bftool

#!/usr/bin/perl -sw
#RE tool, decodes hex into bitfield descriptions {pos,len}
#   supports disjoint bitfields
#   supports mixed 64bit and 32bit (in envydis's endianness) hex words
#   modes: and, or, xor (mask, diff)
#Examples:
#   find a diff between two OPs:
#        ./bftool -op=xor 8540dc00001c0002 8540dc00001c3c02
#     or ./bftool -op=xor 8540dc00001c0002 001c3c02 8540dc00
#     or ./bftool -op=xor 001c0002 8540dc00 001c3c02 8540dc00
#        > x: U8{0x8540dc00001c0002} U4{0x001c0002,0x8540dc00}
#          y: U8{0x8540dc00001c3c02} U4{0x001c3c02,0x8540dc00}
#          z: U8{0x0000000000003c00} U4{0x00003c00,0x00000000}
#          {pos,len} = {10,4} = {0xa,4}
#   find a match against a mask:
#        ./bftool -op=and 3fc0000000000000 8540dc00001c0002
#     or ./bftool -op=and 3fc0000000000000 001c0002 8540dc00
#     ...
#           U8{0x0540000000000000} U4{0x00000000,0x05400000}
#           54,1
#           56,1
#           58,1
use Data::Dumper;
no warnings "portable";
my $op = $op || "nop";
sub readhex{
    my $A = shift;
    my $x = shift(@$A);
    return undef if not defined($x);
    return hex($x) if(length($x)>8 or scalar(@$A)==0 or length($A->[0])>8);
    my $y = shift(@$A);
    return hex($x)|hex($y) << 32;
}
my $x = readhex(\@ARGV) || undef;
my $y = readhex(\@ARGV) || undef;
my $z = 0;
if($op eq "nop"){
    $z = $x;
}
elsif($op eq "and"){
    $z = $x & $y;
}
elsif($op eq "xor"){
    $z = $x ^ $y;
}
elsif($op eq "or"){
    $z = $x | $y;
}
print sprintf("x: U8{0x%016x} U4{0x%08x,0x%08x}\n",$x,$x&0xFFFFFFFF,($x>>32)&0xFFFFFFFF);
print sprintf("y: U8{0x%016x} U4{0x%08x,0x%08x}\n",$y,$y&0xFFFFFFFF,($y>>32)&0xFFFFFFFF);
print sprintf("z: U8{0x%016x} U4{0x%08x,0x%08x}\n",$z,$z&0xFFFFFFFF,($z>>32)&0xFFFFFFFF);
my $pos=0;
while($z!=0){
    while(($z&0x1) eq 0){
        $pos++;
        $z = $z >> 1;
    }
    my $len=0;
    while(($z&0x1) eq 1){
        $len++;
        $z = $z >> 1;
    }
    print sprintf("{pos,len} = {%d,%d} = {0x%x,%d}\n",$pos,$len,$pos,$len);
    $pos+=$len;
}