35 lines
1.4 KiB
Text
35 lines
1.4 KiB
Text
#include "e.h"
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exp $SWAP
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pro $SWAP,0 ; used by twist is A68S1CE to swap two items
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; of any length on the stack. the lengths of
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; the two items to be swapped are passed as two
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; SZWORD byte parameters
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; first copy what was the top item on the stack before the call
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; to the procedural working stack
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lal SZADDR+SZWORD+SZWORD ; address of top of stack before call
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lol SZADDR+SZWORD ; 2nd param is the length of top item
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los SZWORD ; load top item to procedural stack
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; now copy what was the second stack item to the top
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lal SZADDR+SZWORD+SZWORD ; address of top for source of copy
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dup SZADDR ; dup for destination
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dup SZADDR ; and dup to copy top item back
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lol SZADDR+SZWORD ; length of top item
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ads SZWORD ; add length to address of top of stack to get
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; the address of the 2nd param. (source address)
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exg SZADDR ; exchange source and destination address
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lol SZADDR ; 1st param is the length of the 2nd stack item
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bls SZWORD ; copy 2nd item to the top of the pre-call stack
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; now copy the what was the top item from the procedural stack to
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; the second position of the stack before the call
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lol SZADDR ; length of 2nd stack item, now on the top
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ads SZWORD ; add length to address of the top of the stack to
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; get place for 2nd item, the old top item
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lol SZADDR+SZWORD ; length of old top, now to be copied to 2nd position
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sts SZWORD ; move the item that was top
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ret 0
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end 0
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