audio_route/audio_route.c - platform/system/media - Git at Google

 /*
  * Copyright (C) 2013 The Android Open Source Project
  * Inspired by TinyHW, written by Mark Brown at Wolfson Micro
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "audio_route"
 /*#define LOG_NDEBUG 0*/

 #include <errno.h>
 #include <expat.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>

 #include <cutils/log.h>

 #include <tinyalsa/asoundlib.h>

 #define BUF_SIZE 1024
 #define MIXER_XML_PATH "/system/etc/mixer_paths.xml"
 #define INITIAL_MIXER_PATH_SIZE 8

 struct mixer_state {
     struct mixer_ctl *ctl;
     unsigned int num_values;
     int *old_value;
     int *new_value;
     int *reset_value;
     /* If linked is true, only the first element in each array is valid */
     bool old_linked;
     bool new_linked;
     bool reset_linked;
 };

 struct mixer_setting {
     struct mixer_ctl *ctl;
     unsigned int num_values;
     int *value;
     /* If linked is true, only the first element in each array is valid */
     bool linked;
 };

 struct mixer_value {
     struct mixer_ctl *ctl;
     int index;
     int value;
 };

 struct mixer_path {
     char *name;
     unsigned int size;
     unsigned int length;
     struct mixer_setting *setting;
 };

 struct audio_route {
     struct mixer *mixer;
     unsigned int num_mixer_ctls;
     struct mixer_state *mixer_state;

     unsigned int mixer_path_size;
     unsigned int num_mixer_paths;
     struct mixer_path *mixer_path;
 };

 struct config_parse_state {
     struct audio_route *ar;
     struct mixer_path *path;
     int level;
 };

 /* path functions */

 static void path_print(struct mixer_path *path)
 {
     unsigned int i;
     unsigned int j;

     ALOGE("Path: %s, length: %d", path->name, path->length);
     for (i = 0; i < path->length; i++) {
         ALOGE("  id=%d: ctl=%s linked=%c", i,
               mixer_ctl_get_name(path->setting[i].ctl),
               path->setting[i].linked ? 'y' : 'n');
         for (j = 0; j < path->setting[i].num_values; j++)
             ALOGE("    id=%d value=%d", j, path->setting[i].value[j]);
     }
 }

 static void path_free(struct audio_route *ar)
 {
     unsigned int i;

     for (i = 0; i < ar->num_mixer_paths; i++) {
         if (ar->mixer_path[i].name)
             free(ar->mixer_path[i].name);
         if (ar->mixer_path[i].setting) {
             if (ar->mixer_path[i].setting->value)
                 free(ar->mixer_path[i].setting->value);
             free(ar->mixer_path[i].setting);
         }
     }
     free(ar->mixer_path);
 }

 static struct mixer_path *path_get_by_name(struct audio_route *ar,
                                            const char *name)
 {
     unsigned int i;

     for (i = 0; i < ar->num_mixer_paths; i++)
         if (strcmp(ar->mixer_path[i].name, name) == 0)
             return &ar->mixer_path[i];

     return NULL;
 }

 static struct mixer_path *path_create(struct audio_route *ar, const char *name)
 {
     struct mixer_path *new_mixer_path = NULL;

     if (path_get_by_name(ar, name)) {
         ALOGE("Path name '%s' already exists", name);
         return NULL;
     }

     /* check if we need to allocate more space for mixer paths */
     if (ar->mixer_path_size <= ar->num_mixer_paths) {
         if (ar->mixer_path_size == 0)
             ar->mixer_path_size = INITIAL_MIXER_PATH_SIZE;
         else
             ar->mixer_path_size *= 2;

         new_mixer_path = realloc(ar->mixer_path, ar->mixer_path_size *
                                  sizeof(struct mixer_path));
         if (new_mixer_path == NULL) {
             ALOGE("Unable to allocate more paths");
             return NULL;
         } else {
             ar->mixer_path = new_mixer_path;
         }
     }

     /* initialise the new mixer path */
     ar->mixer_path[ar->num_mixer_paths].name = strdup(name);
     ar->mixer_path[ar->num_mixer_paths].size = 0;
     ar->mixer_path[ar->num_mixer_paths].length = 0;
     ar->mixer_path[ar->num_mixer_paths].setting = NULL;

     /* return the mixer path just added, then increment number of them */
     return &ar->mixer_path[ar->num_mixer_paths++];
 }

 static int find_ctl_in_path(struct mixer_path *path, struct mixer_ctl *ctl)
 {
     unsigned int i;

     for (i = 0; i < path->length; i++)
         if (path->setting[i].ctl == ctl)
             return i;

     return -1;
 }

 static int alloc_path_setting(struct mixer_path *path)
 {
     struct mixer_setting *new_path_setting;
     int path_index;

