Late Evening Commit

1 files changed, 787 insertions, 0 deletions

diff --git a/AlsaSound/CoreBinding/AlsaLibMapping.c b/AlsaSound/CoreBinding/AlsaLibMapping.c
new file mode 100644
index 0000000..8dc1772
--- /dev/null
+++ b/AlsaSound/CoreBinding/AlsaLibMapping.c
@@ -0,0 +1,787 @@
+/*
+ * AlsaLibMapping -- provide low level interface with ALSA lib (extracted from alsa-json-gateway code)
+ * Copyright (C) 2015,2016,2017, Fulup Ar Foll fulup@iot.bzh
+ *
+ * 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.
+
+   References:
+   https://github.com/fulup-bzh/AlsaJsonGateway (original code)
+   http://alsa-lib.sourcearchive.com/documentation/1.0.20/modules.html
+   http://alsa-lib.sourcearchive.com/documentation/1.0.8/group__Control_gd48d44da8e3bfe150e928267008b8ff5.html
+   http://alsa.opensrc.org/HowTo_access_a_mixer_control
+   https://github.com/gch1p/alsa-volume-monitor/blob/master/main.c
+
+*/
+
+#define _GNU_SOURCE  // needed for vasprintf
+
+#include <alsa/asoundlib.h>
+#include "AlsaLibMapping.h"
+
+#include <systemd/sd-event.h>
+static struct afb_service srvitf;
+
+// generic structure to pass parsed query values
+typedef struct {
+  const char *devid;
+  int  numid;
+  int  quiet;  
+} queryValuesT;
+
+// generic sndctrl event handle hook to event callback when pooling
+typedef struct {
+    struct pollfd pfds;
+    sd_event_source *src;
+    snd_ctl_t *ctl;
+    struct afb_event afbevt;
+} evtHandleT;
+
+typedef struct {
+    int cardid;
+    int ucount;
+    evtHandleT *evtHandle;
+} sndHandleT;
+
+STATIC json_object *DB2StringJsonOject (long dB) {
+    char label [20];
+	if (dB < 0) {
+		snprintf(label, sizeof(label), "-%li.%02lidB", -dB / 100, -dB % 100);
+	} else {
+		snprintf(label, sizeof(label), "%li.%02lidB", dB / 100, dB % 100);
+	}
+
+    // json function takes care of string copy
+	return (json_object_new_string (label));
+}
+
+
+// Direct port from amixer TLV decode routine. This code is too complex for me.
+// I hopefully did not break it when porting it.
+
+STATIC json_object *decodeTlv(unsigned int *tlv, unsigned int tlv_size) {
+    char label[20];
+    unsigned int type = tlv[0];
+    unsigned int size;
+    unsigned int idx = 0;
+    const char *chmap_type = NULL;
+    json_object * decodeTlvJson = json_object_new_object();
+
+    if (tlv_size < (unsigned int) (2 * sizeof (unsigned int))) {
+        printf("TLV size error!\n");
+        return NULL;
+    }
+    type = tlv[idx++];
+    size = tlv[idx++];
+    tlv_size -= (unsigned int) (2 * sizeof (unsigned int));
+    if (size > tlv_size) {
+        fprintf(stderr, "TLV size error (%i, %i, %i)!\n", type, size, tlv_size);
+        return NULL;
+    }
+    switch (type) {
+
+        case SND_CTL_TLVT_CONTAINER:
+        {
+            json_object * containerJson = json_object_new_array();
+
+            size += (unsigned int) (sizeof (unsigned int) - 1);
+            size /= (unsigned int) (sizeof (unsigned int));
+            while (idx < size) {
+                json_object *embedJson;
+
+                if (tlv[idx + 1] > (size - idx) * sizeof (unsigned int)) {
+                    fprintf(stderr, "TLV size error in compound!\n");
+                    return NULL;
+                }
+                embedJson = decodeTlv(tlv + idx, tlv[idx + 1] + 8);
+                json_object_array_add(containerJson, embedJson);
+                idx += (unsigned int) (2 + (tlv[idx + 1] + sizeof (unsigned int) - 1) / sizeof (unsigned int));
+            }
+            json_object_object_add(decodeTlvJson, "container", containerJson);
+            break;
+        }
+
+        case SND_CTL_TLVT_DB_SCALE:
+        {
+            json_object * dbscaleJson = json_object_new_object();
+
+            if (size != 2 * sizeof (unsigned int)) {
+                json_object * arrayJson = json_object_new_array();
+                while (size > 0) {
+                    snprintf(label, sizeof (label), "0x%08x,", tlv[idx++]);
+                    json_object_array_add(arrayJson, json_object_new_string(label));
