BBS (SPC700): Difference between revisions

Revision as of 18:22, 23 July 2023


Basic Info
Addressing Mode	Opcode	Length	Speed
	03	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	23	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	43	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	63	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	83	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	A3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	C3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
	E3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles


Flags Clobbered
N	V	P	B	H	I	Z	C
.	.	.	.	.	.	.	.

BBS (Branch on Bit Set) is an SPC700 instruction that performs a branch when a bit in the direct page is set. The direct page byte that bit lives in is the first operand. The bit within that byte is a function of the high nibble of the opcode. The target relative address to jump to is the second operand.

References

Appendix C-8 of Book I of the official Super Nintendo development manual

@@ Line 78: / Line 78: @@
 |}
-'''BBS''' (Branch on Bit Set) is an [[SPC700]] that performs a branch when the [[direct page flag]] is set.
+'''BBS''' (Branch on Bit Set) is an [[SPC700]] instruction that performs a branch when a bit in the [[direct page]] is set.  The direct page byte that bit lives in is the first operand.  The bit within that byte is a function of the high nibble of the opcode.  The target relative address to jump to is the second operand.
 === See Also ===