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'''[[Main Page|Home]] * [[Programming]] * [[Data]] * [[Endianness]] * Little-endian'''
'''Little-endian''' is most often referred to the [[Endianness|endianness]] or order of multiple [[Byte|Bytes]] inside a composite item, such as a [[Word]] (two bytes), a [[Double Word]] (four bytes) or a [[Quad Word]] (eight bytes), which keeps the byte order (in the arithmetical sense) in the order of their addresses in [[Memory|memory]] - for instance the double word integer 16909060 or 0x01020304.
=Memory layout=
0x01020304
{| class="wikitable"
|-
! Address
! Byte
! Significance
|-
| 0x0000
| 0x04
| style="text-align:center;" | LS Byte
|-
| 0x0001
| 0x03
| style="text-align:center;" |
|-
| 0x0002
| 0x02
| style="text-align:center;" |
|-
| 0x0003
| 0x01
| style="text-align:center;" | MS Byte
|}
=Runtime Test=
Following [[C]]-routine returns "true" on little-endian machines, such as [[Intel]] [[x86]]:
<pre>
bool isLittleEndian() {
short one = 0x0001; // 16 bit
return (bool) (*(char*)&one);
}
</pre>
=Little-Endian Files=
File index 0 maps the A-File, index 7 the H-File.
=Little-Endian Ranks=
Rank index 0 maps the first Rank, index 7 the eight Rank.
=Least Significant Files=
* [[Files]] are the little-end below [[Ranks|ranks]]:
<pre>
squareIndex = 8*rankIndex + fileIndex
rankIndex = squareIndex div 8
fileIndex = squareIndex mod 8
</pre>
The LERF-coordianetes with Little-Endian Files and Little-Endian Ranks:
<pre>
enum enumSquare {
a1, b1, c1, d1, e1, f1, g1, h1, // 0 .. 7
a2, b2, c2, d2, e2, f2, g2, h2, // 8 .. 15
a3, b3, c3, d3, e3, f3, g3, h3, // 16 .. 23
a4, b4, c4, d4, e4, f4, g4, h4, // 24 .. 31
a5, b5, c5, d5, e5, f5, g5, h5, // 32 .. 39
a6, b6, c6, d6, e6, f6, g6, h6, // 40 .. 47
a7, b7, c7, d7, e7, f7, g7, h7, // 48 .. 55
a8, b8, c8, d8, e8, f8, g8, h8 // 56 .. 63
};
</pre>
''Note: If printing boards from top to bottom, one has to start with the big-end rank.''
<pre>
A B C D E F G H
+----+----+----+----+----+----+----+----+
8 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 8th rank
+----+----+----+----+----+----+----+----+
7 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 7th rank
+----+----+----+----+----+----+----+----+
6 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 6th rank
+----+----+----+----+----+----+----+----+
5 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 5th rank
+----+----+----+----+----+----+----+----+
4 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 4th rank
+----+----+----+----+----+----+----+----+
3 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 3rd rank
+----+----+----+----+----+----+----+----+
2 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 2nd rank
+----+----+----+----+----+----+----+----+
1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 1st rank
+----+----+----+----+----+----+----+----+
A B C D E F G H - file(s)
</pre>
=Date-Format=
The little-endian date format: dd-mm-yyyy.
=See also=
* [[Big-endian]]
* [[Square Mapping Considerations]]
* [[Flipping Mirroring and Rotating]]
* [[Word]]
* [[Double Word]]
* [[Quad Word]]
=External Links=
* [https://en.wikipedia.org/wiki/Endianness Endianness from Wikipedia]
* [https://www.ietf.org/rfc/ien/ien137.txt IEN 137 - DAV's Endian FAQ - On Holy Wars and a Plea for Peace] by [https://en.wikipedia.org/wiki/Danny_Cohen_(engineer) Danny Cohen], [https://en.wikipedia.org/wiki/Information_Sciences_Institute USC/ISI], April 1, 1980
'''[[Endianness|Up one Level]]'''
'''Little-endian''' is most often referred to the [[Endianness|endianness]] or order of multiple [[Byte|Bytes]] inside a composite item, such as a [[Word]] (two bytes), a [[Double Word]] (four bytes) or a [[Quad Word]] (eight bytes), which keeps the byte order (in the arithmetical sense) in the order of their addresses in [[Memory|memory]] - for instance the double word integer 16909060 or 0x01020304.
