HP-UX Reference (11i v2 04/09) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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termio(7) termio(7)
If PARMRK is set, and IGNPAR is clear, a character with a framing or parity error (other than break) is
read as the three-character sequence:
\377, \0, X, where X is the data of the character received in
error. To avoid ambiguity in this case, if
ISTRIP is clear, a valid character of \377 is read as \377,
\377. If both PARMRK and IGNPAR are clear, a framing or parity error (other than break) is read as
the character \0.
If
INPCK is set, input parity checking is enabled. If
INPCK is clear, input parity checking is disabled.
Whether input parity checking is enabled or disabled is independent of whether parity detection is
enabled or disabled (see Control Modes). If
PARENB is set (see Control Modes) and INPCK is clear, par-
ity generation is enabled but input parity checking is disabled; the hardware to which the terminal is con-
nected will recognize the parity bit, but the terminal special file will not check whether this bit is set
correctly or not.
The following table shows the interrelationship between the flags
IGNBRK, BRKINT, IGNPAR, and
PARMRK. The column marked Input gives various types of input characters received, indicated as fol-
lows:
0 NUL character (\0)
C Character other than NUL
P Parity error detected
F Framing error detected
Items enclosed in brackets indicate one or more of the conditions are true.
If the
INPCK flag is clear, characters received with parity errors are not processed according to this
table, but instead, as if no parity error had occurred. Under the flag columns, Set
indicates the flag is
set,
Clear indicates the flag is not set, and X indicates the flag may be set or clear. The column labeled
Read shows the results that will be passed to the application code. A — indicates that no character or
condition is passed to the application code. The value SIGINT indicates that no character is returned,
but that the SIGINT signal is sent to the foreground process group of the controlling terminal.
Input 1IGNBRK BRKINT IGNPAR PARMRK Read
0[PF] Set X X X —
0[PF] Clear Set X X SIGINT
0[PF] Clear Clear X Set ’\377’,’\0’,’\0’
0[PF] Clear Clear X Clear ’\0’
C[PF] X X Set X —
C[PF] X X Clear Set ’\377’,’\0’,C
C[PF] X X Clear Clear ’\0’
’\377’ X X X Set ’\377’,’\377’
If
ISTRIP is set, valid input characters are first stripped to 7-bits, otherwise all 8-bits are processed.
If
INLCR is set, a received NL character is translated into a CR character. If IGNCR is set, a received
CR character is ignored (not read). If
IGNCR is clear and ICRNL is set, a received CR character is
translated into a NL character.
If
IUCLC is set, a received uppercase alphabetic character is translated into the corresponding lowercase
character.
If
IXON is set, start/stop output control is enabled. A received STOP character suspends output and a
received START character restarts output. If IXANY and IXON are set, any input character without a
framing or parity error restarts output that has been suspended. When these three flags are set, output
suspended, and an input character received with a framing or parity error, output resumes if processing
it results in data being read. When IXON is set, START and STOP characters are not read, but merely
perform flow control functions. When IXON is clear, the START and STOP characters are read.
If
IXOFF is set, start/stop input control is enabled. The system transmits a STOP character when the
number of characters in the input queue exceeds a system defined value (high water mark). This is
intended to cause the terminal device to stop transmitting data in order to prevent the number of charac-
ters in the input queue from exceeding MAX_INPUT. When enough characters have been read from the
input queue that the number of characters remaining is less than another system defined value (low
water mark), the system transmits a START character which is intended to cause the terminal device to
resume transmitting data (without risk of overflowing the input queue). In order to avoid potential
deadlock, IXOFF is ignored in canonical mode whenever there is no line delimiter in the input buffer. In
this case, the STOP character is not sent at the high water mark, but will be transmitted later if a delim-
iter is received. If all complete lines are read from the input queue leaving only a partial line with no line
delimiter, the START character is sent, even if the number of characters is still greater than the low
Section 7−−182 Hewlett-Packard Company − 8 − HP-UX 11i Version 2: September 2004