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comparison src/asm.S @ 0:83c23a36980d

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author Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp>
date Fri, 26 May 2017 23:11:05 +0900
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-1:000000000000 0:83c23a36980d
1 #include "arm.h"
2
3 .text
4 .code 32
5
6 .global set_stk
7 .global get_fp
8
9 # set the stack for IRQ mode, we can use r0-r3 for free
10 # input: r0 - #mode, r1 - stk
11 set_stk:
12 # switch to the IRQ mode
13 MRS r2, cpsr
14 BIC r2, r2, #MODE_MASK
15 ORR r2, r2, r0
16 MSR cpsr_cxsf, r2
17
18 # set the stack pointer, sp register is banked, so we need to switch mode
19 MOV sp, r1
20
21 # switch back to the SVC mode
22 BIC r2, r2, #MODE_MASK
23 ORR r2, r2, #SVC_MODE
24 MSR cpsr_cxsf, r2
25
26 # return
27 bx lr
28
29 # return the frame pointer for the current function
30 get_fp:
31 MOV r0, fp
32 bx lr