diff options
| -rw-r--r-- | README.md | 14 | ||||
| -rw-r--r-- | list.s | 22 |
2 files changed, 26 insertions, 10 deletions
@@ -32,9 +32,17 @@ ready to be used. As for the memory mapping, please do note that this library needs 4 bytes in order to store two 16-bit pointers that keep track of the list. By default these 4 bytes are located at \$60-\$63. If that clashes with something from your code, -simply change these variables, named `List::ptr` and `List::last`. Each of these -pointers are 16-bit long (hence 2 bytes long), and they don't need to be in -continguous memory locations. +you can provide alternative locations by defining `LIST_PTR_ADDRESS` and +`LIST_LAST_ADDRESS`. So: + +```assembly +;; Let's say that you want one pointer in $80-$81, and the other at $90-$91. +LIST_PTR_ADDRESS = $80 +LIST_LAST_ADDRESS = $90 + +;; And then include the library. +.include "<vendor directory>/list.s" +``` ### Creating a list @@ -58,13 +58,21 @@ ;; For more information on the usage and the API check the documentation ;; (README.md file on the https://github.com/mssola/list.nes repository). .scope List - ;; NOTE (important): this library needs 4 bytes ($60-$63) to store - ;; information of this list. These are two 16-bit pointers which are used - ;; for the subroutines being defined here. If you have a clash with these - ;; memory addresses, do feel free to change them, but remember that the code - ;; assumes that both pointers are 16-bit (they don't need to be contiguous). - ptr = $60 - last = $62 + ;; NOTE (important): this library needs 4 bytes to store information of this + ;; list. These are two 16-bit pointers which are used for the subroutines + ;; being defined here. The exact location of these pointers are set to + ;; $60-$63 by default, but they can be changed by providing definitions for + ;; `LIST_PTR_ADDRESS` and `LIST_LAST_ADDRESS`. + .ifdef LIST_PTR_ADDRESS + ptr = LIST_PTR_ADDRESS + .else + ptr = $60 + .endif + .ifdef LIST_LAST_ADDRESS + last = LIST_LAST_ADDRESS + .else + last = $62 + .endif ;; Set the value of `a` into the list and advance one position without ;; growing the list. |