290 lines
7.9 KiB
Groff
290 lines
7.9 KiB
Groff
.\" $NetBSD: snprintb.3,v 1.16 2013/08/07 23:22:28 pgoyette Exp $
|
|
.\"
|
|
.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Jeremy Cooper.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd May 7, 2009
|
|
.Dt SNPRINTB 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm snprintb
|
|
.Nd bitmask output conversion
|
|
.Sh LIBRARY
|
|
.Lb libutil
|
|
.Sh SYNOPSIS
|
|
.In util.h
|
|
.Ft int
|
|
.Fn "snprintb" "char *buf" "size_t buflen" "const char *fmt" "uint64_t val"
|
|
.Ft int
|
|
.Fn "snprintb_m" "char *buf" "size_t buflen" "const char *fmt" "uint64_t val" \
|
|
"size_t max"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn snprintb
|
|
function formats a bitmask into a mnemonic form suitable for printing.
|
|
.Pp
|
|
This conversion is useful for decoding bit fields in device registers.
|
|
It formats the integer
|
|
.Fa val
|
|
into the buffer
|
|
.Fa buf ,
|
|
of size
|
|
.Fa buflen ,
|
|
using a specified radix and an interpretation of
|
|
the bits within that integer as though they were flags.
|
|
The buffer is always NUL-terminated.
|
|
If the buffer
|
|
.Fa buf
|
|
is too small to hold the formatted output,
|
|
.Fn snprintb
|
|
will fill as much as it can, and return the number of bytes
|
|
that would have written if the buffer was long enough excluding the
|
|
terminating NUL.
|
|
.Pp
|
|
The decoding directive string
|
|
.Fa fmt
|
|
describes how the bitfield is to be interpreted and displayed.
|
|
It follows two possible syntaxes, referred to as
|
|
.Dq old
|
|
and
|
|
.Dq new .
|
|
The main advantage of the
|
|
.Dq new
|
|
formatting is that it is capable of handling multi-bit fields.
|
|
.Pp
|
|
The first character of
|
|
.Fa fmt
|
|
may be
|
|
.Li \e177 ,
|
|
indicating that the remainder of the format string follows the
|
|
.Dq new
|
|
syntax.
|
|
The second character
|
|
.Pq the first for the old format
|
|
is a binary character representation of the
|
|
output numeral base in which the bitfield will be printed before it is decoded.
|
|
Recognized radix values
|
|
.Pq in C escape-character format
|
|
are
|
|
.Li \e10
|
|
.Pq octal ,
|
|
.Li \e12
|
|
.Pq decimal ,
|
|
and
|
|
.Li \e20
|
|
.Pq hexadecimal .
|
|
.Pp
|
|
The remaining characters in
|
|
.Fa fmt
|
|
are interpreted as a list of bit-position\(endescription pairs.
|
|
From here the syntaxes diverge.
|
|
.Pp
|
|
The
|
|
.Dq old
|
|
format syntax is series of bit-position\(endescription pairs.
|
|
Each 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
|
|
.Pq octal 40, hexadecimal 20, the ASCII space character
|
|
describes the most significant bit.
|
|
.Pp
|
|
The remaining characters in a bit-position\(endescription 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
|
|
.Pq distinguishable by its value being \*[Le] 32 ,
|
|
or the end of the decoding directive string itself.
|
|
.Pp
|
|
For the
|
|
.Dq new
|
|
format syntax, a bit-position\(endescription begins with a field type
|
|
followed by a binary bit-position and possibly a field length.
|
|
The least significant bit is bit-position zero, unlike the
|
|
.Dq old
|
|
syntax where it is one.
|
|
.Bl -tag -width "xxxxx"
|
|
.It Cm b\eB
|
|
Describes a bit position.
|
|
The bit-position
|
|
.Fa B
|
|
indicates the corresponding bit, as in the
|
|
.Dq old
|
|
format.
|
|
.It Cm f\eB\eL
|
|
Describes a multi-bit field beginning at bit-position
|
|
.Fa B
|
|
and having a bit-length of
|
|
.Fa L .
|
|
The remaining characters are printed as a description of the field
|
|
followed by
|
|
.Sq \&=
|
|
and the value of the field.
|
|
The value of the field is printed in the base specified as the second
|
|
character of the decoding directive string
|
|
.Ar fmt .
|
|
.It Cm F\eB\eL
|
|
Describes a multi-bit field like
|
|
.Sq f ,
|
|
but just extracts the value for use with the
|
|
.Sq \&=
|
|
and
|
|
.Sq \&:
|
|
formatting directives described below.
|
|
.It Cm \&=\eV
|
|
The field previously extracted by the last
|
|
.Sq f
|
|
or
|
|
.Sq F
|
|
operator is compared to the byte
|
|
.Sq Cm V
|
|
.Pq for values 0 through 255 .
