4cade/src/prodos.impl.a

;license:MIT
;(c) 2019 by qkumba
;
; Pseudo-ProDOS environment
;

!pseudopc $DA00 {
;------------------------------------------------------------------------------
; ProDOS_enter
; intercept certain ProDOS requests
; wrap them to ProRWTS2 file requests
;
; in:    return address+1 is command and pointer to parameter block
; out:   all flags clobbered
;        A=0, X and Y preserved
;        stack set to next instruction after parameters
;------------------------------------------------------------------------------
packet = first_zp ;word
buffer = first_zp+2 ;word

ProDOS_enter
!set CloseHandles = @imp_close
    stx    ProDOS_savedX+1
    sty    ProDOS_savedY+1
    pha
    jsr    @swap_zp
    pla
    tax
    pla
    tay
    pla
    sta    @fetchaddr+1
    pla
    sta    @fetchaddr+2
    jsr    @fetchbyte
    sta    @request+1
    jsr    @fetchbyte
    sta    packet
    jsr    @fetchbyte
    sta    packet+1
    lda    @fetchaddr+2
    pha
    lda    @fetchaddr+1
    pha
    tya
    pha
    php
    txa
    pha
@request
    lda    #$d1
    cmp    #$80
    beq    @do_readblock
    cmp    #$81 ;I don't remember if I used this, but it's cheap to add
    beq    @do_writeblock
    cmp    #$c4
    beq    @do_getattrib
    cmp    #$c6
    beq    @do_nothing
    cmp    #$c7
    beq    @do_prefix
    cmp    #$c8
    beq    @do_open
    cmp    #$ca
    beq    @do_read
    cmp    #$cb
    beq    @do_write
    cmp    #$cc
    beq    @do_close
    cmp    #$ce
    beq    @do_seek
    cmp    #$d1
    beq    @do_eof
    ;;any others??
    jmp    ProDOS_fatal
@do_readblock
@do_writeblock
    jmp    @imp_rdwrblock
@do_getattrib
    jmp    @imp_getattrib
@do_nothing
    jmp    @restore_zp
@do_prefix
    jmp    @imp_prefix
@do_open
    jmp    @imp_open
@do_read
    jmp    @imp_read
@do_write
    jmp    @imp_write
@do_close
    jsr    @imp_close ;subroutine special case because of dual-use
    jmp    @restore_zp
@do_seek
    jmp    @imp_seek
@do_eof
    jmp    @imp_eof

@imp_rdwrblock
    and    #$7f
    tay
    iny
    sty    @rdwrop+1
    ldx    #$44
    ldy    #2
    jsr    @setbuffer
    iny
    lda    (packet), y
    tax
    iny
    lda    (packet), y
@rdwrop
    ldy    #$d1                      ; SMC
    jsr    hddseekrd+2
    bcc    @jmp_zp2 ;always

@imp_getattrib
    lda    packet+1
    pha
    lda    packet
    pha
    ldx    #namlo
    jsr    @setbuffer1
    lda    #$60
    sta    attribpatch
    jsr    hddopendir
    lda    #$10
    sta    attribpatch
    pla
    sta    packet
    pla
    sta    packet+1
    ldy    #5
    lda    ldrlo2
    sta    (packet), y
    iny
    lda    ldrlo2+1
    sta    (packet), y
    ldy    #$13
    lda    (bloklo), y
    tax
    iny
    lda    (bloklo), y
    ldy    #9
    sta    (packet), y
    txa
    dey
    sta    (packet), y
@jmp_zp2
    jmp    @restore_zp

@imp_prefix
    ldx    #buffer
    jsr    @setbuffer1
    ldy    ProDOS_prefix
    iny
    iny
    tya
    pha
    dey
@copy_prefix
    lda    ProDOS_prefix, y
    iny
    sta    (buffer), y
    dey
    dey
    bne    @copy_prefix
    pla
    sta    (buffer), y
    lda    #'/'
    iny
    sta    (buffer), y
    bne    @jmp_zp2

