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.\"     Title: mtbl_varint
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 01/31/2014
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.\"    Source: \ \&
.\"  Language: English
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.TH "MTBL_VARINT" "3" "01/31/2014" "\ \&" "\ \&"
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.SH "NAME"
mtbl_varint \- Variable\-width encoding and decoding of 32 and 64 bit integers
.SH "SYNOPSIS"
.sp
\fB#include <mtbl\&.h>\fR
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\fBunsigned mtbl_varint_length(uint64_t \fR\fB\fIvalue\fR\fR\fB);\fR
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\fBunsigned mtbl_varint_length_packed(const uint8_t *\fR\fB\fIbuf\fR\fR\fB, size_t \fR\fB\fIlen_buf\fR\fR\fB);\fR
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\fBsize_t mtbl_varint_encode32(uint8_t *\fR\fB\fIptr\fR\fR\fB, uint32_t \fR\fB\fIvalue\fR\fR\fB);\fR
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\fBsize_t mtbl_varint_encode64(uint8_t *\fR\fB\fIptr\fR\fR\fB, uint64_t \fR\fB\fIvalue\fR\fR\fB);\fR
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\fBsize_t mtbl_varint_decode32(const uint8_t *\fR\fB\fIptr\fR\fR\fB, uint32_t *\fR\fB\fIvalue\fR\fR\fB);\fR
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\fBsize_t mtbl_varint_decode64(const uint8_t *\fR\fB\fIptr\fR\fR\fB, uint64_t *\fR\fB\fIvalue\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
\fBmtbl_varint_encode32\fR() and \fBmtbl_varint_encode64\fR() write the 32 or 64 bit quantity, respectively, in the argument \fIvalue\fR to the buffer in the argument \fIdst\fR\&. The quantity will be written in using a variable\-width encoding that uses at most 5 bytes for a 32 bit quantity or 10 bytes for a 64 bit quantity\&.
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\fBmtbl_varint_decode32\fR() and \fBmtbl_varint_decode64\fR() read the 32 or 64 bit varint quantity, respectively, in the argument \fIptr\fR\&. The quantity read will be placed in the argument \fIvalue\fR\&.
.sp
Bounds checking must be performed by the caller\&.
.SH "RETURN VALUE"
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\fBmtbl_varint_encode32\fR() and \fBmtbl_varint_encode64\fR() return the number of bytes written to \fIdst\fR\&.
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\fBmtbl_varint_decode32\fR() and \fBmtbl_varint_decode64\fR() return the number of bytes read from \fIptr\fR\&.
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\fBmtbl_varint_length\fR() returns the number of bytes that its argument \fIvalue\fR would require in the variable\-width encoding\&.
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\fBmtbl_varint_length_packed\fR() returns the number of bytes consumed by the variable\-width encoded quantity at its argument \fIdata\fR\&. It will read at most \fIlen_buf\fR bytes from \fIdata\fR\&. The value 0 is returned if a valid varint is not present\&.