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Adds DLI samples and documentation.
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‎Makefile

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@@ -70,6 +70,7 @@ SAMPLE_FP_BAS=\
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SAMPLE_INT_BAS=\
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int/carrera3d.bas \
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int/dli.bas \
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int/iospeed.bas \
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int/joyas.bas \
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int/pi.bas \

‎manual.md

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@@ -1587,3 +1587,204 @@ modify memory. Use with care!
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the memory location at _address_.
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Display List Interrupts
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-----------------------
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*Note: This is an advanced topic.*
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Display list interrupts (normally called
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`DLI`) are a way to modify display
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registers at certain vertical positions
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on the screen.
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You can use them to:
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- Display more colors in the image, by
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changing color registers - registers
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from $D012 to $D01A.
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- Split one Player/Missile graphics to
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different horizontal positions -
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registers from $D000 to D007.
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- Change scrolling position, screen
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width, P/M width, etc.
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FastBasic allows you to specify one or
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more DLI routines, activate one or
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deactivate all DLI by using the `DLI`
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statement:
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**Define a new DLI**
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**DLI SET _name_ = _op1_, _op2_, ... / DLIS.**
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Setups a new DLI with the given name
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and performing the _op_ operations.
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Each operation is of the form:
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_data_ `INTO` _address_. `INTO` can be
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abbreviated to `I.`.
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_data_ is one constant byte or the
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name of a `DATA BYTE` array, and
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_address_ is a memory location to
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modify.
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If _data_ is a DATA array, the first
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element (at index 0) will be used at
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the first line with DLI active in the
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screen, the second element at the
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second active line, etc.
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You can specify any number of
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operations, but as each one takes some
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time you could see display artifacts
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if you use too many.
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Note that by defining a DLI you are
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simply giving it a name, you need to
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activate the DLI afterwards.
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You can split a DLI definition over
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multiple lines, just like DATA by
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ending a line with a comma and
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starting the next line with `DLI =`
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**Enable a DLI**
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**DLI _name_ / DL.**
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This statement enables the DLI with
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the given name, the DLI must be
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defined before in the program.
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This setups the OS DLI pointer to the
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named DLI and activates the interrupt
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bit in the display processor (the
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ANTIC chip), but does not activates on
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which lines the DLI must be called.
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To define on which lines the DLI is
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active you must modify the _Display
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List_, see the example at the end of
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the section.
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You can also pass the name of a DATA
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BYTE array with a custom machine
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language routine to the `DLI`
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statement, the routine must begin with
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a _PHA_ and end with _PLA_ and _RTI_.
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**Disable a DLI**
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**DLI / DL.**
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This statement simply disables the
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DLI, returning the display to the
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original
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**DLI Examples**
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This is the most basic example of a
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DLI that simply changes the background
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color at the middle of the screen:
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' Define the DLI: set background
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' color to $24 = dark red.
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DLI SET d1 = $24 INTO $D01A
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' Setups screen
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GRAPHICS 0
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' Alter the Display List, adds
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' a DLI at line 11 on the screen
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POKE DPEEK(560) + 16, 130
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' Activate DLI
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DLI d1
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' Wait for any keyu
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? "Press a Key" : GET K
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' Disable the DLI
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DLI
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The next example shows how you can use
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a DLI to change multiple values in the
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screen:
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' An array with color values
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DATA Colors() BYTE = $24,$46,$68
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' Define the DLI: set background
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' color from the Color() array
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' and text color with value $80
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DLI SET d2 = Colors INTO $D01A, $80 INTO $D018
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' Setups screen
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GRAPHICS 0
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' Adds DLI at three lines:
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POKE DPEEK(560) + 13, 130
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POKE DPEEK(560) + 16, 130
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POKE DPEEK(560) + 19, 130
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' Activate DLI
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DLI d2
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' Wait for any keyu
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? "Press a Key" : GET K
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' Disable the DLI
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DLI
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The final example shows how you can
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move multiple P/M using one DLI
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' Player shapes, positions and colors
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DATA p1() BYTE = $E7,$81,$81,$E7
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DATA p2() BYTE = $18,$3C,$3C,$18
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DATA pos() BYTE = $40,$60,$80,$A0
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DATA c1() BYTE = $28,$88,$C8,$08
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DATA c2() BYTE = $2E,$80,$CE,$06
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' Our DLI writes the position and
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' colors to Player 1 and Player 2
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DLI SET d3 = pos INTO $D000, pos INTO $D001,
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DLI = c1 INTO $D012, c2 INTO $D013
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GRAPHICS 0 : PMGRAPHICS 2
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' Setup our 4 DLI and Players
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FOR I = 8 TO 20 STEP 4
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POKE DPEEK(560) + I, 130
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MOVE ADR(p1), PMADR(0)+I*4+5,4
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MOVE ADR(p2), PMADR(1)+I*4+5,4
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NEXT
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' Activate DLI
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DLI d3
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? "Press a Key"
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REPEAT
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PAUSE 0
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pos(0) = pos(0) + 2
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pos(1) = pos(1) + 1
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pos(2) = pos(2) - 1
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pos(3) = pos(3) - 2
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UNTIL KEY()
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DLI
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**Some usefull registers**
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This is a table of some useful
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registers to change during a DLI:
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|Address| Register |
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| ----- | ------------------------- |
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| $D000 | Player 0 horizontal pos. |
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| $D001 | Player 1 horizontal pos. |
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| $D002 | Player 2 horizontal pos. |
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| $D003 | Player 3 horizontal pos. |
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| $D004 | Missile 0 horizontal pos. |
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| $D005 | Missile 0 horizontal pos. |
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| $D006 | Missile 0 horizontal pos. |
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| $D007 | Missile 0 horizontal pos. |
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| $D012 | Color of Player 0 |
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| $D013 | Color of Player 0 |
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| $D014 | Color of Player 0 |
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| $D015 | Color of Player 0 |
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| $D016 | Color register 0 |
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| $D017 | Color register 1 |
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| $D018 | Color register 2 |
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| $D019 | Color register 3 |
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| $D01A | Color of Background |
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‎samples/int/dli.bas

