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(nasm.info)Section B.4.130

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B.4.130. `JMP': Jump
--------------------

     JMP imm                       ; E9 rw/rd             [8086]
     JMP SHORT imm                 ; EB rb                [8086]
     JMP imm:imm16                 ; o16 EA iw iw         [8086]
     JMP imm:imm32                 ; o32 EA id iw         [386]
     JMP FAR mem                   ; o16 FF /5            [8086]
     JMP FAR mem32                 ; o32 FF /5            [386]
     JMP r/m16                     ; o16 FF /4            [8086]
     JMP r/m32                     ; o32 FF /4            [386]

   `JMP' jumps to a given address. The address may be specified as an
absolute segment and offset, or as a relative jump within the current
segment.

   `JMP SHORT imm' has a maximum range of 128 bytes, since the
displacement is specified as only 8 bits, but takes up less code space.
NASM does not choose when to generate `JMP SHORT' for you: you must
explicitly code `SHORT' every time you want a short jump.

   You can choose between the two immediate far jump forms (`JMP
imm:imm') by the use of the `WORD' and `DWORD' keywords: `JMP WORD
0x1234:0x5678') or `JMP DWORD 0x1234:0x56789abc'.

   The `JMP FAR mem' forms execute a far jump by loading the destination
address out of memory. The address loaded consists of 16 or 32 bits of
offset (depending on the operand size), and 16 bits of segment. The
operand size may be overridden using `JMP WORD FAR mem' or `JMP DWORD
FAR mem'.

   The `JMP r/m' forms execute a near jump (within the same segment),
loading the destination address out of memory or out of a register. The
keyword `NEAR' may be specified, for clarity, in these forms, but is
not necessary. Again, operand size can be overridden using `JMP WORD
mem' or `JMP DWORD mem'.

   As a convenience, NASM does not require you to jump to a far symbol
by coding the cumbersome `JMP SEG routine:routine', but instead allows
the easier synonym `JMP FAR routine'.

   The `CALL r/m' forms given above are near calls; NASM will accept the
`NEAR' keyword (e.g. `CALL NEAR [address]'), even though it is not
strictly necessary.