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30 lines
1.1 KiB
ArmAsm
30 lines
1.1 KiB
ArmAsm
AREA ConstrainProg, CODE, READWRITE
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ENTRY
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Start
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ADR sp, Base ;Point to the base of the stack
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LDR r0, LowerVal ;Load the lower value into r0
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LDR r1, UpperVal ;Load the upper value in r1
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LDR r2, ParamToConstrain ;Load the value to constrain into r2
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STR r0,[sp,#-4] ;Load r0 onto the stack pointer
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STR r1,[sp,#-4] ;Load r1 onto the stack pointer
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STR r2,[sp,#-4] ;Load r2 onto the stack pointer
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BL Constrain ;Call constrain procedure
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LDR r2, [sp] ;Load constrained value back into r2
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;r2 should now contain 2000
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ADD sp, sp, #8 ;Fix the stack pointer
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Constrain
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STR LR, [sp, #-4] ;Store return address
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LDR r5, [sp, #12] ;Retrieve lower
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LDR r4, [sp, #8] ;Retrieve upper
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LDR r3, [sp, #4] ;Retrieve val to constrain
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CMP r3, r4 ;Check if higher than max
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LDRHI r3, [sp, #8] ;If so, load max
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CMP r3, r5 ;Check if lower than min
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LDRLO r3, [sp, #12] ;If so, load min
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STR r3, [sp, #4] ;Overwrite constrained val
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LDR PC, [sp], #4 ;Return from procedure
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ParamToConstrain DCD 2200 ;Value to constrain
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UpperVal DCD 2000 ;Value to constrain
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LowerVal DCD 1000 ;Value to constrain
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Base DCD 0xAAAAAAAA
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END |