2018-04-06 12:26:00 +00:00
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.org 0xC000
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start: jsr min3
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stp
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2018-04-04 22:32:53 +00:00
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; min3
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; Takes 3 numbers (A, B, C), passed on stack, finds the minimum.
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; Result is also passed on stack. Assumes it is being called via jsr.
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.set retl,0x10
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.set reth,0x11
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.set res,0x12
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min3: pla ; pull low byte of return address
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sta retl
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pla
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sta reth
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pla ; pull C from stack
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sta res ; save C into res
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pla ; pull B from stack
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cmp res ; compare B and C
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bpl bltc ; branch if B > C
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sta res ; if C is smaller, save it to res
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bltc: pla ; pull A from stack
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cmp res ; compare A and whatever is in res
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bpl ret ; branch if A > res
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sta res ; otherwise save A to res
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ret: lda res ; load res into accumulator
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pha ; save to the stack
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lda reth ; restore return address
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pha
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lda retl
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pha
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rts ; return from function
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