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/*===========================================================================

//

//      vec_xvsr.S

//

//      SPARClite vectors: exception vector service routine

//

//===========================================================================

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// -------------------------------------------

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// or inline functions from this file, or you compile this file and link it

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//####ECOSGPLCOPYRIGHTEND####

//===========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    hmt

// Contributors: hmt

// Date:         1999-02-20

// Purpose:      SPARClite vector code

// Description:  see vectors.S; this is the default vector service routine

//               for exceptions.

//

//####DESCRIPTIONEND####

//

//=========================================================================*/

!-----------------------------------------------------------------------------

//      .file   "vec_xvsr.S"

!----------------------------------------------------------------------------

#include 

#include 

#ifdef CYGPKG_KERNEL

# include 

#endif

!------------------------------------------------------------------------

#include 

#define DELAYS_AFTER_WRPSR_SAME_WINDOW

#define DELAYS_AFTER_WRWIM

!------------------------------------------------------------------------

        .text

!---------------------------------------------------------------------------

! default exception handler VSR, which calls the appropriate ISR after

! interrupt masking - much the same as the interrupt VSR but does not lock

! scheduler or call interrupt_end().

        .global hal_default_exception_vsr

hal_default_exception_vsr:

        ! here,locals have been set up as follows:

        ! %l0 = psr (with this CWP/window-level in it)

        ! %l1 = pc

        ! %l2 = npc

        ! %l3 = vector number (16-25 for traps)

        ! and we are in our own register window, though it is likely that

        ! the next one will need to be saved before we can use it:

        ! ie. this one is the invalid register window.

        ! must establish a safe stack before re-enabling interrupts + traps

        and     %l0, __WINBITS, %l7     ! CWP extracted

        ! no inc/dec here, so no need for special measures for not-8-windows

        mov     1, %l6

        sll     %l6, %l7, %l6           ! 1 << CWP

        rd      %wim, %l5

        cmp     %l5, %l6                ! are they the same?

        bne     1f                      ! No, so the stack is OK as is.

        ! now do by hand an overflow trap, effectively

        mov     %g1, %l7                ! (DELAY SLOT)

        srl     %l5, 1, %l5

        sll     %l6, __WINSIZE-1, %l6

        or      %l6, %l5, %g1           ! new WIM in %g1 so we can get it

                                        ! within the save:

        save                            ! Slip into next window

        mov     %g1, %wim               ! Install the new wim

                                        ! (invalidates current window!)

#ifdef DELAYS_AFTER_WRWIM

        nop

        nop

        nop

#endif

        std     %l0, [%sp + 0 * 4]      ! save L & I registers

        std     %l2, [%sp + 2 * 4]

        std     %l4, [%sp + 4 * 4]

        std     %l6, [%sp + 6 * 4]

        std     %i0, [%sp + 8 * 4]

        std     %i2, [%sp + 10 * 4]

        std     %i4, [%sp + 12 * 4]

        std     %i6, [%sp + 14 * 4]

        restore                         ! Go back to trap window.

        mov     %l7, %g1                ! Restore %g1

1:      ! now save away the regs we must preserve

        sub     %fp, 32 * 4, %sp

        ! save a maximal context regardless: see also

        ! CYGDBG_HAL_COMMON_INTERRUPTS_SAVE_MINIMUM_CONTEXT

        std     %l0, [%sp + 0 * 4]      ! save L & I registers

        std     %l2, [%sp + 2 * 4]

        std     %l4, [%sp + 4 * 4]

        std     %l6, [%sp + 6 * 4]

        std     %i0, [%sp + 8 * 4]

        std     %i2, [%sp + 10 * 4]

        std     %i4, [%sp + 12 * 4]

        std     %i6, [%sp + 14 * 4]

        st      %g1, [%sp + 17 * 4]     ! save G registers

        std     %g2, [%sp + 18 * 4]

        std     %g4, [%sp + 20 * 4]

        std     %g6, [%sp + 22 * 4]

        ! no point whatsoever in saving O registers

        ! and save the CWP in %g0 save place

        st      %l0, [%sp + 16 * 4]

        sub     %sp, 24 * 4, %sp        ! fresh frame including

                                        ! arg spill area for callees

        ! do not lock the scheduler

        ! HELP_GDB_WITH_BACKTRACE

        mov     %i7, %l5                ! preserve it JIC

        mov     %l1, %i7                ! bogus return link here

        ! and we must preserve the Y register (multiply/divide auxiliary)

        ! over these calls; we will keep it in %l4 which is otherwise unused.

        rd      %y, %l4

        ! Now we can reenable traps (preserving interrupt level)

        or      %l0, 0x0e0, %l7         ! set ET (+S,PS), preserve PIL

        wr      %l7, %psr               ! and enable!

#ifdef DELAYS_AFTER_WRPSR_SAME_WINDOW

        nop

        nop

        nop

#endif

        ! now call the XSR and so on with the appropriate args:

        ! ie.

