Memory copy.

As tia, tii, tin, etc... only takes immediate values as arguments, the trick is to have the copy instruction in ram and modify the arguments.

Summary

Memory copy.	As tia, tii, tin, etc...
Copy Modes.
SOURCE_ALT_DEST_INC	Alternate source address and increment destination address (TAI).
SOURCE_DEC_DEST_DEC = $c3	Decrement source and destination addresses (TDD).
SOURCE_INC_DEST_ALT	Increment source address and alternate destination address (TIA).
SOURCE_INC_DEST_NOP	Increment source address and leave destination address unchanged (TIN).
SOURCE_INC_DEST_INC	Increment source and destination addresses (TII).
Memory copy helpers.
memcpy_init	Initialize memcpy routine.
memcpy_mode	Set memcpy mode (see Copy Modes).
memcpy_args	Set memcpy arguments.
memcpy_ex	Copy len bytes from the src to dst.

SOURCE_ALT_DEST_INC = $f3

Alternate source address and increment destination address (TAI).

SOURCE_DEC_DEST_DEC = $c3

Decrement source and destination addresses (TDD).

SOURCE_INC_DEST_ALT = $e3

Increment source address and alternate destination address (TIA).

SOURCE_INC_DEST_NOP = $d3

Increment source address and leave destination address unchanged (TIN).

SOURCE_INC_DEST_INC = $73

Increment source and destination addresses (TII).

Initialize memcpy routine.

This macro basically set memcpy_rts to the RTS instruction value.

Set memcpy mode (see Copy Modes).

mode	memory copy mode.

Set memcpy arguments.

Copy len bytes from the src to dst. This is equivalent to :

memcpy_mode mode
memcpy_args src, dst, len
jsr    memcpy

memcpy_ex <_si, #video_data, #$0100, #SOURCE_INC_DEST_ALT

src	source.
dst	destination.
len	number of bytes to copy.
mode	memory copy mode (see Copy Modes). optinal (default: SOURCE_INC_DEST_ALT).