GB Programming: Difference between revisions
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>ISSOtm (→Flags: Remove flags that don't exist on Game Boy) |
>Bbbbbbbbba m (→A special jp: Change "jp (hl)" to "jp hl") |
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There is one special case of jp, though ! |
There is one special case of jp, though ! |
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{| class="wikitable" |
{| class="wikitable" |
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|JP |
|JP HL |
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|Has execution jumping to the address pointed to by hl.<br/>Does not accept any conditionals. |
|Has execution jumping to the address pointed to by hl.<br/>Does not accept any conditionals. |
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<pre> |
<pre> |
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ld hl, $2457 |
ld hl, $2457 |
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jp |
jp hl |
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</pre> |
</pre> |
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will jump to $2457. Some might argue that "jp $2457" is better, as it'd save 1 byte and preserve the hl register. |
will jump to $2457. Some might argue that "jp $2457" is better, as it'd save 1 byte and preserve the hl register. |
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However, jp |
However, "jp hl" is used to do dynamic jumps: "jp hl" may jump to a different location every time it is ran. When doing "static" (ie. always the same) jumps, it '''is''' better to use jp $xxyy. "jp hl" mostly used with function pointer tables - we'll see that later. |
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===Comparing stuff=== |
===Comparing stuff=== |
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