OpenEuphoria

Re: peek/poke

• Posted by Brian Broker <bkb at CNW.COM> Mar 27, 2000
• 626 views

On Mon, 27 Mar 2000 14:44:13 -0500, Everett Williams wrote:

>On Mon, 27 Mar 2000 14:14:05 -0600, Kat wrote:
>
>>I have a question too!
>>Since we have:
>>s = peek({100, 4})
>>where 4 memory locations (100,101,102,103) are read and dropped into s,
>>where is the corresponding poke command? What if i want to poke a 80K
>>sequence into memory? Can i do:
>>poke(s,{location,length(s)})
>>, where each byte of s lands in the next memory location? What if s
contains
>>nested sequences? It's not in the docs that i can find. What if i want
each
>>char of s to land in the *same* memory addy?
>>
>>Kat
>
>Kat, unless I have completely misread the manual, there is no length
>parameter in either poke or poke4. s in your equation must be an atom,
>not a sequence. The length of the sequence will determine the length
>of the poke.So, you should check the length of the available allocation
>from the point of the poke against the length of the sequence before
>you start the process. Since nothing in Euphoria that is exposed keeps
>track of that remaining length, it is, as usual, an exercise for the user.
>That is why, IMO, the examples use an offset rather than changing the
>address...it makes the available length more obvious. As for nesting,
>another exercise to be tested by the user( I really am not against an
>improved manual   )

I think you both need to re-read the manual:

peek:
=====
Syntax: i = peek(a)
or ...
s = peek({a, i})
Description: Return a single byte value in the range 0 to 255 from machine
address a, or return a sequence containing i consecutive byte values
starting at address a in memory.

(This means you can read a single byte, or consecutive bytes.)

poke:
=====
Syntax: poke(a, x)
Description: If x is an atom, write a single byte value to memory address a.
If x is a sequence, write a sequence of byte values to consecutive memory
locations starting at location a.

(This means you can poke a single byte, or consective bytes.)

>>What if i want each
>>char of s to land in the *same* memory addy?

I have no idea why you would want to do this but you could set up a 'for'
loop and poke the contents of a sequence to the same address.  (or save
yourself the trouble and just poke the last element of the sequence since
that is what the end result will be).

I don't see how the manual could be more clear about the usage of peek and
poke...  It seems quite straight-forward to me.

-- Brian