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Command interpreation loop, END, STOP, DATA, ', REM, ELSE
Add the command interpretation loop, both immediate mode and program mode.
This also includes the END and STOP commands since their function is
intricately tied to the interpretation loop.
Also implement REM and ', which either skip to the next line OR return to
the original caller to the interpretation loop if immediate mode. There is
no need to bother skipping through the bytes to find the end of the line
which is wastefully slow. ELSE is implemented with the same routine for now
though some more complex things may be possible later if ENDIF is
implemented.
Finally, implement the DATA command which skips only to the end of the DATA
statement, but has to make sure it doesn't detect colons inside of quoted
strings.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Tue, 15 Nov 2022 23:37:38 -0700 |
| parents | 5db76d113c37 |
| children | 4488ed12bb67 |
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; LWBasic Version 0.1 ; Copyright © 2022 Lost Wizard Enterprises Incorporated ; ; This is LWBasic, a replacement Basic ROM system for the TRS-80 Color Computer which ; is most definitely not binary compatible with the stock ROMs. ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; *pragmapush list *pragma nolist *pragma noexpandcond *pragma cescapes ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Utility macros ; ; skip next byte; flags preserved skip1 macro noexpand fcb 0x21 ; opcode for BRN endm ; skip next byte and load nonzero to A skip1lda macro noexpand fcb 0x86 ; opcode for LDA immediate endm ; skip next byte and load nonzero to B skip1ldb macro noexpand fcb 0xc6 ; opcoe for LDB immediate endm ; skip next 2 bytes; clobbers flags skip2 macro noexpand fcb 0x8c ; opcode for CMPX immediate endm *pragmapop list ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Various constants console_curdel equ 10 ; delay between cursor blink cycles keyb_bufflen equ 64 ; keyboard ring buffer length keyb_repdeli equ 40 ; ticks before initial repeat (2/3 s) keyb_repdelr equ 6 ; 10 repeats per second keyb_caps equ 0x80 ; capslock enabled keyb_alt equ 0x04 ; alt pressed keyb_ctrl equ 0x02 ; ctrl pressed keyb_shift equ 0x01 ; shift pressed linebuffsize equ 0x100 ; the line input buffer (256 bytes) ifdef COCO3 ; GIME INIT0 GIME_COCO equ 0x80 ; Set for coco2 compatible mode (video display) GIME_MMUEN equ 0x40 ; Set to enable MMU GIME_IEN equ 0x20 ; GIME IRQ enable GIME_FEN equ 0x10 ; GIME FIRQ enable GIME_FExx equ 0x08 ; Enable constant RAM at 0xFExx (comes from block 0x3f) GIME_SCS equ 0x04 ; Set to enable standard SCS (switches 0xFF5x) GIME_ROME16 equ 0x00 ; 16K internal, 16K external ROM mode GIME_ROME32 equ 0x03 ; 32K external ROM GIME_ROMI32 equ 0x02 ; 32K internal ROM ; GIME INIT1 GIME_TMRFAT equ 0x20 ; TIMER ticks approx every 279.365 ns GIME_TMRSLOW equ 0x00 ; TIMER ticks approx every 63.695 µs GIME_TASK0 equ 0x00 ; MMU task 0 GIME_TASK1 equ 0x01 ; MMU task 1 ; GIME interrupt enable/status bits GIME_ITIMER equ 0x20 ; TIMER interrupt (timer reaches 0) GIME_IHBORD equ 0x10 ; HSYNC interrupt (falling edge) GIME_IVBORD equ 0x08 ; VSYNC interrupt (falling edge) GIME_ISERIAL equ 0x04 ; Falling edge of signal on pin 4 of serial port GIME_IKEYBOARD equ 0x02 ; Interrupt if a 0 bit appears on bits 6-0 of PIA0.DA GIME_ICART equ 0x01 ; Interrupt on falling edge of pin 8 of cartridge port ; GIME VMODE GIME_BP equ 0x80 ; enable bit plane mode GIME_BPI equ 0x20 ; colour burst phase inversion (composite output only) GIME_MONO equ 0x10 ; disable colour burst (composite output only) GIME_H50 equ 0x08 ; set to 50Hz operation GIME_LPR1 equ 0x00 ; one line per row GIME_LPR2 equ 0x02 ; two lines per row (also works on graphics) GIME_LPR8 equ 0x03 ; 8 lines per row GIME_LPR9 equ 0x04 ; 9 lines per row GIME_LPR10 equ 0x05 ; 10 lines per row GIME_LPR11 equ 0x06 ; 11 lines per row GIME_LPRINF equ 0x07 ; "infinite" lines per row ; GIME VRES GIME_LPF192 equ 0x00 ; 192 lines on screen GIME_LPF200 equ 0x40 ; 200 lines on screen (actually 199 due to hardware bug) GIME_LPF225 equ 0x60 ; 225 lines on screen GIME_BPR16 equ 0x00 ; 16 bytes per row GIME_BPR20 equ 0x04 ; 20 bytes per row GIME_BPR32 equ 0x08 ; 32 bytes per row GIME_BPR40 equ 0x0c ; 40 bytes per row GIME_BPR64 equ 0x10 ; 64 bytes per row GIME_BPR80 equ 0x14 ; 80 bytes per row GIME_BPR128 equ 0x18 ; 128 bytes per row GIME_BPR160 equ 0x1c ; 160 bytes per row GIME_TXT32 equ 0x00 ; 32 characters per row GIME_TXT40 equ 0x04 ; 40 characters per row GIME_TXT64 equ 0x10 ; 64 characters per row GIME_TXT80 equ 0x14 ; 80 characters per row GIME_BPP1 equ 0x00 ; 1 bit per pixel GIME_BPP2 equ 0x01 ; 2 bits per pixel GIME_BPP4 equ 0x02 ; 4 bits per pixel GIME_TXTATTR equ 0x01 ; text attributes enabled endc ifdef COCO3 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Stuff on the fixed memory page org 0xfe00 rmb 0xed ; unused INT.FLAG rmb 1 ; validity flag INT.SWI3 rmb 3 ; SWI3 bounce vector INT.SWI2 rmb 3 ; SWI2 bounce vector INT.FIRQ rmb 3 ; FIRQ bounce vector INT.IRQ rmb 3 ; IRQ bounce vector INT.SWI rmb 3 ; SWI bounce vector INT.NMI rmb 3 ; NMI bounce vector endc ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Hardware definitions for the I/O page org 0xff00 PIA0 equ * ; Keyboard PIA PIA0.DA rmb 1 ; PIA0 data/direction A PIA0.CA rmb 1 ; PIA0 control A PIA0.DB rmb 1 ; PIA0 data/direction B PIA0.CB rmb 1 ; PIA0 control B rmb 28 ; mirror images of PIA0 PIA1 equ * ; DA/misc stuff PIA1.DA rmb 1 ; PIA1 data/direction A PIA1.CA rmb 1 ; PIA1 control A PIA1.DB rmb 1 ; PIA1 data/direction B PIA1.CB rmb 1 ; PIA1 control B rmb 28 ; mirror images of PIA1 rmb 16 ; SCS/Disk controller rmb 16 ; second half of SCS area rmb 32 ; miscelaneous hardware ifdef COCO3 rmb 16 ; *reserved* (unused but the GIME drives them) GIME.INIT0 rmb 1 ; basic GIME system config GIME.INIT1 rmb 1 ; MMU task and timer rate GIME.IRQ rmb 1 ; GIME IRQ enable/status register GIME.FIRQ rmb 1 ; GIME FIRQ enable/status register GIME.TIMER rmb 2 ; GIME programmable timer rmb 2 ; *reserved* GIME.VMODE rmb 1 ; GIME video mode setting GIME.VRES rmb 1 ; GIME video resolution setting rmb 1 ; *reserved* (used for MMU expansion on some memory boards) GIME.BORDER rmb 1 ; GIME border colour GIME.VSCROLL rmb 1 ; vertical scroll offset register/VDG screen mode variation GIME.VOFFSET rmb 2 ; address of video memory (8 byte increments) GIME.HOFFSET rmb 1 ; horizontal scroll offset GIME.MMU equ * ; MMU registers (two tasks) GIME.MMU0 rmb 8 ; MMU task 0 GIME.MMU1 rmb 8 ; MMU task 1 GIME.PALETTE rmb 16 ; Palette registers else rmb 64 ; unused on Coco 1/2 (GIME on Coco 3) endc SAMREG equ * ; the SAM configuration register SAM.V0CLR rmb 1 ; SAM video mode bits SAM.V0SET rmb 1 SAM.V1CLR rmb 1 SAM.V1SET rmb 1 SAM.V2CLR rmb 1 SAM.V2SET rmb 1 SAM.F0CLR rmb 1 ; SAM screen address bits SAM.F0SET rmb 1 SAM.F1CLR rmb 1 SAM.F1SET