CBNE (SPC700): Difference between revisions

Latest revision as of 19:31, 15 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Direct Page / Program Counter Relative	2E	3 bytes	when condition is false: 5 cycles when condition is true: 7 cycles
Direct Page Indexed by X / Program Counter Relative	DE	3 bytes	when condition is false: 6 cycles when condition is true: 8 cycles


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

CBNE (Compare Branch Not Equal) is an SPC700 instruction that performs a comparison between the accumulator and a direct page value and then branches if they are not equal. The direct page index is the first operand and also the first byte immediately following the opcode, and the relative branch offset is the second operand, the second byte following the opcode.^[3]

No flags are affected.

Syntax

CBNE dp, rel
CBNE dp+X, rel

Where rel is given in two's complement.

External Links

Official Super Nintendo development manual on CBNE: Table C-15, Appendix C-8 of book I
anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L372
lbid: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L270

@@ Line 1: / Line 1: @@
-'''CBNE''' is an [[SPC700]] instruction that performs a comparison between the accumulator and a direct page value and then branches if they are not equal.
+{| class="wikitable" style="float:right;clear:right;width:60%"
-{| class="wikitable" style="float:right;clear:right;width:30%"
 !colspan="8"|Basic Info
 |+
@@ Line 9: / Line 7: @@
 |'''Speed'''
 |+
-|
+|[[Direct Page]] / [[Program Counter Relative]]
 |2E
 |3 bytes
-|5 or 7 cycles
+|when condition is false: 5 cycles
+when condition is true: 7 cycles
 |+
-|
+|[[Direct Page Indexed by X]] / [[Program Counter Relative]]
 |DE
 |3 bytes
-|6 or 8 cycles
+|when condition is false: 6 cycles
+when condition is true: 8 cycles
 |}
 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="8"|Flags Clobbered
+!colspan="8"|Flags Affected
 |+
-|N
+|[[Negative Flag|N]]
-|V
+|[[Overflow Flag|V]]
-|P
+|[[Direct Page Flag|P]]
-|B
+|[[Break Flag|B]]
-|H
+|[[Half-Carry Flag|H]]
-|I
+|[[Interrupt Enable Flag|I]]
-|Z
+|[[Zero Flag|Z]]
-|C
+|[[Carry Flag|C]]
 |+
 |.
@@ Line 41: / Line 41: @@
 |.
 |}
+'''CBNE''' (Compare Branch Not Equal) is an [[SPC700]] instruction that performs a comparison between the [[accumulator]] and a [[direct page]] value and then branches if they are not equal.  The direct page index is the first operand and also the first byte immediately following the opcode, and the relative branch offset is the second operand, the second byte following the opcode.<sup>[3]</sup>
+No flags are affected.
+==== Syntax ====
+<pre>
+CBNE dp, rel
+CBNE dp+X, rel
+</pre>
+Where rel is given in two's complement.
+=== See Also ===
+* [[DBNZ]]
+* [[BNE (SPC700)]]
+=== External Links ===
+# Official Super Nintendo development manual on CBNE: Table C-15, [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of book I]
+# anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L372
+# lbid: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L270
 [[Category:ASM]]
 [[Category:SPC700]]
 [[Category:Branching Commands]]