15,000 DATA POINTS / SEC.
ZERO MAIN-THREAD STUTTER.

// Ring-buffered memory architecture for microsecond ticks
use wasm_bindgen::prelude::*;
use core::arch::wasm32::*;

#[wasm_bindgen]
pub struct OrderbookEngine {
    depth_buffer: Vec<f64>,
    tick_capacity: usize,
    cursor: usize,
}

#[wasm_bindgen]
impl OrderbookEngine {
    pub fn new(capacity: usize) -> Self {
        Self {
            depth_buffer: vec![0.0; capacity * 4],
            tick_capacity: capacity,
            cursor: 0,
        }
    }

    // SIMD vector processing: 4 price levels calculated per instruction
    pub unsafe fn calculate_vwap_simd(&self, ptr: *const f64) -> f64 {
        let mut sum_vol = f64x2_splat(0.0);
        let mut sum_price_vol = f64x2_splat(0.0);

        for i in (0..self.tick_capacity).step_by(2) {
            let p = v128_load(ptr.add(i) as *const v128);
            let v = v128_load(ptr.add(i + 1) as *const v128);
            sum_vol = f64x2_add(sum_vol, v);
            sum_price_vol = f64x2_add(sum_price_vol, f64x2_mul(p, v));
        }
        f64x2_extract_lane::<0>(sum_price_vol) / f64x2_extract_lane::<0>(sum_vol)
    }
}