'===========================================================================
' Subject: PB VGA PALETTES                   Date: 09-09-95 (00:00)       
' Author:  Morry Kapitan                     Code: PB                     
' Origin:  kapitam@ttown.apci.com          Packet: GRAPHICS.ABC
'===========================================================================
'Here are some routines for messing with the 256 color VGA palette.  I wrote
'this early on while learning some x86 asm using PB's in-line assembler.
'This certainly can be improved upon (how about using the les opcode?).
'I compiled this into a .PBU and use it in a graphics library.
'
'
'                       Program:       VGAPALET.BAS
'                       Author:        Morry Kapitan
'                       Compiler:      PowerBASIC 3.x
'                       Version:       0.9
'                       Date:          9/9/95
'
'---------------------------------------------------------------------------
'Routines to copy the existing VGA palette to a temprorary disk file, read
'a new palette from a disk file and load it into the palette registers, and
'reload the original palette.
'---------------------------------------------------------------------------

$DYNAMIC
DEFINT A-Z

'---------------------------------------------------------------------------
'Procedure:  SavePal
'This routine saves the current VGA palette to a temprorary disk file
'---------------------------------------------------------------------------
SUB SavePal PUBLIC

DIM OldPal(767) AS BYTE

ArraySegment = VARSEG(OldPal(0))
ArrayOffset = VARPTR(OldPal(0))


	 !    push ES

	 !    mov  AX, ArraySegment         ; put address of where to store
	 !    mov  ES, AX                   ; register data in ES:DX
	 !    mov  DX, ArrayOffset          ;
	 !    xor  BX, BX                   ; set BX to zero -start at 1st reg
	 !    mov  CX, 255                  ; get all 256 registers

	 !    mov  AX, &h1017               ; load register data into array
	 !    int  &h10                     ;

	 !    pop  ES


OPEN "~OLDPAL.TMP" FOR BINARY AS #1    'Open a file in the default directory
FOR posit = 0 TO 767                   'Write the palette data to the file
    PUT #1, posit, OldPal(posit)
NEXT posit
CLOSE #1

END SUB


'---------------------------------------------------------------------------
'Procedure:  LoadPal
'This routine loads the VGA palette with data from a file whose path and
'name is passed to the routine from the calling program
'---------------------------------------------------------------------------
SUB LoadPal (palFile$) PUBLIC

DIM NewPal(767) AS BYTE

newArraySeg = VARSEG(NewPal(0))
newArrayOff = VARPTR(NewPal(0))

OPEN palFile$ FOR BINARY AS #1              'Open the file passed from user
FOR bytePos = 0 TO 767                      'Retrieve palette data from file
    GET #1, bytePos, NewPal(bytePos)
NEXT bytePos
CLOSE #1

	!   push   ES

	!   mov    AX, newArraySeg               ; Seg of data array...
	!   mov    ES, AX                        ; in ES
	!   mov    DX, newArrayOff               ; put array offset in DX
	!   xor    BX, BX                        ; set BX to 0 - start at 1st reg.
	!   mov    CX, 255                       ; load all 256 registers

	!   mov    AX, &h1012                    ; put array data into VGA
	!   int    &h10                          ; registers

	!   pop    ES

END SUB


'---------------------------------------------------------------------------
'Procedure:  RestorePal
'Routine to reload the original VGA palette saved in a file in the current
'directory
'---------------------------------------------------------------------------
SUB RestorePal  PUBLIC

DIM NewOldPal(767) AS BYTE

oldArraySeg = VARSEG(NewOldPal(0))
oldArrayOff = VARPTR(NewOldPal(0))

OPEN "~OLDPAL.TMP" FOR BINARY AS #1         'Open the temporary palette file
FOR bytepos = 0 TO 767                      'Retrieve palette data from file
    GET #1, bytepos, NewOldPal(bytepos)
NEXT bytepos
CLOSE #1
KILL "~OLDPAL.TMP"                          'Delete the temproary file

	 !    push ES

	 !    mov  AX, oldArraySeg               ; Seg of data array...
	 !    mov  ES, AX                        ; in ES
	 !    mov  DX, oldArrayOff               ; put array offset in DX
	 !    xor  BX, BX                        ; set BX to 0 - start at 1st reg.
	 !    mov  CX, 255                       ; load all 256 registers

	 !    mov  AX, &h1012                    ; put array data into VGA
	 !    int  &h10                          ; registers

	 !    pop  ES

END SUB