+                    size -= (unsigned int) sizeof (unsigned int);
+                }
+                json_object_object_add(dbscaleJson, "array", arrayJson);
+            } else {
+                json_object_object_add(dbscaleJson, "min", DB2StringJsonOject((int) tlv[2]));
+                json_object_object_add(dbscaleJson, "step", DB2StringJsonOject(tlv[3] & 0xffff));
+                json_object_object_add(dbscaleJson, "mute", DB2StringJsonOject((tlv[3] >> 16) & 1));
+            }
+            json_object_object_add(decodeTlvJson, "dbscale", dbscaleJson);
+            break;
+        }
+
+#ifdef SND_CTL_TLVT_DB_LINEAR
+        case SND_CTL_TLVT_DB_LINEAR:
+        {
+            json_object * dbLinearJson = json_object_new_object();
+
+            if (size != 2 * sizeof (unsigned int)) {
+                json_object * arrayJson = json_object_new_array();
+                while (size > 0) {
+                    snprintf(label, sizeof (label), "0x%08x,", tlv[idx++]);
+                    json_object_array_add(arrayJson, json_object_new_string(label));
+                    size -= (unsigned int) sizeof (unsigned int);
+                }
+                json_object_object_add(dbLinearJson, "offset", arrayJson);
+            } else {
+                json_object_object_add(dbLinearJson, "min", DB2StringJsonOject((int) tlv[2]));
+                json_object_object_add(dbLinearJson, "max", DB2StringJsonOject((int) tlv[3]));
+            }
+            json_object_object_add(decodeTlvJson, "dblinear", dbLinearJson);
+            break;
+        }
+#endif
+
+#ifdef SND_CTL_TLVT_DB_RANGE
+        case SND_CTL_TLVT_DB_RANGE:
+        {
+            json_object *dbRangeJson = json_object_new_object();
+
+            if ((size % (6 * sizeof (unsigned int))) != 0) {
+                json_object *arrayJson = json_object_new_array();
+                while (size > 0) {
+                    snprintf(label, sizeof (label), "0x%08x,", tlv[idx++]);
+                    json_object_array_add(arrayJson, json_object_new_string(label));
+                    size -= (unsigned int) sizeof (unsigned int);
+                }
+                json_object_object_add(dbRangeJson, "dbrange", arrayJson);
+                break;
+            }
+            while (size > 0) {
+                json_object * embedJson = json_object_new_object();
+                snprintf(label, sizeof (label), "%i,", tlv[idx++]);
+                json_object_object_add(embedJson, "rangemin", json_object_new_string(label));
+                snprintf(label, sizeof (label), "%i", tlv[idx++]);
+                json_object_object_add(embedJson, "rangemax", json_object_new_string(label));
+                embedJson = decodeTlv(tlv + idx, 4 * sizeof (unsigned int));
+                json_object_object_add(embedJson, "tlv", embedJson);
+                idx += 4;
+                size -= (unsigned int) (6 * sizeof (unsigned int));
+                json_object_array_add(dbRangeJson, embedJson);
+            }
+            json_object_object_add(decodeTlvJson, "dbrange", dbRangeJson);
+            break;
+        }
+#endif
+#ifdef SND_CTL_TLVT_DB_MINMAX
+        case SND_CTL_TLVT_DB_MINMAX:
+        case SND_CTL_TLVT_DB_MINMAX_MUTE:
+        {
+            json_object * dbMinMaxJson = json_object_new_object();
+
+            if (size != 2 * sizeof (unsigned int)) {
+                json_object * arrayJson = json_object_new_array();
+                while (size > 0) {
+                    snprintf(label, sizeof (label), "0x%08x,", tlv[idx++]);
+                    json_object_array_add(arrayJson, json_object_new_string(label));
+                    size -= (unsigned int) sizeof (unsigned int);
+                }
+                json_object_object_add(dbMinMaxJson, "array", arrayJson);
+
+            } else {
+                json_object_object_add(dbMinMaxJson, "min", DB2StringJsonOject((int) tlv[2]));
+                json_object_object_add(dbMinMaxJson, "max", DB2StringJsonOject((int) tlv[3]));
+            }
+
+            if (type == SND_CTL_TLVT_DB_MINMAX_MUTE) {