     /* check if we need to allocate more space for path settings */
     if (path->size <= path->length) {
         if (path->size == 0)
             path->size = INITIAL_MIXER_PATH_SIZE;
         else
             path->size *= 2;

         new_path_setting = realloc(path->setting,
                                    path->size * sizeof(struct mixer_setting));
         if (new_path_setting == NULL) {
             ALOGE("Unable to allocate more path settings");
             return -1;
         } else {
             path->setting = new_path_setting;
         }
     }

     path_index = path->length;
     path->length++;

     return path_index;
 }

 static int path_add_setting(struct mixer_path *path,
                             struct mixer_setting *setting)
 {
     unsigned int i;
     int path_index;

     if (find_ctl_in_path(path, setting->ctl) != -1) {
         ALOGE("Control '%s' already exists in path '%s'",
               mixer_ctl_get_name(setting->ctl), path->name);
         return -1;
     }

     path_index = alloc_path_setting(path);
     if (path_index < 0)
         return -1;

     path->setting[path_index].ctl = setting->ctl;
     path->setting[path_index].num_values = setting->num_values;
     path->setting[path_index].value = malloc(setting->num_values * sizeof(int));
     path->setting[path_index].linked = setting->linked;
     if (setting->linked) {
         path->setting[path_index].value[0] = setting->value[0];
     } else {
         for (i = 0; i < setting->num_values; i++)
             path->setting[path_index].value[i] = setting->value[i];
     }

     return 0;
 }

 static int path_add_value(struct mixer_path *path,
                           struct mixer_value *mixer_value)
 {
     unsigned int i;
     int path_index;
     unsigned int num_values;

     /* Check that mixer value index is within range */
     num_values = mixer_ctl_get_num_values(mixer_value->ctl);
     if (mixer_value->index >= (int)num_values) {
         ALOGE("mixer index %d is out of range for '%s'", mixer_value->index,
               mixer_ctl_get_name(mixer_value->ctl));
         return -1;
     }

     path_index = find_ctl_in_path(path, mixer_value->ctl);
     if (path_index < 0) {
         /* New path */

         path_index = alloc_path_setting(path);
         if (path_index < 0)
             return -1;

         /* initialise the new path setting */
         path->setting[path_index].ctl = mixer_value->ctl;
         path->setting[path_index].num_values = num_values;
         path->setting[path_index].value = malloc(num_values * sizeof(int));
         path->setting[path_index].linked = true;
         path->setting[path_index].value[0] = mixer_value->value;
     }

     if (mixer_value->index == -1) {
         /* Linked, so only set the first value */
         path->setting[path_index].linked = true;
         path->setting[path_index].value[0] = mixer_value->value;
     } else {
         if (path->setting[path_index].linked && (num_values > 1)) {
             /* Unlinking the values, so duplicate them across */
             for (i = 1; i < num_values; i++) {
                 path->setting[path_index].value[i] =
                         path->setting[path_index].value[0];
             }
             path->setting[path_index].linked = false;
         }
         path->setting[path_index].value[mixer_value->index] = mixer_value->value;
     }

     return 0;
 }

 static int path_add_path(struct mixer_path *path, struct mixer_path *sub_path)
 {
     unsigned int i;

     for (i = 0; i < sub_path->length; i++)
         if (path_add_setting(path, &sub_path->setting[i]) < 0)
             return -1;

     return 0;
 }

 static int path_apply(struct audio_route *ar, struct mixer_path *path)
 {
     unsigned int i;
     unsigned int j;
     unsigned int ctl_index;

     for (i = 0; i < path->length; i++) {
         struct mixer_ctl *ctl = path->setting[i].ctl;

         /* locate the mixer ctl in the list */
         for (ctl_index = 0; ctl_index < ar->num_mixer_ctls; ctl_index++)
             if (ar->mixer_state[ctl_index].ctl == ctl)
                 break;

         /* apply the new value(s) */
         for (j = 0; j < ar->mixer_state[ctl_index].num_values; j++) {
             ar->mixer_state[ctl_index].new_value[j] = path->setting[i].value[j];
             if (path->setting[i].linked)
                 break;
         }
         ar->mixer_state[ctl_index].new_linked = path->setting[i].linked;
     }

     return 0;
 }

 /* mixer helper function */
 static int mixer_enum_string_to_value(struct mixer_ctl *ctl, const char *string)
 {
     unsigned int i;

     /* Search the enum strings for a particular one */
     for (i = 0; i < mixer_ctl_get_num_enums(ctl); i++) {
         if (strcmp(mixer_ctl_get_enum_string(ctl, i), string) == 0)
             break;
     }

     return i;
 }

 static void start_tag(void *data, const XML_Char *tag_name,
                       const XML_Char **attr)
 {
     const XML_Char *attr_name = NULL;
     const XML_Char *attr_id = NULL;
     const XML_Char *attr_value = NULL;
     struct config_parse_state *state = data;
     struct audio_route *ar = state->ar;
     unsigned int i;
     unsigned int ctl_index;
     struct mixer_ctl *ctl;
     int value;
     unsigned int id;
     struct mixer_value mixer_value;

     /* Get name, id and value attributes (these may be empty) */
     for (i = 0; attr[i]; i += 2) {
         if (strcmp(attr[i], "name") == 0)
             attr_name = attr[i + 1];
         if (strcmp(attr[i], "id") == 0)
             attr_id = attr[i + 1];
         else if (strcmp(attr[i], "value") == 0)
             attr_value = attr[i + 1];
     }

