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Spin Assembler DirectivesLeading on from [URL="http://www.worldofspectrum.org/forums/showpost.php?p=402514&postcount=65"]jp's recent post in Spin 0.7 Public Testing thread[/U…
... :
[code]
(S: '(BC)'; I: 138), (S: '(C)'; I ... : 177),
(S: 'BC'; I: 113),
(S: 'BC'#39; I: 117 ... : 11+($FFEDB9 shl 8)), (S: 'CPI'; I: 12+($FFEDA1 shl 8 ... -
Spin Assembler DirectivesLeading on from [URL="http://www.worldofspectrum.org/forums/showpost.php?p=402514&postcount=65"]jp's recent post in Spin 0.7 Public Testing thread[/U…
... :
[code]
(S: '(BC)'; I: 138), (S: '(C)'; I ... : 177),
(S: 'BC'; I: 113),
(S: 'BC'#39; I: 117 ... : 11+($FFEDB9 shl 8)), (S: 'CPI'; I: 12+($FFEDA1 shl 8 ... -
Bit functions speedI just stared nonplussed at the documentation for the bit functions. Apparently, if you're using the accumulator, using AND and OR is faster than se…
... the use of CPI to test if BC is zero at the ... ]
inc hl
dec bc
ld a,b
[code]
cpi
jp pe, loop ; or ... -
FMV on +3eOK, so about 6 months ago i posted here that i got full motion video on +3e, with a bunch of scr files called passion. I added the glider rider music…
... ,table
exx
ld bc,49149
exx
ld ... bc,len
loop:
< ...
jr nz,deloop
cpi
jp pe,loop
Thinking in Assembly (first efforts)The following is one small routine to educate myself on a few concepts (jumps, flow control, routines, CPI): [code]searchmem xor a …
... ret po
jr .search ; BC!=0
ret ; not found ... /> push hl
pop bc ; retrieve address
ret< ... the entire memory
.search cpi ; a-(HL)
ret ...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 …
... BC_SPACES with zero in BC, attempting to make " ... 00 10
LD BC, $0020 ; 8021 01 ... 00 C0
LD BC, $1E3C ; 802B 01 ... HL ; 803E EB
CPI ; 803F ED A1
...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?
... CPD and repeat until BC=0.
CPI Compare location (HL) and ... acc., incr HL, decr BC.
CPIR Perform a CPI and repeat until BC=0.
Asking for help: ZXBC to ASM routine translationHallo, In order to save some bytes and gain speed, I'm asking for translation of a very simple ZXBC routine to Assembler [code] sub light(x as uinteg…
... hl,hl
add hl,bc
end asm
light1 ... ;'Counter for candles
ld bc,418 ;'Counter for bytes to ... in level
candles2:
cpi
jp po,candlesend
pop bc ; B=y
ex (sp ...Asking for help: ZXBC to ASM routine translationHallo, In order to save some bytes and gain speed, I'm asking for translation of a very simple ZXBC routine to Assembler [code] sub light(x as uinteg…
... ;'Counter for candles
ld bc,418 ;'Counter for bytes to ... in level
candles2:
cpi
jp po,candlesend
ld bc,417 ;'Counter for bytes to ... in level
candles2:
cpi
jr nz,candles3
Machine code loopsDear all, 30 years too late I know, but I'm finally starting to get to grips with Machine Code - something I could never manage back in my early tee…
... you have,
[code] ld bc,n_iterations
.loop
;(some ... ;or dec hl
dec bc
ld a,b
bc,n_iterations
.loop
;(some kinda code)
cpi ;or ...Machine code loopsDear all, 30 years too late I know, but I'm finally starting to get to grips with Machine Code - something I could never manage back in my early tee…
... ] ld bc,n_iterations
.loop
;(some kinda code)
cpi ;or ... such an ingenious use of CPI/CPD before. This is one ...Relocation with SDCCI desperately need auto- relocation with SDCC. Something that will compile all of my code using start address 0 and generate relocation table so that…
...
pop hl
pop bc
pop de
ex ... /> ; e = char c
; bc = size_t n
ld ... ) ; remember current char
cpi
jr z, match ; ... match:
dec hl ; cpi stepped hl one past last ...Experimenting with turboloadersHello, My first post, having lurked here for a while. I'm a lifelong computer nerd, Spectrum fan since childhood in the eighties, and have recently…
... if different
dec bc ; decrement byte counter ( ... past byte)
push bc ; save byte counter
pop bc ; restore byte counter
cpi ; advance ...Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... addresses in HL: use the CPI instruction, which performs a comparison ... ), then increments HL and decrements BC. It's designed for scanning ... the P/V flag when BC reaches zero, so you can ... /> ld bc, 1024
loop:
ld (hl), 62
cpi
Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... /> ld bc, 1024
loop:
ld (hl), 62
cpi
ld hl, 16384
ld bc, 1024
ld d, 62 ... :
ld (hl), d
cpi
jp pe, loop
Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
[QUOTE] ld hl, 16384
ld bc, 1024
loop:
ld (hl), 62
cpi
jp pe, loop
ret[/QUOTE]
Great trick!
I've never used CPI in my life before.
But I guess I'll be using it now :)Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... ld hl, 16384
ld bc, 1024
ld d, 62 ... /> ld (hl), d
cpi
jp pe, loop
ld bc, #1024
loop2:
ldi ... /> jp pe, loop2 ; Test bc and loop
ret
Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... nice, both the use of CPI, and the tweaking above. At ... /> ld hl, #byte_to_write
ld bc, #1024
loop2:
ldi ... "
jp pe, loop2 ; Test bc and loop
ret
Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... that doesn't show DEC BC/LD A,B/OR C ... . Whats the point of exploiting CPI when you do not know ...Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... that doesn't show DEC BC/LD A,B/OR C ... . Whats the point of exploiting CPI when you do not know ...mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
... ld hl,$stringstart
ld bc,$bytes
loop:
cpi
jp pe,loop
ld bc,$bytes
ld d,$ ... /> ld (hl),a
cpi
jp pe,loop
mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
... ld hl,StringAddress
ld bc,StringLength
.lp0
... /> ld (hl),a
cpi
jp pe,.lp0
ld bc,StringLength
.loop
... ld de,StringAddress
ld bc,StringLength
.lp0
...mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
This just sorta came up all of a sudden.
[code]InPlaceV2
ld hl,StringAddress
ld bc,StringLength
scf
.loop
rr (hl)
jr nc,.loop
cpi
jp pe,.loop
ret[/code]mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
... /> ld hl,StringAddress
ld bc,StringLength
scf
.loop ... )
jr nc,.loop
cpi
jp pe,.loop
mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
... /> ld hl,StringAddress
ld bc,StringLength
scf
.loop ... )
jr nc,.loop
cpi
jp pe,.loop
mirroring bitsIf I have a string of 1408 bytes, each of which has one bit 'b' set, what's the shortest way of mirroring that string, so that each bit set at positi…
... /> ld hl,StringAddress
ld bc,StringLength
scf
.loop ... )
jr nc,.loop
cpi
jp pe,.loop
Pac-Land: can be coloured?All versions of this game are full coloured, but not the Spectrum version. It has large sprites, but maybe the scroll is too fine to make a coloured …
... ;attribute area
LD BC,640 ;nr of chars < ... DE
CPI ;INC HL,DEC BC no change DE
BC=0
DrawBottomAttr ... bottom part
LD BC,160 ;nr of chars
CPI ;INC HL,DEC BC no change DE
LDI questionWhen using LDI (or LDD) is it possible to access the value that is transfered from (HL) to (DE), or does the Z80 use an internal data cache to store …
... .
PF flag Set if BC not 0.
SF, ZF ... 't work the same as CPI where the flags indicate if ... and Z flags like the CPI instruction does.Address bus contents (i.e. PC) during execution of HALTI'm wondering if anyone can tell me what's placed on the address bus during execution of HALT, beyond the initial M1 cycle. The Z80 user manual state…
... behaviour of the LDI and CPI instructions. As in this thread ... HL, the fifth is decrementing BC and PC.
So ...LDI questionWhen using LDI (or LDD) is it possible to access the value that is transfered from (HL) to (DE), or does the Z80 use an internal data cache to store …
... s interesting that LDI and CPI both take 16 T-states ... as the CPI instruction isn't having to ... the final M cycle of CPI. My guess is that ... OR output byte to (BC)
?? decrement BC (or B)
...
Now, where the decrement BC/B occurs I'm not ...
