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Long jump and constants

2009-09-11
2013-04-20
  • Nobody/Anonymous

    Does anybody knows how I can write the following command on jwasm:
    jmp 0000h:7C00h

    For some reason jwasm does not accept it (memory model is TINY)

    Basically, I want to be able to specify constants there. I do not want to use any segment register. Sometimes I may want to use a label instead of 7C00h. In this case I want to jump to the location with other segment but with the offset specified by label in the current code. It is useful when duplicate in memory my program in real mode and if otherwise program do not use any long jumps.

    I think that masm supported this kind of commands but the command mentioned above is not accepted by jwasm.

     
  • Nobody/Anonymous

    This isn't a bug report. Get off my Internet you wanna-be bootloader writer!!!

     
  • Nobody/Anonymous

    > I think that masm supported this kind of commands

    No, Masm also wants a label if operand of jmp/call has type immediate.
    JMP 0000:7C00h must be coded with DB+DW.

     
  • Nobody/Anonymous

    > No, Masm also wants a label if operand of jmp/call has type immediate. JMP 0000:7C00h must be coded with DB+DW.

    thanks.

     

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