memcpy.in

#
# About
#
#  This program copies a bunch of memory about, then jumps to it.
#
#
# Usage
#
#  $ compiler ./memcpy.in ; ./simple-vm ./memcpy.raw
#
#
#

        goto run
    :code

        #
        #  This is the code we're going to copy and execute.
        #
        store #1, "Steve Kemp\n"
        print_str #1
        store #1, "memcpy works\n"
        print_str #1
        exit
    :code_end

    :run
        #
        # Copy the memory between `code` and `code_end` to 0x5000.
        #

        # First of all calcuate the length
        store #2, code
        store #3, code_end
        sub #3, #3, #2

        # Show the length of the code we're copying
        # Remember the result is in #3.
        store #1, "Code length is "
        print_str #1
        print_int #3
        store #1, "\n"
        print_str #1

        # setup the copy and run it
        store #1, 0x5000
        store #2, code
        memcpy #1, #2, #3

        # Jump to the copied code.
        goto 0x5000