     /* Look at tags */
     if (strcmp(tag_name, "path") == 0) {
         if (attr_name == NULL) {
             ALOGE("Unnamed path!");
         } else {
             if (state->level == 1) {
                 /* top level path: create and stash the path */
                 state->path = path_create(ar, (char *)attr_name);
             } else {
                 /* nested path */
                 struct mixer_path *sub_path = path_get_by_name(ar, attr_name);
                 path_add_path(state->path, sub_path);
             }
         }
     }

     else if (strcmp(tag_name, "ctl") == 0) {
         /* Obtain the mixer ctl and value */
         ctl = mixer_get_ctl_by_name(ar->mixer, attr_name);
         switch (mixer_ctl_get_type(ctl)) {
         case MIXER_CTL_TYPE_BOOL:
         case MIXER_CTL_TYPE_INT:
             value = atoi((char *)attr_value);
             break;
         case MIXER_CTL_TYPE_ENUM:
             value = mixer_enum_string_to_value(ctl, (char *)attr_value);
             break;
         default:
             value = 0;
             break;
         }

         if (state->level == 1) {
             /* top level ctl (initial setting) */

             /* locate the mixer ctl in the list */
             for (ctl_index = 0; ctl_index < ar->num_mixer_ctls; ctl_index++) {
                 if (ar->mixer_state[ctl_index].ctl == ctl)
                     break;
             }

             /* apply the new value */
             if (attr_id) {
                 /* set only one value */
                 id = atoi((char *)attr_id);
                 if (id < ar->mixer_state[ctl_index].num_values) {
                     if (ar->mixer_state[ctl_index].new_linked) {
                         /*
                          * We're unlinking the values, so copy old_value[0] into
                          * all the new_value elements.
                          */
                         for (i = 0; i < ar->mixer_state[ctl_index].num_values; i++) {
                             ar->mixer_state[ctl_index].new_value[i] =
                                     ar->mixer_state[ctl_index].old_value[0];
                         }
                         ar->mixer_state[ctl_index].new_linked = false;
                     }
                     ar->mixer_state[ctl_index].new_value[id] = value;
                 } else {
                     ALOGE("value id out of range for mixer ctl '%s'",
                           mixer_ctl_get_name(ctl));
                 }
             } else {
                 ar->mixer_state[ctl_index].new_value[0] = value;
                 ar->mixer_state[ctl_index].new_linked = true;
             }
         } else {
             /* nested ctl (within a path) */
             mixer_value.ctl = ctl;
             mixer_value.value = value;
             if (attr_id)
                 mixer_value.index = atoi((char *)attr_id);
             else
                 mixer_value.index = -1;
             path_add_value(state->path, &mixer_value);
         }
     }

     state->level++;
 }

 static void end_tag(void *data, const XML_Char *tag_name)
 {
     struct config_parse_state *state = data;

     state->level--;
 }

 static int alloc_mixer_state(struct audio_route *ar)
 {
     unsigned int i;
     unsigned int j;
     unsigned int num_values;
     struct mixer_ctl *ctl;
     bool linked;

     ar->num_mixer_ctls = mixer_get_num_ctls(ar->mixer);
     ar->mixer_state = malloc(ar->num_mixer_ctls * sizeof(struct mixer_state));
     if (!ar->mixer_state)
         return -1;

     for (i = 0; i < ar->num_mixer_ctls; i++) {
         ctl = mixer_get_ctl(ar->mixer, i);
         num_values = mixer_ctl_get_num_values(ctl);

         ar->mixer_state[i].old_value = malloc(num_values * sizeof(int));
         ar->mixer_state[i].new_value = malloc(num_values * sizeof(int));
         ar->mixer_state[i].reset_value = malloc(num_values * sizeof(int));

         /*
          * Get all mixer values for controls with multiple values. If all
          * values are the same, set the linked flag.
          */
         linked = true;
         for (j = 0; j < num_values; j++) {
             ar->mixer_state[i].old_value[j] = mixer_ctl_get_value(ctl, j);
             ar->mixer_state[i].new_value[j] = ar->mixer_state[i].old_value[j];

             /*
              * If the next value is different from the last, set linked to
              * false.
              */
             if ((j > 0) && (ar->mixer_state[i].old_value[j - 1] !=
                             ar->mixer_state[i].old_value[j])) {
                 linked = false;
             }
         }
         ar->mixer_state[i].ctl = ctl;
         ar->mixer_state[i].old_linked = linked;
         ar->mixer_state[i].new_linked = linked;
         ar->mixer_state[i].num_values = num_values;
     }

     return 0;
 }

 static void free_mixer_state(struct audio_route *ar)
 {
     unsigned int i;

     for (i = 0; i < ar->num_mixer_ctls; i++) {
         free(ar->mixer_state[i].old_value);
         free(ar->mixer_state[i].new_value);
         free(ar->mixer_state[i].reset_value);
     }

     free(ar->mixer_state);
     ar->mixer_state = NULL;
 }

 /* Update the mixer with any changed values */
 int audio_route_update_mixer(struct audio_route *ar)
 {
     unsigned int i;
     unsigned int j;

     for (i = 0; i < ar->num_mixer_ctls; i++) {
         unsigned int num_values = ar->mixer_state[i].num_values;

