Remove hard-coded values from widget-gain.c and widget-volume.c

Update alsa-sim.c and alsa.c to read the TLV info, and update the gain
and volume widgets to use that info rather than hard-coding the
min/max values.

src/alsa-sim.c

@@ -151,6 +151,42 @@ static void alsa_parse_comment_node(
         elem->type = SND_CTL_ELEM_TYPE_INTEGER;
     } else if (strcmp(key, "item") == 0) {
       alsa_parse_enum_items(node, elem);
+    } else if (strcmp(key, "range") == 0) {
+      if (type != SND_CONFIG_TYPE_STRING) {
+        printf("range type not string\n");
+        return;
+      }
+      const char *range;
+      err = snd_config_get_string(node, &range);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_string error", err);
+
+      // Parse the range string and update elem->min_val and elem->max_val
+      int min_val, max_val;
+      if (sscanf(range, "%d - %d", &min_val, &max_val) == 2) {
+        elem->min_val = min_val;
+        elem->max_val = max_val;
+      }
+    } else if (strcmp(key, "dbmin") == 0) {
+      if (type != SND_CONFIG_TYPE_INTEGER) {
+        printf("dbmin type not integer\n");
+        return;
+      }
+      long dbmin;
+      err = snd_config_get_integer(node, &dbmin);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_integer error", err);
+      elem->min_dB = dbmin / 100;
+    } else if (strcmp(key, "dbmax") == 0) {
+      if (type != SND_CONFIG_TYPE_INTEGER) {
+        printf("dbmax type not integer\n");
+        return;
+      }
+      long dbmax;
+      err = snd_config_get_integer(node, &dbmax);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_integer error", err);
+      elem->max_dB = dbmax / 100;
     }
   }
 }

src/alsa.c

@@ -7,6 +7,8 @@
 #include "stringhelper.h"
 #include "window-iface.h"
 
+#define MAX_TLV_RANGE_SIZE 256
+
 // names for the port categories
 const char *port_category_names[PC_COUNT] = {
   "Hardware Outputs",
@@ -340,6 +342,54 @@ static void alsa_get_elem_list(struct alsa_card *card) {
     if (strstr(alsa_elem.name, "Channel Map"))
       continue;
 
+    // get TLV info if it's a volume control
+    if (alsa_elem.type == SND_CTL_ELEM_TYPE_INTEGER) {
+      snd_ctl_elem_info_t *elem_info;
+
+      snd_ctl_elem_info_alloca(&elem_info);
+      snd_ctl_elem_info_set_numid(elem_info, alsa_elem.numid);
+      snd_ctl_elem_info(card->handle, elem_info);
+
+      if (snd_ctl_elem_info_is_tlv_readable(elem_info)) {
+        snd_ctl_elem_id_t *elem_id;
+        unsigned int tlv[MAX_TLV_RANGE_SIZE];
+        unsigned int *dbrec;
+        int ret;
+        long min_dB, max_dB;
+
+        snd_ctl_elem_id_alloca(&elem_id);
+        snd_ctl_elem_id_set_numid(elem_id, alsa_elem.numid);
+
+        ret = snd_ctl_elem_tlv_read(
+          card->handle, elem_id, tlv, sizeof(tlv)
+        );
+        if (ret < 0) {
+          fprintf(stderr, "TLV read error %d\n", ret);
+          continue;
+        }
+
+        ret = snd_tlv_parse_dB_info(tlv, sizeof(tlv), &dbrec);
+        if (ret <= 0) {
+          fprintf(stderr, "TLV parse error %d\n", ret);
+          continue;
+        }
+
+        int min_val = snd_ctl_elem_info_get_min(elem_info);
+        int max_val = snd_ctl_elem_info_get_max(elem_info);
+
+        ret = snd_tlv_get_dB_range(tlv, min_val, max_val, &min_dB, &max_dB);
+        if (ret != 0) {
+          fprintf(stderr, "TLV range error %d\n", ret);
+          continue;
+        }
+
+        alsa_elem.min_val = min_val;
+        alsa_elem.max_val = max_val;
+        alsa_elem.min_dB = min_dB / 100;
+        alsa_elem.max_dB = max_dB / 100;
+      }
+    }
+
     if (card->elems->len <= alsa_elem.numid)
       g_array_set_size(card->elems, alsa_elem.numid + 1);
     g_array_index(card->elems, struct alsa_elem, alsa_elem.numid) = alsa_elem;

src/alsa.h

@@ -115,6 +115,12 @@ struct alsa_elem {
   int         type;
   int         count;
 
