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Can a guy that traveled on the short bus learn machine code...Hmmm So after some soul searching I figured it was time to finaly nail spectrum machine code. Its so frustrating to sit infront of a basic listing w…
How can I check the state of the flag register?
Example the zero flag.
Is this only possible with JP opps? -
Can a guy that traveled on the short bus learn machine code...Hmmm So after some soul searching I figured it was time to finaly nail spectrum machine code. Its so frustrating to sit infront of a basic listing w…
Can a guy that traveled on the short bus learn machine code...Hmmm So after some soul searching I figured it was time to finaly nail spectrum machine code. Its so frustrating to sit infront of a basic listing w…
... have the whole of the flag register contents right?[/QUOTE]
The jr nz (Non Zero) tests the zero flag, and jumps back to ... 6, e ; bit 6 = Z flag.
jr nz, loop ; If ...Can a guy that traveled on the short bus learn machine code...Hmmm So after some soul searching I figured it was time to finaly nail spectrum machine code. Its so frustrating to sit infront of a basic listing w…
... /> The jr nz (Non Zero) tests the zero flag, and jumps back to ... 6, e ; bit 6 = Z flag.
jr nz, loop ; If ...Compiler conventions for passing args/return valuesI've been mulling over this for a while, but I can't spot it covered anywhere. There are various methods for passing args and return values between …
... state of the carry flag when the function returns? ...
Sure. The carry flag (well, all the flags) are ... to a consistent carry flag state makes things slower ... is >= where the zero flag needs to be taken ... value using the carry flag state and more often ...Compiler conventions for passing args/return valuesI've been mulling over this for a while, but I can't spot it covered anywhere. There are various methods for passing args and return values between …
... ]
Sure. The carry flag (well, all the flags) ... is >= where the zero flag needs to be taken into ... need to complement the flag in the function. This ... the result to test for zero on an integer.
... be the carry flag, sometimes the Z flag, sometimes a ...What would be the simplest tape loading routine?I'm searching for some small assembly snippet I can use to load a (headerless or not) block from tape into RAM I can embed in my C games to load furt…
... INC D This resets the zero flag. (D
cannot ... br /> CP A Set the zero flag.
The ... is an error. The zero flag then signals 'BREAK pressed' ...What would be the simplest tape loading routine?I'm searching for some small assembly snippet I can use to load a (headerless or not) block from tape into RAM I can embed in my C games to load furt…
... interrupts
inc d ; reset zero flag
ex af, af' ; A ... =on)
cp a ; set zero flag
org 0x056b
or d ; zero
jr nz, ld_loop ; jump ...
cp 1 ; set carry flag on zero
ret ; end of ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... /> bit 7, b ; set zero flag for second pass
ld ... interrupts
inc d ; reset zero flag
ex af, af' ... on)
cp a ; set zero flag
org 0x056b ... cp 1 ; set carry flag on zero
ret ; end of ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... IX
scf ; set carry flag
ld a, 0xff ; signal ... , hl ; switch pointers and set zero flag for
inc a ; replacement ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... bit 7, c ; set zero flag for a positive number
... ; leading
inc c ; zero?
jr nz, pf_test_2 ; jump ... /> ld a, '0' ; zero
djnz pf_dec_0s ; loop until ... /> bit 7, (hl) ; set zero flag for positive
set 7 ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... argument
and a ; both zero?
jp z, _get_char ; jump ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... zero
jp c, tokenizer_1 ; jump if carry flag ... :
cp a ; set zero flag
org 0x1c11 ... ) ; exclusive or with p-flag
and %10101010 ; ... calculator
fstk0 ; stack zero
fce ; exit calculator ...SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…
... _vdu_flag), d ; restore VDU flag
ret ; and return ... :
cp a ; clear zero flag
ret ; end of ... and a ; clear carry flag
ret ; end of ... hl, p_flag ; address p-flag
jp co_change ; immediate ...Ending a DJNZ loop prematurelyHow do you exit a DJNZ loop before its finished, I've tried loading b with zero but cant get it to stop.
