Added option to disable the force-to-uppercase behavior of the apple2 target. (#2474)

* Added option to disable the force-to-uppercase behavior of the apple2 target.

* Fixed dangling spaces.

libsrc/apple2/allow_lowercase.s

@@ -0,0 +1,23 @@
+;
+; Oliver Schmidt, 2024-08-06
+;
+; unsigned char __fastcall__ allow_lowercase (unsigned char onoff);
+;
+
+        .export         _allow_lowercase
+        .import         uppercasemask, return0, return1
+
+_allow_lowercase:
+        tax
+        lda     values,x
+        ldx     uppercasemask
+        sta     uppercasemask
+        cpx     #$FF
+        beq     :+
+        jmp     return0
+:       jmp     return1
+
+        .rodata
+
+values: .byte   $DF         ; Force uppercase
+        .byte   $FF         ; Keep lowercase

libsrc/apple2/cputc.s

@@ -11,6 +11,9 @@
         .export         _cputcxy, _cputc
         .export         cputdirect, newline, putchar, putchardirect
         .import         gotoxy, VTABZ
+        .ifndef __APPLE2ENH__
+        .import         uppercasemask
+        .endif
 
         .include        "apple2.inc"
 
@@ -43,7 +46,7 @@ _cputc:
         .ifndef __APPLE2ENH__
         cmp     #$E0            ; Test for lowercase
         bcc     cputdirect
-        and     #$DF            ; Convert to uppercase
+        and     uppercasemask
         .endif
 
 cputdirect:

libsrc/apple2/uppercasemask.s

@@ -0,0 +1,9 @@
+;
+; Oliver Schmidt, 2024-08-06
+;
+
+        .export         uppercasemask
+
+        .data
+
+uppercasemask:  .byte   $DF     ; Convert to uppercase

libsrc/apple2/write.s

@@ -7,6 +7,9 @@
         .export         _write
         .import         rwprolog, rwcommon, rwepilog
         .import         COUT
+        .ifndef __APPLE2ENH__
+        .import         uppercasemask
+        .endif
 
         .include        "zeropage.inc"
         .include        "errno.inc"
@@ -84,7 +87,7 @@ next:   lda     (ptr1),y
         .ifndef __APPLE2ENH__
         cmp     #$E0            ; Test for lowercase
         bcc     output
-        and     #$DF            ; Convert to uppercase
+        and     uppercasemask
         .endif
 output: jsr     COUT            ; Preserves X and Y