rmb 1 SAM.F2CLR rmb 1 SAM.F2SET rmb 1 SAM.F3CLR rmb 1 SAM.F3SET rmb 1 SAM.F4CLR rmb 1 SAM.F4SET rmb 1 SAM.F5CLR rmb 1 SAM.F5SET rmb 1 SAM.F6CLR rmb 1 SAM.F6SET rmb 1 SAM.P1CLR rmb 1 ; SAM "page 1" selection (or extra memory type flag) SAM.P1SET rmb 1 SAM.R0CLR rmb 1 ; SAM R0 bit (address dependent speedup, not used on Coco3) SAM.R0SET rmb 1 SAM.R1CLR rmb 1 ; SAM R1 bit (full speedup/coco 3 speedup) SAM.R1SET rmb 1 SAM.M0CLR rmb 1 ; SAM M0/M1 bits (memory type, not used on Coco3) SAM.M0SET rmb 1 SAM.M1CLR rmb 1 SAM.M1SET rmb 1 SAM.TYCLR rmb 1 ; force ROM mode (map type 0) SAM.TYSET rmb 1 ; set RAM mode (map type 1) rmb 18 ; *MPU reserved* CPU.SWI3 rmb 2 ; CPU SWI3 vector CPU.SWI2 rmb 2 ; CPU SWI2 vector CPU.FIRQ rmb 2 ; CPU FIRQ vector CPU.IRQ rmb 2 ; CPU IRQ vector CPU.SWI rmb 2 ; CPU SWI vector CPU.NMI rmb 2 ; CPU NMI vector CPU.RESET rmb 2 ; CPU RESET/startup vector ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Start of memory which has the direct page and other data. org 0 dpstart equ * ; start of direct page memtop rmb 2 ; absolute top of memory in 64K memory map memsize rmb 2 ; top of memory not reserved freetop rmb 2 ; top of free memory (bottom of string space) stringtab rmb 2 ; bottom of used string space progtext rmb 2 ; pointer to start of program text vartabint rmb 2 ; pointer to start of integer scalars vartabfloat rmb 2 ; pointer to start of floating point scalars vartabstring rmb 2 ; pointer to start of string scalars objecttab rmb 2 ; pointer to start of arrays and other variable sized objects freestart rmb 2 ; pointer to start of unallocated memory readlinenoecho rmb 1 ; if nonzero, the readline routine won't echo its input console_curptr rmb 2 ; current cursor pointer for console driver console_blnkdel rmb 1 ; cursor blink delay console_truelc rmb 1 ; set to nonzero if the console supports true lower case (gfx, etc.) filenum rmb 1 ; current input/output channel fileeof rmb 1 ; flag for whether last read detected EOF keyb_flags rmb 1 ; shift flags for the keyboard keyb_joystate rmb 1 ; joystick button state keyb_repdel rmb 1 ; repeat delay keyb_curscan rmb 1 ; current repeating scan code keyb_buffw rmb 2 ; keyboard ring buffer write pointer keyb_buffr rmb 2 ; keyboard ring buffer read pointer curline rmb 2 ; pointer to current line contline rmb 2 ; pointer to line for CONT contstmt rmb 2 ; interpretation pointer for CONT curstmt rmb 2 ; start of statement currently being interpreted endflag rmb 1 ; 00 = END, FF = STOP rmb 0x71-* ; align RSTFLG/RSTVEC for stock ROM compatibility RSTFLG rmb 1 ; 0x55 if RSTVEC is valid RSTVEC rmb 2 ; points to warm start routine (must start with NOP) inputptr rmb 2 ; pointer to current program execution location rmb 0x100-* ; make sure the stuff that isn't direct page is outside of it SW3VEC rmb 3 ; SWI3 vector (for compatibility) SW2VEC rmb 3 ; SWI2 vector (for compatibility) SWIVEC rmb 3 ; SWI vector (for compatibility) NMIVEC rmb 3 ; NMI vector (for compatibility) IRQVEC rmb 3 ; IRQ vector (for compatibility) FRQVEC rmb 3 ; FIRQ vector (for compatibility) keyb_state rmb 8 ; rollover table state keyb_buff rmb keyb_bufflen ; the keyboard ring buffer linebuff rmb linebuffsize ; the line input buffer tokebuff rmb linebuffsize+50 ; make it as long as line buffer plus a margin ifne *&0x1ff rmb 0x200-(*&0x1ff) endc textscreen rmb 0x200 ; the actual text screen (must be on 512 byte alignment) heapstart equ * ; start of dynamically allocated stuff org 0x8000 ; the hardware puts the ROMs here; it's not negotiable ROMSTART equ * START orcc #0x50 ; make sure interrupts are disabled if we come here in an unusual way ifdef COCO3 ldu #gime_inite ; point to end of GIME initializer ldx #GIME.INIT0+(gime_inite-gime_init) ; point to end of GIME registers ldb #gime_inite-gime_init ; number of bytes to transfer initc0 lda ,-u ; copy byte to GIME (count down so we init MMU before turning it on) sta ,-x decb ; done? bne initc0 ; brif not endc ldd #0xff34 ; initizer for below tfr a,dp ; set DP to I/O page setdp 0xff ; tell assembler about DP value clr PIA0.CA ; set PIA0 A to direction mode clr PIA0.CB ; set PIA0 B to direction mode clr PIA0.DA ; set PIA0 A to all inputs (comparator, keyboard rows) sta PIA0.DB ; set PIA0 B to all outputs (keyboard columns) stb PIA0.CA ; set PIA0 A to data mode, interrupt disabled, MUX to source 0 stb PIA0.CB ; set PIA0 B to data mode, interrupt disabled, MUX to source 0 clr PIA1.CA ; set PIA1 A to direction mode clr PIA1.CB ; set PIA1 B to direction mode deca ; set PIA1 A bits 7-1 output (DAC, RS232), 0 input (cassette) sta PIA1.DA lda #0xf8 ;* set PIA1 B bits 7-3 output (VDG stuff), 2-0 input (single bit sound, sta PIA1.DB ;* RS232 input, ram size input) stb PIA1.CA ; set PIA1 A to data mode, interrupt disabled, cassette motor off stb PIA1.CB ; set PIA1 B to data mode, interrupt disabled, sound off lda #2 ; set RS232 output to "marking" (stop bit) sta PIA1.DA lda #16 ; clear 16 SAM register bits ldu #SAMREG ; point to SAM register bits init0 sta ,u++ ; clear SAM bit deca ; done all? bne init0 ; brif not ; set the SAM to point to the text screen, which the code will handle at any ; arbitrary 512 byte aligned address in memory ifne (textscreen)&0x200 sta SAM.F0SET endc ifne (textscreen)&0x400 sta SAM.F1SET endc ifne (textscreen)&0x800 sta SAM.F2SET endc ifne (textscreen)&0x1000 sta SAM.F3SET endc ifne (textscreen)&0x2000 sta SAM.F4SET endc ifne (textscreen)&0x4000 sta SAM.F5SET endc ifne (textscreen)&0x8000 sta SAM.F6SET endc ifdef COCO2B ; The following SAM configuration sequence is different from the one in the usual ; one used by the earlier models of the Coco because the Coco2B has the '785 variant ; of the SAM instead of the '783 variant. The '785 variant supports 16Kx4 RAMs which ; are used in Coco2B systems. Hence why there is a different version of this ROM ; just for the Coco2B. clr PIA0.DB ; strobe RAM size low ldb #4 ; is input low? bitb PIA1.DB beq init1 ; brif not sta SAM.M0SET ; program SAM for 16Kx4 RAMs sta SAM.P1SET skip2 init1 sta SAM.M1SET ; program SAM for 64Kx1 RAMs else ifndef COCO3 ; Detect the installed memory size so the SAM ('783 variant) can be correctly ; programmed for the installed memory. Note that this sequence is replaced with ; a different one for the Coco2B which has the '785 variant of the SAM. ldb #0xff ; strobe RAM size high stb PIA0.DB ldb #4 ; mask for ram size check bitb PIA1.DB ; is the bit set on ram size input? beq init2 ; brif not - 4Kx1 RAMs sta PIA0.DB ; clear RAM size output to see what happens (A is 0 from above) bitb PIA1.DB ; is it set now? beq init1 ; brif not - 64Kx1 RAMs leau -2,u ; adjust pointer so we set the other RAM size bit for the SAM (16Kx1) init1 sta -3,u ; set M0 (16Kx1) or M1 (64Kx1) endc endc init2 tfr a,dp ; set DP to bottom of memory (A is 0 from above) setdp 0 ; tell assembler about it lds #textscreen ; put the stack just below the text screen ifdef COCO3 ; Check if we need to do a ROM/RAM copy, which will happen if the interrupt vectors are ; not flagged valid OR the reset vector isn't valid ldb INT.FLAG ; are the bounce vectors valid? cmpb #0x55 bne initc4 ; brif not - do ROM/RAM copy ldb RSTFLG ; is reset vector valid? bne initc2 ; brif not - check secondary location ldx RSTVEC ; get reset vector ldb ,x ; is it valid?