static void vecAlignSpTaskCreateHook (WIND_TCB *tcb)
{
unsigned long new_sp;

  new_sp = tcb->regs.spReg;

  /* Note: that the stack chain that runs through the internal        */
  /* kernel routines at the start of the task is 16 byte unaligned,   */
  /* so we need to unalign the stack here rather than align it so     */
  /* that it is correctly 16 aligned when we enter our user code.     */

  /* Also, note that the manual advises using taskRegsGet/Set to      */
  /* access a task's regs in a safe fashion, but I think it is safe   */
  /* to ignore that advice at this point as the task is not actually  */
  /* up and running yet, so there are no MT issues to worry about.    */

  if (bsp_do_align)
    new_sp = (new_sp & ~0x0000000F) | 8;

  tcb->regs.spReg = new_sp;

  /* This is also where we might malloc some memory for saving altivec regs */
  /* when we get around to making the compiler suitable for multitasking    */
  /* altivec applications.                                                  */
}

static void vecAddBspTaskHooks (void)
{
  /* Add a task hook so that new tasks are created with their stack         */
  /* pointers aligned to 16-bytes as required by the altivec                */
  /* extensions to the EABI spec                                            */
  taskCreateHookAdd ((FUNCPTR)vecAlignSpTaskCreateHook);
}

static inline unsigned int ppcArchMsrGet (void)
{
unsigned int result;

  asm volatile ("mfmsr %0" : "=r" (result) );
  return(result);
}

static inline void ppcArchMsrSet (unsigned int val)
{
  asm volatile ("mtmsr %0" : : "r" (val) );
}

void vecInitAltivec (void)
{
  /* Set MSR bit 6 (0=MSB) to enable the altivec unit */
  ppcArchMsrSet (ppcArchMsrGet () | (1 << (31-6)));
  /* And add the task create hook to align the stack */
  vecAddBspTaskHooks ();
  return;
}