mirror of
https://github.com/cc65/cc65.git
synced 2024-12-22 12:30:41 +00:00
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets.
When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
This commit is contained in:
Greg King
parent
24c2da980b
commit
074e10d288
@ -24,6 +24,7 @@ SCREEN_PTR := $D1 ; Pointer to current char in text screen
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CURS_X := $D3 ; Cursor column
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CURS_Y := $D6 ; Cursor row
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CRAM_PTR := $F3 ; Pointer to current char in color RAM
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FREKZP := $FB ; Five unused bytes
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BASIC_BUF := $200 ; Location of command-line
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BASIC_BUF_LEN = 89 ; Maximum length of command-line
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@ -212,4 +213,3 @@ CASSMOT = $20 ; Cassette motor on
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TP_FAST = $80 ; Switch Rossmoeller TurboProcess to fast mode
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RAMONLY = $F8 ; (~(LORAM | HIRAM | IOEN)) & $FF
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@ -1,64 +1,70 @@
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FEATURES {
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STARTADDRESS: default = $0801;
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}
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SYMBOLS {
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__LOADADDR__: type = import;
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__EXEHDR__: type = import;
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__OVERLAYADDR__: type = import;
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__STACKSIZE__: type = weak, value = $0800; # 2k stack
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__OVERLAYSIZE__: type = weak, value = $1000; # 4k overlay
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__STACKSIZE__: type = weak, value = $0800; # 2k stack
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__OVERLAYSIZE__: type = weak, value = $1000; # 4k overlay
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__HIMEM__: type = weak, value = $D000;
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__HIMEM2__: type = export, value = __HIMEM__ - 2;
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}
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MEMORY {
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ZP: file = "", define = yes, start = $0002, size = $001A;
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LOADADDR: file = %O, start = $07FF, size = $0002;
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HEADER: file = %O, start = $0801, size = $000C;
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RAM: file = %O, define = yes, start = $080D, size = $C7F3 - __OVERLAYSIZE__ - __STACKSIZE__;
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OVL1ADDR: file = "%O.1", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL1: file = "%O.1", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL2ADDR: file = "%O.2", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL2: file = "%O.2", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL3ADDR: file = "%O.3", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL3: file = "%O.3", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL4ADDR: file = "%O.4", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL4: file = "%O.4", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL5ADDR: file = "%O.5", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL5: file = "%O.5", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL6ADDR: file = "%O.6", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL6: file = "%O.6", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL7ADDR: file = "%O.7", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL7: file = "%O.7", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL8ADDR: file = "%O.8", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL8: file = "%O.8", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL9ADDR: file = "%O.9", start = $CFFE - __OVERLAYSIZE__, size = $0002;
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OVL9: file = "%O.9", start = $D000 - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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ZP: file = "", define = yes, start = $0002, size = $001A;
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LOADADDR: file = %O, start = %S - 2, size = $0002;
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HEADER: file = %O, define = yes, start = %S, size = $000D;
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RAM: file = %O, start = __HEADER_LAST__, size = __HIMEM__ - __OVERLAYSIZE__ - __STACKSIZE__ - __HEADER_LAST__;
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MOVE: file = %O, start = __ZPSAVE_LOAD__, size = __HIMEM__ - __INIT_RUN__;
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OVL1ADDR: file = "%O.1", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL1: file = "%O.1", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL2ADDR: file = "%O.2", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL2: file = "%O.2", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL3ADDR: file = "%O.3", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL3: file = "%O.3", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL4ADDR: file = "%O.4", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL4: file = "%O.4", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL5ADDR: file = "%O.5", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL5: file = "%O.5", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL6ADDR: file = "%O.6", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL6: file = "%O.6", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL7ADDR: file = "%O.7", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL7: file = "%O.7", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL8ADDR: file = "%O.8", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL8: file = "%O.8", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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OVL9ADDR: file = "%O.9", start = __HIMEM2__ - __OVERLAYSIZE__, size = $0002;
