MVP: Difference between revisions

Latest revision as of 20:25, 6 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Block Move	44	3 bytes	7 cycles per byte moved


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

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). No flags are affected.

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

MVP works even in emulation mode, but the blocks must be in the zeropage.

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

If interrupted, the current byte finishes copying before servicing the interrupt. The destination bank is written to DBR.

External Links

Eyes & Lichty, page 468 on MVP
Labiak, page 154 on MVP
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
Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.6

@@ Line 1: / Line 1: @@
-'''MVN''' (Block Move Positive) is a [[65c816]] instruction that copies a contiguous block of memory.
 {| class="wikitable" style="float:right;clear:right;width:50%"
 !colspan="8"|Basic Info
@@ Line 9: / Line 7: @@
 |'''Speed'''
 |+
-|implied
+|[[Block Move]]
 |44
 |3 bytes
 |7 cycles per byte moved
 |}
+[[File:mvp.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 36: / Line 36: @@
 |.
 |}
+'''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).  No flags are affected.
+In [[Eyes & Lichty]], the "P" in the mnemonic stands for "Previous" not "Positive."
+MVP works even in [[emulation mode]], but the blocks must be in the [[zeropage]].
+=== 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
+If interrupted, the current byte finishes copying before servicing the interrupt.  The destination bank is written to [[DBR]].
 === See Also ===
 * [[MVN]]
+* [[DMA]]
+=== External Links ===
+* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/468 page 468] on MVP
+* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n164 page 154] on MVP
+* 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
+* Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.6
 [[Category:ASM]]
+[[Category:65c816 additions]]
+[[Category:Block Move Instructions]]
+[[Category:Single Admode Mnemonics]]