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Date: Mon, 31 Jul 1995 11:29:53 -0700
From: Bruce Evans <bde>
Message-Id: <199507311829.LAA17382@freefall.cdrom.com>
To: CVS-commiters, cvs-sys
Subject: cvs commit: src/sys/i386/isa cy.c rc.c sio.c
Sender: commit-owner@FreeBSD.org
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bde         95/07/31 11:29:52

  Modified:    sys/kern  tty.c
               sys/sys   tty.h
               sys/i386/isa  cy.c rc.c sio.c
  Log:
  Improve input flow control.
  
  Use input buffer watermarks of TTYHOG-512 (high) and (high)*7/8
  (low) instead of TTYHOG/2 (high) and TTYHOG/5 (low) to agree with
  some drivers.  512 is magic and some things depended on TTYHOG/2
  >= TTYHOG-512 to work; now they depend on the 512 magic not changing
  and TTYHOG-512 being significantly larger than 0.  This should be
  handled in ttsetwater().
  
  Separate the decision about whether to do input flow control from
  doing it.  ttyblock() now just starts input flow control (hardware
  and/or software) and there is a new function ttyunblock() to stop
  it.  The decisions are the same except for the watermark changes
  and allowing for input expansion for PARMRK.
  
  When flushing input, try harder at first to send a start character
  if required, but give up if the first attempt fails.
  
  cy.c, rc.c, sio.c:
  Simplify: let ttyinput() handle input flow control if it is not
  being bypassed.  Use ttyblock() to start flow control otherwise.
  
  rc.c:
  Use same input flow control test as elsewhere: test in a more
  efficient order and start flow control at >= highwater instead of
  at > highwater.