text: /*-
   *   BSD LICENSE
   *
   *   Copyright (c) Intel Corporation.
   *   All rights reserved.
   *
   *   Redistribution and use in source and binary forms, with or without
   *   modification, are permitted provided that the following conditions
   *   are met:
   *
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in
   *       the documentation and/or other materials provided with the
   *       distribution.
   *     * Neither the name of Intel Corporation nor the names of its
   *       contributors may be used to endorse or promote products derived
   *       from this software without specific prior written permission.
   *
   *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "spdk/util.h"
  
  size_t
  spdk_ioviter_first(struct spdk_ioviter *iter,
  		   struct iovec *siov, size_t siovcnt,
  		   struct iovec *diov, size_t diovcnt,
  		   void **src, void **dst)
  {
  	iter->siov = siov;
  	iter->siovcnt = siovcnt;
  
  	iter->diov = diov;
  	iter->diovcnt = diovcnt;
  
  	iter->sidx = 0;
  	iter->didx = 0;
  	iter->siov_len = siov[0].iov_len;
  	iter->siov_base = siov[0].iov_base;
  	iter->diov_len = diov[0].iov_len;
  	iter->diov_base = diov[0].iov_base;
  
  	return spdk_ioviter_next(iter, src, dst);
  }
  
  size_t
  spdk_ioviter_next(struct spdk_ioviter *iter, void **src, void **dst)
  {
  	size_t len = 0;
  
  	if (iter->sidx == iter->siovcnt ||
  	    iter->didx == iter->diovcnt ||
  	    iter->siov_len == 0 ||
  	    iter->diov_len == 0) {
  		return 0;
  	}
  
  	*src = iter->siov_base;
  	*dst = iter->diov_base;
  	len = spdk_min(iter->siov_len, iter->diov_len);
  
  	if (iter->siov_len == iter->diov_len) {
  		/* Advance both iovs to the next element */
  		iter->sidx++;
  		if (iter->sidx == iter->siovcnt) {
  			return len;
  		}
  
  		iter->didx++;
  		if (iter->didx == iter->diovcnt) {
  			return len;
  		}
  
  		iter->siov_len = iter->siov[iter->sidx].iov_len;
  		iter->siov_base = iter->siov[iter->sidx].iov_base;
  		iter->diov_len = iter->diov[iter->didx].iov_len;
  		iter->diov_base = iter->diov[iter->didx].iov_base;
  	} else if (iter->siov_len < iter->diov_len) {
  		/* Advance only the source to the next element */
  		iter->sidx++;
  		if (iter->sidx == iter->siovcnt) {
  			return len;
  		}
  
  		iter->diov_base += iter->siov_len;
  		iter->diov_len -= iter->siov_len;
  		iter->siov_len = iter->siov[iter->sidx].iov_len;
  		iter->siov_base = iter->siov[iter->sidx].iov_base;
  	} else {
  		/* Advance only the destination to the next element */
  		iter->didx++;
  		if (iter->didx == iter->diovcnt) {
  			return len;
  		}
  
  		iter->siov_base += iter->diov_len;
  		iter->siov_len -= iter->diov_len;
  		iter->diov_len = iter->diov[iter->didx].iov_len;
  		iter->diov_base = iter->diov[iter->didx].iov_base;
  	}
  
  	return len;
  }
  
  size_t
  spdk_iovcpy(struct iovec *siov, size_t siovcnt, struct iovec *diov, size_t diovcnt)
  {
  	struct spdk_ioviter iter;
  	size_t len, total_sz;
  	void *src, *dst;
  
  	total_sz = 0;
  	for (len = spdk_ioviter_first(&iter, siov, siovcnt, diov, diovcnt, &src, &dst);
  	     len != 0;
  	     len = spdk_ioviter_next(&iter, &src, &dst)) {
  		memcpy(dst, src, len);
  		total_sz += len;
  	}
  
  	return total_sz;
  }
  