\ cmpb #0x12 bne initc2 ; brif not initc1 jmp ,x ; transfer control to warm start routine initc2 clr GIME.MMU0 ; check again with block 0 in the direct page ldb RSTFLG ; get new RSTFLG cmpb #0x55 ; valid? bne initc3 ; brif not ldx RSTVEC ; get new RSTVEC ldb ,x ; is it valid? cmpb #0x12 beq initc1 ; brif so - transfer control initc3 ldb #0x38 ; restore MMU stb GIME.MMU0 initc4 ldx #initc6 ; point to helper ldu #textscreen ; point to text screen ldb #initc7-initc6 ; bytes to copy initc5 lda ,x+ ; copy byte sta ,u+ decb ; done? bne initc5 ; brif not ldu #0x8000 ; point to start of ROM jmp textscreen ; transfer control to helper in RAM initc6 sta SAM.TYCLR ; drop to ROM mode pulu d,x,y,s ; grab 8 bytes sta SAM.TYSET ; go to RAM mode pshu d,x,y,s ; stick the bytes in RAM leau 8,u ; move to next 8 bytes cmpu #0xfe00 ; end of stuff to copy? blo initc6 ; brif not jmp initc7 ; go back to mainline initc7 lds #textscreen ; reset stack to somewhere safe lda #0x12 ; activate ROM warm start handler sta warmstart ldx #INT.FLAG ; point to bounce vector destination ldu #int_init ; point to initializer for bounce vectors ldb #int_inite-int_init ; number of bytes to copy initc8 lda ,u+ ; copy byte sta ,x+ decb ; done? bne initc8 ; brif not ; now recheck for warm start in case ROM/RAM copy made things valid endc ldb RSTFLG ; is the reset vector valid? cmpb #0x55 bne coldstart ; brif not - do cold start ldx RSTVEC ; get warm start routine pointer ldb ,x ; does it start with NOP? cmpb #0x12 bne coldstart ; brif not - do cold start jmp ,x ; transfer control to warm start routine ifdef COCO3 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; GIME register initializer gime_init fcb GIME_COCO|GIME_MMUEN|GIME_FExx|GIME_SCS|GIME_ROMI32 ; enable MMU, SCS, constant page, internal ROM fcb GIME_TASK0 ; use MMU task 0 fcb 0 ; do not enable IRQ sources fcb 0 ; do not enable FIRQ sources fdb 0xfff ; set timer to max value fdb 0 ; *reserved placeholder* fcb 0,0,0,0 ; SG4 screen settings with black border fcb 0x0f,0xe0,0x00,0x00 ; (puts screen in bottom 64K of memory) fcb 0x38,0x39,0x3a,0x3b ; MMU task 0 (bottom of top 64K of RAM) fcb 0x3c,0x3d,0x3e,0x3f ; (ROM shadow must be in 3c...3f) fcb 0x38,0x39,0x3a,0x3b ; MMU task 1 (copy of task 0) fcb 0x3c,0x3d,0x3e,0x3f fcb 18,54,9,36,63,27,45,38 ; palette values (RGB) fcb 0,18,0,63,0,18,0,38 gime_inite equ * int_init fcb 0x55 ; vectors valid flag jmp SW3VEC ; bounce to stock ROM compatibility vector jmp SW2VEC ; bounce to stock ROM compatibility vector jmp FRQVEC ; bounce to stock ROM compatibility vector jmp IRQVEC ; bounce to stock ROM compatibility vector jmp SWIVEC ; bounce to stock ROM compatibility vector jmp NMIVEC ; bounce to stock ROM compatibility vector int_inite equ * endc ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Cold start handling coldstart ldx #dpstart ; point to start of direct page ldd #0 ; set up for blanking coldstart0 std ,x++ ; blank a couple of bytes cmpx #textscreen ; end of low memory? blo coldstart0 ; brif not ifndef COCO3 ; This is the memory size detection sequence. This runs through memory starting at the bottom of memory ; and stops when it reaches something that can't be modified successfully. This is basically the same ; algorithm used by the stock ROM. It takes less space than doing a more pointed set of probes. The end ; result will be X pointing to the byte one below the top of RAM. This is intentional to ensure there ; is one writeable byte at the top of string space. Note that X will point to the byte after the end ; of the text screen when we get here. ldx #heapstart ; point to start of heap coldstart1 lda 2,x ; get original value at test location coma ; invert all bits sta 2,x ; write it to the memory location cmpa 2,x ; did it take? bne coldstart2 ; brif not com 2,x ; restore memory byte leax 1,x ; move pointer forward bra coldstart1 ; go check next byte else ; For the Coco3, we do not need to concern ourselves about where the top actual memory is so we don't ; bother doing a memory scan in the default 64K memory map. Because we always run from RAM, we can actually ; set the top of memory to the actual top of the 32K space without having to ensure there is an extra byte ; available above the string space. ldx #ROMSTART-1 ; point to top of memory endc coldstart2 stx memtop ; save absolute top of memory stx memsize ; save top of unreserved memory stx stringtab ; mark string space as empty leax -200,x ; allocate 200 bytes of string space stx freetop ; save top of free memory leas ,x ; put the stack there ldx #heapstart ; point to start of free memory stx progtext ; put the start of the program there clr ,x+ ; put a NULL pointer to mark end of program clr ,x+ stx vartabint ; put start of integer variables at end of program stx vartabfloat ; put start of floating point variables after that stx vartabstring ; put start of string variables after that stx objecttab ; also put the start of large objects there stx freestart ; mark the start of free memory ldx #warmstart ; set up warm start handler stx RSTVEC lda #0x55 ; activate warm start handler sta RSTFLG ldd #0x7e3b ; opcodes for JMP extended and RTI ldx #irqhandler ; enable IRQ handler with a JMP at the vector sta IRQVEC stx IRQVEC+1 sta FRQVEC ; initialize FIRQ handler with JMP ldx #firqhandler stx FRQVEC+1 stb NMIVEC ; initialize NMI to RTI stb SW3VEC ; initialize SWI3 to RTI stb SW2VEC ; initialize SWI2 to RTI stb SWIVEC ; initialize SWI to RTI ldx #greeting ; display greeting jsr console_outstr bra warmstartb ; finish up initialization ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Warm start handling ifdef COCO3 warmstart fcb 0xff ; set to 0xff to force ROM/RAM copy on reset else warmstart nop ; flag warm start routine as valid endc jsr console_clear ; clear screen clr filenum ; reset I/O channel to the screen warmstartb jsr keyb_reset ; reset the keyboard lda #0x35 ; enable VSYNC interrupt in PIA sta PIA0.CB andcc #0xaf ; enable interrupts at the cpu jmp immediate ; go start immediate mode ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; System startup message ; (start with form feed to clear screen; saves 2 bytes over 'jsr console_clear' in cold start) greeting fcc '\fLWBASIC VERSION 2022.0\r\n' fcc 'COPYRIGHT (C) 2022 BY LOST\r\n' fcc 'WIZARD ENTERPRISES INC.