/*
   *   This program is free software; you can redistribute it and/or modify
   *   it under the terms of the GNU General Public License as published by
   *   the Free Software Foundation; either version 2 of the License, or
   *   (at your option) any later version.
   *
   *   This program is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *   GNU General Public License for more details.
   *
   *   You should have received a copy of the GNU General Public License
   *   along with this program; if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   *
   */
  
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <linux/usb.h>
  
  #include "usbaudio.h"
  #include "helper.h"
  
  /*
   * combine bytes and get an integer value
   */
  unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
  {
  	switch (size) {
  	case 1:  return *bytes;
  	case 2:  return combine_word(bytes);
  	case 3:  return combine_triple(bytes);
  	case 4:  return combine_quad(bytes);
  	default: return 0;
  	}
  }
  
  /*
   * parse descriptor buffer and return the pointer starting the given
   * descriptor type.
   */
  void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
  {
  	u8 *p, *end, *next;
  
  	p = descstart;
  	end = p + desclen;
  	for (; p < end;) {
  		if (p[0] < 2)
  			return NULL;
  		next = p + p[0];
  		if (next > end)
  			return NULL;
  		if (p[1] == dtype && (!after || (void *)p > after)) {
  			return p;
  		}
  		p = next;
  	}
  	return NULL;
  }
  
  /*
   * find a class-specified interface descriptor with the given subtype.
   */
  void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
  {
  	unsigned char *p = after;
  
  	while ((p = snd_usb_find_desc(buffer, buflen, p,
  				      USB_DT_CS_INTERFACE)) != NULL) {
  		if (p[0] >= 3 && p[2] == dsubtype)
  			return p;
  	}
  	return NULL;
  }
  
  /*
   * Wrapper for usb_control_msg().
   * Allocates a temp buffer to prevent dmaing from/to the stack.
   */
  int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
  		    __u8 requesttype, __u16 value, __u16 index, void *data,

  		    __u16 size)

  {
  	int err;
  	void *buf = NULL;
  
  	if (size > 0) {
  		buf = kmemdup(data, size, GFP_KERNEL);
  		if (!buf)
  			return -ENOMEM;
  	}
  	err = usb_control_msg(dev, pipe, request, requesttype,

  			      value, index, buf, size, 1000);

  	if (size > 0) {
  		memcpy(data, buf, size);
  		kfree(buf);
  	}
  	return err;
  }
  
  unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
  					 struct usb_host_interface *alts)
  {

  	switch (snd_usb_get_speed(chip->dev)) {
  	case USB_SPEED_HIGH:
  	case USB_SPEED_SUPER:
  		if (get_endpoint(alts, 0)->bInterval >= 1 &&
  		    get_endpoint(alts, 0)->bInterval <= 4)
  			return get_endpoint(alts, 0)->bInterval - 1;
  		break;
  	default:
  		break;
  	}
  	return 0;

  }