Optimiz3.Txt

        This text file is the third in a guide for use by QB/QBASIC
programmers to help optimize the program code for greater efficiency.  If
you have any quetions, contact VirtuaSoft at gump@gnt.net.  Address to Danny.

        (Note: This is not for the beginning programmer.  A strong
        background in QB/QBASIC programming is highly recommended.)

        3. PALETTE
                a. PALETTE USING
                b. Hardware Output
                c. Hardware Input

3. PALETTE

        a. PALETTE USING
                PALETTE USING is a QB statement that writes all 256 colors to
        the PALETTE at once instead of one at a time.  This increases the
        speed by several times.  Simply place the color values in a 256
        element LONG INTEGER array with each element having the RGB values
        of that color's PALETTE (65536*red+256*green+blue   Values are 0-63).
                PALETTE USING is used like this:

                        DIM PaletteVariable(255) AS LONG
                        ...
                        PALETTE USING PaletteVariable(0)
                        ...

                But why use this when you can write to the hardware for a
        60x speed increase!?  ...Next section...

        b. Hardware Output
                This is the ultimate PALETTE initiation method.  It can
        change the entire 256 color PALETTE in the blink of an eye.  It's so
        fast that PALETTE rotation and plasma effects can easily be achieved!
        But the downside is that this is slightly more difficult to learn,
        but once it's understood, it's a snap!
                It is used as follows:

                        OUT &H3C8, ColorNumber
                        OUT &H3C9, RedValue
                        OUT &H3C9, GreenValue
                        OUT &H3C9, BlueValue

                The COLOR values, as with PALETTE USING, range from 0-63.
        When using this method, it's easiest to have a 256 element LONG
        INTEGER array as was used for PALETTE USING, above.  Also, a
        little bit of PEEKing should be used to further increase the speed
        and efficiency of the program.  Below is an example:

                        DIM PalVar(255) AS LONG
                        ...
                        DEF SEG=VARSEG(PalVar(0))
                        BLOAD "Palette.pal", VARPTR(PalVar(0))
                        FOR Temp%=0 to 255
                                OUT &H3C8, Temp%
                                OUT &H3C9, PEEK(VARPTR(PalVar(Temp%)))
                                OUT &H3C9, PEEK(VARPTR(PalVar(Temp%))+1)
                                OUT &H3C9, PEEK(VARPTR(PalVar(Temp%))+2)
                        NEXT

                This example BLOADs a separate PALETTE file, but that is not
        necessary if you define all the colors in the program.  If you are
        not rotating the PALETTE, this method isn't always necessary; the
        PALETTE USING method will do fine.

        c. Hardware Input
                This does just the opposite of part (b).  By doing this,
        you can read the palette values from the hardware.

                It is used as follows:

                        OUT &H3C7, ColorNumber
                        RedValue = INP(&H3C9)
                        GreenValue = INP(&H3C9)
                        BlueValue = INP(&H3C9)

                This is very useful for fading the screen or adjusting
        a current palette.

               ... This concludes the lesson ...