xsm.txt

vec3d = float x, float y, float z
quat16 = int16 x, int16 y, int16 z, int16 w; fX = x / 32767
string = uint32 len, char[len]

file:
    byte magic[4] = 58 53 4D 20 ("XSM ")
    byte majorVersion = 1
    byte minorVersion = 0
    byte bBigEndian
    byte pad

    chunk[...]
        int32 chunkType
        int32 length
        int32 version
        byte data[length]

chunk C9: metadata (v2)
    float unused = 1.0f
    float fMaxAcceptableError
    int32 fps
    byte exporterMajorVersion
    byte exporterMinorVersion
    byte pad[2]
    string sourceApp
    string origFileName
    string exportDate
    string motionName

chunk CA: bone animation (v2)
    int32 numSubMotions
    SkeletalSubMotion[numSubMotions]:
        quat16 poseRot
        quat16 bindPoseRot
        quat16 poseScaleRot
        quat16 bindPoseScaleRot
        vec3D posePos
        vec3D poseScale
        vec3D bindPosePos
        vec3D bindPoseScale
        int32 numPosKeys
        int32 numRotKeys
        int32 numScaleKeys
        int32 numScaleRotKeys
        float fMaxError
        string nodeName
        
        // fTime of first item in each array must be 0
        
        PosKey[numPosKeys]:
            vec3d pos
            float fTime
        
        RotKey[numRotKeys]:
            quat16 rot
            float fTime
        
        ScaleKey[numScaleKeys]:
            vec3d scale
            float fTime
        
        ScaleRotKey[numScaleRotKeys]:
            quat16 rot
            float fTime