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movem

Move multiple registers

Moves a list of registers such as d0-d7 and a0-a7 to or from memory.

Sizes .w .l, .w by default

Used in
XNZVC –––––
  • Leaves every flag unchanged

Forms

Operands

<register list>
A register list using / to separate registers and - for ranges. For example, d0-d2/a0 selects d0, d1, d2 and a0. A single data or address register is also valid.
<ea>
An operand using one of the addressing modes listed for this form. The list determines whether it can be a register, memory or an immediate value. With opt p=68020, an allowed d(An,Xn) or d(PC,Xn) mode also permits the corresponding 68020 indexed and memory indirect forms. See 68020 addressing. More

Put the register list first to store the registers and second to load them. This is useful for saving registers before a subroutine uses them and restoring them afterward.

Use / between registers and - for a range. For example, a3-a5/d0-d2 selects d0, d1, d2, a3, a4 and a5. The written order does not control the transfer order: selected data registers are processed from d0 to d7, then selected address registers from a0 to a7. A predecrement store processes them in reverse order, from a7 to a0, then d7 to d0.

move.l #$1, d0
move.l #$2, d1
move.l #$3, d2
move.l #$4, a0
bsr my_function
bra END

my_function:
    ; save d0-d2/a0 to the stack
    movem.l d0-d2/a0, -(sp)
    ; overwrite them inside the function
    move.l #$FF, d0
    move.l #$FF, d1
    move.l #$FF, d2
    move.l #$FF, a0
    ; restore from the stack, values are back
    movem.l (sp)+, d0-d2/a0
    rts
END: