59 lines
1.2 KiB
Plaintext
59 lines
1.2 KiB
Plaintext
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.TH READNUM 9
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.SH NAME
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readnum, readstr \- device read routines
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.SH SYNOPSIS
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.ta \w'\fLint 'u
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.B
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int readstr(ulong off, char *buf, ulong n, char *str)
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.PP
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.B
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int readnum(ulong off, char *buf, ulong n, ulong val, int size)
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.SH DESCRIPTION
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.I Readstr
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and
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.I readnum
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simplify the return of strings and numbers from device
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.I read
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routines,
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because they deal with any buffering and boundary cases.
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Several parameters to the read call are often handed on directly
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to these functions:
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the file offset, as
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.IR off ;
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the address of the user's buffer, as
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.IR buf ;
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and the number of bytes requested, as
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.IR n .
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Both functions return the number of bytes they have stored in
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.IR buf ,
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and which can often be returned directly from the device read routine.
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.PP
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.I Readstr
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satisfies a read by copying data into
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.I buf
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from the NUL-terminated string in
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.IR str .
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The data transferred is selected and limited by
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.IR off ,
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.I n
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and the length of
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.IR str .
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.PP
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.I Readnum
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converts the unsigned integer
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.I val
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to a decimal representation in
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.IR buf .
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The value is right-justified in a field of
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.IR size "-1"
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places and is followed by a blank.
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.I Size
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can be the global constant
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.L NUMSIZE
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for 32-bit integers;
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the largest
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.I size
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allowed is 64 bytes.
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.SH SOURCE
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.B /sys/src/9/port/devcons.c
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