specification

来自「mpc8xx driver(led), based on tqm8」· 代码 · 共 91 行

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 *
 * (C) Copyright 2000
 * Jean-Jacques Germond, Fr閐閞ic Soulier, Christian Batt; Alcatel
 * C/O [e-mail]
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Trivial driver spec


On writing, The files look like files with a "physical" content of at
most TRV_MAX_CHARS at head, followed by a /dev/nill like device.


     +---------------------------+  <---   begining of file
     |                           |
     |                           |
     |                           |
     |                           |
     |      Physical area        |
     |                           |
     |                           |
     |                           |
     |                           |
     |                           |
     +---------------------------+  <--- TRV_MAX_CHARS
     .                           .
     .                           .
     .                           .
     .                           .
     .                           .
     .                           .
     . Infinite unrecorded area  .
     .                           .
     .                           .
     .                           .
     .                           .
     .                           .







On reading, files look like files with a max length of TRV_MAX_CHARS.


open      standard AR open

write     write at most TRV_MAX_CHARS in the driver's static buffer.
          If the buffer becomes full, then switch to the /dev/null mode,
          that is accept and silently drop any incomming bytes.

read      returns:

               "TRV_EMPTY"  if no write was done.
                The string (or max size) if write was done (and update the
                file position)
                EOF as appropriate.

close     standard AR close


seek      standard seek



Note that inod & ivol as statically allocated because dynamic
allocation such as (AR pg 45) (Alesssandro Rubini) requests tools
such as mknod and awk that I do not want to put in the webphone
ramdisk. (ie too costly for embedded application).