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# nmea.tcl --
#
# NMEA protocol implementation
#
# Copyright (c) 2006-2007 Aaron Faupell
#
# RCS: @(#) $Id: nmea.tcl,v 1.3 2007/08/20 21:55:27 andreas_kupries Exp $
package require Tcl 8.2
package provide nmea 0.1.1
namespace eval ::nmea {
set ::nmea::nmea(checksum) 1
set ::nmea::nmea(log) ""
}
proc ::nmea::open_port {port {speed 4800}} {
variable nmea
set nmea(fh) [open $port]
fconfigure $nmea(fh) -mode $speed,n,8,1 -handshake xonxoff -buffering line -translation crlf
fileevent $nmea(fh) readable [list ::nmea::read_port $nmea(fh)]
return 1
}
proc ::nmea::open_file {file rate} {
variable nmea
set nmea(fh) [open $file]
set nmea(rate) $rate
fconfigure $nmea(fh) -buffering line -blocking 0 -translation auto
if {$rate > 0} {
after $rate [list ::nmea::read_file $nmea(fh)]
}
}
proc ::nmea::configure_port {settings} {
variable nmea
fconfigure $nmea(fh) -mode $settings
}
proc ::nmea::close_port {} {
variable nmea
catch {close $nmea(fh)}
}
proc ::nmea::close_file {} {
variable nmea
catch {close $nmea(fh)}
}
proc ::nmea::read_port {f} {
set line [gets $f]
if {$::nmea::nmea(log) != ""} {
puts $::nmea::nmea(log) $line
}
::nmea::parse_nmea $line
}
proc ::nmea::read_file {f} {
variable nmea
if {![eof $f]} {
set line [gets $f]
if {[string match {$*} $line]} {
::nmea::parse_nmea $line
} else {
::nmea::parse_nmea \$$line
}
}
after $nmea(rate) [list ::nmea::read_file $f]
}
proc ::nmea::do_line {} {
variable nmea
if {![eof $nmea(fh)]} {
set line [gets $nmea(fh)]
if {[string match {$*} $line]} {
::nmea::parse_nmea $line
} else {
::nmea::parse_nmea \$$line
}
}
}
proc ::nmea::log {file} {
variable nmea
if {$file != ""} {
if {$nmea(log) != ""} { error "already logging to a file" }
set nmea(log) [open $file a]
} else {
catch {close $nmea(log)}
set nmea(log) ""
}
}
proc ::nmea::parse_nmea {line} {
set line [split $line \$*]
set cksum [lindex $line 2]
set line [lindex $line 1]
if {$cksum == "" || !$::nmea::nmea(checksum) || [checksum $line] == $cksum} {
set line [split $line ,]
set sentence [lindex $line 0]
set line [lrange $line 1 end]
if {[info commands ::nmea::$sentence] != ""} {
$sentence $line
}
}
}
proc ::nmea::checksum {line} {
set sum 0
binary scan $line c* line
foreach char $line {
set sum [expr {$sum ^ ($char % 128)}]
}
return [format %02X [expr {$sum % 256}]]
}
proc ::nmea::write {type args} {
variable nmea
set data $type,[join $args ,]
puts $nmea(fh) \$$data*[checksum $data]
}
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