swab(1) - swap bytes #22

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trinity · 2023-12-30T08:36:22-07:00

trinity commented

2023-12-30 08:36:22 -07:00

This pertains to #23 in that it fulfills functionality offered in POSIX by dd(1p), specifically dd conv=swab.

Usage: swab (-w [word size])

swab(1) swaps bytes in standard input to standard output. The default word size is 2, as in two-byte words with the latter half of the word (in this case, one byte) being output before the former half of the word.

$ swab
hello world
ehll oowlrd

If there are remaining bytes less than the word size they're left unconverted. Word sizes up to 16 (128 bits) will be supported.

$ echo hello world | swab -w 8
o wohellrld

The usefulness of such a tool is limited but this should be small and easy to make, and would fill in more POSIX functionality in a way that is simpler than POSIX.

This pertains to #23 in that it fulfills functionality offered in POSIX by dd(1p), specifically `dd conv=swab`. ``` Usage: swab (-w [word size]) ``` swab(1) swaps bytes in standard input to standard output. The default word size is 2, as in two-byte words with the latter half of the word (in this case, one byte) being output before the former half of the word. ```sh $ swab hello world ehll oowlrd ``` If there are remaining bytes less than the word size they're left unconverted. Word sizes up to 16 (128 bits) will be supported. ```sh $ echo hello world | swab -w 8 o wohellrld ``` The usefulness of such a tool is limited but this should be small and easy to make, and would fill in more POSIX functionality in a way that is simpler than POSIX.

trinity referenced this issue

2023-12-30 08:44:13 -07:00

tests/posix: `dd(1p)` #23

trinity added the

enhancement

label 2023-12-30 09:00:34 -07:00

emma added the

help wanted

label 2023-12-30 14:39:42 -07:00

emma removed the

help wanted

label 2023-12-30 14:41:35 -07:00

emma changed title from ~~swab(1) - swap bytes~~ to `swab(1)` - swap bytes

2024-01-23 15:08:00 -07:00

trinity commented

2024-01-29 22:37:46 -07:00

My current conundrum is that there are multiple useful types of byte reversal:

reversing bits in a byte
reversing bytes within a certain block size (e.g. "swabbing" - swapping bytes within a machine word - and the job of GNU tac(1), where all bytes in a file are reversed)
reversing bytes in blocks delimited by a certain byte sequence (e.g. GNU's rev(1), using '\n' or '\0')

The third should be relegated to a separate utility as it's higher level (plaintext) than endianness/bit order tomfoolery. Should the former two be separate utilities?

My current conundrum is that there are multiple useful types of byte reversal: - reversing bits in a byte - reversing bytes within a certain block size (e.g. "swabbing" - swapping bytes within a machine word - and the job of GNU tac(1), where all bytes in a file are reversed) - reversing bytes in blocks delimited by a certain byte sequence (e.g. GNU's rev(1), using '\n' or '\0') The third should be relegated to a separate utility as it's higher level (plaintext) than endianness/bit order tomfoolery. Should the former two be separate utilities?

emma added the

help wanted

label 2024-02-07 20:25:24 -07:00

emma referenced this issue

2024-02-07 20:38:19 -07:00

`flip(1)` – reverse data #48

emma commented

2024-02-07 20:39:14 -07:00

Ah, I didn’t realize GNU had a utility called rev already. Will come up with another name.

Ah, I didn’t realize GNU had a utility called `rev` already. Will come up with another name.

emma commented

2024-02-15 23:12:39 -07:00