... loop by. Even by the Zero-flag since DJNZ will NOT set ...Ending a DJNZ loop prematurelyHow do you exit a DJNZ loop before its finished, I've tried loading b with zero but cant get it to stop.
... by the Zero-flag since DJNZ will NOT set the zero flag!![/QUOTE]
Ending a DJNZ loop prematurelyHow do you exit a DJNZ loop before its finished, I've tried loading b with zero but cant get it to stop.
... needed. The condition of your flag can be reused without ANY ... , OUTINLOOP ; test was done on ZERO-flag!
BIS0:
NOP ; other ...Ending a DJNZ loop prematurelyHow do you exit a DJNZ loop before its finished, I've tried loading b with zero but cant get it to stop.
... needed. The condition of your flag can be reused without ANY ... , OUTINLOOP ; test was done on ZERO-flag!
BIS0:
NOP ; other ... , if ROUTINE conveniently sets a flag one way or another before ...z80 less than and greater thanI am writing a keyboard routine where the pressed key code number is held in A. I only want to action the number key presses 1 to 9 (codes 49-57) so …
JP Z,loop
for zero flag
JP NZ.loop
for non-zero flag
There are 2 ways of reading the keyboard too, I just use the machine code way which is more reliable.RLD - zero-flag resultI have very rarely found need to use the RLD instruction, well, actually just this once, but everything I can find on it says that the zero-flag is s…
... on it says that the zero-flag is set "to reflect the ... be whether the accumulator is zero or not after the action ... is set if Accumulator is zero after operation; reset otherwise40 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…
... , af' ; restore carry flag
push af ; ... get carry flag
ccf ; swap carry flag
... ;
; f - zero flag set to draw low nibble ...(Collected) Darkhog's noob question about z80 assemblySince when I'm learning new language or library, I tend to ask lots of stupid (for any advanced person) questions and I don't want it to have mess up…
... 25. If A = 25, the zero flag is set
JP Z ... , SOMELABEL ; if the zero flag is set, jump to SOMELABEL ...Saving and loading data in assembly.I want to add a save and load feature to an project I'm working on. Since it's not that much data in size I thought I'd use the ROM functions, but ho…
...
scf ; 4t - set carry flag for error checking
call ...
scf ; 4t - set carry flag for error checking
;; following ...
inc d ; 4t - resets zero flag
ex af,af' ; 4t ...Why doesnt this work???Simple piece of code wont do as it should, just want to fill the top 22 lines of screen with an attribute value (150) but it wont have any of it. Som…
So loading A with B and OR-ing it with C is basically OR-ing the hi and lo bytes of BC?
And the only time that can be a zero flag result is when BC reaches zero yeah?Why doesnt this work???Simple piece of code wont do as it should, just want to fill the top 22 lines of screen with an attribute value (150) but it wont have any of it. Som…
[quote="daveysludge;880860"]So loading A with B and OR-ing it with C is basically OR-ing the hi and lo bytes of BC?
And the only time that can be a zero flag result is when BC reaches zero yeah?[/quote]
Exactly.Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
... action depending on particular flag state. And another ... but also sets [b]zero flag[/b] to 1 ... does a jump if zero flag is not set. ... BC doesn't influence zero flag[/b] Don't ask ... =0 and correctly set zero flag we do
... NZ which tests zero flag as I said earlier ...Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
... ]DEC BC doesn't influence zero flag[/b] Don't ask me ...A few questions about sound and keys in BASICIf I want sound in my BASIC game I have to use BEEP right ? It seems to lock up the CPU for far too long . On Arjun's page I found how to use CALL 94…
... the DE register and the Zero flag indicate which keys are being ... pressed.
. The Zero flag is reset if pressing more ... of the keys.
. The Zero flag is set otherwise, and DE ...
