in process of implementing add/split

diff --git a/libvisor/include/visor.h b/libvisor/include/visor.h
index a9b3ec7..1e79aed 100644 (file)
--- a/libvisor/include/visor.h
+++ b/libvisor/include/visor.h
@@ -142,8 +142,11 @@ int vi_buf_read(struct vi_buffer *vb, const char *path);
 int vi_buf_write(struct vi_buffer *vb, const char *path);
 long vi_buf_size(struct vi_buffer *vb);
 
-/* find the span which corresponds to the specified text position */
-struct vi_span *vi_buf_find_span(struct vi_buffer *vb, vi_addr at);
+/* find the span which corresponds to the specified text position
+ * if soffs is not null, the relative offset of the specified address from the
+ * start of the span is stored there.
+ */
+struct vi_span *vi_buf_find_span(struct vi_buffer *vb, vi_addr at, vi_addr *soffs);
 const char *vi_buf_span_text(struct vi_buffer *vb, struct vi_span *span);
 
 void vi_buf_ins_begin(struct vi_buffer *vb, vi_motion mot);

diff --git a/libvisor/src/visor.c b/libvisor/src/visor.c
index cefc924..1f9804f 100644 (file)
--- a/libvisor/src/visor.c
+++ b/libvisor/src/visor.c
@@ -186,14 +186,37 @@ struct vi_buffer *vi_prev_buf(struct visor *vi)
  * It can't fail, because it's always called with the span array having at
  * least two empty slots (see: add_span).
  */
-void split_span(struct vi_buffer *vb, struct vi_span *sp, vi_addr at, unsigned long size)
+void split_span(struct vi_buffer *vb, struct vi_span *sp, vi_addr spoffs, unsigned long size)
 {
-       struct vi_span *tail = sp + (size ? 2 : 1);
+       int newseg = size > 0 ? 1 : 0;
+       struct vi_span *tail = sp + newseg + 1;
        int num_move = vb->spans + vb->num_spans - sp - 1;
 
-       memmove(tail + 1, sp + 1, num_move);
+       memmove(tail + 1, sp + 1, num_move * sizeof *sp);
        vb->num_spans += tail - sp;
 
+       *tail = *sp;
+       sp->size = spoffs;
+       tail->start += spoffs;
+       tail->size -= spoffs;
+
+       sp = tail;
+       for(;;) {
+               if(size <= tail->size) {
+                       tail->size -= size;
+                       break;
+               }
+               size -= tail->size;
+               tail->size = 0;
+               tail++;
+       }
+
+       if(tail > sp) {
+               /* we produced one or more zero-sized spans, drop them */
+               num_move = vb->spans + vb->num_spans - (tail - sp);
+               memmove(sp, tail, num_move * sizeof *sp);
+               vb->num_spans -= num_move;
+       }
 }
 
 static int add_span(struct vi_buffer *vb, vi_addr at, int src, vi_addr start, unsigned long size)
@@ -210,8 +233,12 @@ static int add_span(struct vi_buffer *vb, vi_addr at, int src, vi_addr start, un
                vb->max_spans = newmax;
        }
 
-       if((sp = vi_buf_find_span(vb, at))) {
-               split_span(vb, sp++, at, size);
+       if((sp = vi_buf_find_span(vb, at, &spoffs))) {
+               if(spoffs > 0) {
+                       split_span(vb, sp++, spoffs, 1);
+               } else {
+                       split_span(vb, sp++, 0, 0);
+               }
        } else {
                sp = vb->spans + vb->num_spans;
        }