Super FX Opcode Matrices

The Super FX has two prefix flags called ALT1 and ALT2 that alter the way the GSU interprets opcodes. These four opcode matrices will show which instruction actually runs depending on how those prefix flags are set.

Note: These matrices are under construction, created from the official dev manual, and are untested on hardware. What instruction happens when an ALT flag/opcode combination which has no dedicated page in the manual runs is particularly unverified. (Some of these are denoted with ?) (edit: fullsnes has a section on "Ignored Prefixes")^[1]

ALT1 = 0, ALT2 = 0

	x0	x1	x2	x3	x4	x5	x6	x7	x8	x9	xA	xB	xC	xD	xE	xF
0x	STOP	NOP	CACHE	LSR	ROL	BRA	BGE	BLT	BNE	BEQ	BPL	BMI	BCC	BCS	BVC	BVS
1x	TO R0	TO R1	TO R2	TO R3	TO R4	TO R5	TO R6	TO R7	TO R8	TO R9	TO R10	TO R11	TO R12	TO R13	TO R14	TO R15
2x	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE	MOVE
3x	STW (R0)	STW (R1)	STW (R2)	STW (R3)	STW (R4)	STW (R5)	STW (R6)	STW (R7)	STW (R8)	STW (R9)	STW (R10)	STW (R11)	LOOP	ALT1	ALT2	ALT3
4x	LDW (R0)	LDW (R1)	LDW (R2)	LDW (R3)	LDW (R4)	LDW (R5)	LDW (R6)	LDW (R7)	LDW (R8)	LDW (R9)	LDW (R10)	LDW (R11)	PLOT	SWAP	COLOR	NOT
5x	ADD R0	ADD R1	ADD R2	ADD R3	ADD R4	ADD R5	ADD R6	ADD R7	ADD R8	ADD R9	ADD R10	ADD R11	ADD R12	ADD R13	ADD R14	ADD R15
6x	SUB R0	SUB R1	SUB R2	SUB R3	SUB R4	SUB R5	SUB R6	SUB R7	SUB R8	SUB R9	SUB R10	SUB R11	SUB R12	SUB R13	SUB R14	SUB R15
7x	MERGE	AND R1	AND R2	AND R3	AND R4	AND R5	AND R6	AND R7	AND R8	AND R9	AND R10	AND R11	AND R12	AND R13	AND R14	AND R15
8x	MULT R0	MULT R1	MULT R2	MULT R3	MULT R4	MULT R5	MULT R6	MULT R7	MULT R8	MULT R9	MULT R10	MULT R11	MULT R12	MULT R13	MULT R14	MULT R15
9x	SBK	LINK #1	LINK #2	LINK #3	LINK #4	SEX	ASR	ROR	JMP R8	JMP R9	JMP R10	JMP R11	JMP R12	JMP R13	LOB	FMULT
Ax	IBT R0	IBT R1	IBT R2	IBT R3	IBT R4	IBT R5	IBT R6	IBT R7	IBT R8	IBT R9	IBT R10	IBT R11	IBT R12	IBT R13	IBT R14	IBT R15
Bx	FROM R0	FROM R1	FROM R2	FROM R3	FROM R4	FROM R5	FROM R6	FROM R7	FROM R8	FROM R9	FROM R10	FROM R11	FROM R12	FROM R13	FROM R14	FROM R15
Cx	HIB	OR R1	OR R2	OR R3	OR R4	OR R5	OR R6	OR R7	OR R8	OR R9	OR R10	OR R11	OR R12	OR R13	OR R14	OR R15
Dx	INC R0	INC R1	INC R2	INC R3	INC R4	INC R5	INC R6	INC R7	INC R8	INC R9	INC R10	INC R11	INC R12	INC R13	INC R14	GETC
Ex	DEC R0	DEC R1	DEC R2	DEC R3	DEC R4	DEC R5	DEC R6	DEC R7	DEC R8	DEC R9	DEC R10	DEC R11	DEC R12	DEC R13	DEC R14	GETB
Fx	IWT R0, #xx	IWT R1, #xx	IWT R2, #xx	IWT R3, #xx	IWT R4, #xx	IWT R5, #xx	IWT R6, #xx	IWT R7, #xx	IWT R8, #xx	IWT R9, #xx	IWT R10, #xx	IWT R11, #xx	IWT R12, #xx	IWT R13, #xx	IWT R14, #xx	IWT R15, #xx

