initial commit
This commit is contained in:
Brad Grantham
commit
d30e8778d5
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CC65 = $(HOME)/trees/cc65/bin/
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CPU = 6502
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a.out: main.o interrupt.o vectors.o apple2rom.cfg apple2rom.lib
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$(CC65)/ld65 -C apple2rom.cfg -m main.map --dbgfile main.dbg interrupt.o vectors.o main.o apple2rom.lib
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clean:
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rm *.o a.out main.s
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main.s: main.c
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$(CC65)/cc65 -t none -O --cpu $(CPU) main.c
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main.o: main.s
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$(CC65)/ca65 --cpu $(CPU) main.s
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interrupt.o: interrupt.s
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$(CC65)/ca65 --cpu $(CPU) interrupt.s
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vectors.o: vectors.s
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$(CC65)/ca65 --cpu $(CPU) vectors.s
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crt0.o: crt0.s
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$(CC65)/ca65 --cpu $(CPU) crt0.s
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apple2rom.lib: crt0.o
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../cc65/bin/ar65 a apple2rom.lib crt0.o
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MEMORY {
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ZP: start = $0, size = $100, type = rw, define = yes;
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RAM: start = $4000, size = $4000, define = yes;
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ROM: start = $D000, size = $3000, file = %O;
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}
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SEGMENTS {
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ZEROPAGE: load = ZP, type = zp, define = yes;
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DATA: load = ROM, type = rw, define = yes, run = RAM;
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BSS: load = RAM, type = bss, define = yes;
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HEAP: load = RAM, type = bss, optional = yes;
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STARTUP: load = ROM, type = ro;
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ONCE: load = ROM, type = ro, optional = yes;
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CODE: load = ROM, type = ro;
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RODATA: load = ROM, type = ro;
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VECTORS: load = ROM, type = ro, start = $FFFA;
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}
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FEATURES {
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CONDES: segment = STARTUP,
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type = constructor,
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label = __CONSTRUCTOR_TABLE__,
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count = __CONSTRUCTOR_COUNT__;
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CONDES: segment = STARTUP,
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type = destructor,
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label = __DESTRUCTOR_TABLE__,
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count = __DESTRUCTOR_COUNT__;
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}
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SYMBOLS {
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# Define the stack size for the application
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__STACKSIZE__: value = $0200, type = weak;
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# __STACKSIZE__: type = weak, value = $0800; # 2k stack
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}
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Binary file not shown.
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; ---------------------------------------------------------------------------
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; crt0.s
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; ---------------------------------------------------------------------------
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;
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; Startup code for cc65 (Single Board Computer version)
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.export _init, _exit
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.import _main
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.export __STARTUP__ : absolute = 1 ; Mark as startup
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.import __RAM_START__, __RAM_SIZE__ ; Linker generated
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.import copydata, zerobss, initlib, donelib
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.include "zeropage.inc"
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; ---------------------------------------------------------------------------
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; Place the startup code in a special segment
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.segment "STARTUP"
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; ---------------------------------------------------------------------------
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; A little light 6502 housekeeping
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_init: LDX #$FF ; Initialize stack pointer to $01FF
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TXS
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CLD ; Clear decimal mode
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; ---------------------------------------------------------------------------
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; Set cc65 argument stack pointer
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LDA #<(__RAM_START__ + __RAM_SIZE__)
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STA sp
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LDA #>(__RAM_START__ + __RAM_SIZE__)
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STA sp+1
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; ---------------------------------------------------------------------------
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; Initialize memory storage
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JSR zerobss ; Clear BSS segment
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JSR copydata ; Initialize DATA segment
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JSR initlib ; Run constructors
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; ---------------------------------------------------------------------------
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; Call main()
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JSR _main
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; ---------------------------------------------------------------------------
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; Back from main (this is also the _exit entry): force a software break
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_exit: JSR donelib ; Run destructors
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BRK
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; ---------------------------------------------------------------------------
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; interrupt.s
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; ---------------------------------------------------------------------------
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;
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; Interrupt handler.
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;
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; Checks for a BRK instruction and returns from all valid interrupts.
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.import _stop
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.export _irq_int, _nmi_int
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.segment "CODE"
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.PC02 ; Force 65C02 assembly mode
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; ---------------------------------------------------------------------------
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; Non-maskable interrupt (NMI) service routine
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_nmi_int: RTI ; Return from all NMI interrupts
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; ---------------------------------------------------------------------------
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; Maskable interrupt (IRQ) service routine
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_irq_int: PHX ; Save X register contents to stack
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TSX ; Transfer stack pointer to X
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PHA ; Save accumulator contents to stack
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INX ; Increment X so it points to the status
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INX ; register value saved on the stack
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LDA $100,X ; Load status register contents
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AND #$10 ; Isolate B status bit
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BNE break ; If B = 1, BRK detected
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; ---------------------------------------------------------------------------
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; IRQ detected, return
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irq: PLA ; Restore accumulator contents
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PLX ; Restore X register contents
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RTI ; Return from all IRQ interrupts
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; ---------------------------------------------------------------------------
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; BRK detected, stop
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break: JMP break ; If BRK is detected, something very bad
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; has happened, so stop running
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@ -0,0 +1,21 @@
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char *title = "Apple IIa";
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unsigned char title_length = 9;
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unsigned char *text_page1_base = (unsigned char *)0x400;
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int main(void)
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{
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int offset = (80 - title_length) / 2;
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unsigned char *loc = text_page1_base + offset;
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int i;
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for(i = 0; i < 80 * 24; i++)
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text_page1_base[i] = ' ' | 0x80;
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for(i = 0; i < title_length; i++)
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loc[i] = title[i] | 0x80;
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while(1);
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}
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@ -0,0 +1,15 @@
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; ---------------------------------------------------------------------------
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; vectors.s
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; ---------------------------------------------------------------------------
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;
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; Defines the interrupt vector table.
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.import _init
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.import _nmi_int, _irq_int
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.segment "VECTORS"
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.addr _nmi_int ; NMI vector
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.addr _init ; Reset vector
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.addr _irq_int ; IRQ/BRK vector
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