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https://github.com/cc65/cc65.git
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495 lines
10 KiB
ArmAsm
495 lines
10 KiB
ArmAsm
;
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; Graphics driver for the lores 64x56x2 mode on the NES
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;
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; Stefan Haubenthal, 2009-03-10
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; Based on Maciej Witkowiak's line routine.
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;
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.include "zeropage.inc"
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.include "tgi-kernel.inc"
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.include "tgi-error.inc"
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.include "nes.inc"
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.include "get_tv.inc"
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.import _clrscr, setcursor, putchar
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.import paldata
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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table and constants.
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.segment "JUMPTABLE"
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; First part of the header is a structure that has a magic and defines the
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; capabilities of the driver
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.byte $74, $67, $69 ; "tgi"
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.byte TGI_API_VERSION ; TGI API version number
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xres: .word charsperline*2 ; Max X resolution
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yres: .word 56 ; Max Y resolution
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.byte 2 ; Number of drawing colors
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.byte 1 ; Number of screens available
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.byte 2 ; System font X size
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.byte 2 ; System font Y size
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.word $100 ; Aspect ratio
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.byte 0 ; TGI driver flags
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; Next comes the jump table. Currently all entries must be valid and may point
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; to an RTS for test versions (function not implemented).
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.addr INSTALL
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.addr UNINSTALL
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.addr INIT
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.addr DONE
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.addr GETERROR
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.addr CONTROL
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.addr CLEAR
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.addr SETVIEWPAGE
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.addr SETDRAWPAGE
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.addr SETCOLOR
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.addr SETPALETTE
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.addr GETPALETTE
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.addr GETDEFPALETTE
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.addr SETPIXEL
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.addr GETPIXEL
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.addr LINE
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.addr BAR
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.addr TEXTSTYLE
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.addr OUTTEXT
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.addr 0 ; IRQ entry is unused
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; ------------------------------------------------------------------------
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; Data.
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; Variables mapped to the zero page segment variables. Some of these are
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; used for passing parameters to the driver.
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X1 = ptr1
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Y1 = ptr2
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X2 = ptr3
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Y2 = ptr4
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RADIUS = tmp1
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ADDR = tmp1
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TEMP = tmp3
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TEMP2 = tmp4
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TEMP3 = sreg
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TEMP4 = sreg+1
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; Line routine stuff (must be on zpage)
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PB = ptr3 ; (2) LINE
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UB = ptr4 ; (2) LINE
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ERR = regsave ; (2) LINE
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NX = regsave+2 ; (2) LINE
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; Absolute variables used in the code
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.bss
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MEM: .res charsperline*2*56/4
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MEMEND:
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ERROR: .res 1 ; Error code
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COLOR: .res 1 ; Current color
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PALETTE: .res 2 ; The current palette
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; Line routine stuff
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OGora:
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COUNT: .res 2
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OUkos:
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NY: .res 2
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Y3:
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DX: .res 1
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DY: .res 1
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AY: .res 1
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; Constants and tables
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.rodata
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DEFPALETTE: .byte $0, $1
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OFFSET: .byte 8, 4, 2, 1
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; 00 00 00 00 01 01 01 01
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; 00 01 10 11 00 01 10 11
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CODE: .byte 32, 29, 26, 25, 28, 24+128, 31+128, 30+128
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; 10 10 10 10 11 11 11 11
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; 00 01 10 11 00 01 10 11
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.byte 30, 31, 24, 28+128, 25+128, 26+128, 29+128, 32+128
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. May
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; initialize anything that has to be done just once. Is probably empty
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; most of the time.
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;
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; Must set an error code: NO
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;
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INSTALL:
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jsr _get_tv
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cmp #TV::NTSC
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beq ntsc
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; TODO ROM!
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inc yres
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inc yres
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ntsc:; rts
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory. May
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; clean up anything done by INSTALL but is probably empty most of the time.
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;
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; Must set an error code: NO
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; INIT: Changes an already installed device from text mode to graphics
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; mode.
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; Note that INIT/DONE may be called multiple times while the driver
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; is loaded, while INSTALL is only called once, so any code that is needed
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; to initializes variables and so on must go here. Setting palette and
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; clearing the screen is not needed because this is called by the graphics
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; kernel later.
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; The graphics kernel will never call INIT when a graphics mode is already
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; active, so there is no need to protect against that.
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;
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; Must set an error code: YES
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;
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INIT:
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; Done, reset the error code
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lda #TGI_ERR_OK
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sta ERROR
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; rts
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; ------------------------------------------------------------------------
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; DONE: Will be called to switch the graphics device back into text mode.
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; The graphics kernel will never call DONE when no graphics mode is active,
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; so there is no need to protect against that.
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;
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; Must set an error code: NO
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;
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DONE:
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rts
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; ------------------------------------------------------------------------
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; GETERROR: Return the error code in A and clear it.
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GETERROR:
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lda ERROR
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ldx #TGI_ERR_OK
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stx ERROR
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rts
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; ------------------------------------------------------------------------
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; CONTROL: Platform/driver specific entry point.
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;
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; Must set an error code: YES
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;
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CONTROL:
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lda #TGI_ERR_INV_FUNC
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sta ERROR
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rts
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; ------------------------------------------------------------------------
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; CLEAR: Clears the screen.
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;
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; Must set an error code: NO
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;
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CLEAR:
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ldx #<MEM
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stx TEMP
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ldx #>MEM
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stx TEMP+1
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lda #0
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tay
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@L1: sta (TEMP),y
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iny
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bne @L1
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inc TEMP+1
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inx
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cpx #>MEMEND
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bne @L1
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jmp _clrscr
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; ------------------------------------------------------------------------
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; SETCOLOR: Set the drawing color (in A). The new color is already checked
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; to be in a valid range (0..maxcolor-1).
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;
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; Must set an error code: NO (will only be called if color ok)
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;
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SETCOLOR:
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sta COLOR
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; rts
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; ------------------------------------------------------------------------
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; SETVIEWPAGE: Set the visible page. Called with the new page in A (0..n).
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; The page number is already checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will only be called if page ok)
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;
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SETVIEWPAGE:
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; ------------------------------------------------------------------------
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; SETDRAWPAGE: Set the drawable page. Called with the new page in A (0..n).
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; The page number is already checked to be valid by the graphics kernel.
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;
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; Must set an error code: NO (will only be called if page ok)
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;
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SETDRAWPAGE:
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rts
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; ------------------------------------------------------------------------
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; SETPALETTE: Set the palette (not available with all drivers/hardware).
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; A pointer to the palette is passed in ptr1. Must set an error if palettes
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; are not supported
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;
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; Must set an error code: YES
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;
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SETPALETTE:
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; Wait for v-blank
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@wait: lda PPU_STATUS
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bpl @wait
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lda #$3F
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sta PPU_VRAM_ADDR2
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lda #$00
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sta PPU_VRAM_ADDR2
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ldy #0
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lda (ptr1),y
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sta PALETTE
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tax
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lda paldata,x
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; sta PPU_VRAM_IO
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iny
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lda (ptr1),y
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sta PALETTE+1
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tax
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lda paldata,x
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sta PPU_VRAM_IO
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lda #TGI_ERR_OK
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sta ERROR
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rts
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; ------------------------------------------------------------------------
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; GETPALETTE: Return the current palette in A/X. Even drivers that cannot
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; set the palette should return the default palette here, so there's no
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; way for this function to fail.
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;
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; Must set an error code: NO
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;
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GETPALETTE:
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lda #<PALETTE
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ldx #>PALETTE
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rts
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; ------------------------------------------------------------------------
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; GETDEFPALETTE: Return the default palette for the driver in A/X. All
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; drivers should return something reasonable here, even drivers that don't
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; support palettes, otherwise the caller has no way to determine the colors
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; of the (not changeable) palette.
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;
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; Must set an error code: NO (all drivers must have a default palette)
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;
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GETDEFPALETTE:
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lda #<DEFPALETTE
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ldx #>DEFPALETTE
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rts
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; ------------------------------------------------------------------------
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; SETPIXEL: Draw one pixel at X1/Y1 = ptr1/ptr2 with the current drawing
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; color. The coordinates passed to this function are never outside the
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; visible screen area, so there is no need for clipping inside this function.