+                json_object_object_add(decodeTlvJson, "dbminmaxmute", dbMinMaxJson);
+            } else {
+                json_object_object_add(decodeTlvJson, "dbminmax", dbMinMaxJson);
+            }
+            break;
+        }
+#endif
+#ifdef SND_CTL_TLVT_CHMAP_FIXED
+        case SND_CTL_TLVT_CHMAP_FIXED:
+            chmap_type = "fixed";
+            /* Fall through */
+        case SND_CTL_TLVT_CHMAP_VAR:
+            if (!chmap_type)
+                chmap_type = "variable";
+            /* Fall through */
+        case SND_CTL_TLVT_CHMAP_PAIRED:
+            if (!chmap_type)
+                chmap_type = "paired";
+
+            json_object * chmapJson = json_object_new_object();
+            json_object * arrayJson = json_object_new_array();
+
+            while (size > 0) {
+                snprintf(label, sizeof (label), "%s", snd_pcm_chmap_name(tlv[idx++]));
+                size -= (unsigned int) sizeof (unsigned int);
+                json_object_array_add(arrayJson, json_object_new_string(label));
+            }
+            json_object_object_add(chmapJson, chmap_type, arrayJson);
+            json_object_object_add(decodeTlvJson, "chmap", chmapJson);
+            break;
+#endif
+        default:
+        {
+            printf("unk-%i-", type);
+            json_object * arrayJson = json_object_new_array();
+
+            while (size > 0) {
+                snprintf(label, sizeof (label), "0x%08x,", tlv[idx++]);
+                size -= (unsigned int) sizeof (unsigned int);
+                json_object_array_add(arrayJson, json_object_new_string(label));
+            }
+            break;
+            json_object_object_add(decodeTlvJson, "unknown", arrayJson);
+        }
+    }
+
+    return (decodeTlvJson);
+}
+
+
+// retreive info for one given card
+STATIC  json_object* alsaCardProbe (const char *rqtSndId) {
+    const char  *info, *name;
+    const char *devid, *driver;
+    json_object *sndcard;
+    snd_ctl_t   *handle;
+    snd_ctl_card_info_t *cardinfo;
+    int err;
+
+
+    snd_ctl_card_info_alloca(&cardinfo);
+
+    if ((err = snd_ctl_open(&handle, rqtSndId, 0)) < 0) {
+        INFO (afbIface, "SndCard [%s] Not Found", rqtSndId);
+        return NULL;
+    }
+
+    if ((err = snd_ctl_card_info(handle, cardinfo)) < 0) {
+        snd_ctl_close(handle);
+        WARNING (afbIface, "SndCard [%s] info error: %s", rqtSndId, snd_strerror(err));
+        return NULL;
+    }
+
+    // start a new json object to store card info
+    sndcard = json_object_new_object();
+
+    devid= snd_ctl_card_info_get_id(cardinfo);
+    json_object_object_add (sndcard, "devid"  , json_object_new_string(devid));
+    name =  snd_ctl_card_info_get_name(cardinfo);
+    json_object_object_add (sndcard, "name", json_object_new_string (name));
+
+    if (afbIface->verbosity > 1) {
+        json_object_object_add (sndcard, "devid", json_object_new_string(rqtSndId));
+        driver= snd_ctl_card_info_get_driver(cardinfo);
+        json_object_object_add (sndcard, "driver"  , json_object_new_string(driver));
+        info  = strdup(snd_ctl_card_info_get_longname (cardinfo));
+        json_object_object_add (sndcard, "info" , json_object_new_string (info));
+        INFO (afbIface, "AJG: Soundcard Devid=%-5s Cardid=%-7s Name=%s\n", rqtSndId, devid, info);
+    }
+
+    // free card handle and return info
+    snd_ctl_close(handle);    
+    return (sndcard);
+}
+
+// Loop on every potential Sound card and register active one
+PUBLIC void alsaGetInfo (struct afb_req request) {
+    int  card;
+    json_object *sndcard, *sndcards;
+    char devid[32];
+    
+    const char *rqtSndId = afb_req_value(request, "devid");
+
+    // if no specific card requested loop on all
+
+    if (rqtSndId != NULL) {
+        // only one card was requested let's probe it
+        sndcard = alsaCardProbe (rqtSndId);
+        if (sndcard != NULL) afb_req_success(request, sndcard, NULL);
+        else afb_req_fail_f (request, "SndCard [%s] Not Found", rqtSndId);
+        
+    } else {
+        // return an array of sndcard
+        sndcards =json_object_new_array();
+
+        // loop on potential card number
+        for (card =0; card < MAX_SND_CARD; card++) {
+
+            // build card devid and probe it
+            snprintf (devid, sizeof(devid), "hw:%i", card);
+            sndcard = alsaCardProbe (devid);
+
+            // Alsa has hole within card list [ignore them]
+            if (sndcard != NULL) {
+                // add current sndcard to sndcards object
+                json_object_array_add (sndcards, sndcard);
+            }    
+        }
+        afb_req_success (request, sndcards, NULL);  
+    }
+}
+
+// pack Alsa element's ACL into a JSON object
+STATIC json_object *getControlAcl (snd_ctl_elem_info_t *info) {
+
+    json_object * jsonAclCtl = json_object_new_object();
+
+    json_object_object_add (jsonAclCtl, "read"   , json_object_new_boolean(snd_ctl_elem_info_is_readable(info)));
+    json_object_object_add (jsonAclCtl, "write"  , json_object_new_boolean(snd_ctl_elem_info_is_writable(info)));
+    json_object_object_add (jsonAclCtl, "inact"  , json_object_new_boolean(snd_ctl_elem_info_is_inactive(info)));
+    json_object_object_add (jsonAclCtl, "volat"  , json_object_new_boolean(snd_ctl_elem_info_is_volatile(info)));
+    json_object_object_add (jsonAclCtl, "lock"   , json_object_new_boolean(snd_ctl_elem_info_is_locked(info)));
+
+    // if TLV is readable we insert its ACL
+    if (!snd_ctl_elem_info_is_tlv_readable(info)) {
+        json_object * jsonTlv = json_object_new_object();
+
+        json_object_object_add (jsonTlv, "read"   , json_object_new_boolean(snd_ctl_elem_info_is_tlv_readable(info)));
+        json_object_object_add (jsonTlv, "write"  , json_object_new_boolean(snd_ctl_elem_info_is_tlv_writable(info)));
+        json_object_object_add (jsonTlv, "command", json_object_new_boolean(snd_ctl_elem_info_is_tlv_commandable(info)));
+
+        json_object_object_add (jsonAclCtl, "tlv", jsonTlv);
+    }
+    return (jsonAclCtl);
+}
+
+
+
+// pack element from ALSA control into a JSON object
+STATIC json_object * alsaGetSingleCtl (snd_hctl_elem_t *elem, snd_ctl_elem_info_t *info, queryValuesT *queryValues) {
+
+    int err;
+    json_object *jsonAlsaCtl,*jsonClassCtl;
+    snd_ctl_elem_id_t *elemid;
+    snd_ctl_elem_type_t elemtype;
+    snd_ctl_elem_value_t *control;
+    int count, idx;
+
+    // allocate ram for ALSA elements
+    snd_ctl_elem_value_alloca(&control);
+    snd_ctl_elem_id_alloca   (&elemid);
+
+    // get elemId out of elem
+    snd_hctl_elem_get_id(elem, elemid);
+
+    // when ctrlid is set, return only this ctrl
+    if (queryValues->numid != -1 && queryValues->numid != snd_ctl_elem_id_get_numid(elemid)) return NULL;
+
+    // build a json object out of element
+    jsonAlsaCtl = json_object_new_object(); // http://alsa-lib.sourcearchive.com/documentation/1.0.24.1-3/group__Control_ga4e4f251147f558bc2ad044e836e449d9.html
+    json_object_object_add (jsonAlsaCtl,"numid", json_object_new_int(snd_ctl_elem_id_get_numid (elemid)));
+    if (queryValues->quiet < 2) json_object_object_add (jsonAlsaCtl,"name" , json_object_new_string(snd_ctl_elem_id_get_name (elemid)));
+    if (queryValues->quiet < 1) json_object_object_add (jsonAlsaCtl,"iface", json_object_new_string(snd_ctl_elem_iface_name(snd_ctl_elem_id_get_interface(elemid))));
+    if (queryValues->quiet < 3)json_object_object_add (jsonAlsaCtl,"actif", json_object_new_boolean(!snd_ctl_elem_info_is_inactive(info)));
+
+    elemtype = snd_ctl_elem_info_get_type(info);
+
+	// number item and value(s) within control.
+	count = snd_ctl_elem_info_get_count (info);
+
+	if (snd_ctl_elem_info_is_readable(info)) {
+	    json_object *jsonValuesCtl = json_object_new_array();
+
+		if ((err = snd_hctl_elem_read(elem, control)) < 0) {
+		       json_object *jsonValuesCtl = json_object_new_object();
+       		   json_object_object_add (jsonValuesCtl,"error", json_object_new_string(snd_strerror(err)));
+		} else {
+			for (idx = 0; idx < count; idx++) { // start from one in amixer.c !!!
