Far Call Trick
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NOTE: This is code for real-address mode only. Something similar may be possible for other modes, but is not recommended.
I found this little trick to use a far call to jump to a segment held in a dw (tested in NASM, probably works with other assemblers.)
mov ax,0 ; New IP = 0 mov bx,[new_segment] ; New CS push bx ; Push new CS push ax ; Push new IP retf ; Sneaky far jump .... new_segment dw 2000h ; Replace 2000h with the new CS
This is real useful if you have your user choose what segment to load and need it used in the middle of a longer piece of code that you do not want to duplicate for each case!