Apple II: Document BLTU alternative

2025-03-06 17:20:23 +01:00
parent 020fe4028a
commit c8eb6e2dd5
3 changed files with 22 additions and 1 deletions
--- a/libsrc/apple2/extra/integer-basic-compat.s
+++ b/libsrc/apple2/extra/integer-basic-compat.s
@@ -0,0 +1,33 @@
+;
+; Colin Leroy-Mira, 06.03.2025
+;
+; Copy the LC segment from the end of the binary to the Language Card
+; using _memcpy. This allows running apple2 programs on the original
+; Integer ROM Apple ][.
+;
+
+        .export         bltu2
+
+        .import         _memcpy, pushax
+        .import         __ONCE_LOAD__, __ONCE_SIZE__    ; Linker generated
+        .import         __LC_START__, __LC_LAST__       ; Linker generated
+
+        .segment        "ONCE"
+
+bltu2:
+        ; Get the destination start address.
+        lda     #<__LC_START__
+        ldx     #>__LC_START__
+        jsr     pushax
+
+        ; Get the source start address.
+        lda     #<(__ONCE_LOAD__ + __ONCE_SIZE__)
+        ldx     #>(__ONCE_LOAD__ + __ONCE_SIZE__)
+        jsr     pushax
+
+        ; Set the length
+        lda     #<(__LC_LAST__ - __LC_START__)
+        ldx     #>(__LC_LAST__ - __LC_START__)
+
+        ; And do the copy
+        jmp     _memcpy