ALT2: Difference between revisions

Latest revision as of 00:49, 22 July 2024


Basic Info
Addressing Mode	Opcode	Length	ROM Speed	RAM Speed	Cache Speed
Implied (type 2)	3E	1 byte	3 cycles	3 cycles	1 cycle


Flags Affected
B	ALT1	ALT2	O/V	S	CY	Z
.	.	1	.	.	.	.

ALT2 is both the name of a Super FX flag and the flag prefix instruction that sets it. It is bit 9 of the status flag register.

Syntax

ALT2

The following instructions require ALT2:

ADD #n
AND #n
GETBL
MULT #n
OR #n
RAMB
SM (xx), R_n
SMS (yy), R_n
SUB #n

Many instructions clear the ALT2 flag, including:

ADC R_n
ADC #n
ADD R_n
ADD #n
AND R_n
AND #n
ASR
BIC R_n
BIC #n
CACHE
CMODE
CMP R_n
COLOR
DEC R_n
DIV2
FMULT
GETB
GETBH
GETBL
GETBS
GETC
HIB
IBT R_n, #pp
INC R_n
IWT R_n, #xx
JMP R_n
LDB (R_m)
LDW (R_m)
LEA R_n, xx
LINK #n
LJMP R_n
LM R_n, (xx)
LMS R_n, (yy)
LMULT
LOB
LOOP
LSR
MERGE
MOVE R_n, R_n'
MOVES R_n, R_n'
MULT R_n
MULT #n
NOP
NOT
OR R_n
OR #n
PLOT
RAMB
ROL
ROMB
ROR
RPIX
SBC R_n
SBK
SEX
SM (xx), R_n
SMS (yy), R_n
STB (R_m)
STOP
STW (R_m)
SUB R_n
SUB #n
SWAP
UMULT R_n
and presumably UMULT #n and XOR too

External Links

Official Nintendo documentation on ALT2: 9.9 on page 2-9-8 of Book II
Table 2-4-2 on page 2-4-4, lbid.

@@ Line 1: / Line 1: @@
-'''ALT2''' is both the name of a [[Super FX]] flag and the flag prefix instruction that sets it.
+{| class="wikitable" style="float:right;clear:right;width:50%"
-{| class="wikitable" style="float:right;clear:right;width:40%"
 !colspan="8"|Basic Info
 |+
+|'''Addressing Mode'''
 |'''Opcode'''
 |'''Length'''
@@ Line 10: / Line 9: @@
 |'''Cache Speed'''
 |+
+|[[Implied]] (type 2)
 |3E
 |1 byte
@@ Line 18: / Line 18: @@
 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="9"|Flags Clobbered
+!colspan="9"|Flags Affected
 |+
-|B
+|[[B Flag|B]]
-|ALT1
+|[[ALT1]]
-|ALT2
+|[[ALT2]]
-|O/V
+|[[O/V]]
-|S
+|[[Sign Flag|S]]
-|CY
+|[[CY]]
-|Z
+|[[Zero Flag|Z]]
 |+
 |.
@@ Line 36: / Line 36: @@
 |.
 |}
+'''ALT2''' is both the name of a [[Super FX]] flag and the flag prefix instruction that sets it.  It is bit 9 of the [[status flag register]].
+==== Syntax ====
+<pre>
+ALT2
+</pre>
+The following instructions require ALT2:
+* [[ADD]] #n
+* [[AND (Super FX)|AND]] #n
+* [[GETBL]]
+* [[MULT]] #n
+* [[OR]] #n
+* [[RAMB]]
+* [[SM]] (xx), R<sub>n</sub>
+* [[SMS]] (yy), R<sub>n</sub>
+* [[SUB]] #n
+Many instructions clear the ALT2 flag, including:
+* [[GSU/ADC|ADC]] R<sub>n</sub>
+* [[GSU/ADC|ADC]] #n
+* [[ADD]] R<sub>n</sub>
+* [[ADD]] #n
+* [[GSU/AND|AND]] R<sub>n</sub>
+* [[GSU/AND|AND]] #n
+* [[ASR]]
+* [[BIC]] R<sub>n</sub>
+* [[BIC]] #n
+* [[CACHE]]
+* [[CMODE]]
+* [[GSU/CMP|CMP]] R<sub>n</sub>
+* [[COLOR]]
+* [[GSU/DEC|DEC]] R<sub>n</sub>
+* [[DIV2]]
+* [[FMULT]]
+* [[GETB]]
+* [[GETBH]]
+* [[GETBL]]
+* [[GETBS]]
+* [[GETC]]
+* [[HIB]]
+* [[IBT]] R<sub>n</sub>, #pp
+* [[GSU/INC|INC]] R<sub>n</sub>
+* [[IWT]] R<sub>n</sub>, #xx
+* [[GSU/JMP|JMP]] R<sub>n</sub>
+* [[LDB]] (R<sub>m</sub>)
+* [[LDW]] (R<sub>m</sub>)
+* [[LEA]] R<sub>n</sub>, xx
+* [[LINK]] #n
+* [[LJMP]] R<sub>n</sub>
+* [[GSU/LM|LM]] R<sub>n</sub>, (xx)
+* [[LMS]] R<sub>n</sub>, (yy)
+* [[LMULT]]
+* [[LOB]]
+* [[LOOP]]
+* [[GSU/LSR|LSR]]
+* [[MERGE]]
+* [[GSU/MOVE|MOVE]] R<sub>n</sub>, R<sub>n</sub>'
+* [[MOVES]] R<sub>n</sub>, R<sub>n</sub>'
+* [[MULT]] R<sub>n</sub>
+* [[MULT]] #n
+* [[GSU/NOP|NOP]]
+* [[NOT]]
+* [[OR]] R<sub>n</sub>
+* [[OR]] #n
+* [[PLOT]]
+* [[RAMB]]
+* [[GSU/ROL|ROL]]
+* [[ROMB]]
+* [[GSU/ROR|ROR]]
+* [[RPIX]]
+* [[GSU/SBC|SBC]] R<sub>n</sub>
+* [[SBK]]
+* [[SEX]]
+* [[SM]] (xx), R<sub>n</sub>
+* [[SMS]] (yy), R<sub>n</sub>
+* [[STB]] (R<sub>m</sub>)
+* [[STOP]]
+* [[STW]] (R<sub>m</sub>)
+* [[SUB]] R<sub>n</sub>
+* [[SUB]] #n
+* [[SWAP]]
+* [[UMULT]] R<sub>n</sub>
+* and presumably UMULT #n and XOR too
+=== See Also ===
+* [[ALT1]]
+* [[ALT3]]
+* [[ALT0]]
+* [[Super_FX_Opcode_Matrices#ALT1_=_0,_ALT2_=_1]]
 === External Links ===
-* Official Nintendo documentation on ALT2: https://archive.org/details/SNESDevManual/book2/page/n164
+* Official Nintendo documentation on ALT2: 9.9 on [https://archive.org/details/SNESDevManual/book2/page/n164 page 2-9-8 of Book II]
+* Table 2-4-2 on [https://archive.org/details/SNESDevManual/book2/page/n110 page 2-4-4], lbid.
 [[Category:ASM]]
@@ Line 44: / Line 138: @@
 [[Category:Super FX]]
 [[Category:Flag Prefix Instructions]]
+[[Category:One-byte Instructions]]