LOAD/SAVE of BASIC files

examples/1DLIFE.BAS

@@ -0,0 +1,24 @@
+10 REM ENDLESS RULE 30
+20 W=78
+30 DIM A(79),B(79)
+40 FOR I=1 TO W
+50 A(I)=INT(RND(1)*2)
+60 NEXT I
+70 E$=CHR$(27)
+80 PRINT E$;"[2J";E$;"[H";
+
+90 A(0)=A(W)
+100 A(W+1)=A(1)
+
+110 FOR I=1 TO W
+120 POKE 48128,32+10*A(I)
+130 B(I)=ABS(A(I-1)-(A(I) OR A(I+1)))
+140 NEXT I
+
+150 POKE 48128,10
+
+160 FOR I=1 TO W
+170 A(I)=B(I)
+180 NEXT I
+
+190 GOTO 90

msbasic/.gitignore

@@ -1 +0,0 @@
-tmp/

rom/init.s

@@ -9,6 +9,7 @@ PR_WRITTEN_BY:
 COLD_START:
       lda     #$00
       sta     CURDVC
+      sta     LOAD_ACTIVE
       ldx     #$FF
       stx     CURLIN+1
       ldx     #$FB

rom/loadsave.s

@@ -1,3 +1,320 @@
 .segment "CODE"
 
