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/* *****************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* 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.
* ****************************************************************************/
# On an exception, push a fake stack thread mode stack frame and redirect
# thread execution to a thread mode error handler
# From RM008:
# The SP is decremented by eight words by the completion of the stack push.
# Figure 5-1 shows the contents of the stack after an exception pre-empts the
# current program flow.
#
# Old SP--> <previous>
# xPSR
# PC
# LR
# r12
# r3
# r2
# r1
# SP--> r0
.text
.globl __exc_hardfault
.globl __exc_nmi
.globl __exc_hardfault
.globl __exc_memmanage
.globl __exc_busfault
.globl __exc_usagefault
.code 16
.thumb_func
__exc_nmi:
mov r0, #1
b __default_exc
.thumb_func
__exc_hardfault:
mov r0, #2
b __default_exc
.thumb_func
__exc_memmanage:
mov r0, #3
b __default_exc
.thumb_func
__exc_busfault:
mov r0, #4
b __default_exc
.thumb_func
__exc_usagefault:
mov r0, #5
b __default_exc
.thumb_func
__default_exc:
ldr r2, NVIC_CCR @ Enable returning to thread mode even if there are
mov r1 ,#1 @ pending exceptions. See flag NONEBASETHRDENA.
str r1, [r2]
cpsid i @ Disable global interrupts
ldr r2, SYSTICK_CSR @ Disable systick handler
mov r1, #0
str r1, [r2]
ldr r1, CPSR_MASK @ Set default CPSR
push {r1}
ldr r1, TARGET_PC @ Set target pc
push {r1}
sub sp, sp, #24 @ Don't care
ldr r1, EXC_RETURN @ Return to thread mode
mov lr, r1
bx lr @ Exception exit
.align 4
CPSR_MASK: .word 0x61000000
EXC_RETURN: .word 0xFFFFFFF9
TARGET_PC: .word __error
NVIC_CCR: .word 0xE000ED14 @ NVIC configuration control register
SYSTICK_CSR: .word 0xE000E010 @ Systick control register
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