GETBS (Super FX): Difference between revisions

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
D_reg : R₈

After executing GETBS:

R₈ = ff85h

External Links

Official Super Nintendo development manual on GETBS: 9.38 on page 2-9-55 of Book II
example: page 2-9-56 of Book II, lbid

@@ Line 1: / Line 1: @@
-'''GETBS''' 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)
+|3FEF
+|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
+|.
+|.
+|.
+|.
+|}
+'''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, R<sub>0</sub> serves as the default.  The [[source register]] is ignored.
+==== Syntax ====
+<pre>
+GETBS
+</pre>
+==== Example ====
+Let:
+ (ROM buffer) = 85h
+ D<sub>reg</sub> : R<sub>8</sub>
+After executing GETBS:
+ R<sub>8</sub> = ff85h
+[[File:gsu getbs.png]]
 === See Also ===
@@ Line 5: / Line 61: @@
 * [[GETBL]]
 * [[GETBH]]
+* [[GETC]]
+* [[ALT3]]
+=== External Links ===
+* Official Super Nintendo development manual on GETBS: 9.38 on [https://archive.org/details/SNESDevManual/book2/page/n211 page 2-9-55 of Book II]
+* example: [https://archive.org/details/SNESDevManual/book2/page/n212 page 2-9-56 of Book II], lbid
 [[Category:ASM]]
-[[Category:Enhancement Chips]]
+[[Category:Super FX]]
+[[Category:Data Transfer Instructions]]
+[[Category:Two-byte Instructions]]
+[[Category:Expects Sreg/Dreg Prearranged]]