=Memory layout=
0x01020304
{| class="wikitable"
|-
! Address
! Byte
! Significance
|-
| 0x0000
| 0x04
| style="text-align:center;" | LS Byte
|-
| 0x0001
| 0x03
| style="text-align:center;" |
|-
| 0x0002
| 0x02
| style="text-align:center;" |
|-
| 0x0003
| 0x01
| style="text-align:center;" | MS Byte
|}
=Runtime Test=
Following [[C]]-routine returns "true" on little-endian machines, such as [[Intel]] [[x86]]:
<pre>
bool isLittleEndian() {
short one = 0x0001; // 16 bit
return (bool) (*(char*)&one);
}
</pre>
=Little-Endian Files=
File index 0 maps the A-File, index 7 the H-File.
=Little-Endian Ranks=
Rank index 0 maps the first Rank, index 7 the eight Rank.
=Least Significant Files=
* [[Files]] are the little-end below [[Ranks|ranks]]:
<pre>
squareIndex = 8*rankIndex + fileIndex
rankIndex = squareIndex div 8
fileIndex = squareIndex mod 8
</pre>
The LERF-coordianetes with Little-Endian Files and Little-Endian Ranks:
<pre>
enum enumSquare {
a1, b1, c1, d1, e1, f1, g1, h1, // 0 .. 7
a2, b2, c2, d2, e2, f2, g2, h2, // 8 .. 15
a3, b3, c3, d3, e3, f3, g3, h3, // 16 .. 23
a4, b4, c4, d4, e4, f4, g4, h4, // 24 .. 31
a5, b5, c5, d5, e5, f5, g5, h5, // 32 .. 39
a6, b6, c6, d6, e6, f6, g6, h6, // 40 .. 47
a7, b7, c7, d7, e7, f7, g7, h7, // 48 .. 55
a8, b8, c8, d8, e8, f8, g8, h8 // 56 .. 63
};
</pre>
''Note: If printing boards from top to bottom, one has to start with the big-end rank.''
<pre>
A B C D E F G H
+----+----+----+----+----+----+----+----+
8 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 8th rank
+----+----+----+----+----+----+----+----+
7 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 7th rank
+----+----+----+----+----+----+----+----+
6 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 6th rank
+----+----+----+----+----+----+----+----+
5 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 5th rank
+----+----+----+----+----+----+----+----+
4 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 4th rank
+----+----+----+----+----+----+----+----+
3 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 3rd rank
+----+----+----+----+----+----+----+----+
2 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 2nd rank
+----+----+----+----+----+----+----+----+
1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 1st rank
+----+----+----+----+----+----+----+----+
A B C D E F G H - file(s)
</pre>
=Date-Format=
The little-endian date format: dd-mm-yyyy.
=See also=
* [[Big-endian]]
* [[Square Mapping Considerations]]
* [[Flipping Mirroring and Rotating]]
* [[Word]]
* [[Double Word]]
* [[Quad Word]]
=External Links=
* [https://en.wikipedia.org/wiki/Endianness Endianness from Wikipedia]
* [https://www.ietf.org/rfc/ien/ien137.txt IEN 137 - DAV's Endian FAQ - On Holy Wars and a Plea for Peace] by [https://en.wikipedia.org/wiki/Danny_Cohen_(engineer) Danny Cohen], [https://en.wikipedia.org/wiki/Information_Sciences_Institute USC/ISI], April 1, 1980
'''[[Endianness|Up one Level]]'''
