Merge pull request #71 from groessler/something_to_pull2

Support to create cartridges for the Atari.

cfg/atari-cart.cfg

@@ -0,0 +1,44 @@
+FEATURES {
+    STARTADDRESS: default = $2000;
+}
+SYMBOLS {
+    __CARTSIZE__:        type = weak,   value = $2000; # possible values: $2000 and $4000
+    __CART_HEADER__:     type = import;
+    __STACKSIZE__:       type = weak,   value = $0800; # 2k stack
+    __STARTADDRESS__:    type = export, value = %S;
+    __RESERVED_MEMORY__: type = export, value = $0000;
+    __CARTFLAGS__:       type = weak,   value = $01;   # see documentation for other possible values
+}
+MEMORY {
+    ZP:         file = "", define = yes, start = $0082,                size = $007E;
+    RAM:        file = "", define = yes, start = %S,                   size = __CARTSIZE__;
+    ROM:        file = %O, define = yes, start = $C000 - __CARTSIZE__, size = __CARTSIZE__ - 6, fill = yes, fillval = $FF;
+    CARTID:     file = %O,               start = $BFFA,                size = $0006;
+}
+SEGMENTS {
+    STARTUP:   load = ROM,            type = ro,  define = yes, optional = yes;
+    LOWCODE:   load = ROM,            type = ro,  define = yes, optional = yes;
+    INIT:      load = ROM,            type = ro,                optional = yes;
+    CODE:      load = ROM,            type = ro,  define = yes;
+    RODATA:    load = ROM,            type = ro,                optional = yes;
+    DATA:      load = ROM, run = RAM, type = rw,  define = yes, optional = yes;
+    BSS:       load = RAM,            type = bss, define = yes, optional = yes;
+    CARTHDR:   load = CARTID,         type = ro;
+    ZEROPAGE:  load = ZP,             type = zp;
+    EXTZP:     load = ZP,             type = zp,                optional = yes;
+}
+FEATURES {
+    CONDES: type    = constructor,
+            label   = __CONSTRUCTOR_TABLE__,
+            count   = __CONSTRUCTOR_COUNT__,
+            segment = INIT;
+    CONDES: type    = destructor,
+            label   = __DESTRUCTOR_TABLE__,
+            count   = __DESTRUCTOR_COUNT__,
+            segment = RODATA;
+    CONDES: type    = interruptor,
+            label   = __INTERRUPTOR_TABLE__,
+            count   = __INTERRUPTOR_COUNT__,
+            segment = RODATA,
+            import  = __CALLIRQ__;
+}

libsrc/atari/carthdr.s

@@ -0,0 +1,22 @@
+; Cartridge "header"
+; (In fact, it's at the end of the cartridge, so more a "trailer".)
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.import         __CARTSIZE__, __CARTFLAGS__, cartinit, cartstart
+.export         __CART_HEADER__: absolute = 1
+
+.include        "atari.inc"
+
+.segment        "CARTHDR"
+
+                .word   cartstart       ; start routine
+                .byte   0               ; must be zero
+                .byte   <__CARTFLAGS__
+                .word   cartinit        ; init routine
+
+.assert         (__CARTSIZE__ = $2000 || __CARTSIZE__ = $4000), error, "Cartridge size must either be $2000 or $4000"
+
+.endif  ; .ifndef __ATARIXL__

libsrc/atari/cartinit.s

@@ -0,0 +1,11 @@
+; Cartridge init routine
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.export         cartinit
+
+cartinit:       rts
+
+.endif  ; .ifndef __ATARIXL__

libsrc/atari/cartstart.s

@@ -0,0 +1,21 @@
+; Cartridge start routine
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.export         cartstart
+
+.import         start, copydata
+.importzp       ptr1, ptr2, tmp1, tmp2
+
+.include        "atari.inc"
+
+; start routine of cartridge
+; copy data segment to RAM and chain to entry point of crt0.s
+
+cartstart:      jsr     copydata
+                jsr     start                   ; run program
+                jmp     (DOSVEC)                ; return to DOS
+
+.endif  ; .ifndef __ATARIXL__