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DEC BC/LD A,B/OR C/JP NZ,loopyesterday i saw nice trick:[code] dec bc ld a, b or c jp nz, loop can be replaced (bc starts >255, short jump) by: dec bc inc b djnz loop [/code] …
yesterday i saw nice trick:[code]
dec bc
ld a, b
or c
jp nz, loop
can be replaced (bc starts >255, short jump) by:
dec bc
inc b
djnz loop
[/code]
..nice -
Happy Birthday JP!Happy Birthday JP! (Though taking the time difference into account it may no longer be your birthday) Happy hacking all the same :smile:
Happy Birthday JP!
(Though taking the time difference into account it may no longer be your birthday)
Happy hacking all the same :smile: -
JP (HL) confusionokay.... JP nn will jump to memory address nn. JP (HL) ,I assumed would read the contents of memory address HL and jump to the location and be a gre…
... to memory address nn.
JP (HL) ,I assumed would ... using a list of CP...JP nn
or ... br /> LD HL,jumptable
JP (HL) ; read/peek the contents ... what instructions do.
JP nn means PC=nn
JP (HL) means PC=nn
JP (IX) means ... -
LINE-routine and other nice pieces of codeThe line-topic came in the end with a nice piece of fast coding. I think that there might be more of these routines out there (where-ever-u-r). Isn…
... /> .......LD DE,0
.......JP MAIN
B2.....INC ... ; fetch highbyte (7)
.......JP (HL) ; jump indirect to emulationroutine ... 00
JP I03
JP I06
...
JP IFF ; last ... #83 (#8301)
...
JP IFD ; last (#8300-#83FF)
Games UNDERated by magazinesYep, a slight twist on the previous topic. Which were the games you thought were underrated by mags, but were really much better in your opinion. …
... reviewer would have thought that JP would be still so popular ...Short Z80 QuizQ1) Which program gives different result ? A) XOR A ADD A,A B) XOR A ADC A,A C) SCF ADD A,A D) SCF ADC A,A Q2) What is the equivalent of NEG …
Z80 Emulator Source?Found a link to this on comp.sys.amstrad.8bit. i havent been with the discussion long but supposedly this is the source for a Z80 emulator. Forgive m…
... hl,hl ;hl=84xxh
jp (hl)
fetchend:
.ds ...Not just a pretty [inter] face!Hi everybody, I've got a DK'Tronics Light Pen up for grabs (see [url="http://www.worldofspectrum.org/infoseek.cgi?regexp=^DK%27Tronics+Light+Pen$&mo…
... /> [ This Message was edited by: jp on 2004-03-09 21 ...TASM, Z80 and Spec emusHi! Having some novice questions here regarding TASM and writing machine code for the Speccy emus... Now I have configured TASM into my EditPlus and…
... .e for using absolute calls - JP, CALL etc - instead of relative ...IM 2 interrupts and smooth scrolling - easy peasy!Okay, been fiddling around with IM 2 and have actually mastered (I think) how to use IM 2! Now I run my game Ragnar Revival in IM2 and use HALT to sy…
... to 0056 in ROM
jp 56 ;for smooth return to ... /> ld hl,58853 ;Create a JP NN at address
ld ...InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... where you could put a JP to your 'real' interrupt routine ...Game loop design?Having some thoughts on how to design the game loop and could do with some hints and tips from folks who have done it before! It's all about how to …
Mysterious bit of codeHi everyone, I found the follow piece of code in a game and was wondering what it does. ld bc,40ffh ld e,40h loop ld a,r …
need help with speed optimization. this procedure draws a sprite with mask from memory onto the screen with x-coordinate in pixels. it doesn't shift sprites in realtime, it just uses …
... ,(SPRXCO) ;
AND 7 ;
JP Z,DRAWNOX ;this part doesnt ... line on the screen.
JP DRAWSPY
DRAWCH1
INC ...IM2 Machine Code Sprites Example Code Using Char Based SystemFurther to my earlier post, here are sprites running using char method with IM2 driving it Note, for 48k spectrum using TASM [code] ; ***********…
... to 0056 in ROM
jp 56 ;for smooth return to ...
