Parse new configs from a comment, to allow 2.9 halscope to open new configs

Author: Luca Toniolo

src/hal/utils/scope.c

@@ -112,9 +112,14 @@ static int read_samples_from_config(const char *filename)
 	return 0;  /* file doesn't exist, use default */
     }
     while (fgets(buf, sizeof(buf), fp) != NULL) {
+	/* Support both "SAMPLES nnn" and "# SAMPLES nnn" for backward compatibility */
+	/* Older halscope versions will ignore "# SAMPLES" as a comment */
 	if (strncasecmp(buf, "SAMPLES ", 8) == 0) {
 	    samples = atoi(buf + 8);
 	    break;
+	} else if (strncasecmp(buf, "# SAMPLES ", 10) == 0) {
+	    samples = atoi(buf + 10);
+	    break;
 	}
     }
     fclose(fp);

src/hal/utils/scope_files.c

@@ -60,8 +60,9 @@
 */
 
 /*
+   # SAMPLES <int>	total sample buffer size (written as comment for compatibility)
    THREAD <string>	name of thread to sample in
-   MAXCHAN <int>	1,2,4,8,16, maximum channel count
+   MAXCHAN <int>	1,2,4,8,16, maximum channel count (ignored, kept for compatibility)
    HMULT <int>		multiplier, sample every N runs of thread
    HZOOM <int>		1-9, horizontal zoom setting
    HPOS <float>		0.0-1.0, horizontal position setting
@@ -467,6 +468,8 @@ static char *samples_cmd(void * arg)
     int *argp;
     /* SAMPLES is handled early in main() before scope_rt is loaded */
     /* Here we just store it in requested_samples so it gets saved back */
+    /* This handles both "SAMPLES nnn" from config files */
+    /* The "# SAMPLES nnn" comment version is handled by read_samples_from_config() */
     argp = (int *)(arg);
     ctrl_usr->horiz.requested_samples = *argp;
     return NULL;

src/hal/utils/scope_horiz.c

@@ -320,7 +320,12 @@ void write_horiz_config(FILE *fp)
     /* save requested_samples if set, otherwise current buf_len */
     samples_to_save = (horiz->requested_samples > 0) ?
 	horiz->requested_samples : ctrl_shm->buf_len;
-    fprintf(fp, "SAMPLES %d\n", samples_to_save);
+    /* Write SAMPLES as a comment for backward compatibility with old halscope */
+    /* Old versions will ignore "# SAMPLES", new versions parse it in read_samples_from_config() */
+    fprintf(fp, "# SAMPLES %d\n", samples_to_save);
+    /* Also write MAXCHAN for backward compatibility with old halscope */
+    /* Old versions use MAXCHAN, new versions ignore it (always use 16 channels) */
+    fprintf(fp, "MAXCHAN 16\n");
     fprintf(fp, "THREAD %s\n", horiz->thread_name);
     fprintf(fp, "HMULT %d\n", ctrl_shm->mult);
     fprintf(fp, "HZOOM %d\n", horiz->zoom_setting);