diff --git a/htsutils.c b/htsutils.c
index 99460fe..4bdede6 100644
--- a/htsutils.c
+++ b/htsutils.c
@@ -8,35 +8,45 @@
 
 #include "htsutils.h"
 
-int parseBAM(char *file_name)
+int parseBAM(Settings *props)
 {
-    samFile *fh_in = sam_open(file_name, "r");
+    samFile *fh_in = sam_open(props->input, "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;
+    
+    uint32_t polyBasePosition = 0;
     
     while (sam_read1(fh_in, header, bam) >= 0)
     {
+        // filter based on MAPQ
+        if (props->mapq > bam->core.qual)
+            continue;
+        
+        // define strand specific base
+        if (bam->core.flag & BAM_FREVERSE)
+        {
+            polyHeadT = findPoly(bam, 'T', POLY_HEAD);
+            polyBasePosition = bam->core.pos;
+        }
+        else
+        {
+            polyTailA = findPoly(bam, 'A', POLY_TAIL);
+            polyBasePosition = bam_calend(&bam->core, bam_get_cigar(bam));
+        }
+        
         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)
+        //if (lines == 20)
         //    break;
         
     }
@@ -144,3 +154,14 @@ int findPoly(bam1_t *bam, int base, int side)
     return polySize;
 }
 
+
+/* bam_calend
+ * Calculate the rightmost coordinate of an alignment on the reference genome.
+ * bam.h https://github.com/samtools/samtools/search?utf8=%E2%9C%93&q=bam_calend
+ */
+
+static inline uint32_t bam_calend(const bam1_core_t *c, const uint32_t *cigar)
+{
+    return c->pos + (c->n_cigar ? bam_cigar2rlen(c->n_cigar, cigar) : 1);
+}
+
diff --git a/htsutils.h b/htsutils.h
index ed85c36..ecd99a9 100644
--- a/htsutils.h
+++ b/htsutils.h
@@ -13,12 +13,15 @@
 #include <stdlib.h>
 #include <ctype.h>
 #include <htslib/sam.h>
+#include "config.h"
 
 #define POLY_HEAD 0
 #define POLY_TAIL 1
 
-int parseBAM(char *);
+int parseBAM(Settings *);
 int findPoly(bam1_t *, int, int);
 void dumpBamSeq(bam1_t *);
 
+static inline uint32_t bam_calend(const bam1_core_t *, const uint32_t *);
+
 #endif /* htsutils_h */