+				switch (elemtype) {
+				case SND_CTL_ELEM_TYPE_BOOLEAN: {
+					json_object_array_add (jsonValuesCtl, json_object_new_boolean (snd_ctl_elem_value_get_boolean(control, idx)));
+					break;
+					}
+				case SND_CTL_ELEM_TYPE_INTEGER:
+					json_object_array_add (jsonValuesCtl, json_object_new_int ((int)snd_ctl_elem_value_get_integer(control, idx)));
+					break;
+				case SND_CTL_ELEM_TYPE_INTEGER64:
+					json_object_array_add (jsonValuesCtl, json_object_new_int64 (snd_ctl_elem_value_get_integer64(control, idx)));
+					break;
+				case SND_CTL_ELEM_TYPE_ENUMERATED:
+					json_object_array_add (jsonValuesCtl, json_object_new_int (snd_ctl_elem_value_get_enumerated(control, idx)));
+					break;
+				case SND_CTL_ELEM_TYPE_BYTES:
+					json_object_array_add (jsonValuesCtl, json_object_new_int ((int)snd_ctl_elem_value_get_byte(control, idx)));
+					break;
+				case SND_CTL_ELEM_TYPE_IEC958: {
+					json_object *jsonIec958Ctl = json_object_new_object();
+					snd_aes_iec958_t iec958;
+					snd_ctl_elem_value_get_iec958(control, &iec958);
+
+					json_object_object_add (jsonIec958Ctl,"AES0",json_object_new_int(iec958.status[0]));
+					json_object_object_add (jsonIec958Ctl,"AES1",json_object_new_int(iec958.status[1]));
+					json_object_object_add (jsonIec958Ctl,"AES2",json_object_new_int(iec958.status[2]));
+					json_object_object_add (jsonIec958Ctl,"AES3",json_object_new_int(iec958.status[3]));
+					json_object_array_add  (jsonValuesCtl, jsonIec958Ctl);
+					break;
+					}
+				default:
+					json_object_array_add (jsonValuesCtl, json_object_new_string ("?unknown?"));
+					break;
+				}
+			}
+		}
+		json_object_object_add (jsonAlsaCtl,"value",jsonValuesCtl);
+    }
+
+
+    if (!queryValues->quiet) {  // in simple mode do not print usable values
+        jsonClassCtl = json_object_new_object();
+        json_object_object_add (jsonClassCtl,"type" , json_object_new_string(snd_ctl_elem_type_name(elemtype)));
+		json_object_object_add (jsonClassCtl,"count", json_object_new_int(count));
+
+		switch (elemtype) {
+			case SND_CTL_ELEM_TYPE_INTEGER:
+				json_object_object_add (jsonClassCtl,"min",  json_object_new_int((int)snd_ctl_elem_info_get_min(info)));
+				json_object_object_add (jsonClassCtl,"max",  json_object_new_int((int)snd_ctl_elem_info_get_max(info)));
+				json_object_object_add (jsonClassCtl,"step", json_object_new_int((int)snd_ctl_elem_info_get_step(info)));
+				break;
+			case SND_CTL_ELEM_TYPE_INTEGER64:
+				json_object_object_add (jsonClassCtl,"min",  json_object_new_int64(snd_ctl_elem_info_get_min64(info)));
+				json_object_object_add (jsonClassCtl,"max",  json_object_new_int64(snd_ctl_elem_info_get_max64(info)));
+				json_object_object_add (jsonClassCtl,"step", json_object_new_int64(snd_ctl_elem_info_get_step64(info)));
+				break;
+			case SND_CTL_ELEM_TYPE_ENUMERATED: {
+				unsigned int item, items = snd_ctl_elem_info_get_items(info);
+				json_object *jsonEnum = json_object_new_array();
+
+				for (item = 0; item < items; item++) {
+					snd_ctl_elem_info_set_item(info, item);
+					if ((err = snd_hctl_elem_info(elem, info)) >= 0) {
+						json_object_array_add (jsonEnum, json_object_new_string(snd_ctl_elem_info_get_item_name(info)));
+					}
+				}
+				json_object_object_add (jsonClassCtl, "enums",jsonEnum);
+				break;
+			}
+			default: break; // ignore any unknown type
+			}
+
+		// add collected class info with associated ACLs
+		json_object_object_add (jsonAlsaCtl,"ctrl", jsonClassCtl);
+		json_object_object_add (jsonAlsaCtl,"acl"  , getControlAcl (info));
+
+		// check for tlv [direct port from amixer.c]
+		if (snd_ctl_elem_info_is_tlv_readable(info)) {
+				unsigned int *tlv;
+				tlv = malloc(4096);
+				if ((err = snd_hctl_elem_tlv_read(elem, tlv, 4096)) < 0) {
