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.

doc/apple2.sgml

@@ -330,6 +330,7 @@ usage.
 <item>_dos_type
 <item>_filetype
 <item>_datetime
+<item>allow_lowercase
 <item>beep
 <item>get_ostype
 <item>gmtime_dt

doc/funcref.sgml

@@ -95,6 +95,7 @@ function.
 
 <itemize>
 <item>_dos_type
+<item>allow_lowercase
 <item><ref id="beep" name="beep">
 <item><ref id="get_ostype" name="get_ostype">
 <item><ref id="gmtime_dt" name="gmtime_dt">

include/apple2.h

@@ -232,6 +232,16 @@ struct tm* __fastcall__ gmtime_dt (const struct datetime* dt);
 time_t __fastcall__ mktime_dt (const struct datetime* dt);
 /* Converts a ProDOS date/time structure to a time_t UNIX timestamp */
 
+#if !defined(__APPLE2ENH__)
+unsigned char __fastcall__ allow_lowercase (unsigned char onoff);
+/* If onoff is 0, lowercase characters printed to the screen via STDIO and
+** CONIO are forced to uppercase. If onoff is 1, lowercase characters are
+** printed to the screen untouched.  By default lowercase characters are
+** forced to uppercase because a stock Apple ][+ doesn't support lowercase
+** display. The function returns the old lowercase setting.
+*/
+#endif
+
 
 
 /* End of apple2.h */

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