Skip to content

Instantly share code, notes, and snippets.

@fdncred

fdncred/bytes_and_bits.md

Last active August 4, 2022 02:14
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save fdncred/6f5fb149c014c6de039401a6a07d3046 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save fdncred/6f5fb149c014c6de039401a6a07d3046 to your computer and use it in GitHub Desktop.
Download ZIP
new nushell commands
Raw
bytes_and_bits.md

Introducing the bytes and the bits command.

Commands specifically made for finding and manipulating binary data. Since naming is hard, we may end up changing the name. :)

the bytes command

potential crates for bytes

  • bytes query the bytes of a buffer

  • bytes at maybe thought of like str sub-string?

    • returns the byte at a specified offset in decimal 10 or hex 0x10
    • returns the bytes in a range if specified like 1..10

  • bytes index-of aka bytes contains

    • finds the index of a specified hex byte 0x10
    • finds the index of a specified byte buffer

  • bytes to-str - point to decode utf-8

    • returns specified bytes as a utf-8 string

  • bytes build

    • kind of like buildstring but for bytes

  • bytes size aka bytes length

    • return the size of something in bytes

  • bytes collect

    • collect bytes like str collect

  • bytes ends-with

    • returns bool of whether a buffer ends with specified byte(s)

  • bytes find-replace aka bytes replace

    • find and replace specified bytes

  • bytes add

    • add specified bytes to the --start, --end, --index

  • bytes remove

    • remove specified bytes from --start, --end, --index

  • bytes reverse

    • reverse a buffer of bytes

  • bytes starts-with

    • returns bool of whether a buffer starts with specified byte(s)

the bits command

protentional crates for bits

  • bits shl aka shift --left aka << -bitwise shift left moves bits left

  • bits shr aka shift --right aka >> -bitwise shift right moves bits right

  • bits rol aka rotate --left

    • bitwise shift left move a bit left and adds it to the right

  • bits ror aka rotate --right

    • bitwise shift right move a bit right and adds it to the left

  • bits and aka &

    • bitwise and performas logical and operation on each pair of bits

  • bits or aka |

    • bitwise or performs logical or operation on each pair of bits

  • bits xor aka ^

    • bitwise xor perofrms logical exclusive or operation on each pair of bits

  • bits not aka ~ aka complement

    • performs logical negation on each bit

TBD - we could add later or make params or leave out and there are many more we could add

  • sal - shift arithmatic left
  • sar - shift arithmatic right
  • rcl - rotate carry left
  • rcr - rotate carry right
  • shld - shift left number of bits
  • shrd - shift right number of bits
@sophiajt
Copy link

sophiajt commented Feb 11, 2022

I was wondering if we should use pseudo-opcodes. Maybe it's just me, but I tend to think in them :D

bits shl, bits shr, bits rol, bits ror

@fdncred
Copy link
Author

fdncred commented Feb 11, 2022 •
edited
Loading

these are the only ones i've ever really used <<, >>, &, |, ^, and ~.

@sholderbach
Copy link

sholderbach commented Mar 2, 2022

How would we define the word size/wrapping condition/endianness for the bit twiddling commands?

@fdncred
Copy link
Author

fdncred commented Mar 2, 2022

@sholderbach Regarding endianness, we did something like this in the nushell into binary command

fn int_to_endian(n: i64) -> Vec<u8> {
    if cfg!(target_endian = "little") {
        n.to_le_bytes().to_vec()
    } else {
        n.to_be_bytes().to_vec()
    }
}

but there's also a sort-of-wrapper also that is to_ne_bytes(). I'm hopeful that this would work.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment