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Tutorial - learn machine code in 30mins[B][I]Message from the moderators[/I] - bigjon has requested that readers' attention be drawn to a better version of this tutorial, one which is easi…
...
We'd like to 'sub hl,de' but there's no such ... de,9
add hl,de
ld (hl),a
inc hl
ld (hl ... de,9
add hl,de
ld (hl),a
inc hl
ld (hl ... de,9
add hl,de
ld (hl),a
inc hl
ld (
bigjon
November 2009
Development
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Clearing the Carry flagI'm reading that sometimes I may want to clear the carry before using ADC or SBC. A simple AND A or OR B will do. However, as I see it, for 8-bit ar…
... / SBC than there are ADD / SUB ops. Although you can do ... no such option as:
SUB HL, DE
but there is
Tutorial - learn machine code in 30mins[B][I]Message from the moderators[/I] - bigjon has requested that readers' attention be drawn to a better version of this tutorial, one which is easi…
...
We'd like to 'sub hl,de' but there's no such ... de,9
add hl,de
ld (hl),a
inc hl
ld (hl ... de,9
add hl,de
ld (hl),a
inc hl
ld (hl ... de,9
add hl,de
ld (hl),a
inc hl
ld (
buzzy
September 2012
Development
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…
... were versions of the ADD, SUB, ADC, SBC, XOR, AND and ... register, so why not ADD, SUB etc. too?
(Yeah ... />
Oh, and also SUB HL,DE and SUB HL,BC. Why were they missing???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…
[QUOTE]Oh, and also SUB HL,DE and SUB HL,BC. Why were they missing???[/ ... />
OR A
SBC HL,DE
Remember also that ...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…
...
Oh, and also SUB HL,DE and SUB HL,BC. Why were they missing ... to use ADD HL,DE to overflow as a SUB HL,DE replacement, or ... (or not) and do SBC HL,DE?
[QUOTE= ... instead of 'SUB' HL,DE (de is 32)
ADD HL,DE (de is 65504) gives ...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…
... =SkoolKid;661292]Oh, and also SUB HL,DE and SUB HL,BC. Why were they ... />
The fake instruction LD HL,DE for example, is internally converted ... and time a supposed LD HL,DE instruction would use (taking into ...The Pros and Cons of "alternative" assembler syntaxContinuing from [URL]http://www.worldofspectrum.org/forums/showpost.php?p=720754&postcount=72[/URL] [QUOTE=u6c87;720754]But that wouldn't change if…
[QUOTE=introspec;721102]SBC HL, DE?[/QUOTE]
But you can't SUB HL, DE. SUB only applies to A.The Pros and Cons of "alternative" assembler syntaxContinuing from [URL]http://www.worldofspectrum.org/forums/showpost.php?p=720754&postcount=72[/URL] [QUOTE=u6c87;720754]But that wouldn't change if…
... 721106]But you can't SUB HL, DE. SUB only applies to A.[/QUOTE ... /> DEC BC BC-
INC (HL) [HL]+ [H]+ M+
DEC ( ... HL,BC HL+BC H+BC H+B HL+B
ADD IX,DE ... X+DE ... X+D
SBC HL,HL HL-*HL HL-*H
...Sort 2 byte words (x, y) on ypos, also question about swap (DE), (HL)Well that was a lot of debugging ;) But if you want a routine which takes an array of 16 byte words x, y and then sort them on y (ignoring x), I'm…
...
push hl
add hl, de
pop de
ex de, hl
swap_word ... /> // Recursively heapify the affected
// sub-tree
heapify(arr, n ...How to get Grahics to wrap vertically around the screen?I am using the following code to draw an image to the screen. First I use HL to contain ROW and COLUM I then call the MapScreenFunction As I draw m…
... br /> ld a,h
sub 8
ld h,a ... hl,hl
ld de,scrtable
add hl,de
add a,(hl)
inc hl ...
ld h,(hl)
de)
or (hl)
ld (hl),a
inc ...Machine Code Sprites Example Code Using Char Based SystemBelow is my WIP code to do smooth screen wrapping sprites using char positions and offsets, as opposed to writing direct to a line (0-191) and shifti…
... LD A,(IX+3)
SUB (ix+7)
ld ... /> LD A,8
SUB (ix+7)
ld ( ... Z,l01
SUB (IX+6)
LD (IX ... br /> ps0:
ADD HL,DE
DJNZ ps0
...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] ; ***********…
... LD A,(IX+3)
SUB (ix+7)
ld ... /> LD A,8
SUB (ix+7)
ld ( ... Z,l01
SUB (IX+6)
LD (IX ... br /> ps0:
ADD HL,DE
DJNZ ps0
...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 …
... SP
EX DE, HL
LD SP, HL
EX DE, HL
LD A,8
SUB E ; take it from 8 ...
ADD HL,DE ; Add onto GFX
EX DE,HL ; Let DE now point ...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 …
... br /> LD A,8
SUB E ; take it from 8 ... br /> ADD HL,DE ; Add onto GFX
EX DE,HL ; Let DE now point ... br /> LD HL,0
LD DE,16
ADD HL,DE
LD ...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…
...
