const byte PRODOS_ALLOC_INTERRUPT  = $40
const byte PRODOS_DEALLOC_INTERRUPT = $41
const byte PRODOS_READ_BLOCK       = $80
const byte PRODOS_WRITE_BLOCK      = $81
const byte PRODOS_GET_TIME         = $82
const byte PRODOS_CREATE           = $c0
const byte PRODOS_DESTROY          = $c1
const byte PRODOS_RENAME           = $c2 
const byte PRODOS_SET_FILE_INFO    = $c3 
const byte PRODOS_GET_FILE_INFO    = $c4
const byte PRODOS_ON_LINE          = $c5 
const byte PRODOS_SET_PREFIX       = $c6
const byte PRODOS_GET_PREFIX       = $c7
const byte PRODOS_OPEN             = $c8
const byte PRODOS_NEWLINE          = $c9
const byte PRODOS_READ             = $ca
const byte PRODOS_WRITE            = $cb 
const byte PRODOS_CLOSE            = $cc 
const byte PRODOS_FLUSH            = $cd 
const byte PRODOS_SET_MARK         = $ce 
const byte PRODOS_GET_MARK         = $cf 
const byte PRODOS_SET_EOF          = $d0 
const byte PRODOS_GET_EOF          = $d1
const byte PRODOS_SET_BUF          = $d2
const byte PRODOS_GET_BUF          = $d3


// ProDOS MLI parameter lists

struct read_block_plist {
    byte param_count
    byte unit_num
    pointer data_buffer 
    word block_num
}

struct write_block_plist {
    byte param_count
    byte unit_num
    pointer data_buffer 
    word block_num
}

struct close_plist {
    byte param_count
    byte ref_num
}

struct flush_plist {
    byte param_count
    byte ref_num
}

struct create_plist {
    byte param_count
    pointer pathname
    byte access 
    byte file_type
    word aux_type
    byte storage_type 
    word create_time
    word create_date
}

struct destroy_plist {
    byte param_count
    pointer pathname
}

struct open_plist {
    byte param_count
    pointer pathname
    pointer io_buffer
    byte ref_num
}

struct newline_plist { 
    byte param_count
    byte ref_num 
    byte enable_mask
    byte newline_char    
}

struct read_plist {
    byte param_count
    byte ref_num 
    pointer data_buffer 
    word request_count
    word trans_count 
}

struct rename_plist {
    byte param_count
    pointer pathname
    pointer new_pathname
}

struct write_plist {
    byte param_count
    byte ref_num
    pointer data_buffer
    word request_count
    word trans_count
}

struct get_prefix_plist {
    byte param_count
    pointer data_buffer
}

struct set_prefix_plist {
    byte param_count
    pointer data_buffer
}

// we'll just reuse the same area for all plists

union prodos_plist {
    read_block_plist read_block
    write_block_plist write_block
    create_plist create
    destroy_plist destroy
    rename_plist rename
    open_plist open
    newline_plist newline
    read_plist read

    write_plist write
    close_plist close
    flush_plist flush

    get_prefix_plist get_prefix
    set_prefix_plist set_prefix

}

prodos_plist plist

byte prodos_error

// Millfork doesn't support self-modification in the assembler yet, so this
// code is placed in the following array:
//
//      jsr $bf00
//      $00
//      plist.addr
//      rts
//
// We modify mli_trampoline[3] ($00 on the second line) to set the specific
// ProDOS call before we jsr to $bf00
// 
// TODO: can we just jmp to bf00 and save the extra rts ? 

array mli_trampoline = [ $20, 0, $bf, 0, plist.addr.lo, plist.addr.hi, $60 ]

asm void prodos_mli_call(byte register(a) pdcall) {
    sta mli_trampoline+3
    jsr mli_trampoline
    sta prodos_error
    rts
}

void prodos_read_block(byte unum, pointer dbuf, word bnum) {
    plist.read_block.param_count = 3
    plist.read_block.unit_num = unum
    plist.read_block.data_buffer = dbuf
    plist.read_block.block_num = bnum

    prodos_mli_call(PRODOS_READ_BLOCK)
}

void prodos_write_block(byte unum, pointer dbuf, word bnum) {
    plist.write_block.param_count = 3 
    plist.write_block.unit_num = unum
    plist.write_block.data_buffer = dbuf
    plist.write_block.block_num = bnum

    prodos_mli_call(PRODOS_WRITE_BLOCK)
}

void prodos_close(byte rnum) {
    plist.close.param_count = 1
    plist.close.ref_num = rnum

    prodos_mli_call(PRODOS_CLOSE)
}

void prodos_flush(byte fp) {
    plist.flush.param_count = 1 
    plist.flush.ref_num = fp
    
    prodos_mli_call(PRODOS_FLUSH)
}

void prodos_get_prefix(pointer fnbuf) { 
    plist.get_prefix.param_count = 1
    plist.get_prefix.data_buffer = fnbuf

    prodos_mli_call(PRODOS_GET_PREFIX)
}

void prodos_set_prefix(pointer fnbuf) { 
    plist.set_prefix.param_count = 1
    plist.set_prefix.data_buffer = fnbuf

    prodos_mli_call(PRODOS_SET_PREFIX)
}

void prodos_create(pointer fn, byte ftype) { 
    plist.create.param_count = 7
    plist.create.pathname = fn
    plist.create.access = $c3 
    plist.create.file_type = ftype
    plist.create.aux_type = $0
    plist.create.storage_type = 1
    plist.create.create_time = 0
    plist.create.create_date = 0

    prodos_mli_call(PRODOS_CREATE)
}

void prodos_destroy (pointer fn) {
    plist.destroy.param_count = 0
    plist.destroy.pathname = fn
    prodos_mli_call(PRODOS_DESTROY)
}

void prodos_rename(pointer fn, pointer newfn) {
    plist.rename.param_count = 2
    plist.rename.pathname = fn
    plist.rename.new_pathname = newfn

    prodos_mli_call(PRODOS_RENAME)
}

// returns file handle if no error
byte prodos_open (pointer fn, pointer b) {
    plist.open.param_count = 3
    plist.open.pathname = fn
    plist.open.io_buffer = b

    prodos_mli_call(PRODOS_OPEN)

    return plist.open.ref_num 
}

void prodos_newline(byte fp, byte mask, byte nlchar) {
    plist.newline.param_count = 3
    plist.newline.ref_num = fp
    plist.newline.enable_mask = mask
    plist.newline.newline_char = nlchar 

    prodos_mli_call(PRODOS_NEWLINE)
}

void prodos_read(byte rnum, pointer dbuf, word rcnt) {
    plist.read.param_count = 4
    plist.read.ref_num = rnum 
    plist.read.data_buffer = dbuf
    plist.read.request_count = rcnt

    prodos_mli_call(PRODOS_READ)
}

void prodos_write(byte rnum, pointer dbuf, word rcnt) {
    plist.write.param_count = 4
    plist.write.ref_num = rnum
    plist.write.data_buffer = dbuf 
    plist.write.request_count = rcnt

    prodos_mli_call(PRODOS_WRITE)
}