        ! isr_retcode = (*(hal_interrupt_handlers[ vector ]))

        !                   ( vector, hal_interrupt_data[ vector ], stackp );

        ! from hal_arch.h

        !// ISR tables

        !CYG_ADDRESS    hal_interrupt_handlers[CYGNUM_HAL_ISR_COUNT];

        !CYG_ADDRWORD   hal_interrupt_data[CYGNUM_HAL_ISR_COUNT];

        !CYG_ADDRESS    hal_interrupt_objects[CYGNUM_HAL_ISR_COUNT];

        mov     %l3, %o0

        sll     %l3, 2, %l3             ! %l3 to a word offset

        sethi   %hi(hal_interrupt_data), %l7

        or      %l7, %lo(hal_interrupt_data), %l7

        ld      [ %l7 + %l3 ], %o1      ! data

        add     %sp, 24 * 4, %o2        ! stackpointer of saved regset

        sethi   %hi(hal_interrupt_handlers), %l7

        or      %l7, %lo(hal_interrupt_handlers), %l7

        ld      [ %l7 + %l3 ], %l6

        call    %l6

        nop

        ! do not call _interrupt_end()

        ! restore the Y register having done our callouts to C

        wr      %l4, %y

        ! We can reinstall the original CWP here; even if interrupt_end()

        ! performed a reschedule (ie. yield/resume pair) we will be in the

        ! same window.  The window is preserved by reschedule precisely

        ! because it is impossible atomically to disable traps here without

        ! involving a CWP living in a register for a time when other

        ! interrupts may occur.

        ! disable traps (using the saved psr is fastest way)

        wr      %l0, %psr       ! restores flags, disables traps, same PIL.

#ifdef DELAYS_AFTER_WRPSR_SAME_WINDOW

        nop

        nop

        nop

#endif

        ! HELP_GDB_WITH_BACKTRACE

        mov     %l5, %i7        ! restore (unused) return link

        ! and restore other saved regs

        add     %sp, 24 * 4, %sp        ! undo fresh frame

        ! restore a maximal context regardless: see also

        ! CYGDBG_HAL_COMMON_INTERRUPTS_SAVE_MINIMUM_CONTEXT

        ldd     [%sp + 0 * 4], %l0      ! restore L & I registers

        ldd     [%sp + 2 * 4], %l2      ! to support the handler

        ldd     [%sp + 4 * 4], %l4      ! having messed with them.

        ldd     [%sp + 6 * 4], %l6

        ldd     [%sp + 8 * 4], %i0

        ldd     [%sp + 10 * 4], %i2

        ldd     [%sp + 12 * 4], %i4

        ldd     [%sp + 14 * 4], %i6

        ld      [%sp + 17 * 4], %g1     ! and G registers

        ldd     [%sp + 18 * 4], %g2

        ldd     [%sp + 20 * 4], %g4

        ldd     [%sp + 22 * 4], %g6

        ! no point whatsoever in loading back O registers.

        ! Now test for window underflow here and fix up if needs be.

        !

        ! Why?  interrupt_end() might have yielded us, when only

        ! its own frame was restored; its own return to us caused a

        ! window underflow trap, as would our return to interruptee

        ! unless we deal with it now.

        add     %l0, 1, %l7             ! interruptee~s CWP plus noise

        and     %l7, __WINBITS, %l7     ! CWP only

#if 8 == __WINSIZE

        ! it is in range already

#else   // expect 5 or 6 or 7 windows

        cmp     %l7, __WINSIZE

        bge,a   567f                    ! taken: do delay slot, handle overflow

         mov    0, %l7                  ! only if .ge. above

567:

#endif

        mov     1, %l6

        sll     %l6, %l7, %l6           ! 1 << CWP

        rd      %wim, %l5

        cmp     %l5, %l6                ! are they the same?

        bne     2f                      ! No, so the stack is OK as is.

        ! now do by hand an underflow trap, effectively

        sll     %l5, 1, %l5             ! Rotate wim left

        srl     %l6, __WINSIZE-1, %l6

        wr      %l5, %l6, %wim

#ifdef DELAYS_AFTER_WRWIM

        nop                             ! are these delays needed?

        nop                             ! (following restore uses wim)

        nop

#endif

        restore                         ! Interruptee~s window

        ldd     [%sp + 0 * 4], %l0      ! restore L & I registers

        ldd     [%sp + 2 * 4], %l2

        ldd     [%sp + 4 * 4], %l4

        ldd     [%sp + 6 * 4], %l6

        ldd     [%sp + 8 * 4], %i0

        ldd     [%sp + 10 * 4], %i2

        ldd     [%sp + 12 * 4], %i4

        ldd     [%sp + 14 * 4], %i6

        save                            ! Back to trap window

2:      ! restore the condition codes, PSR and PIL and return from trap.

        wr      %l0, %psr       ! restores flags, disables traps, and old PIL

#ifdef DELAYS_AFTER_WRPSR_SAME_WINDOW

        nop

        nop

        nop

#endif

        jmpl    %l1,  %g0

        rett    %l2

! end of vec_xvsr.S