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help sought with first foray into machine code - pixel scrolldownI have started to code my first machine code program, a simple roadrace game. I've based it around the pixel scrolldown routine in 40 Best Machine Co…
... /> savscrpos
push hl ;save road left side posn ... copy byte. . .
ld (hl),a ;. . .to next pixel line ... right, 1line up
ex (sp),hl ;?? load posn of byte ... up
ex de, hl ;put 224 into hl, byte to ... to be copied
ex de,hl ;?? but now it' ... -
128 ROM paging alternativeWould this work (with the appropriate code in each ROM)? [code] ; 128 rom paging routine ; use rst 28h with call address stored after restart ;;rom…
... /> inc hl ; to create
inc hl ; return address
ex (sp), hl ; call ... address to hl
; return address to (sp)
(part of) screen to UDGHere is a routine to copy a Y,X-position on screen to a UDG. 0<=y<=23 0<=x<=31 144<=udg<=165 (UDG "A" to UDG "U") [code] ; start code with ; PRINT …
Here is a routine to copy a Y,X-position on screen to a UDG.
0BREAK from GOSUBHere's another one. Just in case you wanted to break out of multiple GOSUB levels with a single command, here's a routine to do it, tested on all mod…
... 3 bytes
EX (SP), HL ; 227 ;restore (ERR_SP)
EX DE, HL ; 235
Optimisations in Exomizer Z80 decrunch codeThis is the 163 bytes old code (simple and optimized): [CODE] ld iy, exo_mapbasebits ld a, 128 ld b, 52 push de exo…
... ]
by:
[CODE]
ex (sp), hl
ld d, h
add hl, de
ex de, hl
inc iyl ... /> call exo_getpair ;bc=offset
ex (sp), hl
ld d, h
Zero 0.5 ReleasedAfter a bit of a hiatus, the next update of Zero is now available [URL="www.ramtop.wordpress.com"]here[/URL]. Feedback and bug-reports appreciated! …
... (Woody).
- Fixed timing for EX (SP), HL/IX/IY instructions (Woody).
Rotronics Wafadrive v.1.80 ROM - Corrupt or purposely broken?I've been digging around the Wafadrive v1.80 ROM (from [URL="http://zxspectrum.it.omegahg.com/_RO.htm"]here[/URL]) and can't decide if the ROM is cor…
...
;
l_0d09: inc hl
push hl
ld (iy+$00 ... de
ld hl, $009f
ex (sp), hl
push hl
ld e ... ?
add hl, de
ld e, (hl)
inc hl
ld ... h, (hl)
ld l ...SCREEN$ bug fixI've been using the SCREEN$() function recently for reading data off the screen rather than taking up space with an array and I got fed up with the s…
... inc sp
inc sp
pop hl ;HL=$000D
ex (sp),hl ;HL=$106E ...
push hl
LZ4 decoderI encountered the [URL="http://code.google.com/p/lz4/"]LZ4 compressor[/URL] a few weeks ago. Reading the [URL="http://fastcompression.blogspot.co.uk…
... /> ;;
;; Leaves HL pointing one byte past compressed ... br /> ex (sp),hl ; switch destination pointer into HL
push hl ; ... ; copy bytes
pop hl ; restore source pointer
...Math Quiz - MultiplicationThe topic is fast multiplication routines, from 8x8 to 32x32 and all points in between. These functions sit underneath floating point libraries, gen…
... /> push hl ; save HL
call l0_mulu_24_16x8 ; ahl = HL * E
ex (sp),hl ... ; save LSW(HL ...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 …
... And 128)
9) EX (SP),HL
10) Set the ...Horizontal scrollDoes anyone know how to do a 2 or 4 pixel left or right horizontal scroll of the spectrum screen. I can make a 1 one pixel scroll with: ... rl (hl…
... br /> ld sp,endofscreen
xor a
...
ex (sp),hl ; don't ... change sp but get screen in hl
... br /> push hl ; store number, point sp to next group ... br /> ; loop next
ex (sp),hl
rla ; get second to ...Horizontal scrollDoes anyone know how to do a 2 or 4 pixel left or right horizontal scroll of the spectrum screen. I can make a 1 one pixel scroll with: ... rl (hl…
... - the clever bit is the ex (sp),hl instruction - basically being used to ... load the contents at SP in HL like a POP would ... but without affecting SP. In ther other ... routines we had to adjust SP after each shift - loosing 8 ...Z80 core testing ?OK, my z80 core is almost finished (apart from RRD, RLD, and block instructions except LDI,LDIR,LDD,LDDR). I run the 48K rom and hurray, it resets co…
Found out the culprit - hadn't emulated EX (SP),HL.... (D'oh!)
