MVN: Difference between revisions

Latest revision as of 12:43, 14 December 2023


Basic Info
Addressing Mode	Opcode	Length	Speed
block move	54	3 bytes	7 cycles per byte moved


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

MVN (Block Move Negative) is a 65c816 instruction that copies a contiguous block of memory. It is intended to copy a block from a higher address to a lower address (moving it in the negative direction).

In Eyes & Lichty, the "N" in the mnemonic stands for "Next" not "Negative."

Parameters

the X index register specifies the starting (lowest) source address of the block
the Y index register specifies the starting (lowest) destination address of the block
the C double accumulator specifies the length of the block in bytes minus one
the first operand byte specifies the destination bank the block will be in
the second operand byte specifies the source bank the block starts out in

Execution Sequence

The following loop is repeated until the value in the C double accumulator is $FFFF:

one byte is copied from the address in X to the address in Y
both X and Y are incremented
C is decremented

Assembler Syntax

Asar:

MVN srds

where "sr" is the source bank, and "ds" is the destination bank, with nothing in between them.^[1]

External Links

Eyes & Lichty page 466 on MVN: https://archive.org/details/0893037893ProgrammingThe65816/page/n492
Labiak page 153 on MVN: https://archive.org/details/Programming_the_65816/page/n163
snes9x implementation of MVN: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3011
undisbeliever on MVN: https://undisbeliever.net/snesdev/65816-opcodes.html#mvn-block-move-next

References

https://github.com/InsaneFirebat/sm_practice_hack/blob/master/src/custompresets.asm#L260

@@ Line 1: / Line 1: @@
-'''MVN''' (Block Move Negative) is a [[65c816]] instruction that copies a contiguous block of memory.  It is intended to copy a block from a higher address to a lower address (moving it in the negative direction).
-[[File:mvn.png|thumb]]
 {| class="wikitable" style="float:right;clear:right;width:50%"
 !colspan="8"|Basic Info
@@ Line 11: / Line 7: @@
 |'''Speed'''
 |+
-|block move
+|[[block move]]
 |54
 |3 bytes
 |7 cycles per byte moved
 |}
+[[File:mvn.png|thumb]]
 {| 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 38: / Line 36: @@
 |.
 |}
+'''MVN''' (Block Move Negative) is a [[65c816]] instruction that copies a contiguous block of memory.  It is intended to copy a block from a higher address to a lower address (moving it in the negative direction).
+In [[Eyes & Lichty]], the "N" in the mnemonic stands for "Next" not "Negative."
+=== Parameters ===
+* the [[X index register]] specifies the starting (lowest) source address of the block
+* the [[Y index register]] specifies the starting (lowest) destination address of the block
+* the [[C double accumulator]] specifies the length of the block in bytes minus one
+* the first operand byte specifies the destination bank the block will be in
+* the second operand byte specifies the source bank the block starts out in
+=== Execution Sequence ===
+The following loop is repeated until the value in the C double accumulator is $FFFF:
+* one byte is copied from the address in X to the address in Y
+* both X and Y are incremented
+* C is decremented
+=== Assembler Syntax ===
+[[Asar]]:
+<pre>
+MVN srds
+</pre>
+where "sr" is the source bank, and "ds" is the destination bank, with nothing in between them.<sup>[1]</sup>
 === See Also ===
 * [[MVP]]
+=== External Links ===
+* [[Eyes & Lichty]] page 466 on MVN: https://archive.org/details/0893037893ProgrammingThe65816/page/n492
+* [[Labiak]] page 153 on MVN: https://archive.org/details/Programming_the_65816/page/n163
+* snes9x implementation of MVN: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3011
+* undisbeliever on MVN: https://undisbeliever.net/snesdev/65816-opcodes.html#mvn-block-move-next
+=== References ===
+# https://github.com/InsaneFirebat/sm_practice_hack/blob/master/src/custompresets.asm#L260
 [[Category:ASM]]
 [[Category:65c816 additions]]
+[[Category:Block Move Instructions]]
+[[Category:Single Admode Mnemonics]]