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Svc::FileUplink Component

1 Introduction

FileUplink is an active ISF component. It manages uplink of files to the spacecraft.

2 Requirements

Requirement Description Rationale Verification Method
ISF-FU-001 FileUplink shall receive file packets, assemble them into files, and store the files in the on-board non-volatile storage. This requirement provides the capability to uplink files to the spacecraft. Test

3 Design

3.1 Assumptions

The design of FileUplink assumes the following:

  1. File uplink occurs by dividing files into packets of type Fw::FilePacket.

  2. In the nominal case of file uplink

    a. Files are received one at a time. All packets of one file are received before receiving any packets of the next file.

    b. Within a file, packets are received in order.

3.2 Block Description Diagram (BDD)

FileUplink BDD

3.3 Ports

3.3.1 Role Ports

Name Type Role
timeCaller Fw::Time TimeGet
tlmOut Fw::Tlm Telemetry
eventOut Fw::LogEvent LogEvent

3.3.2 Component-Specific Ports

Name Type Kind Purpose
bufferSendIn Fw::BufferSend async input Receives buffers containing file packets.
bufferSendOut Fw::BufferSend output Returns buffers for deallocation.

3.4 State

FileUplink maintains the following state:

  • receiveMode: One of START or DATA, recording the type of the next packet that FileUplink expects to receive. The initial value is START.

  • lastSequenceIndex: An integer recording the sequence index of the last packet received. The initial value is zero.

  • writeFileDescriptor: The file descriptor of the file, if any, that is currently open for writing.

3.5 The bufferSendIn Port

FileUplink asynchronously receives buffers on bufferSendIn. Each buffer contains a file packet. When FileUplink receives a buffer, it (a) determines the type of the file packet in the buffer; (b) takes action as specified in section below corresponding to the packet type; and (c) invokes bufferSendOut to return the buffer for deallocation.

3.5.1 START Packets

Upon receipt of a START packet, FileUplink does the following:

  1. If receiveMode is not START, then close the file at writeFileDescriptor and issue an InvalidReceiveMode warning.

  2. Open the file for writing and set writeFileDescriptor.

  3. If step 2 succeeded, then set lastSequenceIndex to zero and go to DATA mode; otherwise issue a FileOpenError warning and go to START mode.

3.5.2 DATA Packets

Upon receipt of a DATA packet P, FileUplink does the following, where I is the sequence index of P:

  1. If receiveMode is not DATA, then issue an InvalidReceiveMode warning and go to START mode.

  2. Otherwise

    a. If I is not equal to lastSequenceIndex + 1, then issue a PacketOutOfOrder warning reporting lastSequenceIndex and I.

    b. If the packet offset and size are in bounds for the current file, then

    1. Using writeFileDescriptor, write the file data in the packet at offset specified in the packet.

    2. If there was an error writing the file, then issue a FileWriteError warning.

    c. Otherwise issue a PacketOutOfBounds warning.

3.5.3 END Packets

Upon receipt of an END packet P, FileUplink does the following:

  1. If receiveMode is DATA, then do the following, where I is the sequence index of P:

    a. If I is not equal to lastSequenceIndex + 1, then issue a PacketOutOfOrder warning reporting lastSequenceIndex and I.

    b. Use writeFileDescriptor to do the following:

    1. Use the method described in § 4.1.2 of the CCSDS File Delivery Protocol (CFDP) Recommended Standard to compute the checksum value for the file.

    2. Compare the value computed in the previous step against the checksum value in the packet. If the two values are different, then issue a BadChecksum warning.

    c. Close the file.

  2. Otherwise issue an InvalidReceiveMode warning.

  3. Set lastSequenceIndex to zero and go to START mode.

3.5.4 CANCEL Packets

Upon receipt of a cancel packet P, FileUplink does the following:

  1. Set lastSequenceIndex to zero.

  2. If receiveMode is not START, then close the file at writeFileDescriptor.

  3. Issue an UplinkCanceled event.

  4. Go to START mode.

4 Dictionary

TBD

5 Checklists

Checklist
Design
Code
Unit Test

6 Unit Testing

TODO