Gotchas: Difference between revisions
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===LEA Does Not Dereference=== |
===LEA Does Not Dereference=== |
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When dereferencing a pointer, it is necessary to use parentheses. For these examples, |
When dereferencing a pointer using an address register, it is necessary to use parentheses. For these examples, |
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<syntaxhighlight lang="68000devpac">MOVEA.L #$A04000,A0 ;load the address $A04000 into A0 |
<syntaxhighlight lang="68000devpac">MOVEA.L #$A04000,A0 ;load the address $A04000 into A0 |
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MOVE.L A0,D0 ;move the quantity $A04000 into D0 |
MOVE.L A0,D0 ;move the quantity $A04000 into D0 |
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<syntaxhighlight lang="68000devpac">LEA $A04000,A0 ;effectively MOVEA.L #$A04000,A0 |
<syntaxhighlight lang="68000devpac">LEA $A04000,A0 ;effectively MOVEA.L #$A04000,A0 |
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LEA (4,A0),A0 ;effectively ADDA.L #4,A0</syntaxhighlight> |
LEA (4,A0),A0 ;effectively ADDA.L #4,A0</syntaxhighlight> |
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Also, as we have seen before, constant pointers do not need parentheses and are automatically dereferenced. |
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===Partitioned Registers=== |
===Partitioned Registers=== |
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