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' Define the DLI: set background
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' color to $24 = dark red.
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DLI SET d1 = $24 INTO $D01A
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' Setups screen
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GRAPHICS 0
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' Alter the Display List, adds
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' a DLI at line 11 on the screen
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POKE DPEEK(560) + 16, 130
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' Activate DLI
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DLI d1
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' Wait for any keyu
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? "Press a Key" : GET K
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' Disable the DLI
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DLI
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? "Again..."
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GET K
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' An array with color values
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DATA Colors() BYTE = $24,$46,$68
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' Define the DLI: set background
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' color from the Color() array
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' and text color with value $80
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DLI SET d2 = Colors INTO $D01A, $80 INTO $D018
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' Setups screen
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GRAPHICS 0
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' Adds DLI at three lines:
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POKE DPEEK(560) + 13, 130
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POKE DPEEK(560) + 16, 130
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POKE DPEEK(560) + 19, 130
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' Activate DLI
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DLI d2
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' Wait for any keyu
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? "Press a Key" : GET K
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' Disable the DLI
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DLI
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? "Again..."
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GET K
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' Player shapes, positions and colors
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DATA p1() BYTE = $E7,$81,$81,$E7
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DATA p2() BYTE = $18,$3C,$3C,$18
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DATA pos() BYTE = $40,$60,$80,$A0
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DATA c1() BYTE = $28,$88,$C8,$08
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DATA c2() BYTE = $2E,$80,$CE,$06
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' Our DLI writes the position and
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' colors to Player 1 and Player 2
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DLI SET d3 = pos INTO $D000, pos INTO $D001,
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DLI = c1 INTO $D012, c2 INTO $D013
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GRAPHICS 0 : PMGRAPHICS 2
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' Setup our 4 DLI and Players
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FOR I = 8 TO 20 STEP 4
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POKE DPEEK(560) + I, 130
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MOVE ADR(p1), PMADR(0)+I*4+5,4
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MOVE ADR(p2), PMADR(1)+I*4+5,4
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NEXT
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' Activate DLI
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DLI d3
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? "Press a Key"
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REPEAT
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PAUSE 0
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pos(0) = pos(0) + 2
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pos(1) = pos(1) + 1
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pos(2) = pos(2) - 1
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pos(3) = pos(3) - 2
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UNTIL KEY()
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DLI
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? "Key to end..."
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GET K
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