Please disregard last message: I'm being stupid.
I wrote:
See I disagree about this...
Won't it be
[4]
[4]
Loop around:
{3},{1 WAIT} 4 cycles
{5},[3 of 5] 8 cycles
[2 of 5],[2 of 4] 4 cycles
[2 of 4], {2 WAIT} 4 cycles
Ignore me. I've missed a [4] out.
Geoff
Yes, I'm still harping on. Sorry :-)
Edwin wrote:
Like the Idea. So I looked a bit better at LDIR in ROM too.
LDIR is made up of 5 M-cycles:
4,4,3,5,5 for standard LDIR = 21T
4,4,3+1,5,5+2 LDIR in RAM with RAM contemption = 24T
4+4,4+4,3+5,5,5+6 LDIR in RAM with Display contemption = 40Ts
Edwin,
I have another question: On Spectrum, it was the basic asm knowledge that
JR
is shorter but slower than JP. But how does it work on Sam? I assume
(without any exact computation) that due to the contention, JR is probably
faster than JP in general cases. Am I right? (I consider
Edwin Blink wrote:
From: Geoff Winkless [EMAIL PROTECTED]
Without wishing to appear stupid (yeah, I know, too late, haha), I'm
still not clear why that's a memory access.
It's not. The delay is added there for convenience. But in fact it
will delay the next
opcode fetch (unless it is in
From: Geoff Winkless [EMAIL PROTECTED]
Please understand that I'm not trying to be awkward; I just don't
comprehend
the logic.
No prob. I hadn't looked this close on ROM Display contention before so it
is interesting to look into and discuss it, also a reminder to get on with a
Z80
T-States
@nvg.ntnu.no
Subject: Re: Fastest memory transfer (on Sam)
I already tried many LDI's and PUSH/POP system on my own, but
unfortunately the process of changing SP makes PUSH/POP slower than
sequence of LDI's.
The fastest scrollleft code I could think of is the folowing code snippet
which should
, February 01, 2005 1:48 PM
To: sam-users@nvg.ntnu.no
Subject: Re: Fastest memory transfer (on Sam)
I already tried many LDI's and PUSH/POP system on my own, but
unfortunately the process of changing SP makes PUSH/POP slower than
sequence of LDI's.
The fastest scrollleft code I could think
- Original Message -
From: Aley Keprt [EMAIL PROTECTED]
I originally though it's number of T-states, but POP must take at least
12T,
definitely not 4T.
Obviously a typing mistake :-)
here are some more timings for PUSH/POP:
PUSH qq (5,3,3) Standard =11Ts
PUSH qq (5+3,3+1,3+1) RAM
Incidentally, what are the 5 cycles for an LDIR?
It uses the same technique as used by relative jumps to add a value of -2
to PC.
so is it really the case that the z80 reads the (erroneous) next
instruction before doing PC-=2 (as
one source on the web suggested)?
I think that suggestion
Edwin Blink wrote:
Incidentally, what are the 5 cycles for an LDIR?
It uses the same technique as used by relative jumps to add a value
of -2 to PC.
Without wishing to appear stupid (yeah, I know, too late, haha), I'm still
not clear why that's a memory access.
I've found a more helpful
From: Geoff Winkless [EMAIL PROTECTED]
Without wishing to appear stupid (yeah, I know, too late, haha), I'm still
not clear why that's a memory access.
It's not. The delay is added there for convenience. But in fact it will
delay the next
opcode fetch (unless it is in rom but read below).
I can't remember if thats the case with Colins device he showed recently?Edwin Blink [EMAIL PROTECTED] wrote:
From: Geoff Winkless <[EMAIL PROTECTED]> Without wishing to appear stupid (yeah, I know, too late, haha), I'm still not clear why that's a memory access.It's not. The delay is added there
On Wed, 2005-02-02 at 19:11, Edwin Blink wrote:
I'd prefer a redesigned ASIC (with a few other fixes). I see little
advantage in
having a accelerator board Because the extra power is needed in handling
video memory. An accelerator board would have to wait just like the Z80
does.
A simple
I already tried many LDI's and PUSH/POP system on my own, but unfortunately
the process of changing SP makes PUSH/POP slower than sequence of LDI's.
The fastest scrollleft code I could think of is the folowing code snippet
which should be repeated 9*height times and
It's best to write a routine
Edwin Blink wrote:
The fastest scrollleft code I could think of is the folowing code snippet
which should be repeated 9*height times and
It's best to write a routine to generate it runtime and fill in the proper
SP values.
[snip]
It's 20% faster and takes 29% less space then LDI's.
BTW
From: Geoff Winkless [EMAIL PROTECTED]
Trying to think this through...
Like the Idea. So I looked a bit better at LDIR in ROM too.
LDIR is made up of 5 M-cycles:
4,4,3,5,5 for standard LDIR = 21T
4,4,3+1,5,5+2 LDIR in RAM with RAM contemption = 24T
4+4,4+4,3+5,5,5+6 LDIR in RAM with Display
Aley Keprt wrote:
I need to move (video) memory on Sam, what's the fastest routine?
Despite its unfinished state, the SimCoupe debugger can be used to time
blocks of code. Whenever you enter the debugger the T-diff value in the
bottom right of the display shows the number of _real_ tstates that
memory transfer (on Sam)
I need to move (video) memory on Sam, what's the fastest routine? I expect
it must utilize push pop instructions, since they take just 10T to move a
byte, but I am unsure what is exact look of the whole routine. Please can
somebody help me?
There is not a single fastest
how it will look on the real machine. (I will test
later.) ;-)
Aley
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Simon Owen
Sent: Monday, January 31, 2005 4:15 AM
To: sam-users@nvg.ntnu.no
Subject: RE: Fastest memory transfer (on Sam)
Aley Keprt wrote
wonder how it will look on the real
machine. (I will testlater.) ;-)Aley-Original
Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
On Behalf Of Simon OwenSent: Monday, January 31, 2005 4:15 AMTo:
sam-users@nvg.ntnu.noSubject: RE: Fastest memory transfer (on
Sam)Aley Keprt wrote: I
I need to move (video) memory on Sam, what's the fastest routine? I expect
it must utilize push pop instructions, since they take just 10T to move a
byte, but I am unsure what is exact look of the whole routine. Please can
somebody help me?
I need to move (video) memory on Sam, what's the fastest routine? I expect
it must utilize push pop instructions, since they take just 10T to move a
byte, but I am unsure what is exact look of the whole routine. Please can
somebody help me?
There is not a single fastest routine for everything.
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