\r\n' fcn '\n' ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; IRQ handler ; ; Note that the interrupt flag in the PIA is cleared at the start of the interrupt handler. That means that if it takes ; a long time to process this interrupt, or processing this interrupt was delayed somewhat, it is far less likely that ; an interrupt gets missed. In that case, we may end up re-interrupting immediately on RTI, but it should reduce the ; number of missed interrupts. irqhandler lda PIA0.CB ; was it VSYNC? bmi irqhandler0 ; brif so lda PIA0.DA ; clear HSYNC flag so we don't get stuck if it gets enabled ifdef COCO3 lda GIME.IRQ ; clear GIME IRQ state flags endc rti irqhandler0 lda PIA0.DB ; clear VSYNC flag clra ; make sure DP is pointing to the right place tfr a,dp lda console_blnkdel ; is the cursor blinking? beq irqhandler1 ; brif not dec console_blnkdel ; time to cycle cursor? bne irqhandler1 ; brif not lda #console_curdel ; reset blink counter sta console_blnkdel lda [console_curptr] ; get character at cursor adda #0x10 ; move to next colour ora #0x8f ; force it to be a full 4x4 colour block sta [console_curptr] ; update cursor on screen irqhandler1 bsr keyb_read ; go handle the keyboard rti ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; FIRQ handler ; ; This handler is present to prevent accidentally enabling the interrupt and thus hanging to system. It may seem to be ; a waste of code space, but consider it a self defense situation. firqhandler pshs a ; need a scratch register ifdef COCO3 lda GIME.FIRQ ; clear GIME FIRQ state flags endc lda PIA1.DA ; clear interrupt flags lda PIA1.DB lda PIA1.CA ; disable interrupts to prevent system hang anda #0xfe sta PIA1.CA lda PIA1.CB anda #0xfe sta PIA1.CB puls a ; restore register rti ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Console keyboard input driver ; ; Reset the keyboard state, which means clearing the buffer and state flags keyb_reset ldx #keyb_buff ; point to start of keyboard ring buffer stx keyb_buffw ; set write point there stx keyb_buffr ; set read point there (pointers equal means empty buffer) clr keyb_flags ; reset keyboard state flags clr keyb_joystate ; clear joystick button state clr keyb_curscan ; stop any keyboard repeating ldx #0xffff ; mark all key state as "unpressed" stx keyb_state stx keyb_state+2 stx keyb_state+4 stx keyb_state+6 rts ; Read character from keyboard ring buffer; return with C set if buffer empty; this doesn't actually need to have ; interrupts disabled because the interrupt only ever updates the write pointer and then only to increase it. As a ; result, worst case is that we don't detect the contents added to the buffer on this call and have to wait for the ; next. keyb_getkey pshs x ; save register ldx keyb_buffr ; get read pointer cmpx keyb_buffw ; same as write pointer? bne keyb_getkey0 ; brif not - we have a result coma ; set carry for empty buffer puls x,pc ; restore register and return keyb_getkey0 lda ,x+ ; get character from buffer cmpx #keyb_buff+keyb_bufflen ; did we run off end of buffer? blo keyb_getkey1 ; brif not ldx #keyb_buff ; reset to start keyb_getkey1 stx keyb_buffr ; save new read pointer andcc #0xfe ; flag key retrieved puls x,pc ; restore register and return ; The PIA reading loop is specifically set up to NOT read PIA0.DB to avoid prematurely clearing the VSYNC interrupt flag ; since that could lead to missing interrupts. Reading PIA0.DA will clear the HSYNC interrupt flag but that's less of a ; problem because that interrupt is basically useless. ; ; As a note, doing the PIA read in a loop ends up using an extra 27 CPU cycles for the BCS instruction. However, it ; saves 70 code bytes. The trade off seems worth it in this case. ; ; Once keyboard state is read, we do the following: ; ; * update the state of SHIFT, CTRL, ALT ; * decode all other keys in a loop keyb_read0a pshs b ; save flag bit ldb a,y ; get state flag bitb #0x40 ; did it change state? bne keyb_read0d ; brif so puls b,pc ; clean up and return keyb_read0d andb #0xbf ; flag it as not changed stb a,y ldb a,u ; get current modifier state eorb #0x40 ; flip the state bit stb a,u ; save new state flags bitb #0x40 ; Z set if not down puls b ; get back flag bit beq keyb_read0b ; brif key is pressed comb ; invert bit flag andb keyb_flags ; clear bit in flags bra keyb_read0c ; finish up keyb_read0b orb keyb_flags ; set the flag keyb_read0c stb keyb_flags ; update flags rts keyb_read leas -9,s ; make temporary buffer leay 1,s ; point to temporary state buffer clra ;* set to 0xff with C clear; start by strobing no columns for joystick deca ;* then rotate the 0 bit through to do the actual keyboard columns ldu #keyb_state ; point to end of keyboard state buffer sta PIA0.DB ; strobe no columns ldb PIA0.DA ; get joystick button state stb keyb_joystate ; save it for later when needed andb #0x7f ; mask off comparator (pretend "button" down) stb ,s ; save button/comparator state mask rola ; set up for first column keyb_read0 sta PIA0.DB ; set column strobe ldb PIA0.DA ; read row data eorb ,u+ ; set bits if state changed andb ,s ; mask off comparator and active buttons stb ,y+ ; save state change information rola ; shift to next column bcs keyb_read0 ; brif we haven't done the last column sta PIA0.DB ; reset column strobe to none ldd #0xff00|keyb_shift bsr keyb_read0a ldd #0xfc00|keyb_ctrl bsr keyb_read0a ldd #0xfb00|keyb_alt bsr keyb_read0a keyb_read3 ldd #0x0701 ; initialize bit probe and counter keyb_read4 leay -1,y ; move pointers to next byte leau -1,u keyb_read5 bitb ,y ; did this key change state? bne keyb_read7 ; brif so keyb_read6 adda #8 ; adjust scan code lslb ; shift bit probe bpl keyb_read5 ; brif we haven't done all bits ldb ,y ; update state flags for this byte eorb ,u stb ,u ldb #1 ; reset bit probe anda #0x07 ; reset scan code deca ; adjust for next column bpl keyb_read4 ; brif not - do another leas 9,s ; clean up stack ldb keyb_curscan ; is key repeating? bne keyb_read9 ; brif so keyb_reada rts keyb_read7 bitb ,u ; get current state bne keyb_read8 ; brif key pressed (make) cmpa keyb_curscan ; is it the currently repeating key? bne keyb_read6 ; brif not - don't need to do anything clr keyb_curscan ; clear the current repeat bra keyb_read6 keyb_read8 sta keyb_curscan ; set the current scan code that is repeating pshs d ; save current bit probe and scan code ldb #keyb_repdeli ; intialize repeat delay stb keyb_repdel bsr keyb_tobuff ; decode key to buffer puls d ; restore scan code and bit probe bra keyb_read6 ; go handle the next bit keyb_read9 dec keyb_repdel ; is it time to repeat it? bne keyb_reada ; brif not ldb #keyb_repdelr ; reset repeat delay stb keyb_repdel lda keyb_curscan ; get current scan code keyb_tobuff tsta ; @? beq keyb_tobuff7 ; brif so cmpa #26 ; is it alpha or @? bhi keyb_tobuff6 ; brif not ldb keyb_flags ; get shift flags bitb #keyb_ctrl|keyb_alt ; ALT or CTRL? bne keyb_tobuff4 ; brif one or both ora #0x60 ; make lower case bitb #keyb_caps ; capslock enabled? beq keyb_tobuff0 ; brif not eora #0x20 ; flip to upper case keyb_tobuff0 bitb #keyb_shift ; shifted? beq keyb_tobuff1 ; brif not eora #0x20 ; flip case