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GETBS (Super FX): Difference between revisions

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'''GETBS''' is a [[Super FX]] instruction that loads one byte from the [[ROM buffer]] into the low byte of the [[destination register]].  Every bit of the high byte of the destination register becomes whatever bit 7 of that loaded byte is.
'''GETBS''' (Get Signed Byte) is a [[Super FX]] instruction that loads one byte from the [[ROM buffer]] into the low byte of the [[destination register]].  Every bit of the destination register's high byte becomes whatever bit 7 of that loaded byte is.


The reason the cycle times can vary is because of the [[ROM buffer]].
The reason the cycle times can vary is because of the [[ROM buffer]].  The [[ALT0]] state is restored.
 
The destination register should be specified in advance using [[WITH]] or [[TO]].  Otherwise, R<sub>0</sub> serves as the default.  The [[source register]] is ignored.


==== Syntax ====
==== Syntax ====
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* [[GETBL]]
* [[GETBL]]
* [[GETBH]]
* [[GETBH]]
* [[GETC]]
* [[ALT3]]
* [[ALT3]]


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[[Category:Data Transfer Instructions]]
[[Category:Data Transfer Instructions]]
[[Category:Two-byte Instructions]]
[[Category:Two-byte Instructions]]
[[Category:Expects Sreg/Dreg Prearranged]]

Latest revision as of 09:19, 31 July 2024

Basic Info
Addressing Mode Opcode Length ROM Speed RAM Speed Cache Speed
Implied (type 1) 3FEF 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 . . . .

GETBS (Get Signed Byte) is a Super FX instruction that loads one byte from the ROM buffer into the low byte of the destination register. Every bit of the destination register's high byte becomes whatever bit 7 of that loaded byte is.

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

The destination register should be specified in advance using WITH or TO. Otherwise, R0 serves as the default. The source register is ignored.

Syntax

GETBS

Example

Let:

(ROM buffer) = 85h
Dreg : R8

After executing GETBS:

R8 = ff85h

gsu getbs.png

See Also

External Links