MVP

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

In Eyes & Lichty, the "P" in the mnemonic stands for "Previous" not "Positive."

Basic Info
Addressing Mode	Opcode	Length	Speed
block move	44	3 bytes	7 cycles per byte moved

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

Parameters

• the X index register specifies the ending (highest) source address of the block
• the Y index register specifies the ending (highest) 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 decremented
• C is decremented

See Also

• MVN

External Links

• Eyes & Lichty page on MVP: https://archive.org/details/0893037893ProgrammingThe65816/page/n494
• Labiak page on MVP: https://archive.org/details/Programming_the_65816/page/n164
• snes9x implementation of MVP: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3077
• undisbeliever on MVP: https://undisbeliever.net/snesdev/65816-opcodes.html#mvp-block-move-previous