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Aztec C AS65 assembler and BRUNABLE program Example available for download

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Now available for download at the following link:

http://www.aztecmuseum.ca/extras/AS65BIN.zip

Just unzip into your AppleX/PROGRAMS directory and you can muck with this to 
your heart's content.

This post is not really about building C Programs. It is more about using 
the Aztec AS65 cross-assembler to build pure little assembly programs in MOS 
6502 and 65C02. Aztec C65 is a 2 pass compiler. Everything in C is 
translated to assembler then assembled so the assembler is also targetted at 
complicated segmented programs, but that doesn't mean you can't make simple 
programs with it... you just need to RTFM and then ignore anything that does 
not apply (as always)! This is admittedly a little like running over a fly 
with a semi-truck but what the heck!

This example uses a simple Assembly Language program (a Hello World program) 
and the Aztec C65 assembler and linker to create a tiny (28 byte) BIN file 
that can be loaded and run in either BASIC.SYSTEM or from within an Aztec C 
SYS program (also provided). Comes with disk images and source code.

The Hello World program is as follows:

x--- snip ---x

; Hello.a65
;
; Hello World in Aztec C's AS65 assembler
; By Bill Buckels 2013
;
; BRUN from BASIC.SYSTEM or load and run in
; an Aztec C65 ProDOS SYS program.
;
; Note: There is no ORG command in AS65 because the Aztec C
; Linker sets the BASE Address, and the Address for the
; CODE and DATA segments... in this case they are all
; the same: $1000

; AS65 hello.a65
; LN65 -O hello.bin hello.r -b 1000 -C 1000 -D 1000

; AS65 does not know about commands for the Apple II Monitor
; So I have used an equate for COUT
COUT EQU $FDED

; I have kept everything in one segment... that's all
; we need for a simple program.

       CSEG
        LDX #12    ; load pointer to end of string into X
LOOP    LDA MSG,X  ; load character at pointer into A
        ORA #$80   ; set hi-bit for ascii string ( |= 0x80)
        JSR COUT   ; print the character
        DEX        ; decrement string pointer
        BPL LOOP   ; branch on plus, loop until X is negative
        RTS        ; return to BASIC (or Aztec C)
MSG     FCC "!DLROW ,OLLEH"
        END

x--- snip ---x

The C Program to load and run the above is as follows:

#include <fcntl.h>

brun(name)
char *name;
{
    int fh;

    /* load subroutine */
   if ((fh = open(name,O_RDONLY,0xc3))==-1) return -1;
    read(fh,(char *)0x1000,0x1000);
    close(fh);

#asm
    jsr $1000 ; call subroutine
#endasm

 return 0;
}

main()
{
    crt80();
    brun("HELLO.BIN");
    getch();
    _exit();
}

Not much more to say about this one except that I have been somewhat terse 
and arbitrary, but bedtime draws near. I should mention that I bload the BIN 
program at the page starting at $1000 below $2000 which is where the SYS 
programs go (see above).

The assembler manual is included in the documentation for the 3.2b compiler 
available from the Aztec C website.

That's about it. I guess a person could write a bunch of these little 
programs and just page them in and out of auxmem as needed by a larger 
program instead of using overlays, but that is a topic for another evening.

All the best,

Bill 

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Aztec C AS65 assembler and BRUNABLE program Example available for download "Bill Buckels" <bbuckels@mts.net> - 2013-09-15 21:25 -0500
  Re: Aztec C AS65 assembler and BRUNABLE program Example available for download "Bill Buckels" <bbuckels@mts.net> - 2013-09-16 18:09 -0500

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