4.3 KiB
| title | TARGET DECK | FILE TAGS | tags | ||
|---|---|---|---|---|---|
| Endianness | Obsidian::STEM | binary::endian |
|
Overview
Platforms with multi-byte objects must establish the object's address and byte ordering. Objects are typically addressed by the smallest address of the bytes used. Bytes are ordered either in big-endian or little-endian. In big-endian, the most significant byte is listed first. In little-endian, the least significant byte is ordered first.
%%ANKI Basic Platforms with multi-byte objects must establish what two conventions? Back: The object's address and byte ordering. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic How are multi-byte objects typically addressed? Back: By the smallest address of the bytes used. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic How are bytes of multi-byte objects typically ordered? Back: As big-endian or little-endian. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What is endianness? Back: The ordering of bytes of a multi-byte object. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What does it mean for a byte to be "most significant"? Back: It contribute most to the byte's (decimal) value. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What does it mean for a byte to be "least significant"? Back: It contribute least to the byte's (decimal) value. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What does it mean to be big-endian? Back: The most significant byte is ordered first. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What does it mean to be little-endian? Back: The least significant byte is ordered first. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI
Basic
How are bytes of int32_t x = 0x01234567 written in big-endian?
Back: 0x01 0x23 0x45 0x67
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
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%%ANKI
Basic
How are bytes of int32_t x = 0x01234567 written in little-endian?
Back: 0x67 0x45 0x23 0x01
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
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%%ANKI Cloze Many microprocessors chips are {bi-endian} meaning they can be {configured as either big- or little-endian}. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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#include <stdint.h>
#include <stdio.h>
int main() {
int32_t x = 0x01234567;
for (int i = 0; i < 4; ++i) {
printf("%.2x ", ((unsigned char *)(&x))[i]);
}
}
The above snippet can be used to check endianness on the current machine. If big-endian, the output should be 01 23 45 67. If little-endian, 67 45 23 01.
References
- Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.