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Update function-buffer-varints.md

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docs/function-buffer-varints.md
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@ -19,30 +19,36 @@ One of the top use cases for buffers is compressing and serializing data as smal
The following are implementations of ULEB-128 reading/writing in Luau:
```lua
local function writeuleb128(stream, value)
local function writeuleb128(stream, offset, value)
local start = offset
while value >= 0x80 do
buffer.writeu8(bit32.bor(bit32.band(value, 0x7f), 0x80))
buffer.writeu8(stream, offset, bit32.bor(bit32.band(value, 0x7f), 0x80))
value = bit32.rshift(value, 7)
offset = offset + 1
end
buffer.writeu8(value)
buffer.writeu8(stream, offset, value)
return (offset - start) + 1
end
```
```lua
local function readuleb128(stream)
local result = 0
local bits = 0
while true do
local byte = buffer.readu8(stream)
result = bit32.bor(result, bit32.lshift(bit32.band(byte, 0x7f), bits))
if byte < 0x80 then
break
end
bits = bits + 7
end
return result
local function readuleb128(stream, offset)
local result, shift = 0, 0
local length = buffer.len(stream)
local start = offset
repeat
local byte = buffer.readu8(stream, offset)
result = bit32.bor(result, bit32.lshift(bit32.band(byte, 0x7f), shift))
shift, offset = shift + 7, offset + 1
until byte < 0x80 or length <= offset
return result, offset - start
end
```
The functions above are inefficient and difficult to understand compared to a library implementation. In some very common examples such as network event compression or data decompression, these functions can be called hundreds or even thousands of times per second. Library implementations would solve all readability/complexity, performance, and compression efficiency problems.
## Design