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;
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; Must set an error code: NO
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;
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SETPIXEL:
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ldx Y1 ; y+2<yres
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inx
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inx
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cpx yres
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bcc @L2
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ldx X1 ; x+2<xres
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inx
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inx
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cpx xres
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bcc @L2
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rts
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@L2: lda X1
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lsr
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tay
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lda Y1
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lsr
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tax
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clc
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jsr setcursor
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jsr CALC
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ldx COLOR
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bne @set2
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eor #%00001111
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@set2: sta TEMP3
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lda (TEMP),y
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ldx COLOR
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bne @set
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and TEMP3
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.byte $2c
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@set: ora TEMP3
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sta (TEMP),y
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tax
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lda CODE,x
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@normal:jmp putchar
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; ------------------------------------------------------------------------
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; GETPIXEL: Read the color value of a pixel and return it in A/X. The
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; coordinates passed to this function are never outside the visible screen
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; area, so there is no need for clipping inside this function.
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GETPIXEL:
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jsr CALC
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sta TEMP3
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lda (TEMP),y
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and TEMP3
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beq @L1
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lda #1
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@L1: ldx #0
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rts
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; ------------------------------------------------------------------------
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; BAR: Draw a filled rectangle with the corners X1/Y1, X2/Y2, where
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; X1/Y1 = ptr1/ptr2 and X2/Y2 = ptr3/ptr4 using the current drawing color.
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; Contrary to most other functions, the graphics kernel will sort and clip
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; the coordinates before calling the driver, so on entry the following
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; conditions are valid:
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; X1 <= X2
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; Y1 <= Y2
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; (X1 >= 0) && (X1 < XRES)
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; (X2 >= 0) && (X2 < XRES)
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; (Y1 >= 0) && (Y1 < YRES)
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; (Y2 >= 0) && (Y2 < YRES)
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;
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; Must set an error code: NO
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;
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BAR:
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inc Y2
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@L1: lda X1
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pha
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@L2: jsr SETPIXEL
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inc X1
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lda X2
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cmp X1
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bne @L2
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pla
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sta X1
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inc Y1
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lda Y2
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cmp Y1
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bne @L1
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rts
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; ------------------------------------------------------------------------
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; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
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; direction is passend in X/Y, the text direction is passed in A.
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;
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; Must set an error code: NO
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;
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TEXTSTYLE:
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rts
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; ------------------------------------------------------------------------
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; OUTTEXT: Output text at X/Y = ptr1/ptr2 using the current color and the
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; current text style. The text to output is given as a zero terminated
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; string with address in ptr3.
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;
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; Must set an error code: NO
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;
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OUTTEXT:
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lda ptr1
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lsr
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tay
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lda ptr2
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lsr
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tax
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clc
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jsr setcursor
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ldy #0
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@L1: lda (ptr3),y
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jsr putchar
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iny
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cmp #$0
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bne @L1
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rts
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; ------------------------------------------------------------------------
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; Calculate all variables to plot the pixel at X1/Y1. If the point is out
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; of range, a carry is returned and INRANGE is set to a value !0 zero. If
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; the coordinates are valid, INRANGE is zero and the carry clear.
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CALC: lda xres
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sta TEMP
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lda #0
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sta TEMP+1
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ldy Y1
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@L1: lda TEMP
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add xres
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lsr
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sta TEMP
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lda TEMP+1
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adc #0
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lsr
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sta TEMP+1
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dey
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bne @L1
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lda TEMP
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add X1
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lsr
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sta TEMP
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lda TEMP+1
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adc #0
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lsr
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sta TEMP+1
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lda TEMP
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add #<MEM
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sta TEMP
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lda TEMP+1
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adc #>MEM
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sta TEMP+1
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lda X1
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and #%00000001
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sta TEMP3
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lda Y1
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asl
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and #%00000010
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ora TEMP3
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tax
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lda OFFSET,x
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rts
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; ------------------------------------------------------------------------
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.include "../tgi/tgidrv_line.inc"
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