[PARPORT] Re: ECPSW mode error?

From: zhu qun ying (qyzhu@krdl.org.sg)
Date: Wed Apr 26 2000 - 07:16:12 EDT

  • Next message: Tim Waugh: "[PARPORT] Re: ECPSW mode error?"

    But there are code like these:

    /* Event 38: Set nAutoFd low */
    parport_frob_control (port,
             PARPORT_CONTROL_AUTOFD,
             PARPORT_CONTROL_AUTOFD);

    that set the slected control to low. There are other codes: like
    In ieee1284.c:180

    /* Event 68: Set nInit low */
    parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
    udelay (50);

    /* Event 69: Set nInit high, nSelectIn low */
    parport_frob_control (port,
                          PARPORT_CONTROL_SELECT
                          | PARPORT_CONTROL_INIT,
                          PARPORT_CONTROL_SELECT
                          | PARPORT_CONTROL_INIT);

    I am totally confused by the usage.

    For the low level frob_control function, the control bits are governed by
    (old_control & ~mask) ^ value,
    That should be what you say about the how frob_control() works.

    Tim Waugh wrote:
    >
    > So, bits not specified in the mask are unchanged, whereas bits
    > specified in the mask take on the corresponding bits in 'value'.
    >
    > frob_control (port, INIT, 0) means set INIT to 0
    > frob_control (port, INIT, INIT) means set INIT to 1
    > frob_control (port, A | B, A) means set A to 1 and B to 0.
    >
    > Yes, please review it.
    >
    > Tim.
    > */
    > 

    -- 
 (~._.~)  Öì Ⱥ Ó¢  (Qun Ying)         (65) 874-6743
  ( O )         Kent Ridge Digital Labs (KRDL)
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