+  // for gain/volume elements, the dB range and step
+  int min_val;
+  int max_val;
+  int min_dB;
+  int max_dB;
+
   // for the number (or translated letter; A = 1) in the item name
   // TODO: move this to struct routing_snk?
   int lr_num;

src/widget-gain.c

@@ -4,11 +4,6 @@
 #include "gtkdial.h"
 #include "widget-gain.h"
 
-// gain controls -80dB - +6dB, 0.5dB steps
-#define DIAL_MIN_VALUE 0
-#define DIAL_MAX_VALUE 172
-#define DIAL_ZERO_DB_VALUE 160
-
 static void gain_changed(GtkWidget *widget, struct alsa_elem *elem) {
   int value = gtk_dial_get_value(GTK_DIAL(widget));
 
@@ -23,7 +18,10 @@ static void gain_updated(struct alsa_elem *elem) {
   gtk_dial_set_value(GTK_DIAL(elem->widget), value);
 
   char s[20];
-  snprintf(s, 20, "%.1f", (value / 2.0) - 80);
+  float scale = (float)(elem->max_dB - elem->min_dB) /
+                       (elem->max_val - elem->min_val);
+
+  snprintf(s, 20, "%.1f", value * scale + elem->min_dB);
   gtk_label_set_text(GTK_LABEL(elem->widget2), s);
 }
 
@@ -32,9 +30,15 @@ GtkWidget *make_gain_alsa_elem(struct alsa_elem *elem) {
   gtk_widget_set_hexpand(vbox, TRUE);
 
   GtkWidget *dial = gtk_dial_new_with_range(
-    DIAL_MIN_VALUE, DIAL_MAX_VALUE, 1
+    elem->min_val, elem->max_val, 1
   );
-  gtk_dial_set_zero_db(GTK_DIAL(dial), DIAL_ZERO_DB_VALUE);
+
+  // calculate 0dB value from min/max dB and min/max value
+  float scale = (float)(elem->max_dB - elem->min_dB) /
+                       (elem->max_val - elem->min_val);
+  int zero_db_value = (int)((0 - elem->min_dB) / scale + elem->min_val);
+
+  gtk_dial_set_zero_db(GTK_DIAL(dial), zero_db_value);
 
   gtk_widget_set_vexpand(dial, TRUE);
 

src/widget-volume.c

@@ -4,11 +4,6 @@
 #include "gtkdial.h"
 #include "widget-volume.h"
 
-// volume controls -127dB - 0dB
-#define DIAL_MIN_VALUE 0
-#define DIAL_MAX_VALUE 127
-#define DIAL_ZERO_DB_VALUE 127
-
 static void volume_changed(GtkWidget *widget, struct alsa_elem *elem) {
   int value = gtk_dial_get_value(GTK_DIAL(widget));
 
@@ -23,7 +18,10 @@ static void volume_updated(struct alsa_elem *elem) {
   gtk_dial_set_value(GTK_DIAL(elem->widget), value);
 
   char s[20];
-  snprintf(s, 20, "%ddB", value - 127);
+  float scale = (float)(elem->max_dB - elem->min_dB) /
+                       (elem->max_val - elem->min_val);
+
+  snprintf(s, 20, "%ddB", (int)(value * scale + elem->min_dB));
   gtk_label_set_text(GTK_LABEL(elem->widget2), s);
 }
 
@@ -32,9 +30,15 @@ GtkWidget *make_volume_alsa_elem(struct alsa_elem *elem) {
   gtk_widget_set_hexpand(vbox, TRUE);
 
   GtkWidget *dial = gtk_dial_new_with_range(
-    DIAL_MIN_VALUE, DIAL_MAX_VALUE, 1
+    elem->min_val, elem->max_val, 1
   );
-  gtk_dial_set_zero_db(GTK_DIAL(dial), DIAL_ZERO_DB_VALUE);
+
+  // calculate 0dB value from min/max dB and min/max value
+  float scale = (float)(elem->max_dB - elem->min_dB) /
+                       (elem->max_val - elem->min_val);
+  int zero_db_value = (int)((0 - elem->min_dB) / scale + elem->min_val);
+
+  gtk_dial_set_zero_db(GTK_DIAL(dial), zero_db_value);
 
   gtk_widget_set_vexpand(dial, TRUE);