         /* if the value has changed, update the mixer */
         if (ar->mixer_state[i].new_linked) {
             if (ar->mixer_state[i].old_value[0] != ar->mixer_state[i].new_value[0]) {
                 /* linked ctl, so set all ctl values the same */
                 for (j = 0; j < num_values; j++)
                     mixer_ctl_set_value(ar->mixer_state[i].ctl, j,
                                         ar->mixer_state[i].new_value[0]);
                 ar->mixer_state[i].old_value[0] = ar->mixer_state[i].new_value[0];
             }
         } else {
             for (j = 0; j < num_values; j++) {
                 /*
                  * unlinked ctl, so set each value if necessary.
                  * Note that if the new value is unlinked but the old is
                  * linked, only value 0 is valid, so we always have to
                  * update the mixer for the other values.
                  */
                 if (ar->mixer_state[i].old_linked ||
                     (ar->mixer_state[i].old_value[j] !=
                             ar->mixer_state[i].new_value[j])) {
                     mixer_ctl_set_value(ar->mixer_state[i].ctl, j,
                                         ar->mixer_state[i].new_value[j]);
                     ar->mixer_state[i].old_value[j] = ar->mixer_state[i].new_value[j];
                 }
             }
         }
         ar->mixer_state[i].old_linked = ar->mixer_state[i].new_linked;
     }

     return 0;
 }

 /* saves the current state of the mixer, for resetting all controls */
 static void save_mixer_state(struct audio_route *ar)
 {
     unsigned int i;
     unsigned int j;

     for (i = 0; i < ar->num_mixer_ctls; i++) {
         for (j = 0; j < ar->mixer_state[i].num_values; j++) {
             ar->mixer_state[i].reset_value[j] = ar->mixer_state[i].new_value[j];

             /* if the values are linked, only need to save value 0 */
             if (ar->mixer_state[i].new_linked)
                 break;
         }
         ar->mixer_state[i].reset_linked = ar->mixer_state[i].new_linked;
     }
 }

 /* Reset the audio routes back to the initial state */
 void audio_route_reset(struct audio_route *ar)
 {
     unsigned int i;
     unsigned int j;

     /* load all of the saved values */
     for (i = 0; i < ar->num_mixer_ctls; i++) {
         for (j = 0; j < ar->mixer_state[i].num_values; j++) {
             ar->mixer_state[i].new_value[j] = ar->mixer_state[i].reset_value[j];

             /* if the values are linked, only need to save value 0 */
             if (ar->mixer_state[i].reset_linked)
                 break;
         }
         ar->mixer_state[i].new_linked = ar->mixer_state[i].reset_linked;
     }
 }

 /* Apply an audio route path by name */
 int audio_route_apply_path(struct audio_route *ar, const char *name)
 {
     struct mixer_path *path;

     if (!ar) {
         ALOGE("invalid audio_route");
         return -1;
     }

     path = path_get_by_name(ar, name);
     if (!path) {
         ALOGE("unable to find path '%s'", name);
         return -1;
     }

     path_apply(ar, path);

     return 0;
 }

 struct audio_route *audio_route_init(unsigned int card, const char *xml_path)
 {
     struct config_parse_state state;
     XML_Parser parser;
     FILE *file;
     int bytes_read;
     void *buf;
     int i;
     struct audio_route *ar;

     ar = calloc(1, sizeof(struct audio_route));
     if (!ar)
         goto err_calloc;

     ar->mixer = mixer_open(card);
     if (!ar->mixer) {
         ALOGE("Unable to open the mixer, aborting.");
         goto err_mixer_open;
     }

     ar->mixer_path = NULL;
     ar->mixer_path_size = 0;
     ar->num_mixer_paths = 0;

     /* allocate space for and read current mixer settings */
     if (alloc_mixer_state(ar) < 0)
         goto err_mixer_state;

     /* use the default XML path if none is provided */
     if (xml_path == NULL)
         xml_path = MIXER_XML_PATH;

     file = fopen(xml_path, "r");

     if (!file) {
         ALOGE("Failed to open %s", xml_path);
         goto err_fopen;
     }

     parser = XML_ParserCreate(NULL);
     if (!parser) {
         ALOGE("Failed to create XML parser");
         goto err_parser_create;
     }

     memset(&state, 0, sizeof(state));
     state.ar = ar;
     XML_SetUserData(parser, &state);
     XML_SetElementHandler(parser, start_tag, end_tag);

     for (;;) {
         buf = XML_GetBuffer(parser, BUF_SIZE);
         if (buf == NULL)
             goto err_parse;

         bytes_read = fread(buf, 1, BUF_SIZE, file);
         if (bytes_read < 0)
             goto err_parse;

         if (XML_ParseBuffer(parser, bytes_read,
                             bytes_read == 0) == XML_STATUS_ERROR) {
             ALOGE("Error in mixer xml (%s)", MIXER_XML_PATH);
             goto err_parse;
         }

         if (bytes_read == 0)
             break;
     }

     /* apply the initial mixer values, and save them so we can reset the
        mixer to the original values */
     audio_route_update_mixer(ar);
     save_mixer_state(ar);

     XML_ParserFree(parser);
     fclose(file);
     return ar;

 err_parse:
     XML_ParserFree(parser);
 err_parser_create:
     fclose(file);
 err_fopen:
     free_mixer_state(ar);
 err_mixer_state:
     mixer_close(ar->mixer);
 err_mixer_open:
     free(ar);
     ar = NULL;
 err_calloc:
     return NULL;
 }

 void audio_route_free(struct audio_route *ar)
 {
     free_mixer_state(ar);
     mixer_close(ar->mixer);
     free(ar);
 }
	/*
	* Copyright (C) 2013 The Android Open Source Project
	* Inspired by TinyHW, written by Mark Brown at Wolfson Micro
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "audio_route"
	/#define LOG_NDEBUG 0/

