flashmax.pl: use symbolic control char names; add --getver

Use symbolic control character names in flashmax.pl for readability
and to make it easier to compare with the esp32 code.

Add a --getver command.

tools/flashmax.pl

@@ -578,8 +578,32 @@ sub tty_write($$$) {
 }
 
 sub upload_fpgadata($$) {
+    use bytes;
+
     my($port, $fpgadata) = @_;
 
+    my $SOH = 001;
+    my $STX = 002;
+    my $ETX = 003;
+    my $EOT = 004;
+    my $ENQ = 005;
+    my $ACK = 006;
+    my $XON = 021;		# A.k.a. DC1
+    my $WRST = 022;		# DC2: window = 0
+    my $XOFF = 023;		# A.k.a. DC3
+    my $WGO = 024;		# DC4: window += 256 bytes
+    my $NAK = 025;
+    my $SYM = 026;
+    my $ETB = 027;
+    my $CAN = 030;
+    my $EM  = 031;		# Packet offset too high
+    my $FS  = 034;
+    my $GS  = 035;
+    my $RS  = 036;
+    my $US  = 037;
+
+    my $WGO_CHUNK = 256;	# Each WGO = 256 bytes
+
     my $SerialPort = eval {
 	require Device::SerialPort;
 	Device::SerialPort->import(qw(:PARAM));
@@ -644,9 +668,9 @@ sub upload_fpgadata($$) {
     while (($tt = time()) - $start_enq < 30) {
 	my $d = tty_read($tty, \$ttybuf, 1000);
 	if ($d eq '') {
-	    tty_write($tty, \$ttybuf, "\005");	# ENQ
+	    tty_write($tty, \$ttybuf, chr($ENQ));
 	} else {
-	    my $ix = index("\026\004\027", $d);
+	    my $ix = index("\026\004\027", $d); # SYN EOT ETB
 	    if ($ix < 0) {
 		print STDERR $d;
 		next;
@@ -669,6 +693,7 @@ sub upload_fpgadata($$) {
 	    die "$0: $port: failed to start FPGA firmware upload\n";
 	}
 	if ($tt != $last_req) {
+	    # FS SOH <string> GS
 	    tty_write($tty, \$ttybuf,
 		      "\034\001: /// MAX80 FW UPLOAD \~\@\~ \$\r\n\035");
 	    $last_req = $tt;
@@ -679,7 +704,7 @@ sub upload_fpgadata($$) {
 	    last if ($d eq '');
 	    my $dc = unpack('C', $d);
 	    print STDERR $a[$dc];
-	    if ($dc == 036) {
+	    if ($dc == $RS) {
 		$winspc = 0;
 		last;
 	    }
@@ -715,13 +740,13 @@ sub upload_fpgadata($$) {
 	    last if ($d eq '');
 
 	    my $dc = unpack('C', $d);
-	    if ($dc == 022) {
+	    if ($dc == $WRST) {
 		$winspc = 0;
-	    } elsif ($dc == 024) {
+	    } elsif ($dc == $WGO) {
 		if (defined($winspc)) {
-		    $winspc += 256;
+		    $winspc += $WGO_CHUNK;
 		}
-	    } elsif ($dc == 006) {
+	    } elsif ($dc == $ACK) {
 		$last_ack = shift(@pktends) || $last_ack;
 		if ($now != $last_ack_time) {
 		    printf STDERR "%s: %s: %d/%d (%d%%) uploaded\n",
@@ -730,11 +755,11 @@ sub upload_fpgadata($$) {
 		}
 	    } else {
 		print STDERR $a[$dc];
-		if ($dc == 025 || $dc == 031 || $dc == 037) {
+		if ($dc == $NAK || $dc == $EM || $dc == $US) {
 		    $offset = $last_ack;
 		    @pktends = ();
 		    undef $winspc;	# Wait for WRST before resuming
-		} elsif ($dc == 030) {
+		} elsif ($dc == $CAN) {
 		    print STDERR "\n";
 		    die "$0: $port: upload aborted by target system\n";
 		}
@@ -745,7 +770,7 @@ sub upload_fpgadata($$) {
 	    if ($bytes > $offset) {
 		if ($now != $last_enq) {
 		    # SYN: request window resync
-		    tty_write($tty, \$ttybuf, "\026");
+		    tty_write($tty, \$ttybuf, chr($SYN));
 		    $last_enq = $now;
 		}
 	    }
@@ -755,14 +780,14 @@ sub upload_fpgadata($$) {
 	my $data = substr($fpgadata, $offset, $chunk);
 	my $hdr = pack("CvVV", $chunk-1, 0, $offset, crc32($data));
 
-	tty_write($tty, \$ttybuf, "\002".mybaseencode($hdr, $data));
+	tty_write($tty, \$ttybuf, chr($STX).mybaseencode($hdr, $data));
 
 	push(@pktends, $offset + $chunk);
 	$offset += $chunk;
 	$winspc -= $chunk;
     }
 
-    tty_write($tty, \$ttybuf, "\004"); # EOT
+    tty_write($tty, \$ttybuf, chr($EOT));
 
     # Final messages out
     while (1) {
@@ -781,6 +806,7 @@ my $fpgaonly = 0;
 my $file;
 my $target_board = undef;
 my $setver = 0;
+my $getver = 0;
 my $port = undef;
 my $which = 0;
 
@@ -797,6 +823,8 @@ while (1) {
     } elsif ($file eq '--setver') {
 	$target_board = shift(@args);
 	$setver = defined($target_board);
+    } elsif ($file eq '--getver') {
+	$getver = 1;
     } elsif ($file eq '--port') {
 	$port = shift(@args);
     } elsif ($file eq '--') {
@@ -859,8 +887,14 @@ if ($which) {
 print STDERR "esptool ${espver} found\n\n";
 
 if (!defined($port)) {
-    die "Usage: $0 [--which][--esponly][--setver version][--port port]\n".
-	"       [file.fw] [--esptool esptool_options...]\n";
+    die "Usage: $0 [options] [file.fw] [--esptool esptool_options...]\n".
+	"  Options:\n".
+	"    --which            print the esptool command discovered, if any\n".
+	"    --setver <version> set the board version string\n".
+	"    --getver           get the board version string, then exit\n".
+	"    --esponly          flash ESP32 only\n".
+	"    --fpgaonly         flash the FPGA only\n".
+	"    --port             serial port to use\n";
 }
 
 if (! -c $port && !File::Spec->file_name_is_absolute($port)) {
@@ -874,7 +908,7 @@ if (! -c $port && !File::Spec->file_name_is_absolute($port)) {
 	die "$0: no such serial port: $port\n";
     }
 }
-print STDERR "Using serial port device $port\n";
+print STDERR "$0: using serial port device $port\n";
 
 my @espfiles = ();
 
@@ -901,6 +935,11 @@ if (defined($target_board)) {
     }
 }
 
+if ($getver) {
+    print "$0: $port: board version: $target_board\n";
+    exit 0;
+}
+
 my $fpgadata;
 if (defined($file)) {
     my $fwfiles;