-
Fastest way to mirror a byte?I.E. turning 01100000 into 00000110, in assembly. I'm trying but I suck at stuff with rotation and the carry bit. Any pointers?
... /> EX (SP),IX Exchange the location (SP) and IX.
EX (SP),IY Exchange the location (SP ... ) and IY.
EX AF ... -
BREAK 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…
... & (ERR_SP)
LD SP, HL ; 249 ;from m/c ... ;entry is 3 bytes
EX (SP), HL ; 227 ;restore (ERR_SP ... ; 225
RES 4, (IY+1) ; 253 203 1 166 ... -
Byte-order backbufferThis is a tool for Z80 coders who wish the Spectrum screen had a serial layout. It runs as an interrupt mode 2 service routine and uses POP and PUSH …
... br /> push hl
ex af, af' ;'
exx ...
pop af
ex af, af' ;'
exx ... br /> pop hl
ex af, af' ;'
exx ... hl
ld sp, iy
push hl ; write 16 ... br /> push af
ex af, af' ;'
exx ... -
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…
... hl, de
ex de, hl
inc iy
pop hl ... ]
by:
[CODE]
ex (sp), hl
ld d, h ... /> add iy, bc
call exo_getpair ;bc=offset
ex (sp), hl
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! …
... ).
- Fixed timing for EX (SP), HL/IX/IY instructions (Woody).
- Fixed ...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…
...
push hl
ld (iy+$00), $ff
set 2 ... , (iy+$01)
cp $36 ; 27 ...
ld hl, $009f
ex (sp), hl
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…
... . Does not use IX or IY. Uses the shadow
... of the token
ex af,af' ; move token ... many bytes
ex af,af' ; switch token back ... length if so
ex (sp),hl ; switch destination pointer ...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. …
... ld iy,0
add iy,sp
ld sp,ix
ex (sp),hl ...
ex (sp),hl
ld sp,iy
ld iy,23610
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…
... 't I need some horrible 'ex(sp), hl'-type instructions to get ... takes?[/QUOTE]
ex (sp),hl takes 19 cycles but ... /> di
push iy
ld (temp),sp
ld hl ... /pop). The "ld sp,hl; ld sp,ix; ld sp,iy" instructions need to ...Spectrum 128K RS232 to PC serial cableIf you have read some of my recent posts then you will know that I am eager to link my Spectrum +3 to a PC. This will be done by wiring a standard PC…
... /> ex (sp),hl
ld (r_pc),hl
ex (sp),hl
ld sp,r_r ...
ex af,af'
push hl
push iy
push ix
ld ...
pop ix
pop iy
pop hl
pop ...yeah - unix for zx spectrumI started a new hobby project. An operating system for ZX Spectrum. A unix clone. Talked to my friend about it and he asked me what if after I'm done…
... absolute addresses, loading up SP and performing a task ... 58
59 pop iy
60 pop ix
75
76 ex (sp),hl
77 push af ... push ix
87 push iy
88 exx
...
; save SP in task structure
; perhaps ...50Hurts - Full-screen 50Hz 1-pixel scrolling on a 128K Speccy50Hurts - Full-screen 50Hz 1-pixel horizontal scrolling on a 128K Speccy. Graphics are an obvious nod to Joffa, whose games and banter were a big ins…
... line address table
ex af,af'
jp ... inc a
ex af,af'
ld sp,hl
...