	#include <errno.h>
	#include <expat.h>
	#include <stdbool.h>
	#include <stdio.h>
	#include <string.h>

	#include <cutils/log.h>

	#include <tinyalsa/asoundlib.h>

	#define BUF_SIZE 1024
	#define MIXER_XML_PATH "/system/etc/mixer_paths.xml"
	#define INITIAL_MIXER_PATH_SIZE 8

	struct mixer_state {
	struct mixer_ctl *ctl;
	unsigned int num_values;
	int *old_value;
	int *new_value;
	int *reset_value;
	/* If linked is true, only the first element in each array is valid */
	bool old_linked;
	bool new_linked;
	bool reset_linked;
	};

	struct mixer_setting {
	struct mixer_ctl *ctl;
	unsigned int num_values;
	int *value;
	/* If linked is true, only the first element in each array is valid */
	bool linked;
	};

	struct mixer_value {
	struct mixer_ctl *ctl;
	int index;
	int value;
	};

	struct mixer_path {
	char *name;
	unsigned int size;
	unsigned int length;
	struct mixer_setting *setting;
	};

	struct audio_route {
	struct mixer *mixer;
	unsigned int num_mixer_ctls;
	struct mixer_state *mixer_state;

	unsigned int mixer_path_size;
	unsigned int num_mixer_paths;
	struct mixer_path *mixer_path;
	};

	struct config_parse_state {
	struct audio_route *ar;
	struct mixer_path *path;
	int level;
	};

	/* path functions */

	static void path_print(struct mixer_path *path)
	{
	unsigned int i;
	unsigned int j;

	ALOGE("Path: %s, length: %d", path->name, path->length);
	for (i = 0; i < path->length; i++) {
	ALOGE(" id=%d: ctl=%s linked=%c", i,
	mixer_ctl_get_name(path->setting[i].ctl),
	path->setting[i].linked ? 'y' : 'n');
	for (j = 0; j < path->setting[i].num_values; j++)
	ALOGE(" id=%d value=%d", j, path->setting[i].value[j]);
	}
	}

	static void path_free(struct audio_route *ar)
	{
	unsigned int i;

	for (i = 0; i < ar->num_mixer_paths; i++) {
	if (ar->mixer_path[i].name)
	free(ar->mixer_path[i].name);
	if (ar->mixer_path[i].setting) {
	if (ar->mixer_path[i].setting->value)
	free(ar->mixer_path[i].setting->value);
	free(ar->mixer_path[i].setting);
	}
	}
	free(ar->mixer_path);
	}

	static struct mixer_path path_get_by_name(struct audio_route ar,
	const char *name)
	{
	unsigned int i;

	for (i = 0; i < ar->num_mixer_paths; i++)
	if (strcmp(ar->mixer_path[i].name, name) == 0)
	return &ar->mixer_path[i];

	return NULL;
	}

	static struct mixer_path path_create(struct audio_route ar, const char *name)
	{
	struct mixer_path *new_mixer_path = NULL;

	if (path_get_by_name(ar, name)) {
	ALOGE("Path name '%s' already exists", name);
	return NULL;
	}

	/* check if we need to allocate more space for mixer paths */
	if (ar->mixer_path_size <= ar->num_mixer_paths) {
	if (ar->mixer_path_size == 0)
	ar->mixer_path_size = INITIAL_MIXER_PATH_SIZE;
	else
	ar->mixer_path_size *= 2;

	new_mixer_path = realloc(ar->mixer_path, ar->mixer_path_size *
	sizeof(struct mixer_path));
	if (new_mixer_path == NULL) {
	ALOGE("Unable to allocate more paths");
	return NULL;
	} else {
	ar->mixer_path = new_mixer_path;
	}
	}

	/* initialise the new mixer path */
	ar->mixer_path[ar->num_mixer_paths].name = strdup(name);
	ar->mixer_path[ar->num_mixer_paths].size = 0;
	ar->mixer_path[ar->num_mixer_paths].length = 0;
	ar->mixer_path[ar->num_mixer_paths].setting = NULL;

	/* return the mixer path just added, then increment number of them */
	return &ar->mixer_path[ar->num_mixer_paths++];
	}

	static int find_ctl_in_path(struct mixer_path path, struct mixer_ctl ctl)
	{
	unsigned int i;

	for (i = 0; i < path->length; i++)
	if (path->setting[i].ctl == ctl)
	return i;

	return -1;
	}

	static int alloc_path_setting(struct mixer_path *path)
	{
	struct mixer_setting *new_path_setting;
	int path_index;

