Thank you,
That is a clear and flexible solution. First I thought that I could
write a 32 bit mapped file from 64 bit system to be directly shared
by 32 bit J. However this is sufficient for me, to transport data
between 32bit and 64bit..
Anssi
At 20:40 8.8.2007, you wrote:
Mapped files of integers can not be shared directly
between j32 and j64, because (as you pointed out)
an integer is 4 bytes in j32 but 8 bytes in j64.
You can use the 3!:x verbs to convert between the
two types of integers. A "limit error" is signalled
on attempting to convert a 8-byte integer to a
4-byte integer which is too large for 4 bytes.
Converting from 4 byte integers to 8 byte integers
will always succeed (space permitting).
The following examples were executed on j32.
The examples use 3!:3 for illustration. In actual
use 3!:1 with a left argument that respects the
byte order of the underlying machine would be
more efficient.
] x=: 5 [EMAIL PROTECTED] 100
63 92 51 92 39
] t64=: 2 (3!:3) x
e200000000000000
0000000000000004
0000000000000005
0000000000000001
0000000000000005
000000000000003f
000000000000005c
0000000000000033
000000000000005c
0000000000000027
3!:2 t64
63 92 51 92 39
] t64a=: 'f' (<8;0)}t64
e200000000000000
0000000000000004
0000000000000005
0000000000000001
0000000000000005
000000000000003f
000000000000005c
0000000000000033
f00000000000005c
0000000000000027
3!:2 t64a
|limit error
| 3!:2 t64a
----- Original Message -----
From: Anssi Seppälä <[EMAIL PROTECTED]>
Date: Tuesday, August 7, 2007 23:19
Subject: [Jprogramming] Sharing mapped file between 64bit and 32bit J
To: Programming forum <[email protected]>
> I am studying methods to share data between 32 and 64 bit J. The
> jfiles seem to work fine, but mapped files are different because
> the
> intergers are 4 and 8 bytes. I wonder it is possible to
> convert in a
> 64 bit J integers to 32 bit representation and write to a mapped
> file
> and vice versa. I wonder if this reasonable idea and how the
> conversion is best to do?
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