Yeaah ! The BASIC editor works perfectly ! I've made an emulator in only 5 days... :)
(1 minute later)
Uh... 5+2 isn't 1E+8, is it.... ? ;)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…
... ld de,22528
ld hl,map
ld ... b,0d7h
ld c,(hl) ; BC -> Colour ... djnz loop
ex (sp),hl
ldi
ldi
pop hl
pop bc< ...Programming MC challengeIn the 80-ies I got the following assignment for a programming course. 2 16-bit values stored in #8000 and #8002 must be added together and stored i…
... :
[code]
ex (sp),hl
ld sp,#8000
pop bc ...
push bc
jp (hl)
[/code]
Which ...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 …
... a,(bc)
ex af,af
ld a,(hl)
ld ... (bc),a
ex af,af
ld (hl),a
inc ... (bc),a
ex af,af
ld (hl),a
ex de,hl ; de = left+1, hl = right
dec ...What do you think.Do you think if you went back in time and made a Sudoku game for the spectrum you would be a millionaire now? (all my get rich quick schemes invole …
... ]
#0008 EX SP,(HL) ; save HL on stack
LD HL,(SYSVARJUMP) ; Fetch JUMP ... -address
JP (HL) ; make the jump
[/code ...What do you think.Do you think if you went back in time and made a Sudoku game for the spectrum you would be a millionaire now? (all my get rich quick schemes invole …
... ]
#0008 EX SP,(HL) ; save HL on stack
LD HL,(SYSVARJUMP) ; Fetch JUMP ... -address
JP (HL) ; make the jump
[/code ...Oh so BRIGHT!What is the SLOWEST way to change the attribute area to BRIGHT? It has to be legit! No meaningless instructions or doing stuff for the sake of it. …
... /> add iy,sp
ld sp,ix
ex (sp),hl
zerobc ...
adc hl,bc
ex (sp),hl
ld sp,iy
...Compressors are available for Speccys ?Hi folks, although I was an wasn't strictly a speccy coder in the glory days (amstrad & amiga for the most part), I have secides to arse about with …
... a,(hl)
pop hl
ld (hl),a
inc hl
ex de,hl ...
ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl
ld hl,1279
or ...Compressors are available for Speccys ?Hi folks, although I was an wasn't strictly a speccy coder in the glory days (amstrad & amiga for the most part), I have secides to arse about with …
... ,(hl)
add hl,bc
ld (hl),a
inc hl
ex de,hl ... /> ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl
ld hl ... /> ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl
ld hl ...New assember ideaAs i work with Eclipse IDE in my job i become more and more lazy. This leads me to idea that it is time to left Notepad+Tasm combo behind and move on…
...
pop hl
pop bc
ex (sp),hl
.asmentry ... /> ld (hl),c
inc hl
ld (hl),b
inc hl
pop hl
pop bc
ex (sp),hl
.asmentry ...Compressors are available for Speccys ?Hi folks, although I was an wasn't strictly a speccy coder in the glory days (amstrad & amiga for the most part), I have secides to arse about with …
... and a
ex de,hl ;write a previous ... hl)
add hl,bc
ld (hl),a
inc hl
ex de,hl ...
jp aploop
apbranch3: ld c,(hl ... ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl ...Compressors are available for Speccys ?Hi folks, although I was an wasn't strictly a speccy coder in the glory days (amstrad & amiga for the most part), I have secides to arse about with …
...
ld a,(hl)
add hl,bc
ex de,hl
ld ... />
ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl
ex (sp),hl ;bc = len, hl=offs
push de
ex de,hl
