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NAME="DEVAPI-SYNCHRONIZATION-LEVELS">Synchronization Levels</H1
><P
>Since it would be dangerous for an ISR or DSR to make a call
that might reschedule the current thread (by trying to lock a mutex
for example) all functions in this API have an associated synchronization
level. These levels are:</P
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>      This function may only be called from within threads. This is
      usually the client code that makes calls into the device driver.
      In a non-kernel configuration, this will be code running at the
      default non-interrupt level.
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>      This function may be called by either DSR or thread code.
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>ISR</DT
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>      This function may be called from ISR, DSR or thread code.
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><P
>The following table shows, for each API function, the levels
at which is may be called:</P
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CLASS="PROGRAMLISTING"
>                                  Callable from:
Function                       ISR     DSR    Thread
-------------------------------------------------------------------------
 
cyg_drv_isr_lock                X       X       X
cyg_drv_isr_unlock              X       X       X
cyg_drv_spinlock_init                           X
cyg_drv_spinlock_destroy                        X
cyg_drv_spinlock_spin           X       X       X
cyg_drv_spinlock_clear          X       X       X
cyg_drv_spinlock_try            X       X       X
cyg_drv_spinlock_test           X       X       X
cyg_drv_spinlock_spin_intsave   X       X       X
cyg_drv_spinlock_clear_intsave  X       X       X
cyg_drv_dsr_lock                        X       X
cyg_drv_dsr_unlock                      X       X
cyg_drv_mutex_init                              X
cyg_drv_mutex_destroy                           X
cyg_drv_mutex_lock                              X
cyg_drv_mutex_trylock                           X
cyg_drv_mutex_unlock                            X
cyg_drv_mutex_release                           X
cyg_drv_cond_init                               X
cyg_drv_cond_destroy                            X
cyg_drv_cond_wait                               X
cyg_drv_cond_signal                     X       X
cyg_drv_cond_broadcast                  X       X
cyg_drv_interrupt_create                        X
cyg_drv_interrupt_delete                        X
cyg_drv_interrupt_attach        X       X       X
cyg_drv_interrupt_detach        X       X       X
cyg_drv_interrupt_mask          X       X       X
cyg_drv_interrupt_unmask        X       X       X
cyg_drv_interrupt_acknowledge   X       X       X
cyg_drv_interrupt_configure     X       X       X
cyg_drv_interrupt_level         X       X       X
cyg_drv_interrupt_set_cpu       X       X       X
cyg_drv_interrupt_get_cpu       X       X       X&#13;</PRE
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