exx
ld sp,iy
pop bc
... /> exx
ld sp,hl ; put screen address ... ld de, 6
add iy, de
add ix, ...Kobrahsoft DB1 - doesn't work?Hi, I've tried loading [URL="http://www.worldofspectrum.org/infoseek.cgi?regexp=^DB1$&pub=^Kobrahsoft$&loadpics=3"]DB1 by Kobrahsoft[/URL] into two …
... is using some unconventional IX/IY index register commands and ... /> XOR B ; 8007 A8
EX (SP), HL ; 8008 E3
XOR ... 8042 DD 23
INC IY ; 8044 FD 23
EXX ...Need help with tzxingI recently got a copy of this Polish text game: [url]http://www.worldofspectrum.org/infoseekid.cgi?id=0006622[/url] I can't make a tzx of it howeve…
... LD HL,16384
LD IY,0
EXX
... PUSH IY
POP DE
... DE,16384
EX DE,HL
EX (SP),HL
... IX+51)
SUB (IY+0)
ADD A,(IX ... /> LD HL,L49650
EX (SP),HL
JR L49557
BREAK 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…
... NOGSUB
DEC SP ;entry is 3 bytes
EX (SP), HL ;restore ... (ERR_SP)
EX DE, HL
NOGSUB: RES 4, (IY+1) ;+2A/+3/+3e fix ...Arkanoid - Hit Squad ReleaseInfoseek (and the [URL="ftp://ftp.worldofspectrum.org/pub/sinclair/games/a/Arkanoid(TheHitSquad).tzx.zip"]TZX[/URL] itself) identifies the Hit Squad …
... exx ; ee50 d9
ex af, af' ; ee51 08
ex af, af' ; ee76 08< ... exx ; eeaf d9
ex af, af' ; eeb0 08< ... rrca ; e0fa 0f
ld sp, iy ; e0fb fd f9
... exx ; e905 d9
ex af, af' ; e906 08< ...Fairlight's use of LDIRYS, comparing Fairlight and Nightshade, said: [quote]Fairlight is much more interesting even though the techniques that Bo Jangeborg uses for screen…
... br /> push hl
ex af, af' ;'
exx ...
pop af
ex af, af' ;'
exx ... br /> pop hl
ex af, af' ;'
exx ... hl
ld sp, iy
push hl ; write 16 ... br /> push af
ex af, af' ;'
exx ...Shadow registers.I assume it's faster to transfer the registers to the shadow registers rather than using the stack? Let's say that I want to temporarily preserve the…
... ,IX[/B]
and [B]EX DE,IY[/B] ?[/QUOTE]
EX (SP),IX[/B].Byte-order backbufferThis is a tool for Z80 coders who wish the Spectrum screen had a serial layout. It runs as an interrupt mode 2 service routine and uses POP and PUSH …
... br /> push hl
ex af, af' ;'
exx ...
pop af
ex af, af' ;'
exx ... br /> pop hl
ex af, af' ;'
exx ... hl
ld sp, iy
push hl ; write 16 ... br /> push af
ex af, af' ;'
exx ...z88dk vs. sdccI've just read this article (in Spanish) [url]http://www.cpcmania.com/index2.asp?urldest=Docs/Programming/SDCC_vs_z88dk_Comparando_tama%F1o_y_velocid…
... IX as 16 bit accumulator. IY is preferably not used due ... hl,#2
add hl,sp
ld e,(hl)
ld b,(hl)
ex de,hl
ld d ... bc
pop de
ex (sp),hl
asm_memset:
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 …
... />
call ap_getgamma2
ex (sp),hl ;bc = len, hl=offs ... iy
push bc
call ap_getgamma
ex (sp ... ),hl ;bc = len, hl=offs
push de
ex de ...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…
... -o
; exoopt
ld iy, exo_mapbasebits
ld a, 128 ... (iy+104), d ;base[i]=b2
add hl, de
ex ... /> add iy, bc
call exo_getpair ;bc=offset
ex (sp), hl
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…
... inc iyh
ld (iy+0), e
inc iyh ... add hl, de
ex de, hl
inc iyl ... >>8
ex de, hl
ld ... h, (hl)
ex de, hl
ld bc ...Fantasy Z80 instructions?This follows on from something catmeows said in another thread, and that I've been meaning to ask for a while. This may sound daft to people with mo…
... , I'd add "ld hl, sp" as well (and of course ... "ld ix, sp") to avoid the "ld hl ... , 0; add hl, sp" combo.
I'd ... like to see "ex de, ix" and "ex de, iy" as quicker ways ...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…
... . Does not use IX or IY. Uses the shadow
... no literals to copy
ex af,af' ; move token ... many bytes
ex af,af' ; switch token ... length if so
ex (sp),hl ; switch destination pointer ...Copy 4Kb in Assembly?Here's an interesting problem: what's the best way to copy a block of 4Kb in assembly? The most obvious solution is to use [B]LDIR[/B]: [CODE] l…
...
LD IY,TARGET
EX AF,AF'
Loop:
EX AF,AF'
... n2
[B] ld sp,IX
INC IXH[/B ... af
[B] ld sp,IY
INC IYH[/B]
ADD IY,nn3[/B]
EX AF,AF'< ...
