MVN: Difference between revisions

Revision as of 03:30, 18 June 2023

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."


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


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

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

External Links

Eyes & Lichty page on MVN: https://archive.org/details/0893037893ProgrammingThe65816/page/n492
Labiak page 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

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+=== 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
 === See Also ===