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MOV R6,stack_begin
LDR R6,[R6] // initialize stack pointer
MOV R4, result // R4 contains address of result
MOV R3,#0
STR R3,[R4] // result = 0;
MOV R0,#1 // R0 contains first parameter
MOV R1,#5 // R1 contains second parameter
MOV R2,#9 // R2 contains third parameter
MOV R3,#20 // R3 contains fourth parameter
BL leaf_example // call leaf_example(1,5,9,20);
STR R0,[R4] // result = leaf_example(1,5,9,20);
HALT
leaf_example:
STR R4,[R6] // save R4 for use afterwards
STR R5,[R6,#-1] // save R5 for use afterwards
ADD R4,R0,R1 // R4 = g + h
ADD R5,R2,R3 // R5 = i + j
MVN R5,R5 // R5 = ~(i + j)
ADD R4,R4,R5 // R4 = (g + h) + ~(i + j)
MOV R5,#1
ADD R4,R4,R5 // R4 = (g + h) - (i + j)
MOV R0,R4 // R0 = return value (g + h) - (i + j)
LDR R5,[R6,#-1] // restore saved contents of R5
LDR R4,[R6] // restore saved contents of R4
BX R7 // return control to caller
stack_begin:
.word 0xFF
result:
.word 0xCCCC
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