Help 2600 Programing

[Scuttle130]

Can anyone figure out what I am doing wrong here?

Or does anyone have a way to make this more efficient?

 

; Ship Version 1.0

; Subsequent versions will allow additions of capabilities

; A learning objective

 

processor 6502

include "vcs.h"

include "macro.h"

 

; Variables

SEG.U variables

ORG $80

 

shipx ds 1

shipy ds 1

visibleship ds 1

shipbuffer ds 2

shipdirection ds 2

SEG variables

; Program

 

; Clear RAM and TIA

Start

sei

cld

ldx $FF

txs

lda #0

ClearMemory

sta 0,x

dex

bne ClearMemory

 

; Initialization

lda #$00 ; Set backgound color to black

sta COLUBK

lda #$1C ; Set ship color to yellow

sta COLUP0

lda #2 ; Set ship x position

sta shipx

lda #80 ; Set ship y position

sta shipy

lda #%0001 ; Set ship facing up

sta shipdirection

 

; VSYNC time

Main

lda #2

sta VSYNC

sta WSYNC

sta WSYNC

sta WSYNC

lda #43 ; Set timer for VSYNC

sta TIM64T ; Just another way to do Vertical Blank

lda #0

sta VSYNC

 

; Check joystick controls for movement

lda #%00010000 ; Down?

bit SWCHA

bne SkipMoveDown

inc shipy

lda #%00001000 ; reflect ship graphics

sta REFP0

lda #%0001

sta shipdirection

SkipMoveDown

lda #%00100000 ; Up?

bit SWCHA

bne SkipMoveUp

dec shipy

lda #%00000000 ; do not reflect ship graphics

sta REFP0

lda #%0001

sta shipdirection

SkipMoveUp

lda #%01000000 ; Left?

bit SWCHA

bne SkipMoveLeft

dec shipx

lda #%00001000 ; reflect ship graphics

sta REFP0

lda #%1000

sta shipdirection

SkipMoveLeft

lda #%10000000 ; Right?

bit SWCHA

bne SkipMoveRight

inc shipx

lda #%00000000 ; do not reflect ship graphics

sta REFP0

lda #%1000

sta shipdirection

SkipMoveRight

lda #0

sta shipbuffer

WaitForVBLANKEnd

lda INTIM

bne WaitForVBLANKEnd

 

; Visible Screen Drawing

ldy #191

sta WSYNC

sta VBLANK

 

; Start to draw screen

DrawScreen

sta WSYNC

lda shipbuffer

sta GRP0

ldx shipx ; horizontal sprite check

cpx #160

bcc LT160

ldx #0

sta shipx

LT160

jsr PositionSprite

CheckVisibleShip

cpy shipy

bne SkipVisibleShip

lda #8

sta visibleship

SkipVisibleShip

lda #0

sta shipbuffer

ldx visibleship

beq FinishDrawScreen

DrawShip

lda #%0001

cmp shipdirection

bne DrawRightShip

lda ShipUp-1,x

sta shipbuffer

dec visibleship

jmp FinishDrawScreen

DrawRightShip

lda ShipRight-1,x

sta shipbuffer

dec visibleship

 

FinishDrawScreen

dey

bne DrawScreen

 

lda #2

sta WSYNC

sta VBLANK

ldx #30

Overscan

sta WSYNC

dex

bne Overscan

jmp Main

 

Divide15

.byte 00,00,00,00,00,00,00,00,00,00,00,00,00,00,00

.byte 01,01,01,01,01,01,01,01,01,01,01,01,01,01,01

.byte 02,02,02,02,02,02,02,02,02,02,02,02,02,02,02

.byte 03,03,03,03,03,03,03,03,03,03,03,03,03,03,03

.byte 04,04,04,04,04,04,04,04,04,04,04,04,04,04,04

.byte 05,05,05,05,05,05,05,05,05,05,05,05,05,05,05

.byte 06,06,06,06,06,06,06,06,06,06,06,06,06,06,06

.byte 07,07,07,07,07,07,07,07,07,07,07,07,07,07,07

; .byte 08,08,08,08,08,08,08,08,08,08,08,08,08,08,08

; .byte 09,09,09,09,09,09,09,09,09,09,09,09,09,09,09

; .byte 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10

; .byte 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11

; .byte 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12

; .byte 13,13,13,13,13,13,13,13,13,13,13,13,13,13,13

; .byte 14,14,14,14,14,14,14,14,14,14,14,14,14,14,14

; .byte 15,15,15,15,15,15,15,15,15,15,15,15,15,15,15

; .byte 16,16,16,16,16,16,16,16,16,16,16,16,16,16,16

; .byte 17,17,17,17,17,17,17,17,17,17,17,17,17,17,17

; .byte 18,18,18,18,18,18,18,18,18,18,18,18,18,18,18

 

PositionSprite

sta WSYNC

lda Divide15,x

tax

Loop dex

bne Loop

sta RESP0

rts

 

ShipUp

.byte #$44 ;01000100

.byte #$28 ;00111000

.byte #$FE ;11111110

.byte #$7C ;01111100

.byte #$28 ;00111000

.byte #$10 ;00010000

.byte #$10 ;00010000

.byte #$10 ;00010000

ShipRight

.byte #$20 ;00100000

.byte #$B0 ;10110000

.byte #$78 ;01111000

.byte #$7F ;01111111

.byte #$78 ;01111000

.byte #$B0 ;10110000

.byte #$20 ;00100000

.byte #$00 ;00000000

 

; Interrupt Vectors

ORG $FFFA

InterruptVectors

.word Start ; NMI

.word Start ; Reset

.word Start ; IRQ

 

; DASM execution code:

; dasm {filename}.asm -l{filename}.txt -f3 -v5 -s{filename}.txt -o{filename}.bin

;

; FSB execution code

; fsb {output file}.asm {red file}.bmp {green file}.bmp {blue file}.bmp

[Cybergoth]

Hi there!

 

I spot several *substandard* techniques in that source.

 

Joystick reading is done way more efficient and horizontal positioning is done in a few bytes without such a giant table for example.

 

I'd suggest you should subscribe [stella] to improve your programming "Kung Fu"

 

Try browsing the [stella] archive for "Battlezone;positioning" for example.

 

Greetings,

Manuel

[Thomas Jentzsch]

BTW: Please use

...

to make your source more readable and formatted as it was.

[Tom]

your trying to cram your whole program into the ram.

change

 

   SEG variables 

  ; Program 

 

into something like

 

   SEG code

   org $f000

  ; Program

 

after this it displays something that might be a ship, but it's still buggy. your timing is totally screwed up, run it with z26 with the -n switch and you'll see.

[Cybergoth]

Hi there!

 

after this it displays something that might be a ship, but it's still buggy. your timing is totally screwed up, run it with z26 with the -n switch and you'll see.

 

Also it will execute only coarse positioning.

 

Greetings,

Manuel

[Scuttle130]

Thank you! Thank you! Thank you! This stuff can be so frustrating, escpecially to a newbie!!!!