-; None yet
+LOADSAVE_LFN = $FF
+
+; ============================================================================
+; COPY STRING EXPRESSION TO FILE_NAME_BUFFER
+;
+; Entry:
+;   TXTPTR points at string expression
+;
+; Exit:
+;   FILE_NAME_BUFFER contains NUL-terminated filename
+;
+; Clobbers:
+;   A,X,Y,INDEX,STRNG2
+; ============================================================================
+PARSE_LOADSAVE_FILENAME:
+        jsr     FRMEVL
+        jsr     CHKSTR
+        jsr     FREFAC
+        ; FREFAC:
+        ;   A = length
+        ;   INDEX = string address
+        sta     STRNG2
+        ldy     #$00
+@copy:
+        cpy     STRNG2
+        beq     @done
+        lda     (INDEX),y
+        sta     FILE_NAME_BUFFER,y
+        iny
+        bne     @copy
+@done:
+        lda     #$00
+        sta     FILE_NAME_BUFFER,y
+        rts
+
+; ============================================================================
+; SET UP THE COMMON FILE ARGUMENTS
+; ============================================================================
+LOADSAVE_SET_FILE:
+        lda     #LOADSAVE_LFN
+        sta     IO_FILE_DESCRIPTOR
+        lda     #<FILE_NAME_BUFFER
+        sta     IO_FILE_DATA
+        lda     #>FILE_NAME_BUFFER
+        sta     IO_FILE_DATA+1
+        rts
+
+; ============================================================================
+; WAIT FOR FILE COMMAND COMPLETION
+;
+; Jumps to IQERR on host-side failure.
+; ============================================================================
+LOADSAVE_WAIT:
+        lda     IO_FILE_STATUS
+        and     #FILE_STATUS_READY
+        beq     LOADSAVE_WAIT
+        lda     IO_FILE_STATUS
+        and     #FILE_STATUS_ERROR
+        beq     @ok
+        jmp     IQERR
+@ok:
+        rts
+
+
+; ============================================================================
+; OPEN FOR READING
+; ============================================================================
+LOADSAVE_OPEN_R:
+        jsr     LOADSAVE_SET_FILE
+        lda     #IO_COMMAND_OPEN_R
+        sta     IO_FILE_COMMAND
+        jmp     LOADSAVE_WAIT
+
+; ============================================================================
+; OPEN FOR WRITING / TRUNCATE
+; ============================================================================
+LOADSAVE_OPEN_W:
+        jsr     LOADSAVE_SET_FILE
+        lda     #IO_COMMAND_OPEN_W
+        sta     IO_FILE_COMMAND
+        jmp     LOADSAVE_WAIT
+
+; ============================================================================
+; CLOSE INTERNAL LOAD/SAVE FILE
+; ============================================================================
+LOADSAVE_CLOSE:
+        lda     #LOADSAVE_LFN
+        sta     IO_FILE_DESCRIPTOR
+        lda     #IO_COMMAND_CLOSE
+        sta     IO_FILE_COMMAND
+        jsr     LOADSAVE_WAIT
+        jsr     CLRCH
+        rts
+
+; ============================================================================
+; SAVE "filename"
+;
+; Saves plain ASCII BASIC source, equivalent to LIST output.
+; ============================================================================
+SAVE:
+        jsr     PARSE_LOADSAVE_FILENAME
+        jsr     LOADSAVE_OPEN_W
+        ; Route OUTDO/CHROUT to our internal file.
+        ldx     #LOADSAVE_LFN
+        jsr     CHKOUT
+        stx     CURDVC
+        ; Start with first BASIC line.
+        lda     TXTTAB
+        sta     LOWTRX
+        lda     TXTTAB+1
+        sta     LOWTRX+1
+SAVE_NEXT_LINE:
+        ; The high byte of the forward link is zero at end of program.
+        ldy     #$01
+        lda     (LOWTRX),y
+        beq     SAVE_DONE
+        ; ------------------------------------------------------------
+        ; Print line number.
+        ;
+        ; record:
+        ; +0/+1 = next line
+        ; +2/+3 = line number
+        ; +4... = tokenized body
+        ; ------------------------------------------------------------
+        iny                     ; Y=2
+        lda     (LOWTRX),y
+        tax
+        iny                     ; Y=3
+        lda     (LOWTRX),y
+        jsr     LINPRT
+        lda     #' '
+        jsr     OUTDO
+        ; DATAFLG follows LIST's quoting/token rules.
+        lda     #$01
+        sta     DATAFLG
+        ldy     #$04
+SAVE_LINE_CHAR:
+        lda     (LOWTRX),y
+        beq     SAVE_LINE_DONE
+        ; Test whether it's plain ASCII/token BEFORE doing CMPs
+        bpl     SAVE_PLAIN_CHAR
+        cmp     #$FF
+        beq     SAVE_PLAIN_CHAR
+        bit     DATAFLG
+        bmi     SAVE_PLAIN_CHAR
+        ; Token
+        sec
+        sbc     #$7F
+        tax
+        sty     FORPNT
+        ldy     #$FF
+SAVE_FIND_TOKEN:
+        dex
+        beq     SAVE_TOKEN_FOUND
+SAVE_SKIP_TOKEN:
+        iny
+        lda     TOKEN_NAME_TABLE,y
+        bpl     SAVE_SKIP_TOKEN
+        bmi     SAVE_FIND_TOKEN
+SAVE_TOKEN_FOUND:
+        iny
+        lda     TOKEN_NAME_TABLE,y
+        bmi     SAVE_TOKEN_LAST
+        jsr     OUTDO
+        bne     SAVE_TOKEN_FOUND
+SAVE_TOKEN_LAST:
+        and     #$7F
+        jsr     OUTDO
+        ldy     FORPNT
+        iny
+        jmp     SAVE_LINE_CHAR
+SAVE_PLAIN_CHAR:
+        and     #$7F
+        jsr     OUTDO
+        ; Quote state must be updated AFTER output/test.
+        cmp     #$22
+        bne     SAVE_PLAIN_DONE
+        lda     DATAFLG
+        eor     #$FF
+        sta     DATAFLG
+SAVE_PLAIN_DONE:
+        iny
+        jmp     SAVE_LINE_CHAR
+SAVE_LINE_DONE:
+        ; Every saved source line ends in LF.
+        jsr     LFDO
+        ; Follow next-line pointer.
+        ldy     #$00
+        lda     (LOWTRX),y
+        tax
+        iny
+        lda     (LOWTRX),y
+        stx     LOWTRX
+        sta     LOWTRX+1
+        jmp     SAVE_NEXT_LINE
+SAVE_DONE:
+        jsr     LOADSAVE_CLOSE
+        rts
+
+; ============================================================================
+; LOAD "filename"
+;
+; Replaces current program.
+; Reads ASCII source one line at a time, tokenizes through the normal
+; BASIC parser, and inserts using NUMBERED_LINE.
+;
+; IMPORTANT:
+; NUMBERED_LINE eventually reaches FIX_LINKS -> SETPTRS -> STKINI, which
+; resets the hardware stack. Therefore LOAD cannot expect NUMBERED_LINE to
+; return with RTS. FIX_LINKS jumps back to LOAD_NEXT_LINE while LOAD_ACTIVE
+; is set.
+; ============================================================================
+
+LOAD:
+        ; Copy the filename before SCRTCH destroys temporary strings.
+        jsr     PARSE_LOADSAVE_FILENAME
+        jsr     LOADSAVE_OPEN_R
+        ; Delete current program.
+        jsr     SCRTCH
+        ; Route CHRIN to the file.
+        ldx     #LOADSAVE_LFN
+        jsr     CHKIN
+        stx     CURDVC
+        ; Tell FIX_LINKS that program insertion belongs to LOAD.
+        lda     #$01
+        sta     LOAD_ACTIVE
+; ----------------------------------------------------------------------------
+; Entry point used both initially and by FIX_LINKS after inserting each line.
+; Must be a globally visible label if FIX_LINKS lives in another source file.
+; ----------------------------------------------------------------------------
+LOAD_NEXT_LINE:
+        ldx     #$00
+; ----------------------------------------------------------------------------
+; Read one physical source line into INPUTBUFFER.
+;
+;   "10 PRINT 1\n"    -> normal line
+;   "10 PRINT 1"<EOF> -> final line still accepted
+;   EOF with X=0      -> done loading
+; ----------------------------------------------------------------------------
+@read_char:
+        jsr     CHRIN
+        ; If host says EOF, A is not considered valid data.
+        pha
+        lda     IO_FILE_STATUS
+        and     #FILE_STATUS_EOF
+        bne     @eof
+        pla
+        ; LF terminates a source line.
+        cmp     #LF
+        beq     @line_complete
+        ; Accept CRLF files too.
+        cmp     #$0D
+        beq     @read_char
+        ; Same practical line limit as interactive INLIN.
+        cpx     #$47
+        bcs     @line_too_long
+        sta     INPUTBUFFER,x
+        inx
+        jmp     @read_char
+@eof:
+        pla
+        ; EOF with no accumulated characters means real end of file.
+        cpx     #$00
+        beq     @load_done
+        ; Otherwise process the unterminated final line.
+@line_complete:
+        lda     #$00
+        sta     INPUTBUFFER,x
+        ; Point CHRGET at INPUTBUFFER-1, exactly like INLIN returns.
+        lda     #<(INPUTBUFFER-1)
+        sta     TXTPTR
+        lda     #>(INPUTBUFFER-1)
+        sta     TXTPTR+1
+        jsr     CHRGET
+        ; Ignore empty physical lines.
+        beq     LOAD_NEXT_LINE
+        ; A source file must consist of numbered program lines.
+        ;
+        ; CHRGET leaves carry clear for a leading decimal digit,
+        ; exactly like the normal RESTART path.
+        bcc     @numbered
+        jmp     @syntax_error
+@numbered:
+        ; NUMBERED_LINE performs:
+        ;
+        ;   LINGET
+        ;   PARSE_INPUT_LINE
+        ;   FNDLIN
+        ;   PUT_NEW_LINE
+        ;   FIX_LINKS
+        ;
+        ; DO NOT JSR here.
+        ;
+        ; FIX_LINKS eventually calls SETPTRS/STKINI, which resets the
+        ; hardware stack. FIX_LINKS will detect LOAD_ACTIVE and jump back
+        ; to LOAD_NEXT_LINE.
+        jmp     NUMBERED_LINE
+@line_too_long:
+@syntax_error:
+        lda     #$00
+        sta     LOAD_ACTIVE
+
+        jsr     CLRCH
+        jsr     LOADSAVE_CLOSE
+        jmp     SYNERR
+@load_done:
+        lda     #$00
+        sta     LOAD_ACTIVE
+        jsr     CLRCH
+        jsr     LOADSAVE_CLOSE
+        ; Do NOT JSR SETPTRS here.
+        ;
+        ; Every successfully inserted line already passed through
+        ; FIX_LINKS -> SETPTRS -> LE33D.
+        ;
+        ; Also do not RTS: SETPTRS/STKINI during loading may have destroyed
+        ; the original LOAD command's return frame.
+        jmp     RESTART

