41 lines
734 B
ArmAsm
41 lines
734 B
ArmAsm
# We will be using R0 to pass pointer to string
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# to cleared by the function
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# R15 will be used as the stack pointer
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:start
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LOADUI R0 @string
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LOADUI R1 22
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LOADUI R2 33
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LOADUI R3 44
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LOADUI R4 55
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LOADUI R15 0x600
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CALLI R15 @clear_string
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HALT
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:string
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HALT
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HALT
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NOP
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;; Our simple string clear function
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:clear_string
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;; Preserve registers
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PUSHR R0 R15
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PUSHR R1 R15
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PUSHR R2 R15
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PUSHR R3 R15
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;; Setup registers
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MOVE R1 R0
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LOADUI R2 0
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LOADUI R3 0
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:clear_byte
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LOADXU8 R0 R1 R2 ; Get the byte
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STOREX8 R3 R1 R2 ; Overwrite with a Zero
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ADDUI R2 R2 1 ; Prep for next loop
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JUMP.NZ R0 @clear_byte ; Stop if byte is NULL
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;; Done
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;; Restore registers
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POPR R3 R15
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POPR R2 R15
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POPR R1 R15
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POPR R0 R15
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RET R15
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