+					fprintf (stderr, "Control %s element TLV read error\n", snd_strerror(err));
+					free(tlv);
+				} else {
+					json_object_object_add (jsonAlsaCtl,"tlv", decodeTlv (tlv, 4096));
+		   }
+		}
+   }
+   return (jsonAlsaCtl);
+}
+
+
+PUBLIC void alsaGetCtl(struct afb_req request) {
+    int err = 0;
+    snd_hctl_t *handle;
+    snd_hctl_elem_t *elem;
+    snd_ctl_elem_info_t *info;
+    json_object *sndctrls, *control;
+    queryValuesT queryValues;
+
+    // get API params
+    queryValues.devid = afb_req_value(request, "devid");
+    
+    const char *rqtNumid = afb_req_value(request, "numid");
+    if (!rqtNumid) queryValues.numid=-1;
+    else if (rqtNumid && ! sscanf (rqtNumid, "%d", &queryValues.numid)) {
+        json_object *query = afb_req_json(request);
+        
+        afb_req_fail_f (request, "Query=%s NumID not integer &numid=%s&", json_object_to_json_string(query), rqtNumid);
+        goto ExitOnError;
+    };
+    
+    const char *rqtQuiet = afb_req_value(request, "quiet");
+    if (!rqtQuiet) queryValues.quiet=99; // default super quiet
+    else if (rqtQuiet && ! sscanf (rqtQuiet, "%d", &queryValues.quiet)) {
+        json_object *query = afb_req_json(request);
+        
+        afb_req_fail_f (request, "Query=%s NumID not integer &numid=%s&", json_object_to_json_string(query), rqtQuiet);
+        goto ExitOnError;
+    };
+    
+    // Open sound we use Alsa high level API like amixer.c
+    if (!queryValues.devid || (err = snd_hctl_open(&handle, queryValues.devid, 0)) < 0) {
+        afb_req_fail_f (request, "alsaGetControl devid=[%s] open fail error=%s\n", queryValues.devid, snd_strerror(err));
+        goto ExitOnError;
+    }
+
+    if ((err = snd_hctl_load(handle)) < 0) {
+        afb_req_fail_f (request, "alsaGetControl devid=[%s] load fail error=%s\n", queryValues.devid, snd_strerror(err));
+        goto ExitOnError;
+    }
+
+    // allocate ram for ALSA elements
+    snd_ctl_elem_info_alloca(&info);
+
+    // create an json array to hold all sndcard response
+    sndctrls = json_object_new_array();
+
+    for (elem = snd_hctl_first_elem(handle); elem != NULL; elem = snd_hctl_elem_next(elem)) {
+
+        if ((err = snd_hctl_elem_info(elem, info)) < 0) {
+            json_object_put(sndctrls); // we abandon request let's free response
+            afb_req_fail_f (request, "alsaGetControl devid=[%s/%s] snd_hctl_elem_info error: %s\n"
+                           , queryValues.devid, snd_hctl_name(handle), snd_strerror(err));
+            goto ExitOnError;           
+        }
+
+        // each control is added into a JSON array
+        control = alsaGetSingleCtl(elem, info, &queryValues);
+        if (control) json_object_array_add(sndctrls, control);
+
+    }
+
+    afb_req_success (request, sndctrls, NULL);
+    return;
+    
+    // nothing special only for debugger breakpoint
+    ExitOnError:
+        return;
+}
+
+// This routine is called when ALSA event are fired
+STATIC  int sndCtlEventCB (sd_event_source* src, int fd, uint32_t revents, void* userData) {
+    int err;
+    evtHandleT *evtHandle = (evtHandleT*)userData; 
+    snd_ctl_event_t *ctlEvent;
+    json_object *ctlEventJson;
+    unsigned int mask;
+    int numid;
+    int iface;
+    int device;
+    int subdev;
+    const char*devname;
+    int index;  
+    
+    if ((revents & EPOLLHUP) != 0) {
+        NOTICE (afbIface, "SndCtl hanghup [car disconnected]");
+        goto ExitOnSucess;
+    }
+    
+    if ((revents & EPOLLIN) != 0)  {
+          
+        snd_ctl_event_alloca(&ctlEvent); // initialise event structure on stack
+        
+        err = snd_ctl_read(evtHandle->ctl, ctlEvent);
+        if (err < 0) goto ExitOnError;
+        
+        // we only process sndctrl element
+        if (snd_ctl_event_get_type(ctlEvent) != SND_CTL_EVENT_ELEM) goto ExitOnSucess;