	/* check if we need to allocate more space for path settings */
	if (path->size <= path->length) {
	if (path->size == 0)
	path->size = INITIAL_MIXER_PATH_SIZE;
	else
	path->size *= 2;

	new_path_setting = realloc(path->setting,
	path->size * sizeof(struct mixer_setting));
	if (new_path_setting == NULL) {
	ALOGE("Unable to allocate more path settings");
	return -1;
	} else {
	path->setting = new_path_setting;
	}
	}

	path_index = path->length;
	path->length++;

	return path_index;
	}

	static int path_add_setting(struct mixer_path *path,
	struct mixer_setting *setting)
	{
	unsigned int i;
	int path_index;

	if (find_ctl_in_path(path, setting->ctl) != -1) {
	ALOGE("Control '%s' already exists in path '%s'",
	mixer_ctl_get_name(setting->ctl), path->name);
	return -1;
	}

	path_index = alloc_path_setting(path);
	if (path_index < 0)
	return -1;

	path->setting[path_index].ctl = setting->ctl;
	path->setting[path_index].num_values = setting->num_values;
	path->setting[path_index].value = malloc(setting->num_values * sizeof(int));
	path->setting[path_index].linked = setting->linked;
	if (setting->linked) {
	path->setting[path_index].value[0] = setting->value[0];
	} else {
	for (i = 0; i < setting->num_values; i++)
	path->setting[path_index].value[i] = setting->value[i];
	}

	return 0;
	}

	static int path_add_value(struct mixer_path *path,
	struct mixer_value *mixer_value)
	{
	unsigned int i;
	int path_index;
	unsigned int num_values;

	/* Check that mixer value index is within range */
	num_values = mixer_ctl_get_num_values(mixer_value->ctl);
	if (mixer_value->index >= (int)num_values) {
	ALOGE("mixer index %d is out of range for '%s'", mixer_value->index,
	mixer_ctl_get_name(mixer_value->ctl));
	return -1;
	}

	path_index = find_ctl_in_path(path, mixer_value->ctl);
	if (path_index < 0) {
	/* New path */

	path_index = alloc_path_setting(path);
	if (path_index < 0)
	return -1;

	/* initialise the new path setting */
	path->setting[path_index].ctl = mixer_value->ctl;
	path->setting[path_index].num_values = num_values;
	path->setting[path_index].value = malloc(num_values * sizeof(int));
	path->setting[path_index].linked = true;
	path->setting[path_index].value[0] = mixer_value->value;
	}

	if (mixer_value->index == -1) {
	/* Linked, so only set the first value */
	path->setting[path_index].linked = true;
	path->setting[path_index].value[0] = mixer_value->value;
	} else {
	if (path->setting[path_index].linked && (num_values > 1)) {
	/* Unlinking the values, so duplicate them across */
	for (i = 1; i < num_values; i++) {
	path->setting[path_index].value[i] =
	path->setting[path_index].value[0];
	}
	path->setting[path_index].linked = false;
	}
	path->setting[path_index].value[mixer_value->index] = mixer_value->value;
	}

	return 0;
	}

	static int path_add_path(struct mixer_path path, struct mixer_path sub_path)
	{
	unsigned int i;

	for (i = 0; i < sub_path->length; i++)
	if (path_add_setting(path, &sub_path->setting[i]) < 0)
	return -1;

	return 0;
	}

	static int path_apply(struct audio_route ar, struct mixer_path path)
	{
	unsigned int i;
	unsigned int j;
	unsigned int ctl_index;

	for (i = 0; i < path->length; i++) {
	struct mixer_ctl *ctl = path->setting[i].ctl;

	/* locate the mixer ctl in the list */
	for (ctl_index = 0; ctl_index < ar->num_mixer_ctls; ctl_index++)
	if (ar->mixer_state[ctl_index].ctl == ctl)
	break;

	/* apply the new value(s) */
	for (j = 0; j < ar->mixer_state[ctl_index].num_values; j++) {
	ar->mixer_state[ctl_index].new_value[j] = path->setting[i].value[j];
	if (path->setting[i].linked)
	break;
	}
	ar->mixer_state[ctl_index].new_linked = path->setting[i].linked;
	}

	return 0;
	}

	/* mixer helper function */
	static int mixer_enum_string_to_value(struct mixer_ctl ctl, const char string)
	{
	unsigned int i;

	/* Search the enum strings for a particular one */
	for (i = 0; i < mixer_ctl_get_num_enums(ctl); i++) {
	if (strcmp(mixer_ctl_get_enum_string(ctl, i), string) == 0)
	break;
	}

	return i;
	}

	static void start_tag(void data, const XML_Char tag_name,
	const XML_Char **attr)
	{
	const XML_Char *attr_name = NULL;
	const XML_Char *attr_id = NULL;
	const XML_Char *attr_value = NULL;
	struct config_parse_state *state = data;
	struct audio_route *ar = state->ar;
	unsigned int i;
	unsigned int ctl_index;
	struct mixer_ctl *ctl;
	int value;
	unsigned int id;
	struct mixer_value mixer_value;

	/* Get name, id and value attributes (these may be empty) */
	for (i = 0; attr[i]; i += 2) {
	if (strcmp(attr[i], "name") == 0)
	attr_name = attr[i + 1];
	if (strcmp(attr[i], "id") == 0)
	attr_id = attr[i + 1];
	else if (strcmp(attr[i], "value") == 0)
	attr_value = attr[i + 1];
	}