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OVL9: file = "%O.9", start = __HIMEM__ - __OVERLAYSIZE__, size = __OVERLAYSIZE__;
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}
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SEGMENTS {
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LOADADDR: load = LOADADDR, type = ro;
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EXEHDR: load = HEADER, type = ro;
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STARTUP: load = RAM, type = ro;
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LOWCODE: load = RAM, type = ro, optional = yes;
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INIT: load = RAM, type = ro, define = yes, optional = yes;
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CODE: load = RAM, type = ro;
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RODATA: load = RAM, type = ro;
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DATA: load = RAM, type = rw;
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ZPSAVE: load = RAM, type = bss;
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BSS: load = RAM, type = bss, define = yes;
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ZEROPAGE: load = ZP, type = zp;
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OVL1ADDR: load = OVL1ADDR, type = ro;
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OVERLAY1: load = OVL1, type = ro, define = yes, optional = yes;
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OVL2ADDR: load = OVL2ADDR, type = ro;
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OVERLAY2: load = OVL2, type = ro, define = yes, optional = yes;
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OVL3ADDR: load = OVL3ADDR, type = ro;
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OVERLAY3: load = OVL3, type = ro, define = yes, optional = yes;
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OVL4ADDR: load = OVL4ADDR, type = ro;
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OVERLAY4: load = OVL4, type = ro, define = yes, optional = yes;
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OVL5ADDR: load = OVL5ADDR, type = ro;
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OVERLAY5: load = OVL5, type = ro, define = yes, optional = yes;
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OVL6ADDR: load = OVL6ADDR, type = ro;
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OVERLAY6: load = OVL6, type = ro, define = yes, optional = yes;
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OVL7ADDR: load = OVL7ADDR, type = ro;
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OVERLAY7: load = OVL7, type = ro, define = yes, optional = yes;
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OVL8ADDR: load = OVL8ADDR, type = ro;
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OVERLAY8: load = OVL8, type = ro, define = yes, optional = yes;
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OVL9ADDR: load = OVL9ADDR, type = ro;
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OVERLAY9: load = OVL9, type = ro, define = yes, optional = yes;
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ZEROPAGE: load = ZP, type = zp;
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LOADADDR: load = LOADADDR, type = ro;
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EXEHDR: load = HEADER, type = ro;
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STARTUP: load = RAM, type = ro;
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LOWCODE: load = RAM, type = ro, optional = yes;
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CODE: load = RAM, type = ro;
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RODATA: load = RAM, type = ro;
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DATA: load = RAM, type = rw;
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ZPSAVE: load = RAM, type = bss, define = yes;
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BSS: load = RAM, type = bss, define = yes;
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INIT: load = MOVE, run = RAM, type = ro, define = yes, optional = yes;
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OVL1ADDR: load = OVL1ADDR, type = ro;
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OVERLAY1: load = OVL1, type = ro, define = yes, optional = yes;
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OVL2ADDR: load = OVL2ADDR, type = ro;
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OVERLAY2: load = OVL2, type = ro, define = yes, optional = yes;
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OVL3ADDR: load = OVL3ADDR, type = ro;
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OVERLAY3: load = OVL3, type = ro, define = yes, optional = yes;
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OVL4ADDR: load = OVL4ADDR, type = ro;
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OVERLAY4: load = OVL4, type = ro, define = yes, optional = yes;
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OVL5ADDR: load = OVL5ADDR, type = ro;
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OVERLAY5: load = OVL5, type = ro, define = yes, optional = yes;
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OVL6ADDR: load = OVL6ADDR, type = ro;
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OVERLAY6: load = OVL6, type = ro, define = yes, optional = yes;
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OVL7ADDR: load = OVL7ADDR, type = ro;
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OVERLAY7: load = OVL7, type = ro, define = yes, optional = yes;
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OVL8ADDR: load = OVL8ADDR, type = ro;
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OVERLAY8: load = OVL8, type = ro, define = yes, optional = yes;
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OVL9ADDR: load = OVL9ADDR, type = ro;
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OVERLAY9: load = OVL9, type = ro, define = yes, optional = yes;
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}
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FEATURES {
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CONDES: type = constructor,
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35
cfg/c64.cfg
35
cfg/c64.cfg
@ -1,26 +1,31 @@
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FEATURES {
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STARTADDRESS: default = $0801;
