Re^5: Displaying bit-vectors with Most Significant Bits to the left?

> Each of the snippets I posted produces the same output on both little-endian and big-endian machines

I believe you, but how do you reliably check the output?

And what does "same output" exactly mean?

I did machine programming on big-endian architectures, I don't know what to trust anymore.

Do I need to check with Devel::Peek to be sure?

Cheers Rolf
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Comment on Re^5: Displaying bit-vectors with Most Significant Bits to the left?

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Re^6: Displaying bit-vectors with Most Significant Bits to the left? by ikegami (Patriarch) on Jan 07, 2020 at 18:47 UTC
I believe you, but how do you reliably check the output? Whether using `vec`, `pack` or some other means, there are two ways: Reading the documentation, or testing experimentally on the appropriate machines. And what does "same output" exactly mean? For the code in Re: Displaying bit-vectors with Most Significant Bits to the left?, the topic was producing `0000011100000101` from `$m0`. For the code in Re^2: Displaying bit-vectors with Most Significant Bits to the left?, the topic was producing a string consisting of the byte 0b00000111 followed by the byte 0b00000101. I did machine programming on big-endian architectures, I don't know what to trust anymore. Do I need to check with Devel::Peek to be sure? Check what? If `pack` or `vec` produced the expected strings? `Devel::Peek::Dump` would be too noisy. I'd use one of the following: `sprintf "%v02X", $bytes unpack 'H', $bytes` [download] For example, `$ perl -e' for my $format (qw( n v )) { my $bytes = pack($format, 0x1234); CORE::say sprintf "%v02X", $bytes; CORE::say unpack "H", $bytes; } ' 12.34 1234 34.12 3412` [download]	[reply] [d/l] [select]

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Re^6: Displaying bit-vectors with Most Significant Bits to the left?
by ikegami (Patriarch) on Jan 07, 2020 at 18:47 UTC

I believe you, but how do you reliably check the output?

Whether using vec, pack or some other means, there are two ways: Reading the documentation, or testing experimentally on the appropriate machines.

And what does "same output" exactly mean?

For the code in Re: Displaying bit-vectors with Most Significant Bits to the left?, the topic was producing 0000011100000101 from $m0.

For the code in Re^2: Displaying bit-vectors with Most Significant Bits to the left?, the topic was producing a string consisting of the byte 0b00000111 followed by the byte 0b00000101.

I did machine programming on big-endian architectures, I don't know what to trust anymore. Do I need to check with Devel::Peek to be sure?

Check what? If pack or vec produced the expected strings? Devel::Peek::Dump would be too noisy. I'd use one of the following:

sprintf "%v02X", $bytes

unpack 'H*', $bytes
[download]

For example,

$ perl -e'
   for my $format (qw( n v )) {
      my $bytes = pack($format, 0x1234);
      CORE::say sprintf "%v02X", $bytes;
      CORE::say unpack "H*", $bytes;
   }
'
12.34
1234
34.12
3412
[download]

[reply]
[d/l]
[select]