Summary

1. Read Block Limits now has the len variable set instead of directly using a magic number, as well as setting the buflen pointer.
2. On some SCSI controllers, the buffer length isn't automatic (so it gets set to -1 until being allocated and set again properly) so adjust the read 6 command to set the total bytes as the allocated buffer length when fixed block mode is set as well as when either filemark or eod are set. This fixes hang ups when using some SCSI controllers with the Archive tape drive.

Checklist

• Closes #xxx
• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/
• This pull request requires changes to the asset set
  • I have opened an assets pull request - https://github.com/86Box/assets/pull/changeme/

References

Archive Viper SCSI