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⌂ ∞ Elite on the BBC Micro and NES

Utility routines: CopySmallBlock

[NES version, Bank 7]

       Name: CopySmallBlock                                          [Show more]
       Type: Subroutine
   Category: Utility routines
    Summary: An unused routine that copies a small number of pages in memory

    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file




 Arguments:

   V(1 0)               Source address

   SC(1 0)              Destination address

   X                    Number of pages of memory to copy



.CopySmallBlock

 LDY #0                 ; Set an index counter in Y

.cops1

 LDA (V),Y              ; Copy the Y-th byte from V(1 0) to SC(1 0)
 STA (SC),Y

 DEY                    ; Decrement the index counter

 BNE cops1              ; Loop back until we have copied a whole page of bytes

 INC V+1                ; Increment the high bytes of V(1 0) and SC(1 0) to
 INC SC+1               ; point to the next page in memory

 DEX                    ; Decrement the page counter

 BNE cops1              ; Loop back until we have copied X pages of memory

 RTS                    ; Return from the subroutine