LOOP (Super FX)

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

Flags Affected
B	ALT1	ALT2	O/V	S	CY	Z
0	0	0	.	S	.	Z

LOOP is a Super FX instruction that decrements R₁₂ by one. If the zero flag is set afterwards, R₁₅ is incremented. Otherwise, R₁₃ is stored to R₁₅.

The next instruction after LOOP is already loaded into the pipeline.

The sign flag is set if R₁₂ is negative and cleared otherwise. The ALT0 state is restored.

Syntax

LOOP

Example

In this program:

00:8014 INC R7
00:8015 INC R6
00:8016 LOOP
00:8017 NOP
00:8018 ADD R4

• If R₁₃ is 8014h and R₁₂ is not 0001h, the program jumps to 00:8014h after the NOP.
• If R₁₂ is 0001h, the program does not jump and control falls through to the ADD.

External Links

• Official Nintendo documentation on LOOP: paragraph 9.54 on page 2-9-77 of Book II