direct static method

Float32List direct(Float32List x, Float32List h, { ConvMode mode = ConvMode.convolution, CorrOutMode outMode = CorrOutMode.full, bool simd = false, })

Computes convolution or cross-correlation directly for one block of data.

mode selects the operation:

• ConvMode.convolution: linear convolution.
• ConvMode.xcorr: linear cross-correlation.

outMode selects output support:

• CorrOutMode.full: length nx + nh - 1.
• CorrOutMode.valid: complete-overlap region only.
• CorrOutMode.same: length nx, centered w.r.t. full.

simd enables SIMD acceleration (SSE/NEON/etc) when available. SIMD may produce tiny floating-point differences vs scalar due to accumulation order.

Example:

final x = Float32List.fromList([1, 2, 3]);
final h = Float32List.fromList([1, 1, 1]);
final yFull = Conv.direct(
  x,
  h,
  mode: ConvMode.convolution,
  outMode: CorrOutMode.full,
);
final rSame = Conv.direct(
  x,
  h,
  mode: ConvMode.xcorr,
  outMode: CorrOutMode.same,
  simd: true,
);

Implementation

static Float32List direct(
  Float32List x,
  Float32List h, {
  ConvMode mode = ConvMode.convolution,
  CorrOutMode outMode = CorrOutMode.full,
  bool simd = false,
}) {
  final nx = x.length;
  final nh = h.length;
  final ny = outLenMode(nx, nh, outMode: outMode);

  ffi.Pointer<ffi.Float> xPtr = ffi.nullptr;
  ffi.Pointer<ffi.Float> hPtr = ffi.nullptr;
  ffi.Pointer<ffi.Float> yPtr = ffi.nullptr;

  try {
    xPtr = calloc<ffi.Float>(nx);
    hPtr = calloc<ffi.Float>(nh);
    yPtr = calloc<ffi.Float>(ny);

    xPtr.asTypedList(nx).setAll(0, x);
    hPtr.asTypedList(nh).setAll(0, h);

    final rc = (outMode == CorrOutMode.full && !simd)
        ? yl_conv_direct_f32_ffi(xPtr, nx, hPtr, nh, yPtr, mode.value)
        : simd
        ? yl_conv_direct_mode_simd_f32_ffi(
            xPtr,
            nx,
            hPtr,
            nh,
            yPtr,
            mode.value,
            outMode.value,
          )
        : yl_conv_direct_mode_f32_ffi(
            xPtr,
            nx,
            hPtr,
            nh,
            yPtr,
            mode.value,
            outMode.value,
          );
    if (rc != 0) {
      throw StateError('Conv.direct native call failed with code $rc');
    }

    return Float32List.fromList(yPtr.asTypedList(ny));
  } finally {
    if (xPtr != ffi.nullptr) calloc.free(xPtr);
    if (hPtr != ffi.nullptr) calloc.free(hPtr);
    if (yPtr != ffi.nullptr) calloc.free(yPtr);
  }
}