mirror of
https://github.com/SSCLI/sscli_20021101
synced 2026-06-08 12:28:57 +00:00
yallie
40 lines
2.0 KiB
HTML
40 lines
2.0 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html> <head>
|
|
<title>Encodings used in the Shared Source CLI</title>
|
|
<link rel="stylesheet" type="text/css" href="../rotor.css">
|
|
</head>
|
|
<body>
|
|
<h1 align="left">Encodings Used in the Shared Source CLI</h1>
|
|
|
|
<p>Three encoding techniques are used repeatedly in the Shared
|
|
Source CLI (SSCLI). These are referred to as
|
|
Unsigned, Signed, and UDelta encodings.</p>
|
|
|
|
<h3><strong style="font-weight: 400">Unsigned</strong></h3>
|
|
|
|
<p>This is a sequence of bytes where every byte but the last has the 0x80 bit
|
|
set. The bytes are stored in order from most to least significant. One byte can
|
|
thus encode the numbers 0 to 127 (0x00 to 0x7F), two bytes can encode 128 (0x81
|
|
0x00) to 16383 (0xFF 0x7F), and so forth. Five bytes would be the maximum number
|
|
of bytes needed to encode the largest 32-bit unsigned values.
|
|
</p>
|
|
<h3><strong style="font-weight: 400">Signed</strong></h3>
|
|
<p>This is a sequence of bytes where every byte but the last has the 0x80 bit
|
|
set. The first byte uses the 0x40 bit to encode the sign. The bytes are stored
|
|
in order from most to least significant. After accumulating the unsigned values
|
|
(6 bits from the first byte and 7 bits from each succeeding byte) the result is
|
|
stored in two's complement format if the sign bit was set. One byte can
|
|
thus encode the numbers -63 (0x7f) to 63 (0x3F), two bytes can encode -8191
|
|
(0xFF 0x7F) to 8191 (0xBF 0x7F), and so forth. Five bytes would be the maximum
|
|
number of bytes needed to encode the largest magnitude 32-bit signed values.
|
|
</p>
|
|
<h3><strong style="font-weight: 400">UDelta</strong></h3>
|
|
<p>This is a series of Unsigned encodings where each is an increment to the sum
|
|
of all of the previous values. This is used to encode a stream of
|
|
ever-increasing values (such as offsets in the code segment or in a stack
|
|
frame).
|
|
</p>
|
|
<hr>
|
|
<p><i>Copyright (c) 2002 Microsoft Corporation. All rights reserved.</i></p>
|
|
</body>
|
|
</html> |