modules/rtv: make channels set configurable

This adds a colon-separated channels setting, with a
setting of "all" for the existing all-modules behavior.

Colon was used since comma is already taken by the settings
separator, maybe in the future comma escaping can be added
everywhere relevant but for now just keep it simple.

The immediate value of this setting is telling rtv to limit
itself to a single module, and using its setting randomizer
to automatically observe a variety of the available settings
in action on a specific module, especially during development.

If knobs ever get added in the future I expect this will become
even more interesting for watching specific modules under their
various settings permutations in combination with their knobs
being twisted - especially if rtv reconstructs random signal
generator chains for the "knob-twisters" on every channel switch.

An immediately interesting TODO complementing this particular
change would be optionally preserving module contexts across
channel switches, so when the same module is revisited it resumes
where it was last seen.  But this conflicts with settings changes
on channel switching, since contexts should probably always be
recreated when settings change - but that's probably a
module-specific detail that modules should just be robust enough
to tolerate as in they'd safely ignore settings changes without a
context recreate, or apply them if they safely can without a
context recreate... TODO.

1 files changed, 76 insertions, 3 deletions

diff --git a/src/modules/rtv/rtv.c b/src/modules/rtv/rtv.c
index 704aca6..010e741 100644
--- a/src/modules/rtv/rtv.c
+++ b/src/modules/rtv/rtv.c
@@ -48,6 +48,7 @@ static int rtv_setup(const settings_t *settings, setting_desc_t **next_setting);
 static unsigned rtv_duration = RTV_DURATION_SECS;
 static unsigned rtv_snow_duration = RTV_SNOW_DURATION_SECS;
 static unsigned rtv_caption_duration = RTV_CAPTION_DURATION_SECS;
+static char **rtv_channels;
 
 
 rototiller_module_t	rtv_module = {
@@ -143,7 +144,7 @@ static void setup_next_module(rtv_context_t *ctxt, unsigned ticks)
 		ctxt->caption = txt_free(ctxt->caption);
 	}
 
-	if (ctxt->module != ctxt->snow_module) {
+	if (!ctxt->n_modules || ctxt->module != ctxt->snow_module) {
 		ctxt->last_module = ctxt->module;
 		ctxt->module = ctxt->snow_module;
 		ctxt->next_switch = now + rtv_snow_duration;
@@ -187,6 +188,24 @@ static void setup_next_module(rtv_context_t *ctxt, unsigned ticks)
 }
 
 
+static int rtv_skip_module(const rtv_context_t *ctxt, const rototiller_module_t *module)
+{
+	if (module == &rtv_module ||
+	    module == ctxt->snow_module)
+		return 1;
+
+	if (!rtv_channels)
+		return 0;
+
+	for (char **channel = rtv_channels; *channel; channel++) {
+		if (!strcmp(module->name, *channel))
+			return 0;
+	}
+
+	return 1;
+}
+
+
 static void * rtv_create_context(unsigned ticks, unsigned num_cpus)
 {
 	rtv_context_t			*ctxt;
@@ -203,8 +222,7 @@ static void * rtv_create_context(unsigned ticks, unsigned num_cpus)
 	ctxt->snow_module = rototiller_lookup_module("snow");
 
 	for (size_t i = 0; i < n_modules; i++) {
-		if (modules[i] == &rtv_module ||
-		    modules[i] == ctxt->snow_module)
+		if (rtv_skip_module(ctxt, modules[i]))
 			continue;
 
 		ctxt->modules[ctxt->n_modules++].module = modules[i];
@@ -264,6 +282,23 @@ static int rtv_setup(const settings_t *settings, setting_desc_t **next_setting)
 	const char	*duration;
 	const char	*caption_duration;
 	const char	*snow_duration;
+	const char	*channels;
+
+	channels = settings_get_value(settings, "channels");
+	if (!channels) {
+		int	r;
+
+		r = setting_desc_clone(&(setting_desc_t){
+						.name = "Colon-Separated List Of Channel Modules",
+						.key = "channels",
+						.preferred = "all",
+						.annotations = NULL
+					}, next_setting);
+		if (r < 0)
+			return r;
+
+		return 1;
+	}
 
 	duration = settings_get_value(settings, "duration");
 	if (!duration) {
@@ -316,6 +351,44 @@ static int rtv_setup(const settings_t *settings, setting_desc_t **next_setting)
 		return 1;
 	}
 
+	/* turn channels colon-separated list into a null-terminated array of strings */
+	if (strcmp(channels, "all")) {
+		const rototiller_module_t	**modules;
+		size_t				n_modules;
+		char				*tokchannels, *channel;
+		int				n = 2;
+
+		rototiller_get_modules(&modules, &n_modules);
+
+		tokchannels = strdup(channels);
+		if (!tokchannels)
+			return -ENOMEM;
+
+		channel = strtok(tokchannels, ":");
+		do {
+			char	**new;
+			size_t	i;
+
+			for (i = 0; i < n_modules; i++) {
+				if (!strcmp(channel, modules[i]->name))
+					break;
+			}
+
+			if (i >= n_modules)
+				return -EINVAL;
+
+			new = realloc(rtv_channels, n * sizeof(*rtv_channels));
+			if (!new)
+				return -ENOMEM;
+
+			new[n - 2] = channel;
+			new[n - 1] = NULL;
+			n++;
+
+			rtv_channels = new;
+		} while (channel = strtok(NULL, ":"));
+	}
+
 	/* TODO FIXME: parse errors */
 	sscanf(duration, "%u", &rtv_duration);
 	sscanf(caption_duration, "%u", &rtv_caption_duration);