rom/msbasic.s

@@ -6,7 +6,6 @@
 .include "defines.s"
 .include "macros.s"
 .include "zeropage.s"
-
 .include "header.s"
 .include "token.s"
 .include "error.s"

rom/program.s

@@ -168,6 +168,10 @@ L23E6:
 FIX_LINKS:
         jsr     SETPTRS
         jsr     LE33D
+        lda     LOAD_ACTIVE
+        beq     :+
+        jmp     LOAD_NEXT_LINE
+:
         jmp     L2351
 LE33D:
         lda     TXTTAB

rom/token.s

@@ -1,6 +1,6 @@
         init_token_tables
 
-        keyword_rts "WOZMON", RESET
+        keyword_rts "WOZ", RESET
 
         keyword_rts "END", END
         keyword_rts "FOR", FOR
@@ -21,6 +21,8 @@
         keyword_rts "STOP", STOP
         keyword_rts "ON", ON
         keyword_rts "WAIT", WAIT
+        keyword_rts "LOAD", LOAD
+        keyword_rts "SAVE", SAVE
         keyword_rts "DEF", DEF
         keyword_rts "POKE", POKE
         keyword_rts "PRINT#", PRINTH

rom/zeropage.s

@@ -151,6 +151,8 @@ STRNG2:
 	.res 2
 CURDVC:
 	.res 1
+LOAD_ACTIVE:
+	.res 1
 FILE_NAME_BUFFER = $0300
 CHRGET:
 TXTPTR = <(GENERIC_TXTPTR-GENERIC_CHRGET + CHRGET)