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MVP: Difference between revisions

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=== External Links ===
=== External Links ===
* [[Eyes & Lichty]] page on MVP: https://archive.org/details/0893037893ProgrammingThe65816/page/n494
* [[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
* [[Labiak]] page 154 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
* 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
* undisbeliever on MVP: https://undisbeliever.net/snesdev/65816-opcodes.html#mvp-block-move-previous

Revision as of 04:38, 5 December 2023

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

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

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

External Links