source: trunk/libs/newlib/src/libgloss/epiphany/epiphany-ivthandlers.S @ 477

# EPIPHANY implementation of wrappers over user C ISR ()

# Copyright (c) 2011, Adapteva, Inc.
# All rights reserved.

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#  * Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
#  * Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
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#    used to endorse or promote products derived from this software without
#    specific prior written permission.

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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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.section RESERVED_CRT0,"a",@progbits     ;
.set sw_exception_v_n, 1
.set page_miss_v_n, 2
.set timer0_expired_v_n, 3;
.set timer1_expired_v_n, 4;
.set message_v_n, 5;
.set dma0_v_n, 6;
.set dma1_v_n, 7;
.set wand_v_n, 8;
.set soft_v_n, 9

// preserve isr-mods to ACTIVE, GID, KERNEL, WAND, & EXCAUSE bits in the status reg
.set status_mask, 0x0007000f;
// for the wand isr, preserve isr-mods to ACTIVE, GID, KERNEL, & EXCAUSE, but
// clear the WAND bit.
.set wand_status_mask, 0x00070007;

//IVT wrappers

.global _DEFAULT_ISR_CALLBACK;
.balign 4
.type   _DEFAULT_ISR_CALLBACK, %function
_DEFAULT_ISR_CALLBACK:
        rts
.size  _DEFAULT_ISR_CALLBACK, .-_DEFAULT_ISR_CALLBACK


.global _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v;
.balign 4
.type   _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v, %function
_DEFAULT_ISR_CALLBACK_FOR_sw_exception_v:
        trap 5;; FAIL
.size  _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v, .-_DEFAULT_ISR_CALLBACK_FOR_sw_exception_v


.set NUMBER_ENTRIES_IN_IVT, 8
.global _ISR_VECTOR;
.balign 4
.type   _ISR_VECTOR, %object
_ISR_VECTOR:
        .word _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v; reset
        .word _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v; sw_exception
        .word _DEFAULT_ISR_CALLBACK_FOR_sw_exception_v; page_miss
        .rept   NUMBER_ENTRIES_IN_IVT
                .word _DEFAULT_ISR_CALLBACK
        .endr
.size  _ISR_VECTOR, .-_ISR_VECTOR

.macro IVT_ENTRY_CALL entry_v_
        ;; assuming we have valid frame poiter

        str fp, [sp],-0x10
        str r0, [sp,+0xf]
        str r1, [sp,+0xe]
        mov r0, \entry_v_
.if \entry_v_ == wand_v_n
        mov   r1, %low(wand_status_mask)  ; this mask will exclude WAND, so it will
        movt  r1, %high(wand_status_mask) ; be forcibly cleared
.else
        mov   r1, %low(status_mask)
        movt  r1, %high(status_mask)
.endif
        str r1, [sp,0x9] ; save the status register isr-preserve mask on the stack
        b   __dispatcher
.endm

.global __dispatcher;
.balign 4
.type   __dispatcher, %function
__dispatcher:
        str lr, [sp,+0xd]
        movfs.l r1,status
        str r1, [sp,+0xc]
        movfs.l r1,iret
        str r1, [sp,+0xb]
        str r2, [sp,+0xa]
        str r3, [sp,+0x8]

        mov fp,sp

        //TODO allow nesting
        //gie

        lsl r2, r0, 2
        mov     r1, %low(_ISR_VECTOR)
        add r2, r2, r1
        ldr r1, [r2,0] ;; r1 = _ISR_VECTOR[entry_v]
        mov r2, 3
        add r0, r0, r2 ;; r0 = signum
        jalr r1

        mov sp,fp

        //gid

        // preserve isr-modifications to some of the bits in the status register,
        // but restore the rest to pre-interrupt values.
        // status = (status[post_isr] & status_mask) | (status[pre_isr] & ~status_mask)

        ldr.l r2, [sp, 9] ; fetch the status register isr preserve mask from the stack
        movfs r1, status
        and   r1, r1, r2; (status[post_isr] & status_mask)

        ldr  r0, [sp,+0xc]
        mov  r2, %low(~status_mask)
        movt r2, %high(~status_mask)
        and  r0, r0, r2; (status[pre_isr] & ~status_mask)

        orr r0, r0, r1 ; combine pre_isr & post_isr status bits
        movts.l status, r0

        ldr r0, [sp,+0xb]
        movts.l iret,r0

        ldr  lr,[sp,+0xd];
        ldr  r1,[sp,+0xe]
        ldr  r0,[sp,+0xf]
        ldr  r2,[sp,+0xa]
        ldr  r3,[sp,+0x8]
        ldr  fp,[sp],+0x10
        ldr  fp,[sp,0]
        rti
.size  __dispatcher, .-__dispatcher


.global .sw_exception_v;
.type   .sw_exception_v, %function
.sw_exception_v:
        IVT_ENTRY_CALL sw_exception_v_n;
.size  .sw_exception_v, .-.sw_exception_v

.global .page_miss_v;
.type   .page_miss_v, %function
.page_miss_v:
        IVT_ENTRY_CALL page_miss_v_n;
.size  .page_miss_v, .-.page_miss_v

.global .timer0_expired_v;
.timer0_expired_v:
        IVT_ENTRY_CALL timer0_expired_v_n;

.global .timer1_expired_v;
.timer1_expired_v:
        IVT_ENTRY_CALL timer1_expired_v_n;

.global .message_v;
.message_v:
        IVT_ENTRY_CALL message_v_n;

.global .dma0_v;
.dma0_v:
        IVT_ENTRY_CALL dma0_v_n;

.global .dma1_v;
.dma1_v:
        IVT_ENTRY_CALL dma1_v_n;

.global .wand_v;
.wand_v:
        IVT_ENTRY_CALL wand_v_n;

.global .soft_v;
.soft_v:
        IVT_ENTRY_CALL soft_v_n;