; Prog8 definitions for the Commodore PET ; Including memory registers, I/O registers, Basic and Kernal subroutines. ; see: https://www.pagetable.com/?p=926 , http://www.zimmers.net/cbmpics/cbm/PETx/petmem.txt %option no_symbol_prefixing, ignore_unused cbm { ; Commodore (CBM) common variables, vectors and kernal routines &ubyte TIME_HI = $8d ; software jiffy clock, hi byte &ubyte TIME_MID = $8e ; .. mid byte &ubyte TIME_LO = $8f ; .. lo byte. Updated by IRQ every 1/60 sec &ubyte STATUS = $96 ; kernal status variable for I/O &uword CINV = $0090 ; IRQ vector (in ram) &uword CBINV = $0092 ; BRK vector (in ram) &uword NMINV = $0094 ; NMI vector (in ram) &uword NMI_VEC = $FFFA ; 6502 nmi vector, determined by the kernal if banked in &uword RESET_VEC = $FFFC ; 6502 reset vector, determined by the kernal if banked in &uword IRQ_VEC = $FFFE ; 6502 interrupt vector, determined by the kernal if banked in ; the default addresses for the character screen chars and colors const uword Screen = $8000 ; to have this as an array[40*25] the compiler would have to support array size > 255 romsub $FFC6 = CHKIN(ubyte logical @ X) clobbers(A,X) -> bool @Pc ; define an input channel romsub $FFC9 = CHKOUT(ubyte logical @ X) clobbers(A,X) ; define an output channel romsub $FFCC = CLRCHN() clobbers(A,X) ; restore default devices romsub $FFCF = CHRIN() clobbers(X, Y) -> ubyte @ A ; input a character (for keyboard, read a whole line from the screen) A=byte read. romsub $FFD2 = CHROUT(ubyte character @ A) ; output a character romsub $FFE1 = STOP() clobbers(X) -> bool @ Pz, ubyte @ A ; check the STOP key (and some others in A) romsub $FFE4 = GETIN() clobbers(X,Y) -> bool @Pc, ubyte @ A ; get a character romsub $FFE7 = CLALL() clobbers(A,X) ; close all files romsub $FFEA = UDTIM() clobbers(A,X) ; update the software clock asmsub STOP2() clobbers(X) -> ubyte @A { ; -- check if STOP key was pressed, returns true if so. More convenient to use than STOP() because that only sets the carry status flag. %asm {{ jsr cbm.STOP beq + lda #0 rts + lda #1 rts }} } asmsub SETTIM(ubyte low @ A, ubyte middle @ X, ubyte high @ Y) { ; PET stub to set the software clock %asm {{ sty TIME_HI stx TIME_MID sta TIME_LO rts }} } asmsub RDTIM() -> ubyte @ A, ubyte @ X, ubyte @ Y { ; PET stub to read the software clock (A=lo,X=mid,Y=high) %asm {{ ldy TIME_HI ldx TIME_MID lda TIME_LO rts }} } asmsub RDTIM16() clobbers(X) -> uword @AY { ; -- like RDTIM() but only returning the lower 16 bits in AY for convenience %asm {{ lda TIME_LO ldy TIME_MID rts }} } } sys { ; ------- lowlevel system routines -------- const ubyte target = 32 ; compilation target specifier. 64 = C64, 128 = C128, 16 = CommanderX16, 32=PET asmsub init_system() { ; Initializes the machine to a sane starting state. ; Called automatically by the loader program logic. ; Uppercase charset is activated. %asm {{ sei cld lda #142 jsr cbm.CHROUT ; uppercase lda #147 jsr cbm.CHROUT ; clear screen clc clv cli rts }} } asmsub init_system_phase2() { %asm {{ rts ; no phase 2 steps on the PET }} } asmsub cleanup_at_exit() { ; executed when the main subroutine does rts %asm {{ _exitcode = *+1 lda #0 ; exit code possibly modified in exit() rts }} } asmsub reset_system() { ; Soft-reset the system back to initial power-on Basic prompt. %asm {{ sei jmp (cbm.RESET_VEC) }} } asmsub waitvsync() clobbers(A) { ; --- busy wait till the next vsync has occurred (approximately), without depending on custom irq handling. ; Note: on PET this simply waits until the next jiffy clock update, I don't know if a true vsync is possible there %asm {{ lda #1 ldy #0 jmp wait }} } asmsub wait(uword jiffies @AY) { ; --- wait approximately the given number of jiffies (1/60th seconds) (N or N+1) ; note: the system irq handler has to be active for this to work as it depends on the system jiffy clock %asm {{ stx P8ZP_SCRATCH_B1 sta P8ZP_SCRATCH_W1 sty P8ZP_SCRATCH_W1+1 _loop lda P8ZP_SCRATCH_W1 ora P8ZP_SCRATCH_W1+1 bne + ldx P8ZP_SCRATCH_B1 rts + lda cbm.TIME_LO sta P8ZP_SCRATCH_B1 - lda cbm.TIME_LO cmp P8ZP_SCRATCH_B1 beq - lda P8ZP_SCRATCH_W1 bne + dec P8ZP_SCRATCH_W1+1 + dec P8ZP_SCRATCH_W1 jmp _loop }} } asmsub internal_stringcopy(uword source @R0, uword target @AY) clobbers (A,Y) { ; Called when the compiler wants to assign a string value to another string. %asm {{ sta P8ZP_SCRATCH_W1 sty P8ZP_SCRATCH_W1+1 lda cx16.r0 ldy cx16.r0+1 jmp prog8_lib.strcpy }} } asmsub memcopy(uword source @R0, uword target @R1, uword count @AY) clobbers(A,X,Y) { ; note: only works for NON-OVERLAPPING memory regions! ; note: can't be inlined because is called from asm as well %asm {{ ldx cx16.r0 stx P8ZP_SCRATCH_W1 ; source in ZP ldx cx16.r0+1 stx P8ZP_SCRATCH_W1+1 ldx cx16.r1 stx P8ZP_SCRATCH_W2 ; target in ZP ldx cx16.r1+1 stx P8ZP_SCRATCH_W2+1 cpy #0 bne _longcopy ; copy <= 255 bytes tay bne _copyshort rts ; nothing to copy _copyshort ; decrease source and target pointers so we can simply index by Y lda P8ZP_SCRATCH_W1 bne + dec P8ZP_SCRATCH_W1+1 + dec P8ZP_SCRATCH_W1 lda P8ZP_SCRATCH_W2 bne + dec P8ZP_SCRATCH_W2+1 + dec P8ZP_SCRATCH_W2 - lda (P8ZP_SCRATCH_W1),y sta (P8ZP_SCRATCH_W2),y dey bne - rts _longcopy sta P8ZP_SCRATCH_B1 ; lsb(count) = remainder in last page tya tax ; x = num pages (1+) ldy #0 - lda (P8ZP_SCRATCH_W1),y sta (P8ZP_SCRATCH_W2),y iny bne - inc P8ZP_SCRATCH_W1+1 inc P8ZP_SCRATCH_W2+1 dex bne - ldy P8ZP_SCRATCH_B1 bne _copyshort rts }} } asmsub memset(uword mem @R0, uword numbytes @R1, ubyte value @A) clobbers(A,X,Y) { %asm {{ ldy cx16.r0 sty P8ZP_SCRATCH_W1 ldy cx16.r0+1 sty P8ZP_SCRATCH_W1+1 ldx cx16.r1 ldy cx16.r1+1 jmp prog8_lib.memset }} } asmsub memsetw(uword mem @R0, uword numwords @R1, uword value @AY) clobbers(A,X,Y) { %asm {{ ldx cx16.r0 stx P8ZP_SCRATCH_W1 ldx cx16.r0+1 stx P8ZP_SCRATCH_W1+1 ldx cx16.r1 stx P8ZP_SCRATCH_W2 ldx cx16.r1+1 stx P8ZP_SCRATCH_W2+1 jmp prog8_lib.memsetw }} } inline asmsub read_flags() -> ubyte @A { %asm {{ php pla }} } inline asmsub clear_carry() { %asm {{ clc }} } inline asmsub set_carry() { %asm {{ sec }} } inline asmsub clear_irqd() { %asm {{ cli }} } inline asmsub set_irqd() { %asm {{ sei }} } inline asmsub irqsafe_set_irqd() { %asm {{ php sei }} } inline asmsub irqsafe_clear_irqd() { %asm {{ plp }} } sub disable_caseswitch() { ; PET doesn't have a key to swap case, so no-op } sub enable_caseswitch() { ; PET doesn't have a key to swap case, so no-op } asmsub save_prog8_internals() { %asm {{ lda P8ZP_SCRATCH_B1 sta save_SCRATCH_ZPB1 lda P8ZP_SCRATCH_REG sta save_SCRATCH_ZPREG lda P8ZP_SCRATCH_W1 sta save_SCRATCH_ZPWORD1 lda P8ZP_SCRATCH_W1+1 sta save_SCRATCH_ZPWORD1+1 lda P8ZP_SCRATCH_W2 sta save_SCRATCH_ZPWORD2 lda P8ZP_SCRATCH_W2+1 sta save_SCRATCH_ZPWORD2+1 rts save_SCRATCH_ZPB1 .byte 0 save_SCRATCH_ZPREG .byte 0 save_SCRATCH_ZPWORD1 .word 0 save_SCRATCH_ZPWORD2 .word 0 }} } asmsub restore_prog8_internals() { %asm {{ lda save_prog8_internals.save_SCRATCH_ZPB1 sta P8ZP_SCRATCH_B1 lda save_prog8_internals.save_SCRATCH_ZPREG sta P8ZP_SCRATCH_REG lda save_prog8_internals.save_SCRATCH_ZPWORD1 sta P8ZP_SCRATCH_W1 lda save_prog8_internals.save_SCRATCH_ZPWORD1+1 sta P8ZP_SCRATCH_W1+1 lda save_prog8_internals.save_SCRATCH_ZPWORD2 sta P8ZP_SCRATCH_W2 lda save_prog8_internals.save_SCRATCH_ZPWORD2+1 sta P8ZP_SCRATCH_W2+1 rts }} } asmsub exit(ubyte returnvalue @A) { ; -- immediately exit the program with a return code in the A register %asm {{ sta cleanup_at_exit._exitcode ldx prog8_lib.orig_stackpointer txs jmp cleanup_at_exit }} } inline asmsub progend() -> uword @AY { %asm {{ lda #prog8_program_end }} } inline asmsub push(ubyte value @A) { %asm {{ pha }} } inline asmsub pushw(uword value @AY) { %asm {{ pha tya pha }} } inline asmsub pop() -> ubyte @A { %asm {{ pla }} } inline asmsub popw() -> uword @AY { %asm {{ pla tay pla }} } } cx16 { ; the sixteen virtual 16-bit registers that the CX16 has defined in the zeropage ; they are simulated on the PET as well but their location in memory is different ; (because there's no room for them in the zeropage) ; we select the top page of RAM (assume 32Kb) &uword r0 = $7fe0 &uword r1 = $7fe2 &uword r2 = $7fe4 &uword r3 = $7fe6 &uword r4 = $7fe8 &uword r5 = $7fea &uword r6 = $7fec &uword r7 = $7fee &uword r8 = $7ff0 &uword r9 = $7ff2 &uword r10 = $7ff4 &uword r11 = $7ff6 &uword r12 = $7ff8 &uword r13 = $7ffa &uword r14 = $7ffc &uword r15 = $7ffe &word r0s = $7fe0 &word r1s = $7fe2 &word r2s = $7fe4 &word r3s = $7fe6 &word r4s = $7fe8 &word r5s = $7fea &word r6s = $7fec &word r7s = $7fee &word r8s = $7ff0 &word r9s = $7ff2 &word r10s = $7ff4 &word r11s = $7ff6 &word r12s = $7ff8 &word r13s = $7ffa &word r14s = $7ffc &word r15s = $7ffe &ubyte r0L = $7fe0 &ubyte r1L = $7fe2 &ubyte r2L = $7fe4 &ubyte r3L = $7fe6 &ubyte r4L = $7fe8 &ubyte r5L = $7fea &ubyte r6L = $7fec &ubyte r7L = $7fee &ubyte r8L = $7ff0 &ubyte r9L = $7ff2 &ubyte r10L = $7ff4 &ubyte r11L = $7ff6 &ubyte r12L = $7ff8 &ubyte r13L = $7ffa &ubyte r14L = $7ffc &ubyte r15L = $7ffe &ubyte r0H = $7fe1 &ubyte r1H = $7fe3 &ubyte r2H = $7fe5 &ubyte r3H = $7fe7 &ubyte r4H = $7fe9 &ubyte r5H = $7feb &ubyte r6H = $7fed &ubyte r7H = $7fef &ubyte r8H = $7ff1 &ubyte r9H = $7ff3 &ubyte r10H = $7ff5 &ubyte r11H = $7ff7 &ubyte r12H = $7ff9 &ubyte r13H = $7ffb &ubyte r14H = $7ffd &ubyte r15H = $7fff &byte r0sL = $7fe0 &byte r1sL = $7fe2 &byte r2sL = $7fe4 &byte r3sL = $7fe6 &byte r4sL = $7fe8 &byte r5sL = $7fea &byte r6sL = $7fec &byte r7sL = $7fee &byte r8sL = $7ff0 &byte r9sL = $7ff2 &byte r10sL = $7ff4 &byte r11sL = $7ff6 &byte r12sL = $7ff8 &byte r13sL = $7ffa &byte r14sL = $7ffc &byte r15sL = $7ffe &byte r0sH = $7fe1 &byte r1sH = $7fe3 &byte r2sH = $7fe5 &byte r3sH = $7fe7 &byte r4sH = $7fe9 &byte r5sH = $7feb &byte r6sH = $7fed &byte r7sH = $7fef &byte r8sH = $7ff1 &byte r9sH = $7ff3 &byte r10sH = $7ff5 &byte r11sH = $7ff7 &byte r12sH = $7ff9 &byte r13sH = $7ffb &byte r14sH = $7ffd &byte r15sH = $7fff asmsub save_virtual_registers() clobbers(A,Y) { %asm {{ ldy #31 - lda cx16.r0,y sta _cx16_vreg_storage,y dey bpl - rts _cx16_vreg_storage .word 0,0,0,0,0,0,0,0 .word 0,0,0,0,0,0,0,0 }} } asmsub restore_virtual_registers() clobbers(A,Y) { %asm {{ ldy #31 - lda save_virtual_registers._cx16_vreg_storage,y sta cx16.r0,y dey bpl - rts }} } }