%import textio
%import syslib

; Note: this code is compatible with C64 and CX16.

diskio {

    sub directory(ubyte drivenumber) -> ubyte {
        ; -- Prints the directory contents of disk drive 8-11 to the screen. Returns success.

        c64.SETNAM(1, "$")
        c64.SETLFS(13, drivenumber, 0)
        void c64.OPEN()          ; open 13,8,0,"$"
        if_cs
            goto io_error
        void c64.CHKIN(13)        ; use #13 as input channel
        if_cs
            goto io_error

        repeat 4 {
            void c64.CHRIN()     ; skip the 4 prologue bytes
        }

        ; while not key pressed / EOF encountered, read data.
        ubyte status = c64.READST()
        while not status {
            ubyte low = c64.CHRIN()
            ubyte high = c64.CHRIN()
            txt.print_uw(mkword(high, low))
            txt.chrout(' ')
            ubyte @zp char
            repeat {
                char = c64.CHRIN()
                if char==0
                    break
                txt.chrout(char)
            }
            txt.chrout('\n')
            void c64.CHRIN()     ; skip 2 bytes
            void c64.CHRIN()
            status = c64.READST()
            if c64.STOP2()
                break
        }

io_error:
        status = c64.READST()
        c64.CLRCHN()        ; restore default i/o devices
        c64.CLOSE(13)

        if status and status != 64 {            ; 64=end of file
            txt.print("\ni/o error, status: ")
            txt.print_ub(status)
            txt.chrout('\n')
            return false
        }

        return true
    }


    ; internal variables for the iterative file lister / loader
    ubyte list_skip_disk_name
    uword list_pattern
    uword list_blocks
    ubyte iteration_in_progress = false
    ubyte @zp first_byte
    ubyte have_first_byte
    str   list_filename = "?" * 32


    ; ----- get a list of files (uses iteration functions internally -----

    sub list_files(ubyte drivenumber, uword pattern_ptr, uword name_ptrs, ubyte max_names) -> ubyte {
        ; -- fill the array 'name_ptrs' with (pointers to) the names of the files requested.
        uword names_buffer = memory("filenames", 512)
        uword buffer_start = names_buffer
        ubyte files_found = 0
        if lf_start_list(drivenumber, pattern_ptr) {
            while lf_next_entry() {
                @(name_ptrs) = lsb(names_buffer)
                name_ptrs++
                @(name_ptrs) = msb(names_buffer)
                name_ptrs++
                names_buffer += strcopy(diskio.list_filename, names_buffer) + 1
                files_found++
                if names_buffer - buffer_start > 512-18
                    break
                if files_found == max_names
                    break
            }
            lf_end_list()
        }
        return files_found
    }

    ; ----- iterative file lister functions -----

    sub lf_start_list(ubyte drivenumber, uword pattern_ptr) -> ubyte {
        ; -- start an iterative file listing with optional pattern matching.
        ;    note: only a single iteration loop can be active at a time!
        lf_end_list()
        list_pattern = pattern_ptr
        list_skip_disk_name = true
        iteration_in_progress = true

        c64.SETNAM(1, "$")
        c64.SETLFS(12, drivenumber, 0)
        void c64.OPEN()          ; open 12,8,0,"$"
        if_cs
            goto io_error
        void c64.CHKIN(12)        ; use #12 as input channel
        if_cs
            goto io_error

        repeat 4 {
            void c64.CHRIN()     ; skip the 4 prologue bytes
        }

        if c64.READST()==0
            return true

io_error:
        lf_end_list()
        return false
    }

    sub lf_next_entry() -> ubyte {
        ; -- retrieve the next entry from an iterative file listing session.
        ;    results will be found in list_blocks and list_filename.
        ;    if it returns false though, there are no more entries (or an error occurred).

        if not iteration_in_progress
            return false

        repeat {
            void c64.CHKIN(12)        ; use #12 as input channel again

            uword nameptr = &list_filename
            ubyte blocks_lsb = c64.CHRIN()
            ubyte blocks_msb = c64.CHRIN()

            if c64.READST()
                goto close_end

            list_blocks = mkword(blocks_msb, blocks_lsb)

            ; read until the filename starts after the first "
            while c64.CHRIN()!='\"'  {
                if c64.READST()
                    goto close_end
            }

