The use case here is that sometimes when dealing with leb128 you'll often have a scenario where a leb128 integer denotes how many bytes left in the region are part of a section or unit. When encoding, though, we often don't know the length of the section up-front, so a common trick is to do something like:
For a u32 encoded as leb128, reserve 5 bytes of space
Encode the entire section
Encode the length of the section into the previously reserved 5 bytes of space
This encoding uses the maximal instead of minimal width, using "padding zero bytes" that look like 0x80 to ensure that leb128 eats up all 5 of the bytes reserved.
It'd be neat if this crate supported such a use case (it's sort of like Seek with writers), although I'd be fine just supporting it with slices for the time being!
This came up during https://github.com/rustwasm/walrus/pull/30, specifically https://github.com/rustwasm/walrus/pull/30#discussion_r251137366.
The use case here is that sometimes when dealing with leb128 you'll often have a scenario where a leb128 integer denotes how many bytes left in the region are part of a section or unit. When encoding, though, we often don't know the length of the section up-front, so a common trick is to do something like:
This encoding uses the maximal instead of minimal width, using "padding zero bytes" that look like 0x80 to ensure that leb128 eats up all 5 of the bytes reserved.
It'd be neat if this crate supported such a use case (it's sort of like
Seekwith writers), although I'd be fine just supporting it with slices for the time being!