Thread Hex to signed Integer (1/256) (9 answers)
Opened by JuMi2006 at 2012-09-17 11:15

FIFO
 2012-09-17 21:41
#161879 #161879
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2005-06-01
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Hi,

Deine Funktion (etwas gestrafft) gibt nicht immer das zurück, was Du angegeben hast (beachte 0xFFF0):

Code (perl): (dl )
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use strict;
use warnings;

while (<DATA>) {
    my ($hb, $lb) = split /\s+/;
    print "$hb $lb -> " . decode_d2b($hb, $lb) . "\n";
}

sub decode_d2b {
    my $hb = hex($_[0]);
    my $lb = hex($_[1]);

    if ($hb & 0x80) {
        return -( (~$hb & 255) + ((~$lb & 255) + 1)/256 );
    }
    else {
        return $hb + $lb/256;
    }
}

__DATA__
00 00 -> 0
00 01 -> 1/256
FF FF -> -1/256
FF F0 -> -1
80 00 -> -128
80 01 -> -127,996
7F FF -> 127,996


Ausgabe:

Code: (dl )
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00 00 -> 0
00 01 -> 0.00390625
FF FF -> -0.00390625
FF F0 -> -0.0625
80 00 -> -128
80 01 -> -127.99609375
7F FF -> 127.99609375


Editiert von FIFO: Bitmaske auf Zw.-Komplement korrigiert
Last edited: 2012-09-17 22:59:34 +0200 (CEST)
Everyone knows that debugging is twice as hard as writing a program in the first place. So if you're as clever as you can be when you write it, how will you ever debug it? -- Brian Kernighan: "The Elements of Programming Style"

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