ustream: tweak ustream_prepare_buf() a bit.

No functional change.

 - Reuse existing NULL check on buf.
 - Add some comments for ease of reading the code.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
This commit is contained in:
Yousong Zhou 2015-06-04 21:41:40 +08:00 committed by Felix Fietkau
parent 791a361ad1
commit 9386d0717a

View file

@ -145,21 +145,26 @@ static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *
int maxlen; int maxlen;
int offset; int offset;
/* nothing to squeeze */
if (buf->data == buf->head) if (buf->data == buf->head)
return false; return false;
maxlen = buf->end - buf->head; maxlen = buf->end - buf->head;
offset = buf->data - buf->head; offset = buf->data - buf->head;
/* less than half is available */
if (offset > maxlen / 2) if (offset > maxlen / 2)
return true; return true;
/* less than 32 bytes data but takes more than 1/4 space */
if (buf->tail - buf->data < 32 && offset > maxlen / 4) if (buf->tail - buf->data < 32 && offset > maxlen / 4)
return true; return true;
/* more buf is already in list or can be allocated */
if (buf != l->tail || ustream_can_alloc(l)) if (buf != l->tail || ustream_can_alloc(l))
return false; return false;
/* no need to move if len is available at the tail */
return (buf->end - buf->tail < len); return (buf->end - buf->tail < len);
} }
@ -255,13 +260,14 @@ static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, i
if (l == &s->r) if (l == &s->r)
ustream_fixup_string(s, buf); ustream_fixup_string(s, buf);
} }
/* some chunks available at the tail */
if (buf->tail != buf->end) if (buf->tail != buf->end)
return true; return true;
} /* next buf available */
if (buf->next) {
if (buf && buf->next) { l->data_tail = buf->next;
l->data_tail = buf->next; return true;
return true; }
} }
if (!ustream_can_alloc(l)) if (!ustream_can_alloc(l))