--- /dev/null
+#!/usr/bin/perl -w
+
+use strict;
+use warnings;
+use Getopt::Std;
+
+&blast2sam;
+
+sub blast2sam {
+ my %opts = ();
+ getopts('s', \%opts);
+ die("Usage: blast2sam.pl <in.blastn>\n") if (-t STDIN && @ARGV == 0);
+ my ($qlen, $slen, $q, $s, $qbeg, $qend, @sam, @cigar, @cmaux, $show_seq);
+ $show_seq = defined($opts{s});
+ @sam = (); @sam[0,4,6..8,10] = ('', 255, '*', 0, 0, '*');
+ while (<>) {
+ if (@cigar && (/^Query=/ || /Score =.*bits.*Expect/)) { # print
+ &blast_print_sam(\@sam, \@cigar, \@cmaux, $qlen - $qend);
+ @cigar = ();
+ }
+ if (/^Query= (\S+)/) {
+ $sam[0] = $1;
+ } elsif (/\((\S+)\s+letters\)/) {
+ $qlen = $1; $qlen =~ s/,//g;
+ } elsif (/^>(\S+)/) {
+ $sam[2] = $1;
+ } elsif (/Length = (\d+)/) {
+ $slen = $1;
+ } elsif (/Score =\s+(\S+) bits.+Expect(\(\d+\))? = (\S+)/) { # the start of an alignment block
+ my ($as, $ev) = (int($1 + .499), $3);
+ $ev = "1$ev" if ($ev =~ /^e/);
+ @sam[1,3,9,11,12] = (0, 0, '', "AS:i:$as", "EV:Z:$ev");
+ @cigar = (); $qbeg = 0;
+ @cmaux = (0, 0, 0, '');
+ } elsif (/Strand = (\S+) \/ (\S+)/) {
+ $sam[1] |= 0x10 if ($2 eq 'Minus');
+ } elsif (/Query\:\s(\d+)\s*(\S+)\s(\d+)/) {
+ $q = $2;
+ unless ($qbeg) {
+ $qbeg = $1;
+ push(@cigar, ($1-1) . "H") if ($1 > 1);
+ }
+ $qend = $3;
+ if ($show_seq) {
+ my $x = $q;
+ $x =~ s/-//g; $sam[9] .= $x;
+ }
+ } elsif (/Sbjct\:\s(\d+)\s*(\S+)\s(\d+)/) {
+ $s = $2;
+ if ($sam[1] & 0x10) {
+ $sam[3] = $3;
+ } else {
+ $sam[3] = $1 unless ($sam[3]);
+ }
+ &aln2cm(\@cigar, \$q, \$s, \@cmaux);
+ }
+ }
+ &blast_print_sam(\@sam, \@cigar, \@cmaux, $qlen - $qend);
+}
+
+sub blast_print_sam {
+ my ($sam, $cigar, $cmaux, $qrest) = @_;
+ push(@$cigar, $cmaux->[1] . substr("MDI", $cmaux->[0], 1));
+ push(@$cigar, $qrest . 'H') if ($qrest);
+ if ($sam->[1] & 0x10) {
+ @$cigar = reverse(@$cigar);
+ $sam->[9] = reverse($sam->[9]);
+ $sam->[9] =~ tr/atgcrymkswATGCRYMKSW/tacgyrkmswTACGYRKMSW/;
+ }
+ $sam->[9] = '*' if (!$sam->[9]);
+ $sam->[5] = join('', @$cigar);
+ print join("\t", @$sam), "\n";
+}
+
+sub aln2cm {
+ my ($cigar, $q, $s, $cmaux) = @_;
+ my $l = length($$q);
+ for (my $i = 0; $i < $l; ++$i) {
+ my $op;
+ # set $op
+ if (substr($$q, $i, 1) eq '-') { $op = 2; }
+ elsif (substr($$s, $i, 1) eq '-') { $op = 1; }
+ else { $op = 0; }
+ # for CIGAR
+ if ($cmaux->[0] == $op) {
+ ++$cmaux->[1];
+ } else {
+ push(@$cigar, $cmaux->[1] . substr("MDI", $cmaux->[0], 1));
+ $cmaux->[0] = $op; $cmaux->[1] = 1;
+ }
+ }
+}