RTS: Difference between revisions

Latest revision as of 20:00, 10 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Stack (RTS)	60	1 byte	6 cycles


Flags Affected
N	V	M	X	D	I	Z	C
.	.	.	.	.	.	.	.

RTS (Return from Subroutine) is a 65x instruction used to return control from a subroutine that was called from the same bank.

RTS pulls the return address from the stack, but increments the value by one before loading it into the program counter. In other words, RTS unwinds what JSR did to the stack. The stack pointer is incremented twice: during cycle 3 and cycle 4.

No flags are affected.

Syntax

RTS

Forgetting to RTS can cause derailment as control falls through the end of the subroutine into the next one or garbage.

External Links

Eyes & Lichty, page 496 on RTS
Labiak, page 178 on RTS
8.2 on MCS6500 Manual, page 108 on RTS
Carr, page 271 on RTS
Leventhal, page 3-90 on RTS
snes9x implementation of RTS: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2982
Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#RTS
Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.2.2.2
https://archive.org/details/mos_microcomputers_programming_manual/page/n128

@@ Line 1: / Line 1: @@
-'''RTS''' (Return from Subroutine) is a [[65c816]] instruction used to return control from a subroutine that was called from the same bank.
+{| class="wikitable" style="float:right;clear:right;width:40%"
-{| class="wikitable" style="float:right;clear:right;width:30%"
 !colspan="8"|Basic Info
 |+
@@ Line 9: / Line 7: @@
 |'''Speed'''
 |+
-|stack
+|[[Stack Addressing|Stack]] (RTS)
 |60
-|1 bytes
+|1 byte
 |6 cycles
 |}
 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="9"|Flags Clobbered
+!colspan="9"|Flags Affected
 |+
-|N
+|[[N Flag|N]]
-|V
+|[[V Flag|V]]
-|M
+|[[M Flag|M]]
-|X
+|[[X Flag|X]]
-|D
+|[[D Flag|D]]
-|I
+|[[I Flag|I]]
-|Z
+|[[Z Flag|Z]]
-|C
+|[[C Flag|C]]
 |+
 |.
@@ Line 36: / Line 34: @@
 |.
 |}
+'''RTS''' (Return from Subroutine) is a 65x instruction used to return control from a subroutine that was called from the same [[bank]].
+RTS pulls the [[return address]] from the [[stack]], but increments the value by one before loading it into the [[program counter]].  In other words, RTS unwinds what [[JSR]] did to the stack.  The [[stack pointer]] is incremented twice: during cycle 3 and cycle 4.
+No flags are affected.
+==== Syntax ====
+<pre>
+RTS
+</pre>
+[[File:rts.png]]
+Forgetting to RTS can cause [[derailment]] as control falls through the end of the subroutine into the next one or garbage.
 === See Also ===
 * [[RTI]]
 * [[RTL]]
+* [[RET]]
+* [[RETI]]
+=== External Links ===
+* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/496 page 496] on RTS
+* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n188 page 178] on RTS
+* 8.2 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n127 page 108] on RTS
+* [[Carr]], [https://archive.org/details/6502UsersManual/page/n284 page 271] on RTS
+* [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n139 page 3-90] on RTS
+* snes9x implementation of RTS: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2982
+* Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#RTS
+* Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.2.2.2
+* https://archive.org/details/mos_microcomputers_programming_manual/page/n128
 [[Category:ASM]]
 [[Category:Inherited from 6502]]
+[[Category:Unconditional Branches]]
+[[Category:One-byte Instructions]]
+[[Category:Single Admode Mnemonics]]