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/******************************************************************************

*                                                                             *

* License Agreement                                                           *

*                                                                             *

* Copyright (c) 2003-2004 Altera Corporation, San Jose, California, USA.      *

* All rights reserved.                                                        *

*                                                                             *

* Permission is hereby granted, free of charge, to any person obtaining a     *

* copy of this software and associated documentation files (the "Software"),  *

* to deal in the Software without restriction, including without limitation   *

* the rights to use, copy, modify, merge, publish, distribute, sublicense,    *

* and/or sell copies of the Software, and to permit persons to whom the       *

* Software is furnished to do so, subject to the following conditions:        *

*                                                                             *

* The above copyright notice and this permission notice shall be included in  *

* all copies or substantial portions of the Software.                         *

*                                                                             *

* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *

* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *

* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *

* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *

* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *

* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *

* DEALINGS IN THE SOFTWARE.                                                   *

*                                                                             *

* This agreement shall be governed in all respects by the laws of the State   *

* of California and by the laws of the United States of America.              *

*                                                                             *

******************************************************************************/

#include "system.h"

/*

 * This is the interrupt exception entry point code, which saves all the

 * registers and calls the interrupt handler.  It should be pulled in using

 * a .globl from alt_irq_register.c.  This scheme is used so that if an

 * interrupt is never registered, then this code will not appear in the

 * generated executable, thereby improving code footprint.

 */

        /*

         * Explicitly allow the use of r1 (the assembler temporary register)

         * within this code. This register is normally reserved for the use of

         * the compiler.

         */

        .set noat

        /*

         * Pull in the exception handler register save code.

         */

        .globl alt_exception

        .globl alt_irq_entry

        .section .exceptions.entry.label, "xa"

alt_irq_entry:

        /*

         * Section .exceptions.entry is in alt_exception_entry.S

         * This saves all the caller saved registers and reads estatus into r5

         */

        .section .exceptions.irqtest, "xa"

#ifdef ALT_CI_INTERRUPT_VECTOR_N

        /*

         * Use the interrupt vector custom instruction if present to accelerate

         * this code.

         * If the interrupt vector custom instruction returns a negative

         * value, there are no interrupts active (estatus.pie is 0

         * or ipending is 0) so assume it is a software exception.

         */

        custom ALT_CI_INTERRUPT_VECTOR_N, r4, r0, r0

        blt r4, r0, .Lnot_irq

#else

        /*

         * Test to see if the exception was a software exception or caused

         * by an external interrupt, and vector accordingly.

         */

        rdctl r4, ipending

        andi  r2, r5, 1

        beq   r2, zero, .Lnot_irq

        beq   r4, zero, .Lnot_irq

#endif /* ALT_CI_INTERRUPT_VECTOR_N */

        .section .exceptions.irqhandler, "xa"

        /*

         * Now that all necessary registers have been preserved, call

         * alt_irq_handler() to process the interrupts.

         */

        call alt_irq_handler

        .section .exceptions.irqreturn, "xa"

        br    .Lexception_exit

        .section .exceptions.notirq.label, "xa"

.Lnot_irq:

        /*

         * Section .exceptions.exit is in alt_exception_entry.S

         * This restores all the caller saved registers

         */

        .section .exceptions.exit.label

.Lexception_exit: