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GETBL (Super FX): Difference between revisions

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'''GETBL''' is a [[Super FX]] instruction that loads one byte from the ROM buffer.
{| class="wikitable" style="float:right;clear:right;width:50%"
!colspan="8"|Basic Info
|+
|'''Addressing Mode'''
|'''Opcode'''
|'''Length'''
|'''ROM Speed'''
|'''RAM Speed'''
|'''Cache Speed'''
|+
|[[Implied]] (type 1)
|3EEF
|2 bytes
|6 to 10 cycles
|6 to 9 cycles
|2 to 6 cycles
|}
 
{| class="wikitable" style="float:right;clear:right;width:30%"
!colspan="9"|Flags Affected
|+
|[[B Flag|B]]
|[[ALT1]]
|[[ALT2]]
|[[O/V]]
|[[Sign Flag|S]]
|[[CY]]
|[[Zero Flag|Z]]
|+
|0
|0
|0
|.
|.
|.
|.
|}
 
'''GETBL''' (Get Byte Low) is a [[Super FX]] instruction that loads one byte from the [[ROM buffer]] into the low byte of the [[destination register]].  GETBL also loads the high byte of the [[source register]] into the high byte of the destination register.
 
The reason the cycle times can vary is because of the [[ROM buffer]].  The [[ALT0]] state is restored.
 
The source and destination registers should be specified in advance using [[WITH]], [[FROM]], or [[TO]].  Otherwise, R<sub>0</sub> serves as the default.
 
==== Syntax ====
<pre>
GETBL
</pre>
 
 
[[File:gsu getbl.png]]
 
==== Example ====
Let:
(ROM Buffer) = 75h
S<sub>reg</sub> : R<sub>2</sub>
D<sub>reg</sub> : R<sub>6</sub>
R<sub>2</sub> = 4abdh
After executing GETBL:
 
R<sub>6</sub> = 4a75h


=== See Also ===
=== See Also ===
* [[GETB]]
* [[GETB]]
* [[GETBH]]
* [[GETBH]]
* [[GETBS]]
* [[GETC]]
* [[ALT2]]
=== External Links ===
* Official Super Nintendo development manual on GETBL: 9.37 on [https://archive.org/details/SNESDevManual/book2/page/n209 page 2-9-53 of Book II]
* example: [https://archive.org/details/SNESDevManual/book2/page/n210 page 2-9-54 of Book II], lbid


[[Category:ASM]]
[[Category:ASM]]
[[Category:Enhancement Chips]]
[[Category:Super FX]]
[[Category:Data Transfer Instructions]]
[[Category:Two-byte Instructions]]
[[Category:Expects Sreg/Dreg Prearranged]]

Latest revision as of 22:19, 16 July 2024

Basic Info
Addressing Mode Opcode Length ROM Speed RAM Speed Cache Speed
Implied (type 1) 3EEF 2 bytes 6 to 10 cycles 6 to 9 cycles 2 to 6 cycles
Flags Affected
B ALT1 ALT2 O/V S CY Z
0 0 0 . . . .

GETBL (Get Byte Low) is a Super FX instruction that loads one byte from the ROM buffer into the low byte of the destination register. GETBL also loads the high byte of the source register into the high byte of the destination register.

The reason the cycle times can vary is because of the ROM buffer. The ALT0 state is restored.

The source and destination registers should be specified in advance using WITH, FROM, or TO. Otherwise, R0 serves as the default.

Syntax

GETBL


gsu getbl.png

Example

Let:

(ROM Buffer) = 75h
Sreg : R2
Dreg : R6
R2 = 4abdh

After executing GETBL:

R6 = 4a75h

See Also

External Links