Increase input polling frequency in the Cocoa and SDL frontends, should make inputs look less synthetic and potentially reduce input lag

Core/gb.c

@@ -372,7 +372,6 @@ uint8_t GB_run(GB_gameboy_t *gb)
     gb->cycles_since_run = 0;
     GB_cpu_run(gb);
     if (gb->vblank_just_occured) {
-        GB_update_joyp(gb);
         GB_rtc_run(gb);
         GB_debugger_handle_async_commands(gb);
         GB_rewind_push(gb);
@@ -812,3 +811,8 @@ unsigned GB_get_player_count(GB_gameboy_t *gb)
 {
     return GB_is_sgb(gb)? gb->sgb->player_count : 1;
 }
+
+void GB_set_update_input_hint_callback(GB_gameboy_t *gb, GB_update_input_hint_callback_t callback)
+{
+    gb->update_input_hint_callback = callback;
+}

Core/gb.h

@@ -238,6 +238,7 @@ typedef void (*GB_infrared_callback_t)(GB_gameboy_t *gb, bool on, long cycles_si
 typedef void (*GB_rumble_callback_t)(GB_gameboy_t *gb, bool rumble_on);
 typedef void (*GB_serial_transfer_bit_start_callback_t)(GB_gameboy_t *gb, bool bit_to_send);
 typedef bool (*GB_serial_transfer_bit_end_callback_t)(GB_gameboy_t *gb);
+typedef void (*GB_update_input_hint_callback_t)(GB_gameboy_t *gb);
 
 typedef struct {
     bool state;
@@ -527,6 +528,7 @@ struct GB_gameboy_internal_s {
         GB_rumble_callback_t rumble_callback;
         GB_serial_transfer_bit_start_callback_t serial_transfer_bit_start_callback;
         GB_serial_transfer_bit_end_callback_t serial_transfer_bit_end_callback;
+        GB_update_input_hint_callback_t update_input_hint_callback;
                
         /* IR */
         long cycles_since_ir_change; // In 8MHz units
@@ -674,6 +676,7 @@ void GB_set_async_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback)
 void GB_set_rgb_encode_callback(GB_gameboy_t *gb, GB_rgb_encode_callback_t callback);
 void GB_set_infrared_callback(GB_gameboy_t *gb, GB_infrared_callback_t callback);
 void GB_set_rumble_callback(GB_gameboy_t *gb, GB_rumble_callback_t callback);
+void GB_set_update_input_hint_callback(GB_gameboy_t *gb, GB_update_input_hint_callback_t callback);
 
 /* These APIs are used when using internal clock */
 void GB_set_serial_transfer_bit_start_callback(GB_gameboy_t *gb, GB_serial_transfer_bit_start_callback_t callback);

Core/joypad.c

@@ -65,6 +65,7 @@ void GB_set_key_state(GB_gameboy_t *gb, GB_key_t index, bool pressed)
 {
     assert(index >= 0 && index < GB_KEY_MAX);
     gb->keys[0][index] = pressed;
+    GB_update_joyp(gb);
 }
 
 void GB_set_key_state_for_player(GB_gameboy_t *gb, GB_key_t index, unsigned player, bool pressed)
@@ -72,4 +73,5 @@ void GB_set_key_state_for_player(GB_gameboy_t *gb, GB_key_t index, unsigned play
     assert(index >= 0 && index < GB_KEY_MAX);
     assert(player < 4);
     gb->keys[player][index] = pressed;
+    GB_update_joyp(gb);
 }

Core/memory.c

@@ -307,6 +307,7 @@ static uint8_t read_high_memory(GB_gameboy_t *gb, uint16_t addr)
                 return (gb->apu.is_active[GB_NOISE] ? (gb->apu.samples[GB_NOISE] << 4) : 0) |
                        (gb->apu.is_active[GB_WAVE] ? (gb->apu.samples[GB_WAVE]) : 0);
             case GB_IO_JOYP:
+                GB_timing_sync(gb);
             case GB_IO_TMA:
             case GB_IO_LCDC:
             case GB_IO_SCY:

Core/sm83_cpu.c

@@ -234,6 +234,7 @@ static void stop(GB_gameboy_t *gb, uint8_t opcode)
         
     }
     else {
+        GB_timing_sync(gb);
         if ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF) {
             /* HW Bug? When STOP is executed while a button is down, the CPU halts forever
                yet the other hardware keeps running. */
@@ -1397,6 +1398,7 @@ void GB_cpu_run(GB_gameboy_t *gb)
         return;
     }
     if (gb->stopped) {
+        GB_timing_sync(gb);
         GB_advance_cycles(gb, 4);
         if ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF) {
             gb->stopped = false;
@@ -1409,6 +1411,10 @@ void GB_cpu_run(GB_gameboy_t *gb)
         return;
     }
     
+    if ((gb->interrupt_enable & 0x10) && (gb->ime || gb->halted)) {
+        GB_timing_sync(gb);
+    }
+    
     if (gb->halted && !GB_is_cgb(gb) && !gb->just_halted) {
         GB_advance_cycles(gb, 2);
     }

Core/timing.c

@@ -73,6 +73,9 @@ void GB_timing_sync(GB_gameboy_t *gb)
     }
 
     gb->cycles_since_last_sync = 0;
+    if (gb->update_input_hint_callback) {
+        gb->update_input_hint_callback(gb);
+    }
 }
 #else
 

SDL/main.c

@@ -435,6 +435,7 @@ restart:
         GB_set_color_correction_mode(&gb, configuration.color_correction_mode);
         GB_set_highpass_filter_mode(&gb, configuration.highpass_mode);
         GB_set_rewind_length(&gb, configuration.rewind_length);
+        GB_set_update_input_hint_callback(&gb, handle_events);
     }
     
     SDL_DestroyTexture(texture);