NdsBannerAnimationStep.cs

namespace NdsForge;

#if DOXYGEN
public record NdsBannerAnimationStep(
#else
public readonly record struct NdsBannerAnimationStep(
#endif
    byte Duration,
    byte TileFrame,
    byte PaletteFrame,
    bool FlipHorizontal = false,
    bool FlipVertical = false)
{
    public ushort Pack()
    {
        Validate();
        return (ushort)(
            Duration |
            (TileFrame << 8) |
            (PaletteFrame << 11) |
            (FlipHorizontal ? 1 << 14 : 0) |
            (FlipVertical ? 1 << 15 : 0));
    }

    public static NdsBannerAnimationStep FromPacked(ushort value)
    {
        if (value == 0)
        {
            throw new InvalidDataException("A zero DSi animation word terminates the sequence and is not a step.");
        }
 
        return new(
            (byte)value,
            (byte)((value >> 8) & 0x07),
            (byte)((value >> 11) & 0x07),
            (value & (1 << 14)) != 0,
            (value & (1 << 15)) != 0);
    }

    internal void Validate()
    {
        if (Duration == 0)
        {
            throw new InvalidDataException("A DSi animation step must last at least one 60 Hz tick.");
        }
 
        if (TileFrame > 7 || PaletteFrame > 7)
        {
            throw new InvalidDataException("DSi animation tile and palette frame indices must be between zero and seven.");
        }
    }
}