LD A,4
SUB B
ADD A,A ... />
LD A,5
SUB C
LD (COLMODA+1 ... ,CLOOPB
EX DE,HL ;DE = SCREEN ADDR.
ZERO ... in background data table
SUB 12
LD L,A ...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…
... /> jr nc,fin21
add hl,de
adc a,0
;argumenty: hl i de
;wynik: hl i de
;============================================================================
... />
ld a,e
sub c
ld e,a ...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…
... if not line2 yet
sub a ;?? prepare blank byte ... into accum??
sbc hl,de ;move pointer of line to ... /> add hl, de ;to posn to be copied
ex de,hl ;?? but ... next line up
sub 7 ;next line up is ... next line up
sub 7 ;next line up is ...Probing the variables in 128K modeHello again! Briefly, I'm writing an m/c routine to read some BASIC variables. So, before I start, I try to get an idea for the structure of how var…
... Z,STRINGARRAY
SUB 128
LD DE,19
PRINT
ADD HL,DE
JR NEXTVAR
STRINGARRAY
SUB 96
LASTCHAR
SUB 128
JUMP
LD DE,6
JR ... PRINT
ARRAY
SUB 32
A fast DRAW routineI was investigating how to speed up the line drawing for the [URL="http://www.worldofspectrum.org/forums/showthread.php?t=20225"]BASIC compiler[/URL]…
...
exx
add hl, de ; error -= dX
... HL = error = DX / 2
; DE = -dY
xor a
sub ... br /> exx
add hl, de ; error -= dY
ld de, (SCREEN_ADDR)
add hl, de ;; Final screen ...joining lines of BASICDue to overwhelming demand - well, one demand - well, more of a suggestion, really - here's a routine to join together lines of BASIC. The vertical c…
... A,(VECTOR+1) ;65136
SUB 1
LD I,A ...
inc hl
add hl,de
dec hl
ld (hl),":" ;replace ENTER ...40 Column Printing RoutineI've written a 40 column printing routine, which I'd like to share... It's my first piece of 'public' code so go easy on me! I don't think it is a…
... ) ; getscharater from charterno variable
sub 32
ld e,a ...
ld hl,coordslookup
add hl,de
ld a,(hl)
push ...Graph Plothi! please, help with code: [PHP]For x=-100 To 100 For y=-100 To 100 If (x/2-25)*(x/2-25)+(y-50)*(y-50)<200 Or (x/2+25)*(x/2+25)+(y-50)*(y-50)<200 th…
hi! please, help with code:
[PHP]For x=-100 To 100
For y=-100 To 100
If (x/2-25)*(x/2-25)+(y-50)*(y-50)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…
... ld a, b
sub 4
and 15
add hl, de
ex de, hl
inc iy ... ld a, b
sub 4
and 15
add hl, de
ex de, hl
inc iyl ...Full 16*16-digit BASIC multiplicationI liked Andre Adrian's 32-bit long multiplication routine so much that I decided to a decimal version. After all, 2^63 is only 9223372036854775808, a…
... SBC HL,HL ; RESULT BITS 32..47 = 0
1030 GO SUB EXX ... SBC HL,HL ; RESULT BITS 48..63 = 0
1050 GO SUB EXX ... LET I=0 : REM ADD HL,DE ; RESULT += MPD
1121 ... REM LMULNOADD:
1210 GO SUB EXX : REM EXX
...Z80: ABS(HL) functionI must be very tired but I cannot get my head around whether this function provides a correct implementation of a ABS function for a signed 16-bit va…
... 16-bit value in HL. Can somebody check by ...
[code]
; Input: HL contains a signed 16-bit ... value
; Output: HL = ABS(HL)
ABSFunc:
BIT ... a SBC HL, DE with HL containing 0 and DE the input ... PUSH, POP, two EX DE, HL and something (OR A) ...Scrolling Bi-Colour Engine for 4-Player GamesJust putting this code up for people to have a look at. Far from finished. Should simply compile and run a bit of a demo. Only good for 128K and +…
... /> add hl,bc ;hl = address of start of row
add hl,de ;hl = address ... ,a
ex de,hl
add hl,bc
ex de,hl ;de = address of ... a,(SPRITE_BASE) ;sprite Y
sub l
sla a
SBC IX,DE/BCAlways wondered why there wasn't a SBC IX, DE/BC command.... so have to use PUSH HL ; save original HL PUSH IX ; IX on stack POP HL ; IX …
... wasn't a SBC IX, DE/BC command....
PUSH HL ; save original HL
PUSH IX ; ... into HL
SBC HL,DE ; do calc
PUSH HL ; ... IX
POP HL ; get original HL back again
... at the same time, DE is the value to ...ZXSCLZF - Yet another Screen CompressorQuick disclaimer before I continue, this compressor does not shrink screens as small as some of the others posted here, in particular the very good z…
... a greedy parser so is sub-optimal, would love to know ... - start screen pos into de
inc hl ; 6t
ld a ... - move de on one
ex de,hl ; 4t - swap hl&de to use ... _ulzfa050 ; 17t - move hl on one
ex de,hl ; 4t - swap back ...
