C02/include/vic20/file.a02

; Requires external routines SETSRC and SETDST
; Requires the following RAM locations be defined
; external zero page byte pairs SRCLO,SRCHI and DSTLO,DSTHI
; and external bytes TEMP0 and TEMP1

;fsetup(fn, fs, fd) - Set Parameters for fsopen()
;Args: A = Logical file number
;      Y = Secondary address (255 for None)
;      X = Device 0=Keyboard, 1=Cassette, 2=RS232, 3=Screen
;                 4-7=Printers, 8-15=Disks, 31=All Devices 
;Affects None
FSETUP  EQU SETLFS    ;Set up a logical file

;fsname(n, &s) - Set Filename for Load, Open, Save
;Args: A = Length of filename string
;      X,Y = Pointer to string containing filename
;Affects: A,X,Y
;Returns: A = 1,2,3,4,6,240 (see FERROR)

;fsload(v, &a) - Load Memory from File
;Prereqs: fsetup(), fsname()
;Args: A = Mode 0=Load, 1=Verify
;      Y,X = Address to Load File
;Stack: 9
;Affects: A,X,Y
;Sets: STATUS = 0,4,5,8,9 (see FERROR)
FSLOAD  EQU LOAD      ;Load RAM from device

;fssave(v, &a) - Save Memory to File
;Prereqs: fsdst fsetup(), fsname()
;Requires: DSTLO, DSTHI - Start Address
;Args: Y,X = End Address
;Stack: 9
;Affects: A,X,Y
;Sets: STATUS = 0,4,5,8,9 (see FERROR)
FSSAVE: LDA #SRCLO    ;Load Pointer to Start Address
        JMP SAVE      ;Save memory to device

;fsopen() - Open
;Prereqs: fsetup(), fsname()
;Affects: A,X,Y
;Sets: STATUS = 1,2,3,4,6,240 (see FERROR)
STRCHR: JSR SETNAM      ;Set file name
        JMP OPEN        ;Open File

;fopen(n, &s) - Open File with Specified Name
;Not Implemented

;fclose(fn) - Close File
;Args: A = Logical file number
;Returns: A = 0,240 (see FERROR)
FCLOSE  EQU CLOSE       ;Close a logical file

;feof(fn) - Check for End of File
;Args: A = Logical file number
;Affects: A,X
;Returns: A = 0,240 (see FERROR)
FEOF:   JSR READST      ;Read status word
        AND #$C0        ;$40=End of File, $80 End of Tape
        BEQ FRTS        ;If Not 0
FERR:	LDA #$FF        ;  Set Generic Error Condition
FRTS:	RTS             ;Return from Subroutine

;ferror(fn) - Check for Error
;Args: A = Logical file number
;Affects: A,X
;Returns: A = Error Bit Mask  
;         Bit  Cassette Read  Serial Bus I/O     Tape Load/Verify
;         $01                  Write Timeout
;         $02                  Read Timeout
;         $04   Short Block                         Short Block
;         $08   Long Block                          Long Block
;         $10   Read Error                          Any Mismatch
;         $20   Checksum Err                        Checksum Err
;         $40   End of File    EOI Line
;         $80   End of Tape    Device Not Present   End of Tape
FERROR  EQU READST      ;Read status word

;fflush() - Flush file buffer
; No-Op - Not Needed
FFLUSH:	RTS

;fgetc(fn) - Read character from file
;Args: A = Logical file number
;Stack:   9
;Affects: A,X
;Returns: A = 0,240 (see FERROR)
FGETC:  TAX                ;Move logical file number to X register
        JSR CHKIN       ;Open channel for input
        JSR CHRIN       ;Get character from input channel
        PHA	            ;Save read character
        JSR CLRCHN      ;Clear I/O channels
        PLA             ;Retrieve read Character
        RTS
        
;fputc(fn) - Write character from file
;Args: A = Logical file number
;      Y = Character to Write
;Stack:   9
;Affects: A,X
;Returns: A = 0,240 (see FERROR)
FPUTC:  TAX                ;Move logical file number to X register
        JSR CHKOUT      ;Open channel for input
        TYA             ;Move character to accumulator
FPUTCH: JSR CHROUT      ;Output a character
         JMP CLRCHN      ;Clear I/O channels and return

;fgets(fn, &s) - Read string from file
;Requires: DSTLO, DSTHI - Pointer to destination string
;Args: A = Logical file number
;      Y,X = Pointer to String
;Stack: 9
;Affects: X,Y
;Returns: A = Number of bytes read
FGETS:  JSR SETDST        ;Save string address & initialize pointer 
        TAX                ;Move logical file number to X register
        JSR CHKIN       ;Open channel for input
FGETSL: JSR CHRIN       ;Get character from input channel
        PHA               ;Save read character
        JSR READST      ;Read status word
        BNE FGETSX      ;If Not 0, Exit
        PLA             ;Retrieve read character
        STA SRCLO,Y     ;Store character in string
        CMP $0D         ;If Carriage Return
        BEQ FGETSX      ;  Then Exit
        INY             ;Increment pointer
        BPL FGETSL      ;and loop if less than 128
FGETSX: LDA #$00        ;Terminate String        
        STA (SRCLO),Y   ; 
FGETSY: JSR CLRCHN      ;Clear I/O channels
        TYA             ;Return string length
        RTS

;fputs(fn, &s) - Write String to File
;Requires: DSTLO, DSTHI - Pointer to source string
;Args: A = Logical file number
;      Y,X = Pointer to String
;Stack: 9
;Affects: X,Y
;Returns: A = Number of bytes written
FPUTS:  JSR SETDST        ;Save string address & initialize pointer 
        TAX                ;Move logical file number to X register
        JSR CHKIN       ;Open channel for input
FPUTSL: LDA SRCLO,Y     ;Load next character
        PHA               ;Save write character	
        JSR CHROUT      ;Write character to output channel
        PLA             ;Retrieve write character
        CMP $0D         ;If Carriage Return
        BEQ FGETSY      ;  Then Exit
        JSR READST      ;Read status word
        BNE FGETSY      ;If Not 0, Exit
        INY             ;Increment pointer
        BPL FPUTSL      ;If less than 128 then loop
        BMI FGESTY        ;Else exit