;---------------------------------------------------------------------------
; simple example that demonstrates how to write to the flash ROM
;---------------------------------------------------------------------------

        !src "../include/gmod3.inc"

        * = $0801
        !word nextline
        !word 2016 
        !byte $9e
        !byte $32, $30, $36, $31
nextline:
        !byte 0,0,0
        jmp start
        
        !src "../lib/gmod3.asm"
        
statusdisplay = $0400 + 39
bufferpage = $0400 + 10*40

bytecount=$ae
pagecount=$af

;-------------------------------------------------------------------------------        

start:
        ;sei

        ; clear screen
        ldx #0
-
        lda #$20
        sta $0400,x
        sta $0500,x
        sta $0600,x
        sta $0700,x
        lda #$01
        sta $d800,x
        sta $d900,x
        sta $da00,x
        sta $db00,x
        inx
        bne -

        ; input filename

        ldx #(promptend-prompt)-1
-
        lda prompt,x
        sta $0400+(40*2),x
        dex
        bpl -
        
        ldx #2      ; line
        ldy #(promptend-prompt)      ; column
        clc
        jsr $fff0   ; set cursor

        jsr inputname

        jsr file_open

        lda #$00
        sta pagecount
        sta pagecount64k
        sta eof
        
        ; before we can write to the flash, we must erase it
;        inc $0400   ; to indicate progress
;        jsr flash_chiperase
;        inc $0401   ; to indicate progress

;        ldy #0
;--
;        ldx #0
.flashloop
;        tya
;        pha
        
;         txa
;         pha

;        inc $0405   ; to indicate progress

        jsr showpage
        
        
        
        lda #'R' & $3f
        sta statusdisplay
        
        lda #0
        sta bytecount
-
        jsr file_read
        ldx bytecount
        sta bufferpage,x
        inc bytecount
        bne -

        ; every time the page counter is 0, we need to erase a 64k page in the
        ; flash memory
        lda pagecount
        bne +
        jsr erasepage
+
        
        lda #'F' & $3f
        sta statusdisplay
        
        ; set byte program command and flash address
;         pla
;         pha
;         tax
        lda pagecount64k
        sta addr2
        ;ldx #0
        ldx pagecount
        stx addr1
        ;lda #0
        ;sta addr0

        
        lda #<bufferpage
        ldx #>bufferpage
        ; program one 256byte page
        jsr flash_writepage

        lda #' ' & $3f
        sta statusdisplay

        
;         pla
;         tax
;        pla
;        tay

        inc pagecount
        bne +
        inc pagecount64k
+

eof=*+1
        lda #0
        sta $0400+9
        bne +
        
        jmp .flashloop
+
        ; done
-
        inc $d020
        dec $d020
        jmp -

;-------------------------------------------------------------------------------

erasepage:
        lda #'E' & $3f
        sta statusdisplay
        
pagecount64k=*+1
        lda #0
        jsr flash_erase
        
        lda #' ' & $3f
        sta statusdisplay
        
        rts
        
showpage:
        lda pagecount64k
        pha
        lsr
        lsr
        lsr
        lsr
        tay
        lda hexdigits,y
        sta $0400
        pla
        and #$0f
        tay
        lda hexdigits,y
        sta $0401        
        
        lda pagecount
        pha
        lsr
        lsr
        lsr
        lsr
        tay
        lda hexdigits,y
        sta $0402
        pla
        and #$0f
        tay
        lda hexdigits,y
        sta $0403        
        rts

hexdigits:
        !scr "0123456789abcdef"
        
        ; this is very naive, does not support editing etc
inputname:
        ldx #0
-
        jsr $ffcf
        cmp #$0d
        beq +
        sta fname,x
        inx
        cpx #16
        bne -
+
        stx namelen
        rts
        
        
;-------------------------------------------------------------------------------

file_open:
        LDA namelen
        LDX #<fname
        LDY #>fname
        JSR $FFBD     ; call SETNAM

        LDA #$02      ; file number 2
        LDX $BA       ; last used device number
        BNE .skip
        LDX #$08      ; default to device 8
.skip   LDY #$02      ; secondary address 2
        JSR $FFBA     ; call SETLFS

        JSR $FFC0     ; call OPEN
        BCS .error    ; if carry set, the file could not be opened

        ; check drive error channel here to test for
        ; FILE NOT FOUND error etc.

        LDX #$02      ; filenumber 2
        JSR $FFC6     ; call CHKIN (file 2 now used as input)

        rts
        
file_read:
        jmp $FFB7     ; call READST (read status byte)
        bne .eof      ; either EOF or read error
        jmp $FFCF     ; call CHRIN (get a byte from file)

.eof
        and #$40      ; end of file?
        beq .readerror
.close
        lda #$02      ; filenumber 2
        jsr $FFC3     ; call CLOSE

        jsr $FFCC     ; call CLRCHN
        
        lda #1
        sta eof
        rts
.error
        ; Akkumulator contains BASIC error code

        ; most likely errors:
        ; A = $05 (DEVICE NOT PRESENT)

        ;... error handling for open errors ...
        jmp .close    ; even if OPEN failed, the file has to be closed
.readerror
        ; for further information, the drive error channel has to be read

        ;... error handling for read errors ...
        jmp .close

fname:  
!pet "cart.bin        "

namelen: !byte 0

prompt:
!scr "filename:"
promptend: