Implement mixer setting in tinymix

- re-add function to set enum type by string
- implement setting of mixer values in tinymix
- fix bug: read current mixer values before writing

include/tinyalsa/asoundlib.h

@@ -129,5 +129,6 @@ int mixer_ctl_set_percent(struct mixer_ctl *ctl, unsigned int id, int percent);
 
 int mixer_ctl_get_value(struct mixer_ctl *ctl, unsigned int id);
 int mixer_ctl_set_value(struct mixer_ctl *ctl, unsigned int id, int value);
+int mixer_ctl_set_enum_by_string(struct mixer_ctl *ctl, const char *string);
 
 #endif

mixer.c

@@ -348,6 +348,8 @@ int mixer_ctl_set_value(struct mixer_ctl *ctl, unsigned int id, int value)
 
     memset(&ev, 0, sizeof(ev));
     ev.id.numid = ctl->info->id.numid;
+    if (ioctl(ctl->mixer->fd, SNDRV_CTL_IOCTL_ELEM_READ, &ev))
+        return -1;
 
     switch (ctl->info->type) {
     case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
@@ -400,3 +402,29 @@ int mixer_ctl_get_enum_string(struct mixer_ctl *ctl, unsigned int enum_id,
     return 0;
 }
 
+int mixer_ctl_set_enum_by_string(struct mixer_ctl *ctl, const char *string)
+{
+    unsigned int i, num_enums;
+    struct snd_ctl_elem_value ev;
+
+    if (!ctl || (ctl->info->type != SNDRV_CTL_ELEM_TYPE_ENUMERATED)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    num_enums = ctl->info->value.enumerated.items;
+    for (i = 0; i < num_enums; i++) {
+        if (!strcmp(string, ctl->ename[i])) {
+            memset(&ev, 0, sizeof(ev));
+            ev.value.enumerated.item[0] = i;
+            ev.id.numid = ctl->info->id.numid;
+            if (ioctl(ctl->mixer->fd, SNDRV_CTL_IOCTL_ELEM_WRITE, &ev) < 0)
+                return -1;
+            return 0;
+        }
+    }
+
+    errno = EINVAL;
+    return -1;
+}
+

tinymix.c

@@ -32,6 +32,8 @@
 
 static void tinymix_list_controls(struct mixer *mixer);
 static void tinymix_detail_control(struct mixer *mixer, unsigned int id);
+static void tinymix_set_value(struct mixer *mixer, unsigned int id,
+                              char *value);
 
 int main(int argc, char **argv)
 {
@@ -43,8 +45,10 @@ int main(int argc, char **argv)
         tinymix_list_controls(mixer);
     else if (argc == 2)
         tinymix_detail_control(mixer, atoi(argv[1]));
+    else if (argc == 3)
+        tinymix_set_value(mixer, atoi(argv[1]), argv[2]);
     else
-        printf("Usage: tinymix [control id]\n");
+        printf("Usage: tinymix [control id] [value to set]\n");
 
     mixer_close(mixer);
 
@@ -129,3 +133,34 @@ static void tinymix_detail_control(struct mixer *mixer, unsigned int id)
     printf("\n");
 }
 
+static void tinymix_set_value(struct mixer *mixer, unsigned int id,
+                              char *string)
+{
+    struct mixer_ctl *ctl;
+    enum mixer_ctl_type type;
+    unsigned int num_values;
+    unsigned int i;
+
+    ctl = mixer_get_ctl(mixer, id);
+    type = mixer_ctl_get_type(ctl);
+    num_values = mixer_ctl_get_num_values(ctl);
+
+    if (isdigit(string[0])) {
+        int value = atoi(string);
+
+        for (i = 0; i < num_values; i++) {
+            if (mixer_ctl_set_value(ctl, i, value)) {
+                fprintf(stderr, "Error: invalid value\n");
+                return;
+            }
+        }
+    } else {
+        if (type == MIXER_CTL_TYPE_ENUM) {
+            if (mixer_ctl_set_enum_by_string(ctl, string))
+                fprintf(stderr, "Error: invalid enum value\n");
+        } else {
+            fprintf(stderr, "Error: only enum types can be set with strings\n");
+        }
+    }
+}
+