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1 #include "arm.h"
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2
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3 .text
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4 .code 32
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5
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6 .global set_stk
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7 .global get_fp
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8
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9 # set the stack for IRQ mode, we can use r0-r3 for free
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10 # input: r0 - #mode, r1 - stk
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11 set_stk:
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12 # switch to the IRQ mode
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13 MRS r2, cpsr
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14 BIC r2, r2, #MODE_MASK
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15 ORR r2, r2, r0
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16 MSR cpsr_cxsf, r2
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17
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18 # set the stack pointer, sp register is banked, so we need to switch mode
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19 MOV sp, r1
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20
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21 # switch back to the SVC mode
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22 BIC r2, r2, #MODE_MASK
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23 ORR r2, r2, #SVC_MODE
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24 MSR cpsr_cxsf, r2
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25
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26 # return
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27 bx lr
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28
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29 # return the frame pointer for the current function
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30 get_fp:
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31 MOV r0, fp
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32 bx lr |
