diff --git a/htsutils.c b/htsutils.c
new file mode 100644
index 0000000..99460fe
--- /dev/null
+++ b/htsutils.c
@@ -0,0 +1,146 @@
+//
+//  htsutils.c
+//  PASSFinder
+//
+//  Created by Georgi Tushev on 07/09/16.
+//  Copyright © 2016 Scientific Computing. All rights reserved.
+//
+
+#include "htsutils.h"
+
+int parseBAM(char *file_name)
+{
+    samFile *fh_in = sam_open(file_name, "r");
+    bam_hdr_t *header = sam_hdr_read(fh_in);
+    bam1_t *bam = bam_init1();
+    
+    int lines = 0;
+    int poly = 0;
+    int polyTailA = 0;
+    int polyTailT = 0;
+    int polyHeadA = 0;
+    int polyHeadT = 0;
+    //int polyHead = 0;
+    
+    while (sam_read1(fh_in, header, bam) >= 0)
+    {
+        lines++;
+        
+        
+        polyTailA = findPoly(bam, 'A', POLY_TAIL);
+        polyTailT = findPoly(bam, 'T', POLY_TAIL);
+        polyHeadA = findPoly(bam, 'A', POLY_HEAD);
+        polyHeadT = findPoly(bam, 'T', POLY_HEAD);
+        
+        //printf("Tail: %d|%d\tHead: %d|%d\tSeq:: ", polyTailA,polyTailT,polyHeadA,polyHeadT);
+        //dumpBamSeq(bam);
+        //printf("\n");
+        
+        //if (lines == 10)
+        //    break;
+        
+    }
+    
+    bam_destroy1(bam);
+    bam_hdr_destroy(header);
+    sam_close(fh_in);
+    
+    //printf("BAM Lines: %d / %d\n", poly, lines);
+    
+    return 0;
+}
+
+/* dumpSeq
+ * return pointer to sequence in BAM file
+ */
+void dumpBamSeq(bam1_t *bam)
+{
+    int i;
+    
+    for (i = 0; i < bam->core.l_qseq; ++i)
+    {
+        printf("%c", seq_nt16_str[bam_seqi(bam_get_seq(bam),i)]);
+    }
+}
+
+
+/* findPoly
+ * modified findTailPolyAMaybeMask
+ * https://github.com/jstjohn/KentLib/blob/master/lib/dnautil.c
+ * Kent et.al., 2002
+ */
+int findPoly(bam1_t *bam, int base, int side)
+{
+    int i = 0;
+    
+    int currScore = 10;
+    int bestScore = 10;
+    
+    int currPosition = 0;
+    int bestPosition = -1;
+    
+    int polySize = 0;
+    
+    int smallBase = tolower(base);
+    int bigBase = toupper(base);
+    
+    char currBase = 'X';
+    
+    for (i = 0; i < bam->core.l_qseq; ++i)
+    {
+        // define current position based on sequence side
+        currPosition = i;
+        if (side == POLY_TAIL)
+            currPosition = bam->core.l_qseq - i - 1;
+        
+        // get current base from BAM
+        currBase = seq_nt16_str[bam_seqi(bam_get_seq(bam), currPosition)];
+        
+        // skip N match
+        if (currBase == 'N' || currBase == 'n')
+            continue;
+        
+        // compare to query base
+        if (currBase == bigBase || currBase == smallBase)
+        {
+            // add match score
+            currScore += 1;
+            
+            // update best score
+            if (currScore >= (bestScore - 6))
+            {
+                bestScore = currScore;
+                bestPosition = currPosition;
+            }
+        }
+        else
+        {
+            // add mismatch score
+            currScore -= 8;
+        }
+        
+        // break if score is negative
+        if (currScore < 0)
+            break;
+        
+        // cap if score is too big
+        if (currScore > 20)
+            currScore = 20;
+        
+    }
+    
+    /* assign result */
+    if (bestPosition >= 0)
+    {
+        polySize = bestPosition + 1;
+        
+        if (side == POLY_TAIL)
+            polySize = bam->core.l_qseq - bestPosition;
+        
+        if (polySize < 0)
+            polySize = 0;
+    }
+    
+    return polySize;
+}
+
diff --git a/htsutils.h b/htsutils.h
new file mode 100644
index 0000000..ed85c36
--- /dev/null
+++ b/htsutils.h
@@ -0,0 +1,24 @@
+//
+//  htsutils.h
+//  PASSFinder
+//
+//  Created by Georgi Tushev on 07/09/16.
+//  Copyright © 2016 Scientific Computing. All rights reserved.
+//
+
+#ifndef htsutils_h
+#define htsutils_h
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <htslib/sam.h>
+
+#define POLY_HEAD 0
+#define POLY_TAIL 1
+
+int parseBAM(char *);
+int findPoly(bam1_t *, int, int);
+void dumpBamSeq(bam1_t *);
+
+#endif /* htsutils_h */