text: #include	"lib9.h"
  #include	<bio.h>
  
  long
  Bread(Biobuf *bp, void *ap, long count)
  {
  	long c;
  	uchar *p;
  	int i, n, ic;
  
  	p = ap;
  	c = count;
  	ic = bp->icount;
  
  	while(c > 0) {
  		n = -ic;
  		if(n > c)
  			n = c;
  		if(n == 0) {
  			if(bp->state != Bractive)
  				break;
  			i = bp->iof(bp, bp->bbuf, bp->bsize);
  			if(i <= 0) {
  				bp->state = Bracteof;
  				if(i < 0) {
  					Berror(bp, "read error: %r");
  					bp->state = Binactive;
  				}
  				break;
  			}
  			bp->gbuf = bp->bbuf;
  			bp->offset += i;
  			if(i < bp->bsize) {
  				memmove(bp->ebuf-i, bp->bbuf, i);
  				bp->gbuf = bp->ebuf-i;
  			}
  			ic = -i;
  			continue;
  		}
  		memmove(p, bp->ebuf+ic, n);
  		c -= n;
  		ic += n;
  		p += n;
  	}
  	bp->icount = ic;
  	if(count == c && bp->state == Binactive)
  		return -1;
  	return count-c;
  }
  