BVC (Super FX): Difference between revisions

Latest revision as of 08:02, 14 July 2024


Basic Info
Addressing Mode	Opcode	Length	ROM Speed	RAM Speed	Cache Speed
Program Counter Relative	0E??	2 bytes	6 cycles	6 cycles	2 cycles


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

BVC (Branch Overflow Clear) is a Super FX instruction that performs a branch when the overflow flag (O/V) is clear. The instruction following BVC is already in the pipeline and will run even if the branch occurs.

If the overflow flag is set, control simply falls through and the branch does not happen.

No flags are affected.

Syntax

BVC e

where e is a relative offset from -128 to 127.

Example

Let the O/V flag be clear. This instruction jumps the program forward 4 bytes:

BVC $+4h

External Links

Official Nintendo documentation on BVC: 9.25 on Page 2-9-34 of Book II
example: Page 2-9-35 of Book II, lbid.

@@ Line 9: / Line 9: @@
 |'''Cache Speed'''
 |+
-|
+|[[Program Counter Relative]]
 |0E??
 |2 bytes
@@ Line 26: / Line 26: @@
 |[[Sign Flag|S]]
 |[[CY]]
-|Z
+|[[Zero Flag|Z]]
 |+
 |.
@@ Line 37: / Line 37: @@
 |}
-'''BVC''' (Branch Overflow Clear) is a [[Super FX]] instruction that performs a branch when the overflow flag is clear.
+'''BVC''' (Branch Overflow Clear) is a [[Super FX]] instruction that performs a branch when the overflow flag ([[O/V]]) is clear.  The instruction following BVC is already in the pipeline and will run even if the branch occurs.
+If the overflow flag is set, control simply falls through and the branch does not happen.
 No flags are affected.
+==== Syntax ====
+<pre>
+BVC e
+</pre>
+where e is a relative offset from -128 to 127.
+==== Example ====
+Let the O/V flag be clear.  This instruction jumps the program forward 4 bytes:
+<pre>
+BVC $+4h
+</pre>
 === See Also ===