            ; read the filename
            repeat {
                ubyte char = c64.CHRIN()
                if char==0
                    break
                if char=='\"'
                    break
                @(nameptr) = char
                nameptr++
            }

            @(nameptr) = 0

            while c64.CHRIN() {
                ; read the rest of the entry until the end
            }

            void c64.CHRIN()     ; skip 2 bytes
            void c64.CHRIN()

            if not list_skip_disk_name {
                if not list_pattern
                    return true
                if prog8_lib.pattern_match(list_filename, list_pattern)
                    return true
            }
            list_skip_disk_name = false
        }

close_end:
        lf_end_list()
        return false
    }

    sub lf_end_list() {
        ; -- end an iterative file listing session (close channels).
        if iteration_in_progress {
            c64.CLRCHN()
            c64.CLOSE(12)
            iteration_in_progress = false
        }
    }


    ; ----- iterative file loader functions -----

    sub f_open(ubyte drivenumber, uword filenameptr) -> ubyte {
        ; -- open a file for iterative reading with f_read
        ;    note: only a single iteration loop can be active at a time!
        f_close()

        c64.SETNAM(strlen(filenameptr), filenameptr)
        c64.SETLFS(11, drivenumber, 3)
        void c64.OPEN()          ; open 11,8,0,"filename"
        if_cc {
            iteration_in_progress = true
            have_first_byte = false
            void c64.CHKIN(11)        ; use #11 as input channel
            if_cc {
                first_byte = c64.CHRIN()   ; read first byte to test for file not found
                if not c64.READST() {
                    have_first_byte = true
                    return true
                }
            }
        }
        f_close()
        return false
    }

    sub f_read(uword bufferpointer, uword num_bytes) -> uword {
        ; -- read from the currently open file, up to the given number of bytes.
        ;    returns the actual number of bytes read.  (checks for End-of-file and error conditions)
        if not iteration_in_progress or not num_bytes
            return 0

        list_blocks = 0     ; we reuse this variable for the total number of bytes read
        if have_first_byte {
            have_first_byte=false
            @(bufferpointer) = first_byte
            bufferpointer++
            list_blocks++
            num_bytes--
        }

        void c64.CHKIN(11)        ; use #11 as input channel again
        %asm {{
            lda  bufferpointer
            sta  _in_buffer+1
            lda  bufferpointer+1
            sta  _in_buffer+2
        }}
        repeat num_bytes {
            %asm {{
                jsr  c64.CHRIN
_in_buffer      sta  $ffff
                inc  _in_buffer+1
                bne  +
                inc  _in_buffer+2
+               inc  list_blocks
                bne  +
                inc  list_blocks+1
+
            }}
            first_byte = c64.READST()
            if first_byte==64
                f_close()       ; end of file, close it
            if first_byte
                return list_blocks
        }
        return list_blocks
    }

    sub f_read_exact(uword bufferpointer, uword num_bytes) {
        ; -- read from the currently open file, the given number of bytes. File must contain enough data!
        ;    doesn't check for error conditions or end of file, to make the read as fast as possible.
        if not iteration_in_progress or not num_bytes
            return

        if have_first_byte {
            have_first_byte=false
            @(bufferpointer) = first_byte
            bufferpointer++
            num_bytes--
        }

        void c64.CHKIN(11)        ; use #11 as input channel again
        ; repeat num_bytes {
        ;     @(bufferpointer) = c64.CHRIN()
        ;     bufferpointer++
        ; }
        %asm {{
            lda  bufferpointer
            sta  P8ZP_SCRATCH_W1
            lda  bufferpointer+1
            sta  P8ZP_SCRATCH_W1+1
            lda  #0
            sta  P8ZP_SCRATCH_B1
            lda  num_bytes+1
            sta  P8ZP_SCRATCH_W2
            beq  _no_msb
-           jsr  c64.CHRIN
            ldy  P8ZP_SCRATCH_B1
            sta  (P8ZP_SCRATCH_W1),y
            inc  P8ZP_SCRATCH_B1
            bne  -
            inc  P8ZP_SCRATCH_W1+1
            dec  P8ZP_SCRATCH_W2
            bne  -
_no_msb
            lda  num_bytes
            beq  _done
-           jsr  c64.CHRIN
            ldy  P8ZP_SCRATCH_B1
            sta  (P8ZP_SCRATCH_W1),y
            iny
            sty  P8ZP_SCRATCH_B1
            cpy  num_bytes
            bne  -
_done
        }}
    }

