Mailman 3 wordlength etc - Distutils-SIG

wordlength etc

Robin Becker

29 Jun 2003 29 Jun '03

4:17 p.m.

Are there standard ways to determine things like wordlength etc in distutils? I suppose one can use sys.maxint, but I thought this might be a standard kind of requirement now that we're slipping from 32 to 64 bits. -- Robin Becker

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M.-A. Lemburg

29 Jun 29 Jun

6:49 p.m.

Robin Becker wrote:

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Are there standard ways to determine things like wordlength etc in distutils?

I suppose one can use sys.maxint, but I thought this might be a standard kind of requirement now that we're slipping from 32 to 64 bits.

I'd use the struct module for these things. -- Marc-Andre Lemburg eGenix.com Professional Python Software directly from the Source (#1, Jun 29 2003)

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Python/Zope Products & Consulting ... http://www.egenix.com/ mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/

Robin Becker

8 p.m.

In article <3EFF188F.3020607@lemburg.com>, M.-A. Lemburg writes

...

Robin Becker wrote:

...
Are there standard ways to determine things like wordlength etc in distutils?

I suppose one can use sys.maxint, but I thought this might be a standard kind of requirement now that we're slipping from 32 to 64 bits.

I'd use the struct module for these things.

So we assume struct units are 8 bits and then use calcsize("i")*8 as the wordlength. -- Robin Becker

M.-A. Lemburg

8:14 p.m.

Robin Becker wrote:

...

In article <3EFF188F.3020607@lemburg.com>, M.-A. Lemburg writes

...
Robin Becker wrote:

...
Are there standard ways to determine things like wordlength etc in distutils?

I suppose one can use sys.maxint, but I thought this might be a standard kind of requirement now that we're slipping from 32 to 64 bits.

I'd use the struct module for these things.

So we assume struct units are 8 bits and then use calcsize("i")*8 as the wordlength.

sizeofint = len(struct.pack('i',1)) -- Marc-Andre Lemburg eGenix.com Professional Python Software directly from the Source (#1, Jun 29 2003)

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Python/Zope Products & Consulting ... http://www.egenix.com/ mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/

Jeremy Hylton

30 Jun 30 Jun

9:52 p.m.

On Sun, 2003-06-29 at 14:14, M.-A. Lemburg wrote:

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So we assume struct units are 8 bits and then use calcsize("i")*8 as the wordlength.

sizeofint = len(struct.pack('i',1))

Why not sizeofint = struct.calcsize("i") ? Jeremy

M.-A. Lemburg

10:14 p.m.

Jeremy Hylton wrote:

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On Sun, 2003-06-29 at 14:14, M.-A. Lemburg wrote:

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So we assume struct units are 8 bits and then use calcsize("i")*8 as the wordlength.

sizeofint = len(struct.pack('i',1))

Why not

sizeofint = struct.calcsize("i")

?

Even better :-) -- Marc-Andre Lemburg eGenix.com Professional Python Software directly from the Source (#1, Jun 30 2003)

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Python/Zope Products & Consulting ... http://www.egenix.com/ mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/

Robin Becker

1 Jul 1 Jul

12:27 a.m.

In article <3F009A40.1040303@lemburg.com>, M.-A. Lemburg writes

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Jeremy Hylton wrote:

...
On Sun, 2003-06-29 at 14:14, M.-A. Lemburg wrote:

...
...
So we assume struct units are 8 bits and then use calcsize("i")*8 as the wordlength.

sizeofint = len(struct.pack('i',1))

Why not

sizeofint = struct.calcsize("i")

?

Even better :-)

well if I wish to store 4 bits/int then this works

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import struct print struct.calcsize("i") 4

but I assume we can store more than 4 bits per int, so waht tells us we cans store 8 bits/struct unit? -- Robin Becker

M.-A. Lemburg

9:14 a.m.

Robin Becker wrote:

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sizeofint = struct.calcsize("i")

well if I wish to store 4 bits/int then this works

s/bits/bytes calcsize returns the number of 8-bit characters the format string needs to store the given C types.

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import struct print struct.calcsize("i")

4

but I assume we can store more than 4 bits per int, so waht tells us we cans store 8 bits/struct unit?

characters map to 8 bits == 1 byte and it's rather unlikely that a C compiler will use a different mapping any time soon. -- Marc-Andre Lemburg eGenix.com Professional Python Software directly from the Source (#1, Jul 01 2003)

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Python/Zope Products & Consulting ... http://www.egenix.com/ mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/

Robin Becker

10 a.m.

In article <3F0134E4.10907@lemburg.com>, M.-A. Lemburg writes ......

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characters map to 8 bits == 1 byte and it's rather unlikely that a C compiler will use a different mapping any time soon.

that's what I thought, but it's wise to be sure, and though I suppose there are few Pdp-18's or CDC 6000's running these days, it doesn't seem unreasonable given the changes over the last 20 years that unicode of 16/32 bits might become more acceptable as a 'char unit'. -- Robin Becker

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