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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: The following are implementations of ULEB-128 reading/writing in Luau:
```lua ```lua
local function writeuleb128(stream, value) local function writeuleb128(stream, offset, value)
local start = offset
while value >= 0x80 do 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) value = bit32.rshift(value, 7)
offset = offset + 1
end end
buffer.writeu8(value) buffer.writeu8(stream, offset, value)
return (offset - start) + 1
end end
``` ```
```lua ```lua
local function readuleb128(stream) local function readuleb128(stream, offset)
local result = 0 local result, shift = 0, 0
local bits = 0 local length = buffer.len(stream)
while true do local start = offset
local byte = buffer.readu8(stream)
result = bit32.bor(result, bit32.lshift(bit32.band(byte, 0x7f), bits)) repeat
if byte < 0x80 then local byte = buffer.readu8(stream, offset)
break result = bit32.bor(result, bit32.lshift(bit32.band(byte, 0x7f), shift))
end shift, offset = shift + 7, offset + 1
bits = bits + 7 until byte < 0x80 or length <= offset
end
return result return result, offset - start
end 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. 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 ## Design