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}
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SYMBOLS {
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__LOADADDR__: type = import;
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__EXEHDR__: type = import;
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__STACKSIZE__: type = weak, value = $0800; # 2k stack
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__HIMEM__: type = weak, value = $D000;
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}
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MEMORY {
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ZP: file = "", define = yes, start = $0002, size = $001A;
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LOADADDR: file = %O, start = $07FF, size = $0002;
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HEADER: file = %O, start = $0801, size = $000C;
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RAM: file = %O, define = yes, start = $080D, size = $C7F3 - __STACKSIZE__;
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ZP: file = "", define = yes, start = $0002, size = $001A;
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LOADADDR: file = %O, start = %S - 2, size = $0002;
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HEADER: file = %O, define = yes, start = %S, size = $000D;
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RAM: file = %O, start = __HEADER_LAST__, size = __HIMEM__ - __STACKSIZE__ - __HEADER_LAST__;
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MOVE: file = %O, start = __ZPSAVE_LOAD__, size = __HIMEM__ - __INIT_RUN__;
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}
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SEGMENTS {
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LOADADDR: load = LOADADDR, type = ro;
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EXEHDR: load = HEADER, type = ro;
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STARTUP: load = RAM, type = ro;
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LOWCODE: load = RAM, type = ro, optional = yes;
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INIT: load = RAM, type = ro, define = yes, optional = yes;
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CODE: load = RAM, type = ro;
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RODATA: load = RAM, type = ro;
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DATA: load = RAM, type = rw;
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ZPSAVE: load = RAM, type = bss;
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BSS: load = RAM, type = bss, define = yes;
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ZEROPAGE: load = ZP, type = zp;
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ZEROPAGE: load = ZP, type = zp;
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LOADADDR: load = LOADADDR, type = ro;
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EXEHDR: load = HEADER, type = ro;
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STARTUP: load = RAM, type = ro;
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LOWCODE: load = RAM, type = ro, optional = yes;
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CODE: load = RAM, type = ro;
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RODATA: load = RAM, type = ro;
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DATA: load = RAM, type = rw;
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ZPSAVE: load = RAM, type = bss, define = yes;
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BSS: load = RAM, type = bss, define = yes;
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INIT: load = MOVE, run = RAM, type = ro, define = yes, optional = yes;
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}
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FEATURES {
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CONDES: type = constructor,
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@ -3,13 +3,13 @@
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;
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.export _exit
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.exportzp init_load_, init_run_
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.export __STARTUP__ : absolute = 1 ; Mark as startup
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.import initlib, donelib
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.import zerobss
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.import callmain
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.import move_init, zerobss, callmain
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.import RESTOR, BSOUT, CLRCH
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.import __RAM_START__, __RAM_SIZE__ ; Linker generated
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.import __STACKSIZE__ ; Linker generated
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.import __HIMEM__ ; from configure file
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.importzp ST
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.include "zeropage.inc"
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@ -19,18 +19,17 @@
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; ------------------------------------------------------------------------
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; Startup code
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; Two zero-page pointers are needed before any zero-page stuff is saved.
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; Choose locations that are not used by anything.
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init_load_ := FREKZP
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init_run_ := FREKZP+2
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.segment "STARTUP"
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Start:
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; Save the zero-page locations that we need.
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ldx #zpspace-1
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L1: lda sp,x
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sta zpsave,x
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dex
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bpl L1
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; Switch to the second charset.
