PEI: Difference between revisions

Latest revision as of 23:16, 12 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Stack (Direct Page Indirect)	D4	2 bytes	6 cycles*


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

PEI (Push Effective Indirect address) is a 65c816 instruction that pushes a 16-bit value to the stack. This value need not actually be an address. This value is found at the address formed by adding the operand byte to the direct page register. The high byte (found at the effective address plus one) is pushed first, then the low byte.

No flags are affected.

PEI works even in emulation mode.

Syntax

PEI (dp)
PEI dp

Cycle Penalty

PEI takes one extra cycle if the low byte of the direct page register is nonzero.

External Links

Eyes & Lichty, page 474 on PEI
Labiak, page 158 on PEI
snes9x implementation of PEI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1658
undisbeliever on PEI: https://undisbeliever.net/snesdev/65816-opcodes.html#pei-push-effective-indirect-address
how PEI behaves in emulation mode - section 7.2 of 65c816 datasheet: https://www.westerndesigncenter.com/wdc/documentation/w65c816s.pdf
Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.8.1

@@ Line 1: / Line 1: @@
-'''PEI''' (Push Effective Indirect address) is a [[65c816]] instruction that pushes a 16-bit value to the stack.  This value need not actually be an address.
+{| 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]] (Direct Page Indirect)
 |D4
 |2 bytes
-|6 cycles
+|6 cycles*
 |}
 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="9"|Flags Clobbered
+!colspan="9"|Flags Affected
 |+
-|N
+|[[Negative Flag|N]]
-|V
+|[[Overflow Flag|V]]
-|M
+|[[M Flag|M]]
-|X
+|[[X Flag|X]]
-|D
+|[[Decimal Flag|D]]
-|I
+|[[I Flag|I]]
-|Z
+|[[Zero Flag|Z]]
-|C
+|[[Carry Flag|C]]
 |+
 |.
@@ Line 36: / Line 34: @@
 |.
 |}
+'''PEI''' (Push Effective Indirect address) is a [[65c816]] instruction that pushes a 16-bit value to the [[stack]].  This value need not actually be an address.  This value is found at the address formed by adding the operand byte to the [[direct page register]].  The high byte (found at the effective address plus one) is pushed first, then the low byte.
+No flags are affected.
+PEI works even in [[emulation mode]].
+==== Syntax ====
+<pre>
+PEI (dp)
+PEI dp
+</pre>
+===== Cycle Penalty =====
+*  PEI takes one extra cycle if the low byte of the [[direct page register]] is nonzero.
+=== See Also ===
+* [[PEA]]
+* [[PER]]
+* [[PHA]]
 === External Links ===
-* [[Eyes & Lichty]] page on PEI: https://archive.org/details/0893037893ProgrammingThe65816/page/n500
+* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/474 page 474] on PEI
-* [[Labiak]] page on PEI: https://archive.org/details/Programming_the_65816/page/n168
+* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n168 page 158] on PEI
 * snes9x implementation of PEI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1658
+* undisbeliever on PEI: https://undisbeliever.net/snesdev/65816-opcodes.html#pei-push-effective-indirect-address
+* how PEI behaves in [[emulation mode]] - section 7.2 of 65c816 datasheet: https://www.westerndesigncenter.com/wdc/documentation/w65c816s.pdf
+* Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.8.1
 [[Category:ASM]]
 [[Category:65c816 additions]]
+[[Category:Push Instructions]]
+[[Category:Two-byte Instructions]]