# (c) Altera

# Setup USB hardware  - assumes only USB Blaster is installed and
# and FPGA is the only device in the JTAG chain

set usb [lindex [get_hardware_names] 0]
set device_name [lindex [get_device_name -hardware_name $usb] 0]

# write procedure : argument value is integer
proc write (value) {
    global device_name usb
    variable full

    start_insystem_source_probe -device_name $device_name -hardware-name $usb
    # read full flag
    set full [read_probe_data -instance_index 0]

    if {$full == 1} {end_insystem_source_probe
    return "Write Buffer Full"
    }

    # toggle select line, drive value onto port, toggle enable
    # bits 7:0 of instance 0 is S_data[7:0]; bit 8 = S_write_reg;
    # bit 9 = Source_write_sel

    # int2bits is custom procedure that returns a bitstring from an integer argument
    write_source_data -instance_index 0 -value [int2bit [expr 0x200 | $value]]
    write_source_data -instance_index 0 -value [int2bit [expr 0x200 | $value]]

    # clear transaction
    write_source_data -instance_index 0 -value 0

    end_insystem_source_probe
}

proc read {} {
    global device_name usb
    variable empty
    start_insystem_source_probe -device_name $device_name -hardware_name $usb

    # read empty flag : probe  port [7:0] reads FIFO output; bit 8 reads empty_flag
    set empty [read_probe_data -instance_index 1]

    if {[regexp {1........} $empty}} {end_insystem_source_probe
    return "FIFO empty" }

    # toggle select line for read transaction
    # Source_read_sel = bit 0; s_read_reg = bit 1
    # pulse read enable on DC FIFO
    write_source_data -instance_index 1 -value 0x1 -value_in_hex
    write_source_data -instance_index 1 -value 0x3 -value_in_hex
    set x [read_probe_data -instance_index 1]

    end_insystem_source_probe
    return $x
}