Revert "remove inter-frame input polling"

This reverts commit 089c3016cc.

src/emulator.c

@@ -62,7 +62,6 @@ struct emu {
   struct render_backend *r, *r2;
   struct imgui *imgui;
   struct microprofile *mp;
-
   struct trace_writer *trace_writer;
 
   /* hosts which support creating multiple gl contexts will render video on
@@ -565,6 +564,12 @@ static void emu_paint(struct emu *emu) {
 /*
  * dreamcast guest interface
  */
+static void emu_guest_poll_input(void *userdata) {
+  struct emu *emu = userdata;
+
+  input_poll(emu->host);
+}
+
 static void emu_guest_vertical_blank(void *userdata) {
   struct emu *emu = userdata;
 
@@ -827,6 +832,7 @@ struct emu *emu_create(struct host *host) {
   emu->dc->start_render = &emu_guest_start_render;
   emu->dc->finish_render = &emu_guest_finish_render;
   emu->dc->vertical_blank = &emu_guest_vertical_blank;
+  emu->dc->poll_input = &emu_guest_poll_input;
 
   /* start up the video thread */
   emu->multi_threaded = video_supports_multiple_contexts(emu->host);

src/guest/dreamcast.c

@@ -16,6 +16,14 @@
 #include "guest/scheduler.h"
 #include "guest/sh4/sh4.h"
 
+void dc_poll_input(struct dreamcast *dc) {
+  if (!dc->poll_input) {
+    return;
+  }
+
+  dc->poll_input(dc->userdata);
+}
+
 void dc_vertical_blank(struct dreamcast *dc) {
   if (!dc->vertical_blank) {
     return;

src/guest/dreamcast.h

@@ -126,6 +126,7 @@ typedef void (*push_audio_cb)(void *, const int16_t *, int);
 typedef void (*start_render_cb)(void *, struct tile_context *);
 typedef void (*finish_render_cb)(void *);
 typedef void (*vertical_blank_cb)(void *);
+typedef void (*poll_input_cb)(void *);
 
 struct dreamcast {
   int running;
@@ -155,6 +156,7 @@ struct dreamcast {
   start_render_cb start_render;
   finish_render_cb finish_render;
   vertical_blank_cb vertical_blank;
+  poll_input_cb poll_input;
 };
 
 struct dreamcast *dc_create();
@@ -193,5 +195,6 @@ void dc_push_audio(struct dreamcast *dc, const int16_t *data, int frames);
 void dc_start_render(struct dreamcast *dc, struct tile_context *ctx);
 void dc_finish_render(struct dreamcast *dc);
 void dc_vertical_blank(struct dreamcast *dc);
+void dc_poll_input(struct dreamcast *dc);
 
 #endif

src/guest/maple/controller.c

@@ -33,6 +33,12 @@ struct controller {
   struct maple_cond cnd;
 };
 
+static void controller_update(struct controller *ctrl) {
+  /* dc_poll_input will call into controller_input if new values are
+     available */
+  dc_poll_input(ctrl->dc);
+}
+
 static int controller_input(struct maple_device *dev, int button,
                             int16_t value) {
   struct controller *ctrl = (struct controller *)dev;
@@ -95,6 +101,8 @@ static int controller_frame(struct maple_device *dev,
     }
 
     case MAPLE_REQ_GETCOND: {
+      controller_update(ctrl);
+
       res->header.command = MAPLE_RES_TRANSFER;
       res->header.recv_addr = frame->header.send_addr;
       res->header.send_addr = frame->header.recv_addr;

src/host/sdl_host.c

@@ -858,6 +858,9 @@ int main(int argc, char **argv) {
 
     if (emu_load_game(emu, load)) {
       while (!g_host->closed) {
+        /* even though the emulator itself will poll for events when updating
+           controller input, the main loop needs to also poll to ensure the
+           close event is received */
         host_poll_events(g_host);
 
         /* only step the emulator if the available audio is running low. this