ORG 0FDFDH
JP MainLoop
END
Smooth Color Masked Sprites using fast page flip on 48kHere is a quick demo of using char based sprites using the Page flip method: a) Background is copied to buffer b) Sprites drawn on buffer c) Buffer …
... />
HALT
JP MAIN
RET
CP 0
JP Z,INTEND
ORG 0FDFDH
JP MAINLOOP
END ...Smooth Masked Sprites using fast page flip on 48k Part 2Ok, After all the suggestions in Part 1, which were all excellent (Thankyou), I opted on the following: I have 2 x 6k Offscreen areas (Yes, that's …
... A
JP MAIN
RET
CP 0
JP Z,INTEND
... +1),A
JP NZ,gob
... />
ORG 0FDFDH
JP MAINLOOP
...Smooth Screen Scrolling RoutineHi everyone, this is a follow up to the thread on smooth screen scrolling. As promised here is the code for the routine. It's pretty long and fairl…
... A ;increase scroll position
JP NZ, MLOOP
RET< ... ;decrease loop counter
JP NZ, MODHLB ;and jump back ... />
DJNZ CLEARLP2
JP ZERO ;Skip the next bit ... ;decrease row loop counter
JP NZ, ROWLOOP ;jump back to ...The incredible shrinking screendumpIn this topic I stated that I would be impressed if the screendump could be smaller than 37 bytes. [url="http://www.worldofspectrum.org/forums/viewt…
... at end of table
jp z,#1ff8 ; Do last carriagereturn ...Highly OT:unless the topic is pc arcade games :p did you know you can play classic arcade games in microsoft excel???? i didnt i do now :) [url="http://www.…
... />
[url="http://www.geocities.jp/nchikada/pac/"]http://www.geocities ... .jp/nchikada/pac/[/url]
...Help needed to speed up functionCan anyone help me to re-factor this code snippet. The "MAP" section holds information about which tiles go where on the screen (handled by another f…
Anyone help re-factoring a tile functionI had some excellent feedback for re-factoring my function that displays the colour for my screen tiles. Can anyone offer some help to improve the fu…
... NXTROW3 DEC C
JP NZ,PRTTILELOOPY
EI ... /> AND 7
JP NZ,TILERENDEREND
LD ... LD E,A
JP C,TILERENDEREND
LD ...Lerm MicroMate - SDPHi All, I'm having a go at preserving a microdrive version of Lerm MicroMate. I?ve got a few problems, though, as the software has been unbelievably…
... /> [ This Message was edited by: jp on 2005-06-22 11 ... /> [ This Message was edited by: jp on 2005-06-22 11 ...Key press to ASCII valueI need a bit of code that will give me an ASCII value when the key is pressed. I only really need a-z. I tried using the following code but it only s…
...
AND 31
JP Z,NPRESS
INC D ... br /> SRL H
JP NC,KLOOP
RET ... /> RLC B
JP C,NXHALF
CP ...Optimisation Needed! Is this the Fastest way to copy bytes from screen and back again?I have the screen address (say 0,0 i.e 16384) I want to copy 4 bytes wide by 32 bytes high from the screen to an area of memory. I then want to cop…
... ,h
AND 7
JP NZ,C2S_2
LD A ... ,h
AND 7
JP NZ,C2SC_2
LD ... /> LD L,A
JP C,C2SC_2
LD A ... ,h
AND 7
JP NZ,DRAWBEG
LD A ...
LD L,A
JP C,DRAWBEG
LD A ...SupadriveHere's an MDR image of Supadrive. Works with Spectaculator, but I haven't tested it with any other emulators. [url="http://www.superfudge.demon.co.u…
... /> [ This Message was edited by: jp on 2006-01-08 04 ...Machine Code: quicksort optimisationI came across this z80 quicksort implementation when going through the wikipedia article on the same. It's 44 bytes long. I was wondering if any of …
... sbc hl,de
jp c,next1 ;loop until ... sbc hl,bc
jp c,next2
ld ... hl ;restore pivot
jp fleft
next2 pop ... ;bc=lo,de=right
jp qsloop
< ...Problem with rotating procedureHi folks! I wrote a proc in z80 asm, based on: x' = x * cos (z) - y * sin (z) y' = x * sin (z) + y * cos (z) I used a precalculated table of sin a…
... /> ;============================================================================
start: call rotator
jp start
;============================================================================
;mult21 - mnozenie ...Screen LoaderCouple days ago i find very interesting loader routine in ex Yugoslavia magazine "Svet Kompjutera" from january 1987. Authors of article, calls this …
... , game not start with JP 36000, than wants to ...
ORG 65024
JP START
HIL DEFS 2 ... EI
CALL 1366
JP 36000
LFED5 INC D ... br /> DJNZ LOPP
JP KRAJ
KRAJ EXX
JP KRAJ
RP EXX< ...Pixel Explosion CodeJust a little snippet to cause explosive effects. It uses table lookups for the screen address, and can handle up to 32 pixel particles. A particle…
... address
madp_poke:
jp madp_move
madp_move:
; xmove ...
