Data Encoding

Custom data types

Sphinx uses several custom data types on top of the primitive types offered by Cairo.

We do not rely on the native signed integer type as we rely on math operations that are not currently implemented by the Cairo core lib.

i32

i32 {
    val: u32
    sign: bool
}

The i32 type is used for storing unshifted limits.

i128

i128 {
    val: u128
    sign: bool
}

The i128 type is used for storing liquidity deltas.

i256

i256 {
    val: u256
    sign: bool
}

The i256 type is used for storing token amount deltas.

Limit shifting

For simplicity and efficiency, limits are stored in shifted form by mapping unshifted i32 limits to shifted u32 limits.

Specifically, an offset equal to the largest possible multiple of the market width is applied for shifting and unshifting.