Initial import.
diff --git a/src/libframe/frdelete.c b/src/libframe/frdelete.c
new file mode 100644
index 0000000..04ef6a0
--- /dev/null
+++ b/src/libframe/frdelete.c
@@ -0,0 +1,122 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <mouse.h>
+#include <frame.h>
+
+int
+frdelete(Frame *f, ulong p0, ulong p1)
+{
+ Point pt0, pt1, ppt0;
+ Frbox *b;
+ int n0, n1, n;
+ ulong cn1;
+ Rectangle r;
+ int nn0;
+ Image *col;
+
+ if(p0>=f->nchars || p0==p1 || f->b==nil)
+ return 0;
+ if(p1 > f->nchars)
+ p1 = f->nchars;
+ n0 = _frfindbox(f, 0, 0, p0);
+ if(n0 == f->nbox)
+ drawerror(f->display, "off end in frdelete");
+ n1 = _frfindbox(f, n0, p0, p1);
+ pt0 = _frptofcharnb(f, p0, n0);
+ pt1 = frptofchar(f, p1);
+ if(f->p0 == f->p1)
+ frtick(f, frptofchar(f, f->p0), 0);
+ nn0 = n0;
+ ppt0 = pt0;
+ _frfreebox(f, n0, n1-1);
+ f->modified = 1;
+
+ /*
+ * Invariants:
+ * - pt0 points to beginning, pt1 points to end
+ * - n0 is box containing beginning of stuff being deleted
+ * - n1, b are box containing beginning of stuff to be kept after deletion
+ * - cn1 is char position of n1
+ * - f->p0 and f->p1 are not adjusted until after all deletion is done
+ */
+ b = &f->box[n1];
+ cn1 = p1;
+ while(pt1.x!=pt0.x && n1<f->nbox){
+ _frcklinewrap0(f, &pt0, b);
+ _frcklinewrap(f, &pt1, b);
+ n = _frcanfit(f, pt0, b);
+ if(n==0)
+ drawerror(f->display, "_frcanfit==0");
+ r.min = pt0;
+ r.max = pt0;
+ r.max.y += f->font->height;
+ if(b->nrune > 0){
+ if(n != b->nrune){
+ _frsplitbox(f, n1, n);
+ b = &f->box[n1];
+ }
+ r.max.x += b->wid;
+ draw(f->b, r, f->b, nil, pt1);
+ cn1 += b->nrune;
+ }else{
+ r.max.x += _frnewwid0(f, pt0, b);
+ if(r.max.x > f->r.max.x)
+ r.max.x = f->r.max.x;
+ col = f->cols[BACK];
+ if(f->p0<=cn1 && cn1<f->p1)
+ col = f->cols[HIGH];
+ draw(f->b, r, col, nil, pt0);
+ cn1++;
+ }
+ _fradvance(f, &pt1, b);
+ pt0.x += _frnewwid(f, pt0, b);
+ f->box[n0++] = f->box[n1++];
+ b++;
+ }
+ if(n1==f->nbox && pt0.x!=pt1.x) /* deleting last thing in window; must clean up */
+ frselectpaint(f, pt0, pt1, f->cols[BACK]);
+ if(pt1.y != pt0.y){
+ Point pt2;
+
+ pt2 = _frptofcharptb(f, 32767, pt1, n1);
+ if(pt2.y > f->r.max.y)
+ drawerror(f->display, "frptofchar in frdelete");
+ if(n1 < f->nbox){
+ int q0, q1, q2;
+
+ q0 = pt0.y+f->font->height;
+ q1 = pt1.y+f->font->height;
+ q2 = pt2.y+f->font->height;
+ if(q2 > f->r.max.y)
+ q2 = f->r.max.y;
+ draw(f->b, Rect(pt0.x, pt0.y, pt0.x+(f->r.max.x-pt1.x), q0),
+ f->b, nil, pt1);
+ draw(f->b, Rect(f->r.min.x, q0, f->r.max.x, q0+(q2-q1)),
+ f->b, nil, Pt(f->r.min.x, q1));
+ frselectpaint(f, Pt(pt2.x, pt2.y-(pt1.y-pt0.y)), pt2, f->cols[BACK]);
+ }else
+ frselectpaint(f, pt0, pt2, f->cols[BACK]);
+ }
+ _frclosebox(f, n0, n1-1);
+ if(nn0>0 && f->box[nn0-1].nrune>=0 && ppt0.x-f->box[nn0-1].wid>=(int)f->r.min.x){
+ --nn0;
+ ppt0.x -= f->box[nn0].wid;
+ }
+ _frclean(f, ppt0, nn0, n0<f->nbox-1? n0+1 : n0);
+ if(f->p1 > p1)
+ f->p1 -= p1-p0;
+ else if(f->p1 > p0)
+ f->p1 = p0;
+ if(f->p0 > p1)
+ f->p0 -= p1-p0;
+ else if(f->p0 > p0)
+ f->p0 = p0;
+ f->nchars -= p1-p0;
+ if(f->p0 == f->p1)
+ frtick(f, frptofchar(f, f->p0), 1);
+ pt0 = frptofchar(f, f->nchars);
+ n = f->nlines;
+ f->nlines = (pt0.y-f->r.min.y)/f->font->height+(pt0.x>f->r.min.x);
+ return n - f->nlines;
+}
