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Speeding up PRINT code in ROMHi Folks, I seem to recall that someone stated the PRINT command is rather slow because it has to handle screen and printer printing - is this cor…
... with
ex (sp),hl ; character address (from stack)
ex de,hl
add hl, hl
add hl, hl
add hl, hl
add hl, hl
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…
... 88 T-States (if HL and DE are aligned ... for
swap (HL), (DE) ; swap_word macro does this ...
I was looking at ex (sp), hl but that's no good ... swapping CONTENTS of DE, HL as far as I ... br /> swap_word as is preserves HL and DE and only trashes ...SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
...
There is also [b]EX (SP),HL[/b] (and its DD and ... same as a POP HL, but it exchanges the ... what you had in HL, and it doesn't ... stack pointer.
(SP) L; (SP+1) H
...
I always wanted a PUSH (HL ...SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
... br /> There is also [b]EX (SP),HL[/b] (and its DD and ... what you had in HL, and it doesn't ... stack pointer.
(SP) L; (SP+1) H
...
I always wanted a PUSH (HL ... I was confused thinking HL would end up with ...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 …
... (restorec+1), SP
EX DE, HL
LD SP, HL
EX DE, HL
SP
EX DE, HL
LD SP, HL
EX DE, HL
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 …
... /> ADD HL,DE ; Add onto GFX
EX DE,HL ; Let ... POP BC
EXX
EX AF,AF'
POP AF ... INC H
LD SP,HL
POP AF
POP ...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 SP,HL
EX DE,HL
LD ... SBC HL,BC
EX DE,HL
LD SP,HL
EX DE,HL
LD SP,HL
EX DE,HL
LD D, ...
PUTBLOCK LD SP,HL
EX DE,HL
LD D ...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…
... sp,hl
ex de,hl
pop bc
ld (hl),c
inc hl ... sp,hl
c2sc_dest:
ld de,16384
ex de,hl
Urgent Help needed to fix this: calling all machine code gurusI am currently trying to write tutorials on the amazing Orfeus music composer by Proxima which allows you to do multi channel music through the beepe…
... br /> l88c9: ld a,(hl)
ex af,af'
ld ... de)
ld (hl),a
ex af,af'
ld ... sp
ld sp,hl
pop hl
ld (l8c0c+1),hl
pop hl ... ,(hl)
inc hl
ld d,(hl)
ex de,hl
jp (hl ...So you want to make a cardgame......but you haven't got a good deck to display. Well here is a fully relocatable routine that will do the job for you. Place the code anywhere in me…
... HL,14
ADD HL,SP
LD SP,HL ; undo USR command
LD HL ...Common pitfalls and solutionsLet's discuss some of the common problems in Speccy programming, and the methods we use to avoid them. For an example, here is a piece of code that …
... /> LD HL,#1303
PUSH HL
LD (#5C3D),SP
LD HL,#1BB0 ...
PUSH HL
LD HL ... /> LD DE,#1B5E
EX DE,HL
LD BC,4
automatic relocating of non-relocatable codeI was pondering upon the problem of changing absolute addresses used by CALL, JP, etc. when code is moved, without reassembling at the new location; …
... /> ld hl,CHANGE
add hl,bc
ld sp,hl ;point SP to list ... hl,bc
ex de,hl
pop hl
add hl,bc
ex de,hl ;HL ...Tile based graphics and scrolling thingy...Here's my best attempt so far at a tile based rendering and scrolling routine. It draws in 22 8*8 graphics tiles along the top of the screen (junk i…
... !
add hl,de
ex de,hl ; Put the result ... /> pop hl ; POP source address. 10
dec sp ; Point SP back ... scanline!!!
ld sp,(32859) ; Restore SP & registers then return ...Procrustean PrintingHere's a short routine to manage printing of text with command tokens, to avoid messing up the screen when they are expanded. It just prints as many …
... STACK: ld hl,14
add hl,sp
ld sp,hl ;undo ... pop af
ex de,hl ;HL=string pointer
ld ... a character
pop hl ;HL=string pointer
djnz ...Indirect Variable AssignmentHere's another wacky routine. This allows assignment of values to variables where the source & destination variables can themselves be defined in var…
Here's another wacky routine. This allows assignment of values to variables where the source & destination variables can themselves be defined in variables (or expressions which evaluate to variables). Some of this can already be done with VAL or VAL$, ...Undefine functionHere's a routine to selectively remove variables from the VARS area and reclaim the space. This can be done partially from BASIC already by assigning…
... UNDEF: ld hl,14
add hl,sp
ld sp,hl ;undo USR
NOTFOR: ex de,hl
add hl,bc
ld ... )+(length of variable)
ex de,hl ;HL=address of variable
...multi-scroll m/c subroutine for BASICArising from recent posts, here's a scrolling routine that will manage multiple left/right scrollings for any (sensible) line width or step; (ie. whe…
Arising from recent posts, here's a scrolling routine that will manage multiple left/right scrollings for any (sensible) line width or step; (ie. where width isCopy 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…
... /> push de
push hl
ex af,af'
exx
push de
push hl
ex af,af'
exx
add hl,sp
ld sp,hl
ld hl,counter_addr
dec ...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 ... perform a SBC HL, DE with HL containing 0 and ... a PUSH, POP, two EX DE, HL and something (OR A ...Ghosts n' Goblins loaderI'm trying to put Ghosts n' Goblins onto a +3 disk but struggling to understand the mc loader. Basic loader [code] ink 7 : clear 25000 : load "" cod…
... /> 65122: JR 65161
65124: EX AF, AF'
65125: JR ... HL, DE
65252: LD SP, HL
65253: POP HL
65254: LD SP, HL ... (65375), A
65283: EX DE, HL
65284: LD A, 255 ... /> 65365: JR 65408
65367: EX AF, AF'
65368: JR ...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 +…
... a
ex de,hl
add hl,bc
ex de,hl ;de = address ... /> ld l,c
ld sp,hl
ld c,h ... 8 times
ex de,hl
ld a,(multicolour_A_offset) ;'HW ... /> ld sp,hl
ex de,hl
;now b=X, hl=attrs, sp=attr ...Hooky - hook ZX ROM and rewire RST and NMI to RAM - rantThis is a rather long rant. Not for short tempered. :) The objective is to hook into RST "vectors" and NMI on a Spectrum without affecting the normal…
... BC,00A8
0x1209 EX DE,HL ; HL=3EAF, DE=FFFF
0x120A ... 0xff57
0x120C EX DE, HL
0x120D INC HL ; hl back to 0xff58 ... DEC HL ; hl=ff56
0x1228 LD SP,HL ; setting sys. stack to SP=ff56 ...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…
... copy
push hl ; 11t - store hl for later (sp=store pos)
ex de,hl ; 4t - swap hl&de to ... _ulzfa050 ; 17t - move hl on one
ex de,hl ; 4t - swap back ... pop hl ; 10t - bring back mem pos (sp=free)
inc hl ; 6t ...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…
... a
add hl, de
inc hl
ex af, af' ; ... a
add hl, de
inc hl
ex af, af' ; ...
add hl, de
ex de, hl
pop hl
swap_word< ... /> push hl
add hl, de
pop de
ex de, hl
line routineWondered if anyone can help me out. I have been programming a 3d graphics library for the spectrum, in Machine code. The line routine that I have i…
... stack)
ld (sstack),sp
ld sp,tad_desc+384 ;okay, i ... for me ;o)
ld hl,tad_asc
ld de,#4000 ... /> ld (hl),e
inc hl
ld (hl),d
inc hl
jr nz,filltab
ld sp,(sstack)
;so here ...