if shifted keyb_tobuff1 ldx keyb_buffw ; get write pointer for keyboard buffer sta ,x+ ; put it in the buffer cmpx #keyb_buff+keyb_bufflen ; end of buffer? blo keyb_tobuff2 ; brif not ldx #keyb_buff ; reset pointer to start keyb_tobuff2 cmpx keyb_buffr ; did we run into the read pointer? beq keyb_tobuff3 ; brif so - there wasn't room so don't save pointer stx keyb_buffw ; update the write pointer keyb_tobuff3 rts keyb_tobuff4 bitb #keyb_alt ; is ALT? beq keyb_tobuff1 ; brif not - scan code is CTRL-<letter> code ora #0x80 ; set bit 7 for "ALT" codes bitb #keyb_shift ; shifted? beq keyb_tobuff5 ; brif not ora #0x20 ; set bit 5 keyb_tobuff5 bitb #keyb_ctrl ; ctrl? beq keyb_tobuff1 ; brif not - stash it in the buffer ora #0x40 ; set bit 6 for "ctrl bra keyb_tobuff1 ; stash it the buffer keyb_tobuff6 suba #26 ; codes above 26 down to 1; @ will be 0 keyb_tobuff7 cmpa #6 ; is it "0"? bne keyb_tobuff8 ; brif not ldb keyb_flags ; get shift flags bitb #keyb_shift|keyb_ctrl ; CTRL-0 or SHIFT-0? beq keyb_tobuff8 ; brif not - not "capslock" eorb #keyb_caps ; flip the capslock state stb keyb_flags keyb_tobuffa rts ; and don't put it in the buffer keyb_tobuff8 cmpa #25 ; is it at or above ALT? blo keyb_tobuff9 ; brif not suba #2 ; close gap for ALT/CTRL keyb_tobuff9 ldb #8 ;* 8 codes; multiply by 8 and move to B mul ;* ldx #keyb_codetab ; point to special code table abx ; now X points to the base entry in the table ldb keyb_flags ; get shift flags andb #keyb_shift|keyb_ctrl|keyb_alt ; keep only shift/ctrl/alt lda b,x ; fetch key code beq keyb_tobuffa ; brif no code to return bra keyb_tobuff1 ; go stash it in the buffer ; This is the keyboard code table; there are 8 bytes per entry in the following order: ; 0: unmodified ; 1: shift ; 2: ctrl ; 3: ctrl-shift ; 4: alt ; 5: alt-shift ; 6: alt-ctrl ; 7: alt-ctrl-shift ; ; No entries for ALT, CTRL, SHIFT, or letters keyb_codetab fcb 0x40,0x13,0x40,0x40,0x80,0xa0,0xc0,0xe0 ; @ fcb 0x5e,0x5f,0x00,0x00,0x00,0x00,0x00,0x00 ; <UP> fcb 0x0a,0x5b,0x00,0x00,0x00,0x00,0x00,0x00 ; <DOWN> fcb 0x08,0x15,0x00,0x00,0x00,0x00,0x00,0x00 ; <LEFT> fcb 0x09,0x5d,0x00,0x00,0x00,0x00,0x00,0x00 ; <RIGHT> fcb 0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20 ; <SPACE> fcb 0x30,0x00,0x00,0x00,0x00,0x00,0x00,0x00 ; 0 (shift/ctrl variants shadowed above) fcb 0x31,0x21,0x00,0x00,0x00,0x00,0x00,0x00 ; 1 ! fcb 0x32,0x22,0x00,0x00,0x00,0x00,0x00,0x00 ; 2 " fcb 0x33,0x23,0x00,0x00,0x00,0x00,0x00,0x00 ; 3 # fcb 0x34,0x24,0x00,0x00,0x00,0x00,0x00,0x00 ; 4 $ fcb 0x35,0x25,0x00,0x00,0x00,0x00,0x00,0x00 ; 5 % fcb 0x36,0x26,0x00,0x00,0x00,0x00,0x00,0x00 ; 6 & fcb 0x37,0x27,0x00,0x00,0x00,0x00,0x00,0x00 ; 7 ' fcb 0x38,0x28,0x00,0x00,0x00,0x00,0x00,0x00 ; 8 ( fcb 0x39,0x29,0x00,0x00,0x00,0x00,0x00,0x00 ; 9 ) fcb 0x3a,0x2a,0x00,0x00,0x00,0x00,0x00,0x00 ; : * fcb 0x3b,0x2b,0x00,0x00,0x00,0x00,0x00,0x00 ; ; + fcb 0x2c,0x3c,0x00,0x00,0x00,0x00,0x00,0x00 ; , < fcb 0x2d,0x3d,0x00,0x00,0x00,0x00,0x00,0x00 ; - = fcb 0x2e,0x3e,0x00,0x00,0x00,0x00,0x00,0x00 ; . > fcb 0x2f,0x3f,0x00,0x00,0x00,0x00,0x00,0x00 ; / ? fcb 0x0d,0x0d,0x0d,0x0d,0x0d,0x0d,0x0d,0x0d ; <ENTER> fcb 0x0c,0x5c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c ; <CLEAR> fcb 0x03,0x03,0x1b,0x1b,0x9b,0xbb,0xdb,0xfb ; <BREAK> fcb 0x1c,0x1d,0x1c,0x1d,0x00,0x00,0x00,0x00 ; <F1> fcb 0x1e,0x1f,0x1e,0x1f,0x00,0x00,0x00,0x00 ; <F2> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Console screen output driver ; ; Clear screen console_clear ldb #0x60 ; VDG space character ldx #textscreen ; point to text screen stx console_curptr ; set cursor pointer to start of screen console_clear0 stb ,x+ ; blank a character cmpx #textscreen+0x200 ; end of screen? blo console_clear0 ; brif not rts ; Output NUL terminated string console_outstr0 bsr console_outchr ; output the character console_outstr lda ,x+ ; get byte from string bne console_outstr0 ; brif not end of string rts ; Output NUL terminated string followed by a newline console_outstrn bsr console_outstr ; output the string ; fallthrough intentional ; Output a newline (CR LF) console_outnl lda #0x0d ; do the CR bsr console_outchr lda #0x0a ; do the LF ; fallthrough intentional ; Output a single character to the screen; enter with character in A console_outchr pshs d,x ; save registers ldx console_curptr ; get current cursor pointer cmpa #0x20 ; printable character? blo console_outchr5 ; brif not tsta ; is it a graphics block? bmi console_outchr1 ; brif so - don't do anything to it cmpa #0x40 ; number or most non-alpha characters? blo console_outchr0 ; brif so - will need to flip bit 6 cmpa #0x60 ; upper case? blo console_outchr1 ; brif so - don't need to do anything to it anda #0xdf ; clear bit 5 of lower case; moves it to bottom of character set console_outchr0 eora #0x40 ; flip bit 6 - the "inversion" bit console_outchr1 sta ,x+ ; stick it on screen console_outchr2 stx console_curptr ; save new cursor pointer cmpx #textscreen+0x200 ; end of screen? blo console_outchr4 ; brif not leax -32,x ; move pointer back one line stx console_curptr ldx #textscreen ; point to start of screen console_outchr3 ldd 32,x ; get bytes from next line std ,x++ ; stick them here cmpx #textscreen+0x1e0 ; at last row? blo console_outchr3 ; brif not ldb #0x60 ; space character for VDG screen bsr console_clear0 ; blank out last row (borrowing screen clear loop) console_outchr4 puls d,x,pc ; restore registers and return console_outchr5 cmpa #0x0c ; form feed? bne console_outchr6 ; brif not bsr console_clear ; clear screen puls d,x,pc ; restore registers and return console_outchr6 cmpa #0x0d ; carriage return? bne console_outchr7 ; brif not ldb console_curptr+1 ; get current screen pointer LSB andb #0xe0 ; reset offset to start of line stb console_curptr+1 ; save new pointer LSB puls d,x,pc ; restore registers and return console_outchr7 cmpa #0x0a ; line feed? bne console_outchr8 ; brif not ldx console_curptr ; get cursor pointer leax 32,x ; move it forward exactly one line bra console_outchr2 ; go update stuff check for scroll console_outchr8 cmpa #0x08 ; backspace? bne console_outchr9 ; brif not cmpx #textscreen ; at start of screen? beq console_outchr4 ; brif so - backspace does nothing leax -1,x ; back up pointer (backspace is non-destructive) bra console_outchr2 ; go update pointers, etc. console_outchr9 cmpa #0x09 ; TAB character? bne console_outchr4 ; brif not ldb console_curptr ; get LSB of pointer andb #7 ; 8 space tabs - only keep low 3 bits lda #0x60 ; space character (tab is destructive) console_outchra sta ,x+ ; put a space out incb ; bump counter cmpb #8 ; at next tab stop? blo console_outchra ; brif not bra console_outchr2 ; go update details and check for scroll ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; General I/O handling package ; ; These routines operate on the I/O channel specified by filenum. The defined values of filenum are: ; ; 0: keyboard/screen console ; ; Read a line from