+       
+        // we only process value changed events
+        mask = snd_ctl_event_elem_get_mask(ctlEvent);
+        if (!(mask & SND_CTL_EVENT_MASK_VALUE)) goto ExitOnSucess;
+       
+        numid  = snd_ctl_event_elem_get_numid(ctlEvent);
+        iface  = snd_ctl_event_elem_get_interface(ctlEvent);
+        device = snd_ctl_event_elem_get_device(ctlEvent);
+        subdev = snd_ctl_event_elem_get_subdevice(ctlEvent);
+        devname= snd_ctl_event_elem_get_name(ctlEvent);
+        index  = snd_ctl_event_elem_get_index(ctlEvent);
+        
+        DEBUG(afbIface, "sndCtlEventCB: (%i,%i,%i,%i,%s,%i)", numid, iface, device, subdev, devname, index);
+
+        // proxy ctlevent as a binder event        
+        ctlEventJson = json_object_new_object();
+        json_object_object_add(ctlEventJson, "numid"  ,json_object_new_int (numid));
+        json_object_object_add(ctlEventJson, "iface"  ,json_object_new_int (iface));
+        json_object_object_add(ctlEventJson, "device" ,json_object_new_int (device));
+        json_object_object_add(ctlEventJson, "subdev" ,json_object_new_int (subdev));
+        json_object_object_add(ctlEventJson, "devname",json_object_new_string (devname));
+        json_object_object_add(ctlEventJson, "index"  ,json_object_new_int (index));
+        afb_event_push(evtHandle->afbevt, ctlEventJson);
+    }
+
+    ExitOnSucess:
+        return 0;
+    
+    ExitOnError:
+        WARNING (afbIface, "sndCtlEventCB: ignored unsupported event type");
+	return (0);    
+}
+
+// Subscribe to every Alsa CtlEvent send by a given board
+PUBLIC void alsaSubcribe (struct afb_req request) {
+    static sndHandleT sndHandles[MAX_SND_CARD];
+    evtHandleT *evtHandle;
+    snd_ctl_t  *ctlHandle;
+    snd_ctl_card_info_t *card_info; 
+    int err, idx, cardid;
+    int idxFree=-1;
+    
+    const char *devid = afb_req_value(request, "devid");
+    if (devid == NULL) {
+        afb_req_fail_f (request, "devid-missing", "devid=hw:xxx missing");
+        goto ExitOnError;
+    }
+    
+    // open control interface for devid
+    err = snd_ctl_open(&ctlHandle, devid, SND_CTL_READONLY);
+    if (err < 0) {
+    afb_req_fail_f (request, "devid-unknown", "SndCard devid=%s Not Found err=%d", devid, err);
+    goto ExitOnError;
+    }
+    
+    // get sound card index use to search existing subscription
+    snd_ctl_card_info_alloca(&card_info);  
+    snd_ctl_card_info(ctlHandle, card_info);
+    cardid = snd_ctl_card_info_get_card(card_info);
+    
+    // search for an existing subscription and mark 1st free slot
+    for (idx= 0; idx < MAX_SND_CARD; idx ++) {
+      if (sndHandles[idx].ucount > 0 && sndHandles[idx].cardid == cardid) {
+         evtHandle= sndHandles[idx].evtHandle;
+         break;
+      } else if (idxFree == -1) idxFree= idx; 
+    };
+      
+    // if not subscription exist for the event let's create one
+    if (idx == MAX_SND_CARD) {
+        
+        // reach MAX_SND_CARD event registration
+        if (idxFree == -1) {
+            afb_req_fail_f (request, "register-toomany", "Cannot register new event Maxcard==%devent name=%s", idx);
+            snd_ctl_close(ctlHandle);
+            goto ExitOnError;            
+        } 
+        
+        evtHandle = malloc (sizeof(evtHandleT));
+        evtHandle->ctl = ctlHandle;
+        sndHandles[idxFree].ucount = 0;
+        sndHandles[idxFree].cardid = cardid;
+        sndHandles[idxFree].evtHandle = evtHandle;
+        
+        // subscribe for sndctl events attached to devid
+        err = snd_ctl_subscribe_events(evtHandle->ctl, 1);
+        if (err < 0) {
+            afb_req_fail_f (request, "subscribe-fail", "Cannot subscribe events from devid=%s err=%d", devid, err);
+            snd_ctl_close(ctlHandle);
+            goto ExitOnError;
