(bool flag)
+{
+      vpip_mcd0_disable = flag;
+}
+
 void vvp_set_verbose_flag(bool flag)
 {
       verbose_flag = flag;

vvp/libvvp.h

@@ -21,6 +21,13 @@ extern "C" {
 
 extern void vvp_set_stop_is_finish(bool flag, int exit_code);
 
+/* vvp_set_quiet_flag(true) is equivalent to vvp's "-q" option.
+ *
+ * This function may be called at any time.
+ */
+
+extern void vvp_set_quiet_flag(bool flag);
+
 /* vvp_set_verbose(true) is equivalent to vvp's "-v" option.
  *
  * This function may be called at any time.

vvp/main.cc

@@ -53,7 +53,7 @@ int main(int argc, char*argv[])
       unsigned flag_errors = 0;
       const char *logfile_name = 0x0;
 
-      while ((opt = getopt(argc, argv, "+hil:M:m:nNsvV")) != EOF) switch (opt) {
+      while ((opt = getopt(argc, argv, "+hil:M:m:nNqsvV")) != EOF) switch (opt) {
          case 'h':
            fprintf(stderr,
                    "Usage: vvp [options] input-file [+plusargs...]\n"
@@ -66,6 +66,7 @@ int main(int argc, char*argv[])
                    " -m module      Load vpi module.\n"
 		   " -n             Non-interactive ($stop = $finish).\n"
                    " -N             Same as -n, but exit code is 1 instead of 0\n"
+		   " -q             Quiet mode (suppress output on MCD bit 0).\n"
 		   " -s             $stop right away.\n"
                    " -v             Verbose progress messages.\n"
                    " -V             Print the version information.\n" );
@@ -92,6 +93,9 @@ int main(int argc, char*argv[])
           case 'N':
             vvp_set_stop_is_finish(true, 1);
             break;
+	  case 'q':
+	    vvp_set_quiet_flag(true);
+	    break;
 	  case 's':
 	    schedule_stop(0);
 	    break;

vvp/vpi_mcd.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2020 Stephen G. Tell <steve@telltronics.org>
+ * Copyright (c) 2000-2024 Stephen G. Tell <steve@telltronics.org>
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -34,8 +34,8 @@ extern FILE* vpi_trace;
 /*
  * This table keeps track of the MCD files. Note that there may be
  * only 31 such files, and mcd bit0 (32'h00_00_00_01) is the special
- * standard output file, which may be replicated to a logfile
+ * standard output file, which may be replicated to a logfile and/or
- * depending on flags to the command line.
+ * suppressed depending on flags to the command line.
  */
 
 /*
@@ -55,6 +55,8 @@ static unsigned fd_table_len = 0;
 
 static FILE* logfile;
 
+bool vpip_mcd0_disable = false;
+
 /* Initialize mcd portion of vpi.  Must be called before
  * any vpi_mcd routines can be used.
  */
@@ -217,9 +219,12 @@ vpi_mcd_vprintf(PLI_UINT32 mcd, const char*fmt, va_list ap)
       for(int i = 0; i < 31; i++) {
 	    if((mcd>>i) & 1) {
 		  if(mcd_table[i].fp) {
-			  // echo to logfile
+			if (i == 0) {
-			if (i == 0 && logfile)
+			      if (logfile)
-			      fputs(buf_ptr, logfile);
+				    fputs(buf_ptr, logfile);
+			      if (vpip_mcd0_disable)
+				    continue;
+			}
 			fputs(buf_ptr, mcd_table[i].fp);
 		  } else {
 			rc = EOF;
@@ -251,10 +256,13 @@ extern "C" void vpip_mcd_rawwrite(PLI_UINT32 mcd, const char*buf, size_t cnt)
 	    if (mcd_table[idx].fp == 0)
 		  continue;
 
+	    if (idx == 0) {
+		  if (logfile)
+			fwrite(buf, 1, cnt, logfile);
+		  if (vpip_mcd0_disable)
+			continue;
+	    }
 	    fwrite(buf, 1, cnt, mcd_table[idx].fp);
-	    if (idx == 0 && logfile)
-		  fwrite(buf, 1, cnt, logfile);
-
       }
 }
 
@@ -265,7 +273,12 @@ extern "C" PLI_INT32 vpi_mcd_flush(PLI_UINT32 mcd)
 	if (IS_MCD(mcd)) {
 		for(int i = 0; i < 31; i++) {
 			if((mcd>>i) & 1) {
-				if (i == 0 && logfile) fflush(logfile);
+				if (i == 0) {
+				      if (logfile)
+					    fflush(logfile);
+				      if (vpip_mcd0_disable)
+					    continue;
+				}
 				if (fflush(mcd_table[i].fp)) rc |= 1<<i;
 			}
 		}

vvp/vpi_priv.h

@@ -1154,4 +1154,7 @@ extern vpiHandle vpip_module(__vpiScope*scope);
 
 extern int vpip_delay_selection;
 
+/* A flag to disable output to MCD bit 0. */
+extern bool vpip_mcd0_disable;
+
 #endif /* IVL_vpi_priv_H */