ALT1 = 0, ALT2 = 1

	x0	x1	x2	x3	x4	x5	x6	x7	x8	x9	xA	xB	xC	xD	xE	xF
0x	STOP	NOP	CACHE	LSR	ROL	BRA	BGE	BLT	BNE	BEQ	BPL	BMI	BCC	BCS	BVC	BVS
1x	TO R0	TO R1	TO R2	TO R3	TO R4	TO R5	TO R6	TO R7	TO R8	TO R9	TO R10	TO R11	TO R12	TO R13	TO R14	TO R15
2x
3x													LOOP	ALT1	ALT2	ALT3
4x													PLOT	SWAP	COLOR	NOT
5x
6x	SUB #0	SUB #1	SUB #2	SUB #3	SUB #4	SUB #5	SUB #6	SUB #7	SUB #8	SUB #9	SUB #10	SUB #11	SUB #12	SUB #13	SUB #14	SUB #15
7x	MERGE
8x	MULT #0	MULT #1	MULT #2	MULT #3	MULT #4	MULT #5	MULT #6	MULT #7	MULT #8	MULT #9	MULT #10	MULT #11	MULT #12	MULT #13	MULT #14	MULT #15
9x	SBK	LINK #1	LINK #2	LINK #3	LINK #4	SEX	ASR	ROR							LOB	FMULT
Ax	IBT R0	IBT R1	IBT R2	IBT R3	IBT R4	IBT R5	IBT R6	IBT R7	IBT R8	IBT R9	IBT R10	IBT R11	IBT R12	IBT R13	IBT R14	IBT R15
Bx	FROM R0	FROM R1	FROM R2	FROM R3	FROM R4	FROM R5	FROM R6	FROM R7	FROM R8	FROM R9	FROM R10	FROM R11	FROM R12	FROM R13	FROM R14	FROM R15
Cx	HIB	OR #1	OR #2	OR #3	OR #4	OR #5	OR #6	OR #7	OR #8	OR #9	OR #10	OR #11	OR #12	OR #13	OR #14	OR #15
Dx																RAMB
Ex	DEC R0	DEC R1	DEC R2	DEC R3	DEC R4	DEC R5	DEC R6	DEC R7	DEC R8	DEC R9	DEC R10	DEC R11	DEC R12	DEC R13	DEC R14	GETBL
Fx	IWT R0, #xx	IWT R1, #xx	IWT R2, #xx	IWT R3, #xx	IWT R4, #xx	IWT R5, #xx	IWT R6, #xx	IWT R7, #xx	IWT R8, #xx	IWT R9, #xx	IWT R10, #xx	IWT R11, #xx	IWT R12, #xx	IWT R13, #xx	IWT R14, #xx	IWT R15, #xx