+        }
+            
+        // get pollfd attach to this sound board
+        snd_ctl_poll_descriptors(evtHandle->ctl, &evtHandle->pfds, 1);
+
+        // register sound event to binder main loop
+        err = sd_event_add_io(afb_daemon_get_event_loop(afbIface->daemon), &evtHandle->src, evtHandle->pfds.fd, EPOLLIN, sndCtlEventCB, evtHandle);
+        if (err < 0) {
+            afb_req_fail_f (request, "register-mainloop", "Cannot hook events to mainloop devid=%s err=%d", devid, err);
+            snd_ctl_close(ctlHandle);
+            goto ExitOnError;
+        }
+
+        // create binder event attached to devid name
+        evtHandle->afbevt = afb_daemon_make_event (afbIface->daemon, devid);
+        if (!afb_event_is_valid (evtHandle->afbevt)) {
+            afb_req_fail_f (request, "register-event", "Cannot register new binder event name=%s", devid);
+            snd_ctl_close(ctlHandle);
+            goto ExitOnError; 
+        }
+
+        // everything looks OK let's move forward 
+        idx=idxFree;
+    }
+    
+    // subscribe to binder event    
+    err = afb_req_subscribe(request, evtHandle->afbevt);
+    if (err != 0) {
+        afb_req_fail_f (request, "register-eventname", "Cannot subscribe binder event name=%s [invalid channel]", devid, err);
+        goto ExitOnError;
+    }
+
+    // increase usage count and return success
+    sndHandles[idx].ucount ++;
+    afb_req_success(request, NULL, NULL);
+    return;
+    
+  ExitOnError:
+        return;
+}
+
+// Subscribe to every Alsa CtlEvent send by a given board
+PUBLIC void alsaGetCardId (struct afb_req request) {
+    char devid [10];
+    int card, err, index;
+    json_object *respJson;
+    snd_ctl_t   *ctlHandle;
+    snd_ctl_card_info_t *cardinfo;
+    
+    const char *sndname = afb_req_value(request, "sndname");
+    if (sndname == NULL) {
+        afb_req_fail_f (request, "argument-missing", "sndname=SndCardName missing");
+        goto ExitOnError;
+    }
+    
+    // loop on potential card number
+    snd_ctl_card_info_alloca(&cardinfo);  
+    for (card =0; card < MAX_SND_CARD; card++) {
+
+        // build card devid and probe it
+        snprintf (devid, sizeof(devid), "hw:%i", card);
+        
+        // open control interface for devid
+        err = snd_ctl_open(&ctlHandle, devid, SND_CTL_READONLY);
+        if (err < 0) continue;   
+        
+        snd_ctl_card_info(ctlHandle, cardinfo);
+        index    = snd_ctl_card_info_get_card(cardinfo);
+
+        // check if short|long name match        
+        if (!strcmp (sndname, snd_ctl_card_info_get_id(cardinfo))) break;
+        if (!strcmp (sndname, snd_ctl_card_info_get_name(cardinfo))) break;
+        if (!strcmp (sndname, snd_ctl_card_info_get_longname(cardinfo))) break;
+    }
+    
+    if (card == MAX_SND_CARD) {
+        afb_req_fail_f (request, "sndcard-notfound", "Fail to find card with name=%s", sndname);
+        goto ExitOnError;
+    }
+    
+    // proxy ctlevent as a binder event        
+    respJson = json_object_new_object();
+    json_object_object_add(respJson, "index"     ,json_object_new_int (index));
+    json_object_object_add(respJson, "devid"     ,json_object_new_string (devid));
+    json_object_object_add(respJson, "shortname" ,json_object_new_string (snd_ctl_card_info_get_name(cardinfo)));
+    json_object_object_add(respJson, "longname"  ,json_object_new_string (snd_ctl_card_info_get_longname(cardinfo)));
+        
+    afb_req_success(request, respJson, NULL);    
+    return;
+    
+  ExitOnError:
+        return;  
+}
+
+
+
+// This function is call when all plugins are loaded
+PUBLIC int alsaLibInit (struct afb_service service) {
+
+    // For future use    
+    srvitf = service;
+    
+    return 0;
+}
\ No newline at end of file