printf man page on OpenBSD

Man page or keyword search:  
man Server   11362 pages
apropos Keyword Search (all sections)
Output format
OpenBSD logo
[printable version]

PRINTF(9)		     OpenBSD Kernel Manual		     PRINTF(9)

NAME
     printf, snprintf, vprintf, vsnprintf, uprintf, ttyprintf, db_printf -
     kernel formatted output conversion

SYNOPSIS
     #include <sys/types.h>
     #include <sys/systm.h>

     int
     printf(const char *format, ...);

     int
     snprintf(char *buf, size_t size, const char *format, ...);

     int
     vprintf(const char *format, va_list ap);

     int
     vsnprintf(char *buf, size_t size, const char *fmt, va_list ap);

     void
     uprintf(const char *format, ...);

     void
     ttyprintf(struct tty *tty, const char *format, ...);

     void
     db_printf(const char *format, ...);

DESCRIPTION
     The printf(), snprintf(), vprintf(), vsnprintf(), uprintf(), ttyprintf(),
     and db_printf() functions allow the kernel to send formatted messages to
     various output devices.  The functions printf() and vprintf() send
     formatted strings to the system console and to the system log.  The
     functions uprintf() and ttyprintf() send formatted strings to the current
     process's controlling tty and a specific tty, respectively.  The function
     db_printf() sends formatted strings to the ddb console, and is only used
     to implement ddb(4).

     Since each of these kernel functions is a variant of its user space
     counterpart, this page describes only the differences between the user
     space and kernel versions.	 Refer to printf(3) for functional details.

   FORMAT OPTIONS
     The kernel functions don't support any floating point formatting
     specifiers.  In addition to other formatting specifiers common with the
     user space functions, the kernel functions accept the following format
     specifiers in the format string format:

     %b	   Bit field expansion.	 This format specifier is useful for decoding
	   bit fields in device registers.  It displays an integer using a
	   specified radix (base) and an interpretation of the bits within
	   that integer as though they were flags.  It requires two arguments
	   from the argument vector, the first argument being the bit field to
	   be decoded (as an integer) and the second being a decoding
	   directive string.

	   The decoding directive string describes how the bitfield is to be
	   interpreted and displayed.  The first character of the string is a
	   binary character representation of the output numeral base in which
	   the bitfield will be printed before it is decoded.  Recognized
	   radix values (in C escape-character format) are \10 (octal), \12
	   (decimal), and \20 (hexadecimal).

	   The remaining characters in the decoding directive string are
	   interpreted as a list of bit-position-description pairs.  A bit-
	   position-description pair begins with a binary character value that
	   represents the position of the bit being described.	A bit position
	   value of one describes the least significant bit.  Whereas a
	   position value of 32 (octal 40, hexadecimal 20, the ASCII space
	   character) describes the most significant bit.

	   To deal with more than 32 bits, the characters 128 (octal 200,
	   hexadecimal 80) through 255 (octal 377, hexadecimal FF) are used.
	   The value 127 is subtracted from the character to determine the bit
	   position (1 is least significant, and 128 is most significant).

	   The remaining characters in a bit-position-description pair are the
	   characters to print should the bit being described be set.
	   Description strings are delimited by the next bit position value
	   character encountered (distinguishable by its value being <= 32 or
	   >= 128), or the end of the decoding directive string itself.

     %r	   Displays an integer using the current DDB radix.  This non-standard
	   interpretation of %r is only available to db_printf().

     %z	   Displays a signed integer using the C-style hexadecimal constant
	   format.  This format specifier is only available to db_printf().

RETURN VALUES
     The printf() and vprintf() functions return the number of characters
     printed.

     The snprintf() and vsnprintf() functions return the number of characters
     that would have been put into the buffer buf if the size were unlimited.

EXAMPLES
     Use of the %b format specifier for decoding device registers.

	   printf("reg=%b\n", 3, "\10\2BITTWO\1BITONE")
	   => "reg=3<BITTWO,BITONE>"

	   printf("enablereg=%b\n", 0xe860,
		  "\20\x10NOTBOOT\x0fFPP\x0eSDVMA\x0cVIDEO"
		  "\x0bLORES\x0aFPA\x09DIAG\x07CACHE"
		  "\x06IOCACHE\x05LOOPBACK\x04DBGCACHE")
	   => "enablereg=e860<NOTBOOT,FPP,SDVMA,VIDEO,CACHE,IOCACHE>"

CODE REFERENCES
     sys/kern/subr_prf.c

SEE ALSO
     revoke(2), printf(3), ddb(4), log(9)

OpenBSD 4.9			 June 26, 2008			   OpenBSD 4.9
[top]

List of man pages available for OpenBSD

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net