How to resolve the algorithm Generic swap step by step in the 6502 Assembly programming language
How to resolve the algorithm Generic swap step by step in the 6502 Assembly programming language
Table of Contents
Problem Statement
Write a generic swap function or operator which exchanges the values of two variables (or, more generally, any two storage places that can be assigned), regardless of their types. If your solution language is statically typed please describe the way your language provides genericity. If variables are typed in the given language, it is permissible that the two variables be constrained to having a mutually compatible type, such that each is permitted to hold the value previously stored in the other without a type violation. That is to say, solutions do not have to be capable of exchanging, say, a string and integer value, if the underlying storage locations are not attributed with types that permit such an exchange. Generic swap is a task which brings together a few separate issues in programming language semantics. Dynamically typed languages deal with values in a generic way quite readily, but do not necessarily make it easy to write a function to destructively swap two variables, because this requires indirection upon storage places or upon the syntax designating storage places. Functional languages, whether static or dynamic, do not necessarily allow a destructive operation such as swapping two variables regardless of their generic capabilities. Some static languages have difficulties with generic programming due to a lack of support for (Parametric Polymorphism). Do your best!
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Step by Step solution about How to resolve the algorithm Generic swap step by step in the 6502 Assembly programming language
Source code in the 6502 programming language
;swap X with Y
pha ;push accumulator
txa
pha ;push x
tya
pha ;push y
pla
tax ;pop y into x
pla
tay ;pop x into y
pla ;pop accumulator
sta temp ;a label representing a zero page memory address
txa
pha ;push x
ldx temp
pla ;pop x into accumulator
temp equ $00
temp2 equ $01 ;these values don't matter.
lda temp
pha ;push temp
lda temp2
pha ;push temp2
pla
sta temp ;pop temp2 into temp
pla
sta temp2 ;pop temp into temp2
lda #$33
ldx #$44
ldy #$55
pha
phx
phy
pla ;a=#$55
ply ;y=#$44
plx ;x=#$33
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