	/* Look at tags */
	if (strcmp(tag_name, "path") == 0) {
	if (attr_name == NULL) {
	ALOGE("Unnamed path!");
	} else {
	if (state->level == 1) {
	/* top level path: create and stash the path */
	state->path = path_create(ar, (char *)attr_name);
	} else {
	/* nested path */
	struct mixer_path *sub_path = path_get_by_name(ar, attr_name);
	path_add_path(state->path, sub_path);
	}
	}
	}

	else if (strcmp(tag_name, "ctl") == 0) {
	/* Obtain the mixer ctl and value */
	ctl = mixer_get_ctl_by_name(ar->mixer, attr_name);
	switch (mixer_ctl_get_type(ctl)) {
	case MIXER_CTL_TYPE_BOOL:
	case MIXER_CTL_TYPE_INT:
	value = atoi((char *)attr_value);
	break;
	case MIXER_CTL_TYPE_ENUM:
	value = mixer_enum_string_to_value(ctl, (char *)attr_value);
	break;
	default:
	value = 0;
	break;
	}

	if (state->level == 1) {
	/* top level ctl (initial setting) */

	/* locate the mixer ctl in the list */
	for (ctl_index = 0; ctl_index < ar->num_mixer_ctls; ctl_index++) {
	if (ar->mixer_state[ctl_index].ctl == ctl)
	break;
	}

	/* apply the new value */
	if (attr_id) {
	/* set only one value */
	id = atoi((char *)attr_id);
	if (id < ar->mixer_state[ctl_index].num_values) {
	if (ar->mixer_state[ctl_index].new_linked) {
	/*
	* We're unlinking the values, so copy old_value[0] into
	* all the new_value elements.
	*/
	for (i = 0; i < ar->mixer_state[ctl_index].num_values; i++) {
	ar->mixer_state[ctl_index].new_value[i] =
	ar->mixer_state[ctl_index].old_value[0];
	}
	ar->mixer_state[ctl_index].new_linked = false;
	}
	ar->mixer_state[ctl_index].new_value[id] = value;
	} else {
	ALOGE("value id out of range for mixer ctl '%s'",
	mixer_ctl_get_name(ctl));
	}
	} else {
	ar->mixer_state[ctl_index].new_value[0] = value;
	ar->mixer_state[ctl_index].new_linked = true;
	}
	} else {
	/* nested ctl (within a path) */
	mixer_value.ctl = ctl;
	mixer_value.value = value;
	if (attr_id)
	mixer_value.index = atoi((char *)attr_id);
	else
	mixer_value.index = -1;
	path_add_value(state->path, &mixer_value);
	}
	}

	state->level++;
	}

	static void end_tag(void data, const XML_Char tag_name)
	{
	struct config_parse_state *state = data;

	state->level--;
	}

	static int alloc_mixer_state(struct audio_route *ar)
	{
	unsigned int i;
	unsigned int j;
	unsigned int num_values;
	struct mixer_ctl *ctl;
	bool linked;

	ar->num_mixer_ctls = mixer_get_num_ctls(ar->mixer);
	ar->mixer_state = malloc(ar->num_mixer_ctls * sizeof(struct mixer_state));
	if (!ar->mixer_state)
	return -1;

	for (i = 0; i < ar->num_mixer_ctls; i++) {
	ctl = mixer_get_ctl(ar->mixer, i);
	num_values = mixer_ctl_get_num_values(ctl);

	ar->mixer_state[i].old_value = malloc(num_values * sizeof(int));
	ar->mixer_state[i].new_value = malloc(num_values * sizeof(int));
	ar->mixer_state[i].reset_value = malloc(num_values * sizeof(int));

	/*
	* Get all mixer values for controls with multiple values. If all
	* values are the same, set the linked flag.
	*/
	linked = true;
	for (j = 0; j < num_values; j++) {
	ar->mixer_state[i].old_value[j] = mixer_ctl_get_value(ctl, j);
	ar->mixer_state[i].new_value[j] = ar->mixer_state[i].old_value[j];

	/*
	* If the next value is different from the last, set linked to
	* false.
	*/
	if ((j > 0) && (ar->mixer_state[i].old_value[j - 1] !=
	ar->mixer_state[i].old_value[j])) {
	linked = false;
	}
	}
	ar->mixer_state[i].ctl = ctl;
	ar->mixer_state[i].old_linked = linked;
	ar->mixer_state[i].new_linked = linked;
	ar->mixer_state[i].num_values = num_values;
	}

	return 0;
	}

	static void free_mixer_state(struct audio_route *ar)
	{
	unsigned int i;

	for (i = 0; i < ar->num_mixer_ctls; i++) {
	free(ar->mixer_state[i].old_value);
	free(ar->mixer_state[i].new_value);
	free(ar->mixer_state[i].reset_value);
	}

	free(ar->mixer_state);
	ar->mixer_state = NULL;
	}

	/* Update the mixer with any changed values */
	int audio_route_update_mixer(struct audio_route *ar)
	{
	unsigned int i;
	unsigned int j;

	for (i = 0; i < ar->num_mixer_ctls; i++) {
	unsigned int num_values = ar->mixer_state[i].num_values;