the active file into linebuff. The resulting line will be NUL terminated leading to at most ; linbuffsize-1 character input. The trailing CR/LF will not be included. The input will be echoed if linebuffecho is ; enabled. Exit with the length of the input line in B. readline ldx #linebuff ; point to line input buffer clr ,x ; make sure buffer is NUL terminated readline0 bsr readchr ; read an input character bcs readline1 ; brif not EOF cmpa #0x0d ; CR (carriage return) beq readline1 ; brif so - return cmpa #0x03 ; BREAK? bne readline3 ; brif not coma ; set carry for irregular exit skip1 readline1 clra ; clear carry for regular exit pshs cc ; save carry state lda readlinenoecho ; are we echoing? bne readline2 ; brif not lda #0x0d ; echo carriage return + line feed bsr writechr readline2 tfr x,d ; get end address after input subd #linebuff ; subtract start of buffer; D is now length and C is clear clr ,x ; make sure line is NUL terminated puls cc,pc ; restore BREAK flag (C) and return readline3 cmpa #0x08 ; backspace? bne readline4 ; brif not cmpx #linebuff ; at start of buffer? beq readline0 ; brif so - do nothing leax -1,x ; move back buffer pointer bsr readlinee ; write a BS lda #0x20 ; write a space bsr readlinee lda #0x08 ; and finally a BS bsr readlinee bra readline0 ; go process more characters readline4 cmpa #0x0c ; form feed? bne readline5 ; brif not bsr readlinee ; go echo character if needed bra readline ; go restart line entry readline5 cmpa #0x20 ; is it non-printing? blo readline0 ; brif so - don't store it and continue bsr readlines ; stash character in buffer and echo if necessary bra readline0 ; go get another character readlines cmpx #linebuff+linebuffsize-1 ; is the line buffer full? bhs readlinee0 ; brif so - don't store character OR echo it sta ,x+ ; stash character readlinee ldb readlinenoecho ; are we echoing? bne readlinee0 ; brif not bsr writechr ; echo the character readlinee0 rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Write a newline if not at left margin. This will unconditinally output a newline for devices where the horizontal ; position is not knowable. writecondnl lda filenum ; get file number bne writenl ; brif not screen - we'll do it unconditionally lda console_curptr+1 ; get LSB of cursor pointer anda #0x1f ; keep only the low 5 bits (32 characters per line) beq writecondnl0 ; brif no newline is needed ; fallthrough intended ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Write a newline to the chosen device. writenl lda #0x0d ; code for carriage return - will serve as newline ; fallthrough intended ; Write a character to the active file; all registers preserved but C will be set if the output file cannot handle ; an output character (doesn't exist, etc.) writechr tst filenum ; is it screen? beq writechr_scr ; brif writing to screen orcc #1 ; unknown device flag writecondnl0 rts ; Handle output to the screen. This is where we convert CR to CRLF writechr_scr jsr console_outchr ; output the character cmpa #0x0d ; was it CR? bne writechr_scr0 ; brif not lda #0x0a ; ouptut an LF jsr console_outchr lda #0x0d ; restore original value writechr_scr0 andcc #0xfe ; clear error flag rts ; Read a character from the active file and return it in A; in the event that EOF is detected, readeof will be nonzero ; and the call will return with carry set. readchr clr fileeof ; flag not end of file (and clear carry) lda filenum ; get input file number beq readchr_kb ; brif keyboard input com fileeof ; flag end of file (C set and fileeof nonzero) rts ; Read character from keyboard; blink cursor while doing so readchr_kb pshs b ; preserve B as temp storage ldb [console_curptr] ; get character at cursor inc console_blnkdel ; activate cursor blinking (first interrupt will cycle it) readchr_kb0 jsr keyb_getkey ; read keyboard bcc readchr_kb1 ; brif we got a result cwai #0xaf ; wait for interrupt to scan keyboard bra readchr_kb0 ; see if we have something yet readchr_kb1 clr console_blnkdel ; disable cursor blinking stb [console_curptr] ; restore screen character clrb ; clear carry to indicate not eof puls b,pc ; restore temp and return ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Write a character to the selected output device. If the device is one that does not support actual lower case, then ; conver the character to upper case. Otherwise, pass it through as is. Currently, only the console screen falls into ; this category. This *will* modify the character in A if a change is made. writechrconduc tst filenum ; is it screen? bne writechr ; brif not - just output it tst console_truelc ; does the current text screen support actual lower case? beq writechr ; brif so - just output character cmpa #'a ; is it lower case? blo writechr ; brif not cmpa #'z ; is it still lower case? bhi writechr ; brif not suba #0x20 ; shift to upper case bra writechr ; go output it ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Fetch next input character, skip spaces. This is structured the way it is to avoid burning any register except A ; which is used for the returned value. Z will be set if the input character is NUL or a colon. C will be set if the ; input character is an ASCII digit. This allows testing Z to identify the end of a command due to either a colon or ; the end of a line. ; ; Compared to Color Basic, the instruction sequence only varies in the handling of the LDA. In Color Basic, the sequence ; is an LDA extended followed by a JMP extended. This totals to 9 cycles (5 for LDA, 4 for JMP). In LWBasic, an LDA ; with extended indirect addressing is used. This also totals 9 cycles. The only other difference is when a space is ; detected where the branch can be direct to the nextchar code instead of having to branch around a direct page JUMP ; which saves 3 cycles for the case where a space is detected. In other words, this is only slower by virtue of the ; fact that it is called with an extended JSR instead of a direct JSR which causes one extra cycle to be used there ; and one extra byte for each call to nextchar or curchar. ; ; On 6309, native move saves an extra cycle in the LDA sequence using the LDA extended followed by JMP extended ; sequence. ; ; This whole thing could be sped up by keeping the input pointer in a register. However, retaining the ability to ; use Y without having to save it first is likely more beneficial. nextchar inc inputptr+1 ; bump LSB of input pointer bne curchar ; brif no carry inc inputptr ; bump MSB curchar lda [inputptr] ; read the byte cmpa #'9+1 ; clear C if above ASCII digits, Z if colon bhs curchar0 ; brif above the ASCII digits cmpa #0x20 ; is it a space? beq nextchar ; brif so - skip over it suba #'0 ; clever way to set C if >= ASCII 0, Z if zero suba #-'0 curchar0 rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; The error handler ; ; Enter with the error number in B. This routine will do some cleanup and handle any ON