@imp_open
    ldx    #namlo
    jsr    @setbuffer1
    iny
    inc    @handles+1
@handles
    ldx    #0
    iny
    lda    (packet), y
    sta    @handle-1, x
    jsr    @patch_buffer
    iny
    lda    #1
    sta    (packet), y
    lda    #0
    sta    reqcmd
    sta    sizehi
    sta    sizelo
    jsr    hddopendir
    lda    #0
    sta    blkidx
    beq    @jmp_zp ;always

@imp_seek
    jsr    @set_rdwrbuff
    lda    #0
    sta    blkidx
    sta    blkofflo
    sta    blkoffhi
    sta    reqcmd
    jsr    @reset
    ldx    sizelo
    beq    @seek64
    sta    sizehi
    sta    sizelo
    jsr    @seekreset
    inc    ldrlo
    bne    @seek64
    inc    ldrhi

@seek64
    lda    ldrhi
    sta    sizehi
    lda    ldrlo
    sta    sizelo
    jsr    @seekreset
    lda    ldrhi
    ora    ldrlo
    bne    @jmp_zp
    dec    blkidx
    beq    @jmp_zp ;always

@seekreset
    jsr    hddrdwrpart
@reset
    lda    #$ff
    sta    blefthi
    sta    bleftlo
    rts

@imp_read
    clc
@imp_write
    php
    lda    #cmdread
    adc    #0
    sta    reqcmd
    jsr    @set_rdwrbuff
    plp
    bcc    @skip_align
    lda    sizelo
    adc    #$fe
    lda    sizehi
    adc    #1
    and    #$fe
    sta    sizehi
    lda    bleftlo
    adc    #$ff
    lda    blefthi
    adc    #1
    and    #$fe
    sta    blefthi

@skip_align
    jsr    hddrdwrpart
    ldy    #6
    lda    sizelo2
    sta    (packet), y
    iny
    lda    sizehi2
    sta    (packet), y
@jmp_zp
    jmp    @restore_zp

@imp_eof
    ldy    #2
    lda    bleftlo
    sta    (packet), y
    iny
    lda    blefthi
    sta    (packet), y
    bcs    @restore_zp ;always

@imp_close
    lda    @handles+1
    beq    @close_ret
    dec    @handles+1
    bne    @close_ret
    lda    #>hddencbuf

@patch_buffer
    sta    encbufpatch1+1
    sta    encbufpatch2+1
    tax
    inx
    stx    dirbufpatch1+1
    inx
    stx    dirbufpatch2+2
    stx    dirbufpatch3+2
    stx    dirbufpatch4+2
    stx    dirbufpatch6+1
    stx    dirbufpatch7+2
    stx    dirbufpatch9+2
    stx    dirbufpatch10+1
    inx
    stx    dirbufpatch5+2
    stx    dirbufpatch8+2
@close_ret
    rts

@fetchbyte
    inc    @fetchaddr+1
    bne    @fetchaddr
    inc    @fetchaddr+2
@fetchaddr
    lda    $d1d1
    rts

@set_rdwrbuff
    ldy    #1
    lda    (packet), y
    tax
    lda    @handle-1, x
    jsr    @patch_buffer
    ldx    #ldrlo
    iny
    jsr    @setbuffer
    ldx    #sizelo
    iny
    !byte  $2c
@setbuffer1
    ldy    #1

@setbuffer
    lda    (packet), y
    sta    $0,x
    iny
    lda    (packet), y
    sta    $1,x
    rts

@swap_zp
    ldx    #last_zp-first_zp
@save_zp
    lda    first_zp,x
    ldy    @saved_zp,x
    sta    @saved_zp,x
    sty    first_zp,x
    dex
    bpl    @save_zp
    rts

@restore_zp
    jsr    @swap_zp
    pla
    lsr
    lsr
    lsr
    lsr
    and    #8
    plp
    adc    #0
    tax
    jmp    ProDOS_exit

@handle
    !byte  0, 0 ;only up to two handles at a time

@saved_zp
    !fill  (last_zp - first_zp) + 1
}