|
|
If they are equal,
|
|
.Sq \&=
|
|
followed by the string following
|
|
.Sq Cm V
|
|
is printed.
|
|
This and the
|
|
.Sq \&:
|
|
operator may be repeated to annotate multiple possible values.
|
|
.It Cm :\eV
|
|
Operates like the
|
|
.Sq \&=
|
|
operator, but omits the leading
|
|
.Sq \&= .
|
|
.El
|
|
.Pp
|
|
Finally, each field is delimited by a NUL
|
|
.Pq Sq \e0
|
|
character.
|
|
By convention, the format string has an additional NUL character at
|
|
the end, following that delimiting the last bit-position\(endescription
|
|
pair.
|
|
.Pp
|
|
The
|
|
.Fn snprintb_m
|
|
function accepts an additional
|
|
.Fa max
|
|
argument.
|
|
If this argument is zero, the
|
|
.Fn snprintb_m
|
|
function returns exactly the same results in the
|
|
.Fa buf
|
|
as the
|
|
.Fn snprintb
|
|
function.
|
|
If the
|
|
.Fa max
|
|
argument is present and has a non-zero value, it represents the maximum
|
|
length of a formatted string.
|
|
If the formatted string would require more than
|
|
.Fa max
|
|
characters, the
|
|
.Fn snprintb_m
|
|
function returns multiple formatted strings in the output buffer
|
|
.Fa buf .
|
|
Each string is NUL-terminated, and the last string is followed by an
|
|
additional NUL character (or, if you prefer, a zero-length string).
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn snprintb
|
|
and
|
|
.Fn snprintb_m
|
|
functions return the number of bytes that would have written to the buffer
|
|
if there was adequate space, excluding the final terminating NUL, or \-1 in
|
|
case an error occurred.
|
|
For
|
|
.Fn snprintb_m ,
|
|
the NUL characters terminating each individual string are included in the
|
|
total number of bytes.
|
|
.Sh EXAMPLES
|
|
Two examples of the old formatting style:
|
|
.Bd -literal -offset indent
|
|
snprintb(buf, buflen, "\e10\e2BITTWO\e1BITONE", 3)
|
|
\(rA "03<BITTWO,BITONE>"
|
|
|
|
snprintb(buf, buflen,
|
|
"\e20\ex10NOTBOOT\ex0f" "FPP\ex0eSDVMA\ex0cVIDEO"
|
|
"\ex0bLORES\ex0a" "FPA\ex09" "DIAG\ex07" "CACHE"
|
|
"\ex06IOCACHE\ex05LOOPBACK\ex04" "DBGCACHE",
|
|
0xe860)
|
|
\(rA "0xe860<NOTBOOT,FPP,SDVMA,VIDEO,CACHE,IOCACHE>"
|
|
.Ed
|
|
.Pp
|
|
An example of the new formatting style:
|
|
.Bd -literal -offset indent
|
|
snprintb(buf, buflen,
|
|
"\e177\e020b\e0LSB\e0b\e1_BITONE\e0f\e4\e4NIBBLE2\e0"
|
|
"f\ex10\e4BURST\e0=\e4FOUR\e0=\exfSIXTEEN\e0"
|
|
"b\ex1fMSB\e0\e0",
|
|
0x800f0701)
|
|
\(rA "0x800f0701<LSB,NIBBLE2=0x0,BURST=0xf=SIXTEEN,MSB>"
|
|
.Ed
|
|
.Pp
|
|
An example using snprintb_m:
|
|
.Bd -literal -offset indent
|
|
snprintb_m(buf, buflen,
|
|
"\e177\e020b\e0LSB\e0b\e1_BITONE\e0f\e4\e4NIBBLE2\e0"
|
|
"f\ex10\e4BURST\e0=\e4FOUR\e0=\exfSIXTEEN\e0"
|
|
"b\ex1fMSB\e0\e0",
|
|
0x800f0701, 34)
|
|
\(rA "0x800f0701<LSB,NIBBLE2=0x0>\e00x800f0701<BURST=0xf=SIXTEEN,MSB>\e0"
|
|
.Ed
|
|
.Sh ERRORS
|
|
.Fn snprintb
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The leading character does not describe a supported format,
|
|
or
|
|
.Fn snprintf
|
|
failed.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr printf 3 ,
|
|
.Xr snprintf 3
|
|
.Sh HISTORY
|
|
The
|
|
.Fn snprintb
|
|
function was originally implemented as a non-standard
|
|
.Li %b
|
|
format string for the kernel
|
|
.Fn printf
|
|
function in
|
|
.Nx 1.5
|
|
and earlier releases.
|
|
It was called
|
|
.Fn bitmask_snprintf
|
|
in
|
|
.Nx 5.0
|
|
and earlier releases.
|
|
.Sh AUTHORS
|
|
The
|
|
.Dq new
|
|
format was the invention of
|
|
.An Chris Torek .
|