ERROR GOTO handler that ; may be active. ; ; Note the error message lookup does not need to be efficient which is why the lookup just runs through the list ; of error messages in sequence looking for NUL terminators. The specific handling of B (error number) below avoids ; issues if there happen to be error codes above 128. ERROR clr filenum ; reset display device to console jsr writecondnl ; do a newline if needed (will preserve B) ldx #errormsg ; point to error message list incb ; account for decb below bra ERROR0 ; go search for correct message ERROR0 lda ,x+ ; end of message? bne ERROR0 ; brif not end of message ERROR1 decb ; at the correct one? bne ERROR0 ; brif not - skip to next one ERROR2 lda ,x+ ; get character to output beq ERROR3 ; brif end of message jsr writechrconduc ; output the character, converted to upper case situationally bra ERROR2 ; handle another character ERROR3 ; fall through to immediate mode intentional ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Immediate mode handler immediate jsr writecondnl ; do newline if required ldx #prompt ; point to prompt string jsr console_outstrn immediate0 jsr readline ; read input line bcs immediate0 ; brif ended with BREAK ldx #linebuff ; point to start of line input buffer stx inputptr ; set input pointer jsr curchar ; skip spaces and set flags bcs immediate1 ; brif there's a line number tsta ; is there anything there at all (end of line)? beq immediate0 ; brif not - read another line ldx inputptr ; get the modified input pointer processing above jsr tokenize ; tokenize the line at inputptr, return with result at tokebuff ; jsr interpretline ; go interpret the tokenized line bra immediate ; go handle another line immediate1 ; handle line insert/delete/modify bra immediate0 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Main interpretation loop ; ; Enter at interpret with inputptr pointing to the code stream to interpret. ; Enter at interpretline with X pointing to the command stream to interpret which will return to the caller one the ; command stream has completed. STOP or BREAK will return with carry set while END or falling off the end of the ; code will return with carry clear. In the event of an error, the usual error processing will be done and control ; will return to immediate mode with the stack reset. interpret ldx inputptr ; get interpration address stx curstmt ; save address of the current statement (needed for some stuff) lda ,x+ ; are we at the end of the line? beq interpret0 ; brif so cmpa #': ; end of statement? beq interpret3 ; brif so - do a statement SNERROR ldb #err_sn ; raise a syntax error jmp ERROR interpret0 sta endflag ; flag the program exit state as "END" (will be zero) ldd curline ; were we in immediate mode? bne interpret1 ; brif not clra ; clear carry to indicate normal exit rts ; return to caller interpret1 ldd ,x++ ; are we at the end of the program? beq interpret4 ; brif so - bail out stx curline ; save pointer to current line leax 1,x ; set input pointer one before the start of the line text interpret2 stx inputptr interpret3 jsr nextchar ; fetch first character of next statement beq interpret ; brif end of statement - do the next statement dance ;lbpl cmd_let ; brif no command - do assignment (LET command is optional) ldx primaryjump ; point to jump table anda #0x7f ; lose bit 7 leax a,x ; get half way to the correct offset ldx a,x ; get the address the other half of the way from here jsr nextchar ; skip past token and set flags jsr ,x ; call the routine bra interpret ; go handle the next statement dance interpret4 bsr cmd_stop1 ; make sure stack is aligned correctly (will not return) interpretline clr curline ; blank out current line pointer (for immediate mode) clr curline+1 leax -1,x ; move back before start of code stream bra interpret2 ; go interpret this statement and then continue with stuff ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; The END command. cmd_end bne SNERROR ; error out if there is an argument ;jsr closeall ; close all files for END clra ; flag END bra cmd_stop0 ; go do the stop/end cmd_stop bne SNERROR ; raise error if there was an argument lda #0xff ; flag STOP cmd_stop0 sta endflag ; set stop/end flag cmd_stop1 clr filenum ; reset I/O to console ldx curline ; in immediate mode? beq cmd_stop2 ; brif so - don't save the continue pointers stx contline ; save pointer to current line for CONT ldx curstmt ; get current statement address stx contstmt ; save it for CONT cmd_stop2 rol endflag ; get STOP/END to C (1=STOP) ldx curline ; immediate mode? beq cmd_stop3 ; brif so - just return END/STOP status ldx #breakmsg ; do "BREAK IN" jmp ERROR2 ; the bottom half of the error handler can deal with the details cmd_stop3 puls x,pc ; lose return address and return to caller of interpretation loop ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; REM and ' commands; also ELSE comes here since it needs to skip the rest of the line in that case. cmd_else cmd_apos cmd_rem clra ; clear carry ldx curline ; get start of current line beq cmd_stop3 ; brif immediate mode - fall back to caller ldx ,x ; get address of next line leax -1,x ; move back one stx inputptr ; put input pointer there rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; DATA command ; ; need to skip to the end of the current statement, which is either the end of the line OR a colon not included inside ; a quoted string cmd_data ldx inputptr ; get input pointer cmd_data0 lda ,x+ ; get character at pointer beq cmd_data2 ; brif end of line cmpa #': ; end of statement? bne cmd_data1 ; brif not cmd_data1 leax -1,x ; move back to the NUL or colon stx inputptr ; reset input pointer for interpreter rts cmd_data2 cmpa #'" ; start of constant string? bne cmd_data0 ; brif not - process more characters cmd_data3 lda ,x+ ; get next string character beq cmd_data1 ; brif end of line cmpa #'" ; string delimiter? bne cmd_data3 ; brif not - keep going bra cmd_data0 ; process stuff outside string ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Miscelaneous strings prompt fcn 'OK' ; general prompt breakmsg fcn 'BREAK' ; "BREAK" message ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Error messages ; ; Each error begins with a deferr macro invocation which will define a symbol err_slug with the next error number ; ; deferr slug ; ; This is then followed by the error message defined with fcn. ; ; Real error numbers start at 1; 0 is used to indicate no error. *pragmapush list *pragma nolist __errnum set 0 deferr macro noexpand err_{1} equ __errnum __errnum set __errnum+1 endm *pragmapop list errormsg deferr none fcn 'No error' deferr nf fcn 'NEXT without FOR' deferr sn fcn 'Syntax error' ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Set carry if upper/lower case alpha setcifalpha cmpa #'z+1 ; is it above lower case Z? bhs setcifalpha0 ; brif so, C clear suba #'a ; set C if >= lower case A suba #-'a bcs setcifalpha0 ; brif lower case alpha setcifualpha cmpa #'Z+1 ; is it above upper case Z? bhs setcifalpha0 ; brif so, C clear suba #'A ; set C if >= upper case A suba #-'A setcifalpha0 rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Set carry if digit setcifdigit cmpa #'9+1 ; is it above digit 9? bhs setcifdigit0 ; brif so, C clear suba #'0 ; set C if >= digit 0 suba #-'0 setcifdigit0 rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Tokenize line to tokebuff ; ; Enter with X pointing to the text to tokenize. ; Exit with X pointing to the start of the tokenized line and D holding the length of the tokenized line. tokenize clra ; clear "not token" flag clrb ; clear the "in data" flag ldy #tokebuff ; point to destination buffer pshs d,u ; set return value, the "not token" flag, and the "in data" flag tokenize0 lda ,x+ ; get input character bne tokenize1 ; brif not end of input tokenize0a sta ,y+ ; blank out final byte in result tokenize0b leas 2,s ; clean up temporaries on stack tfr y,d ; get end address to accumulator subd #tokebuff ; subtract out start; gives length of result puls x,pc ; set return pointer and return tokenize1 tst ,s ; are we in the middle of a "not token"? beq tokenize2 ; brif not bsr setcifalpha ; is it alpha bcs tokenize2 ; brif so - store it and continue bsr setcifdigit ; is it numeric? bcc tokenize3 ; brif not tokenize2 sta ,y+ ; save output character bra tokenize0 ; check for another tokenize3 clr ,s ; clear the "not token" flag cmpa #'" ; is it a string? bne tokenize5 ; brif not sta ,y+ ; save string delimiter tokenize4 lda ,x+ ; get input character beq tokenize0a ; brif end of input sta ,y+ ; save it in output cmpa #'" ; end of string? bne tokenize4 ; brif not bra tokenize0 ; brif tokenize5 cmpa #': ; end of statement? bne tokenize6 ; brif not clr 1,s ; reset "in data" flag bra tokenize0a ; stash it and continue tokenize6 cmpa #0x20 ; is it a space? beq tokenize0a ; brif so - stash it unmodified tst 1,s ; are we "in data"? bne tokenize0a ; brif so - don't tokenize it cmpa #'' ; ' shortcut for remark? bne tokenize9 ; brif not ldd #':*256+tok_apos ; put token for ' and an implied colon std ,y++ ; stash it tokenize8 lda ,x+ ; fetch byte from input sta ,y+ ; stash in output bne tokenize8 ; brif not end of input bra tokenize0b ; go finish up tokenize9 bsr setcifdigit ; is it a digit? bcs tokenize0a ; brif so - pass it through tsta ; is the high bit set? bmi tokenize0 ; ignore it if so ldu #primarydict ; point to keyword table leax -1,x ; back up input to start of potential token clrb ; initialize the token number clra ; initialize secondary table flag pshs d,x ; save start of input token and the token counter tokenize10 ldb ,u ; are we at the end of the table? bne tokenize11 ; brif not ldu #secondarydict ; point to secondary token dictionary clr ,s ; reset token counter com 1,s ; flip to secondary token flag bne tokenize10 ; brif we haven't already done the secondaries puls d,x ; get back input pointer and clear stack temporaries com ,s ; set "not token flag" lda ,x+ ; get character bra tokenize0a ; stash it and continue tokenize11 ldx 2,s ; get back start of input token tokenize12 ldb ,x+ ; get input character cmpb #'z ; is it above lower case Z? bhi tokenize13 ; brif so cmpb #'a ; is it below lower case A? blo tokenize13 ; brif so subb #0x20 ; convert to upper case tokenize13 subb ,u+ ; does it match? beq tokenize12 ; brif so - check another cmpb #0x80 ; did it match with high bit set? beq tokenize15 ; brif so - exact match leau -1,u ; back up to current test character tokenize14 ldb ,u+ ; end of token? bpl tokenize14 ; brif not inc ,s ; bump token counter bra tokenize11 ; go check another one tokenize15 orb ,s+ ; merge token number with the high bit (bit 7 set from above) lda ,s+ ; get back secondary flag and set flags on it leas 2,s ; clean up saved input pointer from stack bpl tokenize17 ; brif primary token skip2 tokenize18 lda #': ; for putting implied colons in tokenize16 std ,y++ ; put output into buffer jmp tokenize0 ; go handle more input tokenize17 cmpb #tok_else ; is it ELSE? beq tokenize18 ; brif so - stash it with colon cmpb #tok_data ; is it DATA? bne tokenize18a ; brif not stb 1,s ; set "in data" flag tokenize20 stb ,y+ ; stash token jmp tokenize0 ; go handle more tokenize18a cmpb #tok_rem ; is it REM? beq tokenize19 ; brif so cmpb #tok_apos ; apostrophe REM? bne tokenize20 ; brif not - stash token and continue lda #': ; stash the implied colon sta ,y+ bra tokenize19 tokenize19a ldb ,x+ ; fetch next input character tokenize19 stb ,y+ ; stash the character bne tokenize19a ; brif not end of input - do another jmp tokenize0b ; stash end of buffer and handle cleanup ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Keyword dictionaries and jump tables. These are defined by several macros which ensure that each command or function ; entry has an associated jump table entry. These macros are: ; ; defcmd string,symbase ; deffunc string,symbase,flags ; cmdtab ; functab ; cmdjump ; funcjump ; defcmd and deffunc will add an entry into the relevant dictionary table as well as adding one to the relevant jump ; tables. The cmdtab, functab, cmdjump, and funcjump will output the table definitions. *pragmapush list *pragma nolist __cmdnum set 0x80 __funcnum set 0x80 defcmd macro noexpand setstr __cmdtab="%(__cmdtab)\tfcs {1}\n" setstr __cmdjump="%(__cmdjump)\tfdb cmd_{2}\n" tok_{2} equ __cmdnum __cmdnum set __cmdnum+1 endm deffunc macro noexpand setstr __functab="%(__functab)\tfcs {1}\n" setstr __funcjump="%(__funcjump)\tfcb {3}\n\tfdb func_{2}\n" tok_{2} equ __funcnum __funcnum set __funcnum+1 endm cmdtab macro *pragmapush list *pragma nolist includestr "%(__cmdtab)" *pragmapop list fcb 0 ; flag end of table endm functab macro *pragmapush list *pragma nolist includestr "%(__functab)" *pragmapop list fcb 0 ; flag end of table endm cmdjump macro *pragmapush nolist *pragma nolist includestr "%(__cmdjump)" *pragmapop list endm funcjump macro *pragmapush nolist *pragma nolist includestr "%(__funcjump)" *pragmapop list endm *pragmapop list defcmd 'REM',rem defcmd /'/,apos defcmd 'DATA',data defcmd 'ELSE',else defcmd 'END',end defcmd 'STOP',stop primarydict cmdtab secondarydict functab primaryjump cmdjump secondaryjump funcjump ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Need to ensure the vectors are at 0xbff2 zmb 0xbff2-* ; pad ROM up to the vector point fdb SW3VEC ; SWI3 vector fdb SW2VEC ; SWI2 vector fdb FRQVEC ; FIRQ vector fdb IRQVEC ; IRQ vector fdb SWIVEC ; SWI vector fdb NMIVEC ; NMI vector fdb START ; RESET vector (ROM entry point) endc ifdef COCO3 zmb 0xfff2-* ; pad ROM to bottom of vectors fdb INT.SWI3 ; SWI3 vector fdb INT.SWI2 ; SWI2 vector fdb INT.FIRQ ; FIRQ vector fdb INT.IRQ ; IRQ vector fdb INT.SWI ; SWI vector fdb INT.NMI ; NMI vector fdb START ; RESET vector (ROM entry point) else zmb 0x10000-* ; pad ROM to full size endc