trop/tri/encoding.tri

// ---
// tags: trop, trident
// crystal-type: circuit
// crystal-domain: comp
// ---

//  U32 <-> Tropical serialization utilities.
//
//  Tropical elements are stored as raw U32 values.
//  INF (4294967295) encodes +infinity (tropical zero).
//  0 encodes tropical one (multiplicative identity).

module trop.encoding

use trop.element.{INF, Tropical, from_u32, is_inf}

/// Encode a Tropical element to a U32 for serialization.
pub fn encode(t: Tropical) -> U32 {
    t.val
}

/// Decode a U32 into a Tropical element.
pub fn decode(v: U32) -> Tropical {
    from_u32(v)
}

/// Encode a finite value, returning INF if the input equals the sentinel.
/// This is identity — included for explicit documentation in circuits.
pub fn encode_finite(v: U32) -> U32 {
    v
}

/// Decode and check finiteness. Returns 1 if finite, 0 if infinity.
pub fn is_finite_u32(v: U32) -> U32 {
    if v == INF {
        0
    } else {
        1
    }
}

/// Batch encode: copy n Tropical values from an array to raw U32 output.
pub fn batch_encode(src: [Tropical; 64], n: U32) -> [U32; 64] {
    let mut dst: [U32; 64] = [INF; 64]
    for i in 0..64 {
        if i < n {
            dst[i] = src[i].val
        }
    }
    dst
}

/// Batch decode: copy n raw U32 values into Tropical elements.
pub fn batch_decode(src: [U32; 64], n: U32) -> [Tropical; 64] {
    let mut dst: [Tropical; 64] = [Tropical { val: INF }; 64]
    for i in 0..64 {
        if i < n {
            dst[i] = from_u32(src[i])
        }
    }
    dst
}