ALT1 = 1, ALT2 = 0

	x0	x1	x2	x3	x4	x5	x6	x7	x8	x9	xA	xB	xC	xD	xE	xF
0x	STOP	NOP	CACHE	LSR	ROL	BRA	BGE	BLT	BNE	BEQ	BPL	BMI	BCC	BCS	BVC	BVS
1x	TO R0	TO R1	TO R2	TO R3	TO R4	TO R5	TO R6	TO R7	TO R8	TO R9	TO R10	TO R11	TO R12	TO R13	TO R14	TO R15
2x
3x	STB (R0)	STB (R1)	STB (R2)	STB (R3)	STB (R4)	STB (R5)	STB (R6)	STB (R7)	STB (R8)	STB (R9)	STB (R10)	STB (R11)	LOOP	ALT1	ALT2	ALT3
4x													RPIX	SWAP	CMODE	NOT
5x	ADC R0	ADC R1	ADC R2	ADC R3	ADC R4	ADC R5	ADC R6	ADC R7	ADC R8	ADC R9	ADC R10	ADC R11	ADC R12	ADC R13	ADC R14	ADC R15
6x
7x	MERGE
8x	UMULT R0	UMULT R1	UMULT R2	UMULT R3	UMULT R4	UMULT R5	UMULT R6	UMULT R7	UMULT R8	UMULT R9	UMULT R10	UMULT R11	UMULT R12	UMULT R13	UMULT R14	UMULT R15
9x	SBK	LINK #1	LINK #2	LINK #3	LINK #4	SEX	DIV2	ROR	LJMP R8	LJMP R9	LJMP R10	LJMP R11	LJMP R12	LJMP R13	LOB	FMULT
Ax	IBT R0	IBT R1	IBT R2	IBT R3	IBT R4	IBT R5	IBT R6	IBT R7	IBT R8	IBT R9	IBT R10	IBT R11	IBT R12	IBT R13	IBT R14	IBT R15
Bx	FROM R0	FROM R1	FROM R2	FROM R3	FROM R4	FROM R5	FROM R6	FROM R7	FROM R8	FROM R9	FROM R10	FROM R11	FROM R12	FROM R13	FROM R14	FROM R15
Cx	HIB
Dx																GETC
Ex	DEC R0	DEC R1	DEC R2	DEC R3	DEC R4	DEC R5	DEC R6	DEC R7	DEC R8	DEC R9	DEC R10	DEC R11	DEC R12	DEC R13	DEC R14	GETBH
Fx	IWT R0, #xx	IWT R1, #xx	IWT R2, #xx	IWT R3, #xx	IWT R4, #xx	IWT R5, #xx	IWT R6, #xx	IWT R7, #xx	IWT R8, #xx	IWT R9, #xx	IWT R10, #xx	IWT R11, #xx	IWT R12, #xx	IWT R13, #xx	IWT R14, #xx	IWT R15, #xx

ALT1 = 1, ALT2 = 1

	x0	x1	x2	x3	x4	x5	x6	x7	x8	x9	xA	xB	xC	xD	xE	xF
0x	STOP	NOP	CACHE	LSR	ROL	BRA	BGE	BLT	BNE	BEQ	BPL	BMI	BCC	BCS	BVC	BVS
1x	TO R0	TO R1	TO R2	TO R3	TO R4	TO R5	TO R6	TO R7	TO R8	TO R9	TO R10	TO R11	TO R12	TO R13	TO R14	TO R15
2x
3x													LOOP	ALT1	ALT2	ALT3
4x													PLOT ?	SWAP	COLOR ?	NOT
5x
6x	CMP R0	CMP R1	CMP R2	CMP R3	CMP R4	CMP R5	CMP R6	CMP R7	CMP R8	CMP R9	CMP R10	CMP R11	CMP R12	CMP R13	CMP R14	CMP R15
7x	MERGE	BIC #1	BIC #2	BIC #3	BIC #4	BIC #5	BIC #6	BIC #7	BIC #8	BIC #9	BIC #10	BIC #11	BIC #12	BIC #13	BIC #14	BIC #15
8x
9x	SBK	LINK #1	LINK #2	LINK #3	LINK #4	SEX	DIV2 ?	ROR							LOB	FMULT
Ax	IBT R0	IBT R1	IBT R2	IBT R3	IBT R4	IBT R5	IBT R6	IBT R7	IBT R8	IBT R9	IBT R10	IBT R11	IBT R12	IBT R13	IBT R14	IBT R15
Bx	FROM R0	FROM R1	FROM R2	FROM R3	FROM R4	FROM R5	FROM R6	FROM R7	FROM R8	FROM R9	FROM R10	FROM R11	FROM R12	FROM R13	FROM R14	FROM R15
Cx	HIB
Dx																ROMB
Ex	DEC R0	DEC R1	DEC R2	DEC R3	DEC R4	DEC R5	DEC R6	DEC R7	DEC R8	DEC R9	DEC R10	DEC R11	DEC R12	DEC R13	DEC R14	GETBS
Fx	IWT R0, #xx	IWT R1, #xx	IWT R2, #xx	IWT R3, #xx	IWT R4, #xx	IWT R5, #xx	IWT R6, #xx	IWT R7, #xx	IWT R8, #xx	IWT R9, #xx	IWT R10, #xx	IWT R11, #xx	IWT R12, #xx	IWT R13, #xx	IWT R14, #xx	IWT R15, #xx

Reference

1. https://problemkaputt.de/fullsnes.htm#snescartgsuncpujmpandprefixopcodes