Refine logic for removing superfluous P ops (still testing ...)

diff --git a/padding.c b/padding.c
index 033a7916237f94314bcf9661880a3fcde4604156..fe11da29e3bd285066fc3cb41cf80717c7b0cfc1 100644 (file)
--- a/padding.c
+++ b/padding.c
@@ -97,12 +97,16 @@ int bam_pad2unpad(bamFile in, bamFile out)
                                return -1;
                        }
                        unpad_seq(b, &q);
-                       if (bam_cigar_op(cigar[0]) == BAM_CSOFT_CLIP) write_cigar(cigar2, n2, m2, cigar[0]);
-                       if (bam_cigar_op(cigar[0]) == BAM_CHARD_CLIP) {
+                       if (bam_cigar_op(cigar[0]) == BAM_CSOFT_CLIP) {
+                               write_cigar(cigar2, n2, m2, cigar[0]);
+                       } else if (bam_cigar_op(cigar[0]) == BAM_CHARD_CLIP) {
                                write_cigar(cigar2, n2, m2, cigar[0]);
                                if (b->core.n_cigar > 2 && bam_cigar_op(cigar[1]) == BAM_CSOFT_CLIP) {
                                        write_cigar(cigar2, n2, m2, cigar[1]);
                                }
+                       } else {
+                               /* Insert a dummy 0M entry to let use remove superfluous leading P ops */
+                               write_cigar(cigar2, n2, m2, 0);
                        }
                        /* Include any pads if starts with an insert */
                        for (k = 0; k+1 < b->core.pos && !r.s[b->core.pos - k - 1]; ++k);
@@ -118,17 +122,34 @@ int bam_pad2unpad(bamFile in, bamFile out)
                                } else ++k;
                        }
                        write_cigar(cigar2, n2, m2, bam_cigar_gen(k, op));
-                       if (bam_cigar_op(cigar[b->core.n_cigar-1]) == BAM_CSOFT_CLIP) write_cigar(cigar2, n2, m2, cigar[b->core.n_cigar-1]);
-                        if (bam_cigar_op(cigar[b->core.n_cigar-1]) == BAM_CHARD_CLIP) {
+                       if (bam_cigar_op(cigar[b->core.n_cigar-1]) == BAM_CSOFT_CLIP) {
+                               write_cigar(cigar2, n2, m2, cigar[b->core.n_cigar-1]);
+                        } else if (bam_cigar_op(cigar[b->core.n_cigar-1]) == BAM_CHARD_CLIP) {
                                if (b->core.n_cigar > 2 && bam_cigar_op(cigar[b->core.n_cigar-2]) == BAM_CSOFT_CLIP) {
                                        write_cigar(cigar2, n2, m2, cigar[b->core.n_cigar-2]);
                                }
                                write_cigar(cigar2, n2, m2, cigar[b->core.n_cigar-1]);
                        }
-                       /* Remove redundant P operators between M operators, e.g. 5M2P10M -> 15M */
+                       /* Remove redundant P operators between M/X/=/D operators, e.g. 5M2P10M -> 15M */
+                       /* or right at the start before M/X/=/D */
+                       int pre_op, post_op;
                        for (i = 2; i < n2; ++i)
-                               if (bam_cigar_op(cigar2[i]) == BAM_CMATCH && bam_cigar_op(cigar2[i-1]) == BAM_CPAD && bam_cigar_op(cigar2[i-2]) == BAM_CMATCH)
-                                       cigar2[i] += cigar2[i-2], cigar2[i-2] = cigar2[i-1] = 0;
+                               if (bam_cigar_op(cigar2[i-1]) == BAM_CPAD) {
+                                       pre_op = bam_cigar_op(cigar2[i-2]);
+                                       post_op = bam_cigar_op(cigar2[i]);
+                                       /* Note don't need to check for X/= as code above will use M only */
+                                       if ((pre_op == BAM_CMATCH || pre_op == BAM_CDIFF || pre_op == BAM_CSOFT_CLIP || pre_op == BAM_CHARD_CLIP) || (post_op == BAM_CMATCH || post_op == BAM_CDIFF)) {
+                                               /* This is a redundant P operator */
+                                               cigar2[i-1] = 0; // i.e. 0M
+                                               /* If had same operator either side, combine them in post_op */
+                                               if (pre_op == post_op) {
+                                                       /* If CIGAR M, could treat as simple integers since BAM_CMATCH is zero*/
+                                                       cigar2[i] = bam_cigar_gen(bam_cigar_oplen(cigar2[i-2]) + bam_cigar_oplen(cigar2[i]), post_op);
+                                                       cigar2[i-2] = 0; // i.e. 0M
+                                               }
+                                       }
+                               }
+                       /* Remove the zero'd operators (0M) */
                        for (i = k = 0; i < n2; ++i)
                                if (cigar2[i]) cigar2[k++] = cigar2[i];
                        n2 = k;