	/* if the value has changed, update the mixer */
	if (ar->mixer_state[i].new_linked) {
	if (ar->mixer_state[i].old_value[0] != ar->mixer_state[i].new_value[0]) {
	/* linked ctl, so set all ctl values the same */
	for (j = 0; j < num_values; j++)
	mixer_ctl_set_value(ar->mixer_state[i].ctl, j,
	ar->mixer_state[i].new_value[0]);
	ar->mixer_state[i].old_value[0] = ar->mixer_state[i].new_value[0];
	}
	} else {
	for (j = 0; j < num_values; j++) {
	/*
	* unlinked ctl, so set each value if necessary.
	* Note that if the new value is unlinked but the old is
	* linked, only value 0 is valid, so we always have to
	* update the mixer for the other values.
	*/
	if (ar->mixer_state[i].old_linked \|\|
	(ar->mixer_state[i].old_value[j] !=
	ar->mixer_state[i].new_value[j])) {
	mixer_ctl_set_value(ar->mixer_state[i].ctl, j,
	ar->mixer_state[i].new_value[j]);
	ar->mixer_state[i].old_value[j] = ar->mixer_state[i].new_value[j];
	}
	}
	}
	ar->mixer_state[i].old_linked = ar->mixer_state[i].new_linked;
	}

	return 0;
	}

	/* saves the current state of the mixer, for resetting all controls */
	static void save_mixer_state(struct audio_route *ar)
	{
	unsigned int i;
	unsigned int j;

	for (i = 0; i < ar->num_mixer_ctls; i++) {
	for (j = 0; j < ar->mixer_state[i].num_values; j++) {
	ar->mixer_state[i].reset_value[j] = ar->mixer_state[i].new_value[j];

	/* if the values are linked, only need to save value 0 */
	if (ar->mixer_state[i].new_linked)
	break;
	}
	ar->mixer_state[i].reset_linked = ar->mixer_state[i].new_linked;
	}
	}

	/* Reset the audio routes back to the initial state */
	void audio_route_reset(struct audio_route *ar)
	{
	unsigned int i;
	unsigned int j;

	/* load all of the saved values */
	for (i = 0; i < ar->num_mixer_ctls; i++) {
	for (j = 0; j < ar->mixer_state[i].num_values; j++) {
	ar->mixer_state[i].new_value[j] = ar->mixer_state[i].reset_value[j];

	/* if the values are linked, only need to save value 0 */
	if (ar->mixer_state[i].reset_linked)
	break;
	}
	ar->mixer_state[i].new_linked = ar->mixer_state[i].reset_linked;
	}
	}

	/* Apply an audio route path by name */
	int audio_route_apply_path(struct audio_route ar, const char name)
	{
	struct mixer_path *path;

	if (!ar) {
	ALOGE("invalid audio_route");
	return -1;
	}

	path = path_get_by_name(ar, name);
	if (!path) {
	ALOGE("unable to find path '%s'", name);
	return -1;
	}

	path_apply(ar, path);

	return 0;
	}

	struct audio_route audio_route_init(unsigned int card, const char xml_path)
	{
	struct config_parse_state state;
	XML_Parser parser;
	FILE *file;
	int bytes_read;
	void *buf;
	int i;
	struct audio_route *ar;

	ar = calloc(1, sizeof(struct audio_route));
	if (!ar)
	goto err_calloc;

	ar->mixer = mixer_open(card);
	if (!ar->mixer) {
	ALOGE("Unable to open the mixer, aborting.");
	goto err_mixer_open;
	}

	ar->mixer_path = NULL;
	ar->mixer_path_size = 0;
	ar->num_mixer_paths = 0;

	/* allocate space for and read current mixer settings */
	if (alloc_mixer_state(ar) < 0)
	goto err_mixer_state;

	/* use the default XML path if none is provided */
	if (xml_path == NULL)
	xml_path = MIXER_XML_PATH;

	file = fopen(xml_path, "r");

	if (!file) {
	ALOGE("Failed to open %s", xml_path);
	goto err_fopen;
	}

	parser = XML_ParserCreate(NULL);
	if (!parser) {
	ALOGE("Failed to create XML parser");
	goto err_parser_create;
	}

	memset(&state, 0, sizeof(state));
	state.ar = ar;
	XML_SetUserData(parser, &state);
	XML_SetElementHandler(parser, start_tag, end_tag);

	for (;;) {
	buf = XML_GetBuffer(parser, BUF_SIZE);
	if (buf == NULL)
	goto err_parse;

	bytes_read = fread(buf, 1, BUF_SIZE, file);
	if (bytes_read < 0)
	goto err_parse;

	if (XML_ParseBuffer(parser, bytes_read,
	bytes_read == 0) == XML_STATUS_ERROR) {
	ALOGE("Error in mixer xml (%s)", MIXER_XML_PATH);
	goto err_parse;
	}

	if (bytes_read == 0)
	break;
	}

	/* apply the initial mixer values, and save them so we can reset the
	mixer to the original values */
	audio_route_update_mixer(ar);
	save_mixer_state(ar);

	XML_ParserFree(parser);
	fclose(file);
	return ar;

	err_parse:
	XML_ParserFree(parser);
	err_parser_create:
	fclose(file);
	err_fopen:
	free_mixer_state(ar);
	err_mixer_state:
	mixer_close(ar->mixer);
	err_mixer_open:
	free(ar);
	ar = NULL;
	err_calloc:
	return NULL;
	}

	void audio_route_free(struct audio_route *ar)
	{
	free_mixer_state(ar);
	mixer_close(ar->mixer);
	free(ar);
	}