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lda #14
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@ -39,35 +38,30 @@ L1: lda sp,x
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; Switch off the BASIC ROM.
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lda $01
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pha ; Remember the value
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sta mmusave ; Save the memory configuration
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and #$F8
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ora #$06 ; Enable Kernal+I/O, disable BASIC
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sta $01
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; Clear the BSS data.
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jsr zerobss
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; Save some system settings; and, set up the stack.
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pla
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sta mmusave ; Save the memory configuration
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tsx
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stx spsave ; Save the system stack ptr
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lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
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sta sp
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lda #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
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sta sp+1 ; Set argument stack ptr
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; Allow some re-entrancy by skipping the next task if it already was done.
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; This often can let us rerun the program without reloading it.
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; Call the module constructors.
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ldx moveinit
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beq L0
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jsr initlib
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; Move the INIT segment from where it was loaded (over ZPSAVE and BSS)
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; into where it must be run (in the heap).
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; Push the command-line arguments; and, call main().
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jsr move_init
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dec moveinit ; set to false
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jsr callmain
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; Save space by putting the rest of the start-up code in the INIT segment,
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; which can be re-used by the heap.
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L0: jsr initstart
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; Back from main() [this is also the exit() entry]. Run the module destructors.
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@ -98,14 +92,51 @@ L2: lda zpsave,x
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rts
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; ------------------------------------------------------------------------
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.segment "INIT"
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initstart:
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; Save the zero-page locations that we need.
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ldx #zpspace-1
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L1: lda sp,x
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sta zpsave,x
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dex
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bpl L1
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; Clear the BSS data.
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jsr zerobss
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; Set up the stack.
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lda #<__HIMEM__
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ldx #>__HIMEM__
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sta sp
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stx sp+1 ; Set argument stack ptr
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; Call the module constructors.
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jsr initlib
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; Push the command-line arguments; and, call main().
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jmp callmain
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; ------------------------------------------------------------------------
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; Data
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.data
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mmusave:.res 1
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spsave: .res 1
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moveinit:
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.byte 1
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.segment "ZPSAVE"
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zpsave: .res zpspace
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.bss
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spsave: .res 1
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mmusave:.res 1
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54
libsrc/common/moveinit.s
Normal file
54
libsrc/common/moveinit.s
Normal file
@ -0,0 +1,54 @@
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;
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; 2015-10-04, Greg King
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;
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.export move_init
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.import __INIT_LOAD__, __INIT_RUN__, __INIT_SIZE__ ; Linker-generated
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.importzp init_load_, init_run_
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.macpack cpu
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.macpack generic
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; Move the INIT segment from where it was loaded (over the bss segments)
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; into where it must be run (in the heap). The two areas might overlap; and,
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; the segment is moved upwards. Therefore, this code starts at the highest
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; address, and decrements to the lowest address. The low bytes of the starting
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; pointers are not sums. The high bytes are sums; but, they do not include the
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; carry. Both the low-byte sums and the carries will be done when the pointers
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; are indexed by the .Y register.
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move_init:
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lda #<__INIT_LOAD__
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ldx #>__INIT_LOAD__ + >__INIT_SIZE__
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sta init_load_
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stx init_load_+1
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lda #<__INIT_RUN__
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ldx #>__INIT_RUN__ + >__INIT_SIZE__
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sta init_run_
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stx init_run_+1
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; First, move the last, partial page.
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; Then, move all of the full pages.
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ldx #>__INIT_SIZE__ + 1 ; number of pages, including partial
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ldy #<__INIT_SIZE__ ; size of partial page
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.if .cpu & CPU_ISET_65SC02
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bra L3
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.else
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jmp L3
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.endif
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L1: dec init_load_+1
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dec init_run_+1
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L2: dey
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lda (init_load_),y
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sta (init_run_),y
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tya
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L3: bnz L2 ; page not finished
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dex
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bnz L1 ; move next page
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rts
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