IFNE      VDGDEFS-1

VDGDEFS        SET       1

********************************************************************
* VDGDefs - VDG Interface Definititions
*
* $Id$
*
* Edt/Rev  YYYY/MM/DD  Modified by
* Comment
* ------------------------------------------------------------------
*          1991/05/07  Alan DeKok
* Wrote original from VDGInt source.

               NAM       VDGDefs
               TTL       VDG Interface Definitions

* Notes:
*
* All offsets from 'U' (address of device memory area)
* (see p. 6-9, technical reference: U=start of driver data memory
* NOTE: There is LOTS of stuff which is only used once, and some which
* is not needed.  Here's a list of the un-needed, and un-used (other than
* once)
*
* It would probably be benificial to patch VDGint to fix these problems,
* unless anyone else has ideas as to why VDGint is doing things this way.
*
* Un-needed
* VD.EPlt1  - (2) set to VD.NChar, and then read only
* VD.EPlt2  - (2) set to same as VD.EPlt1, and then unused
* VD.Chr1   - (1) set to same as VD.CChar, and then unused
* VD.PlFlg  - (1) initialized to $08, and unused
*
* Un-used
*
* $1D       - (1) end of SCF memory requirements
* VD.Strt1  - (2) CLRed, and then read (LDD) - left as $0000
* $24-$2B   - (8)
* $33-$34   - (2)
* $7E-$FF   - (130)
*
* Total of 22 (150 in whole page) bytes unneeded or unused.

               ORG       $1E
VD.Start       RMB       1                   start of VD.XXXX data: number of VDG screens in use
VD.Strt1       RMB       2                   (2) and another start
VD.Caps        RMB       2                   caps lock info: $00=lower $FF=upper
VD.DFlag       RMB       1                   0=current screen is valid, $01-$FF = update video
* $24-$2B unused
               RMB       8
VD.NGChr       RMB       1                   number of additional characters to get
VD.RTAdd       RMB       2                   (2) return address after getting characters
VD.EPlt1       RMB       2                   (2) pointer to where to put next character
VD.EPlt2       RMB       2                   (2) as above.
* $33-$34 unused
               RMB       2
VD.CFlag       RMB       1                   true lowercase flag $10=true, $00=false
VD.CFlg1       RMB       1                   VDG display code values
VD.DGBuf       RMB       1                   number of currently displayed buffer
VD.ScrnA       RMB       2                   (2) screen start address in system memory
VD.ScrnE       RMB       2                   (2) address of end of screen
VD.CrsrA       RMB       1                   (2) cursor address
VD.CrsAL       RMB       1                   cursor address low
VD.CChar       RMB       1                   value of character under cursor
VD.Mode        RMB       1                   mode: 0=256x192 x2, 1=128x192 x4
VD.Chr1        RMB       1                   same as under cursor character
VD.CColr       RMB       1                   cursor color
VD.Col         RMB       1                   number of columns for this screen
VD.Row         RMB       1                   number of rows
VD.TFlg1       RMB       1                   see WRITE ($0E)
VD.Alpha       RMB       1                   0 when in alpha mode
VD.Rdy         RMB       1                   device ready (see SS.DStat 0=not ready)
VD.SBAdd       RMB       2                   (2) address of block screen is in
VD.Blk         RMB       1                   Block number of screen
VD.GBuff       RMB       1                   allocation for graphics buffers (block#)
VD.AGBuf       RMB       2                   (2) additional graphics buffer
VD.HiRes       RMB       1                   hi-res screen table (block value)
VD.NBlk        RMB       1                   number of blocks in this screen
VD.SType       RMB       1                   screen type 0-4
VD.HR2         RMB       3                   (3) for screen number 2
VD.HR3         RMB       3                   (3) for screen 3 (same 3 bytes as above)
VD.FFMem       RMB       2                   (2) bottom of stack for flood fill
VD.FFSPt       RMB       2                   (2) flood fill stack pointer
VD.FFSTp       RMB       2                   (2) flood fill stack top pointer
VD.FF6         RMB       1                   flood fill flag
VD.MTabl       RMB       2                   (2) address of mask table for pixels in byte
VD.PixBt       RMB       1                   bit mask for modes (0=$07, 1=$03 )#pixels/byte
VD.GCrsX       RMB       1                   graphics cursor X value
VD.GCrsY       RMB       1                   graphics cursor Y
VD.Msk1        RMB       1                   mask byte 1
VD.Msk2        RMB       1                   mask byte 2 (00,55,AA,FF)
VD.MCol        RMB       1                   color? (C003,8001)
VD.MCol2       RMB       1                   color
VD.PMask       RMB       1                   pixel mask for colors (i.e. $55, $CC etc)
VD.FF1         RMB       1                   data for flood fill
VD.FF2         RMB       1                   data for flood fill
VD.FFMsk       RMB       1                   flood fill mask
VD.FFFlg       RMB       1                   flood fill flag
VD.Palet       RMB       16                  (16) current palette values
VD.PlFlg       RMB       1                   initialized to $08 by L00DB, and then unused!
VD.NChar       RMB       1                   character to process
VD.NChr2       RMB       1                   and the next one

* and RMB until we get 256 bytes reserved

               ENDC