scheme-libraries/retropikzel/leb128

LEB128 or Little Endian Base 128 is a variable-length code compression used to store arbitrarily large integers in a small number of bytes.

(integer->leb128 value)

value must be exact integer. Returns the integer as leb128 bytevector.

(leb128->integer bv . start-index)

bv must be bytevector. Reading of leb128 values start at index 0, unless start-index is given. start-index must be exact integer. Returns exact integer of leb128 value.

(leb128->integer-and-length bv . start-index)

Sams as leb128->integer but returns a pair with integer as car and leb128 bytevector length, as in how many bytes long the leb128 was, as cdr.

(integer->uleb128 value)

value must be exact positive integer or 0. Returns the integer as leb128 bytevector.

(uleb128->integer bv)

bv must be bytevector. Reading of uleb128 values start at index 0, unless start-index is given. start-index must be exact integer. Returns exact positive integer or 0 of uleb128 value.

(uleb128->integer-and-length bv)

Sams as uleb128->integer but returns a pair with integer as car and uleb128 bytevector length, as in how many bytes long the leb128 was, as cdr.

Resources used: https://en.wikipedia.org/wiki/LEB128 - Mostly turning pseudocode from here to Scheme https://github.com/mohanson/leb128 - Code for leb128 to integer handling as we dont know integer size like in C