    sub f_read_all(uword bufferpointer) -> uword {
        ; -- read the full contents of the file, returns number of bytes read.
        if not iteration_in_progress
            return 0

        list_blocks = 0     ; we reuse this variable for the total number of bytes read
        if have_first_byte {
            have_first_byte=false
            @(bufferpointer) = first_byte
            bufferpointer++
            list_blocks++
        }

        while not c64.READST() {
            list_blocks += f_read(bufferpointer, 256)
            bufferpointer += 256
        }
        return list_blocks
    }


    sub f_close() {
        ; -- end an iterative file loading session (close channels).
        if iteration_in_progress {
            c64.CLRCHN()
            c64.CLOSE(11)
            iteration_in_progress = false
        }
    }


    sub status(ubyte drivenumber) -> uword {
        ; -- retrieve the disk drive's current status message
        uword messageptr = &filename
        c64.SETNAM(0, filename)
        c64.SETLFS(15, drivenumber, 15)
        void c64.OPEN()          ; open 15,8,15
        if_cs
            goto io_error
        void c64.CHKIN(15)        ; use #15 as input channel
        if_cs
            goto io_error

        while not c64.READST() {
            @(messageptr) = c64.CHRIN()
            messageptr++
        }

io_error:
        @(messageptr) = 0
        c64.CLRCHN()        ; restore default i/o devices
        c64.CLOSE(15)
        return filename
    }


    sub save(ubyte drivenumber, uword filenameptr, uword address, uword size) -> ubyte {
        c64.SETNAM(strlen(filenameptr), filenameptr)
        c64.SETLFS(1, drivenumber, 0)
        uword end_address = address + size

        %asm {{
            lda  address
            sta  P8ZP_SCRATCH_W1
            lda  address+1
            sta  P8ZP_SCRATCH_W1+1
            stx  P8ZP_SCRATCH_REG
            lda  #<P8ZP_SCRATCH_W1
            ldx  end_address
            ldy  end_address+1
            jsr  c64.SAVE
            php
            ldx  P8ZP_SCRATCH_REG
            plp
        }}

        first_byte = 0      ; result var reuse
        if_cc
            first_byte = c64.READST()==0

        c64.CLRCHN()
        c64.CLOSE(1)

        return first_byte
    }

    sub load(ubyte drivenumber, uword filenameptr, uword address_override) -> uword {
        c64.SETNAM(strlen(filenameptr), filenameptr)
        ubyte secondary = 1
        uword end_of_load = 0
        if address_override
            secondary = 0
        c64.SETLFS(1, drivenumber, secondary)
        %asm {{
            stx  P8ZP_SCRATCH_REG
            lda  #0
            ldx  address_override
            ldy  address_override+1
            jsr  c64.LOAD
            bcs  +
            stx  end_of_load
            sty  end_of_load+1
+           ldx  P8ZP_SCRATCH_REG
        }}

        c64.CLRCHN()
        c64.CLOSE(1)

        if end_of_load
            return end_of_load - address_override

        return 0
    }


    str filename = "0:??????????????????????????????????????"

    sub delete(ubyte drivenumber, uword filenameptr) {
        ; -- delete a file on the drive
        ubyte flen = strlen(filenameptr)
        filename[0] = 's'
        filename[1] = ':'
        memcopy(filenameptr, &filename+2, flen+1)
        c64.SETNAM(flen+2, filename)
        c64.SETLFS(1, drivenumber, 15)
        void c64.OPEN()
        c64.CLRCHN()
        c64.CLOSE(1)
    }

    sub rename(ubyte drivenumber, uword oldfileptr, uword newfileptr) {
        ; -- rename a file on the drive
        ubyte flen_old = strlen(oldfileptr)
        ubyte flen_new = strlen(newfileptr)
        filename[0] = 'r'
        filename[1] = ':'
        memcopy(newfileptr, &filename+2, flen_new)
        filename[flen_new+2] = '='
        memcopy(oldfileptr, &filename+3+flen_new, flen_old+1)
        c64.SETNAM(3+flen_new+flen_old, filename)
        c64.SETLFS(1, drivenumber, 15)
        void c64.OPEN()
        c64.CLRCHN()
        c64.CLOSE(1)
    }
}