git.y1.nz

commit ed8c9529954ea6d415ff8681d0aa2df9891df6bc
parent 421fd132e316c88defd80b60dff29210496b84fb
Author: Lior Halphon <LIJI32@gmail.com>
Date:   Tue, 14 Oct 2025 15:31:31 +0300

The volume envelope is delayed on CGB-D and CGB-E in double speed mode

Diffstat:
M
Core/apu.c
49
+++++++++++++++++++++++++++++++++++++------------
M
Core/apu.h
2
++
M
Core/timing.c
3
+++

3 files changed, 42 insertions(+), 12 deletions(-)
diff --git a/Core/apu.c b/Core/apu.c
@@ -630,7 +630,27 @@ static void trigger_sweep_calculation(GB_gameboy_t *gb)
     }
 }
 
-void GB_apu_div_event(GB_gameboy_t *gb)
+noinline void GB_apu_delayed_envelope_tick(GB_gameboy_t *gb)
+{
+    gb->apu.pending_envelope_tick = false;
+    if (!gb->apu.global_enable) return;
+    
+    GB_apu_run(gb, true);
+    gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
+
+
+    unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
+        if (gb->apu.square_channels[i].envelope_clock.clock) {
+            tick_square_envelope(gb, i);
+        }
+    }
+    
+    if (gb->apu.noise_channel.envelope_clock.clock) {
+        tick_noise_envelope(gb);
+    }
+}
+
+noinline void GB_apu_div_event(GB_gameboy_t *gb)
 {
     GB_apu_run(gb, true);
     gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
@@ -648,7 +668,7 @@ void GB_apu_div_event(GB_gameboy_t *gb)
     }
 
     if ((gb->apu.div_divider & 7) == 7) {
-        unrolled for (unsigned i = GB_SQUARE_2 + 1; i--;) {
+        unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
             if (!gb->apu.square_channels[i].envelope_clock.clock) {
                 gb->apu.square_channels[i].volume_countdown--;
                 gb->apu.square_channels[i].volume_countdown &= 7;
@@ -660,18 +680,23 @@ void GB_apu_div_event(GB_gameboy_t *gb)
         }
     }
 
-    unrolled for (unsigned i = GB_SQUARE_2 + 1; i--;) {
-        if (gb->apu.square_channels[i].envelope_clock.clock) {
-            tick_square_envelope(gb, i);
-        }
+    if (gb->cgb_double_speed && (gb->model == GB_MODEL_CGB_D || gb->model == GB_MODEL_CGB_E)) {
+        gb->apu.pending_envelope_tick = true;
     }
-    
-    if (gb->apu.noise_channel.envelope_clock.clock) {
-        tick_noise_envelope(gb);
+    else {
+        unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
+            if (gb->apu.square_channels[i].envelope_clock.clock) {
+                tick_square_envelope(gb, i);
+            }
+        }
+        
+        if (gb->apu.noise_channel.envelope_clock.clock) {
+            tick_noise_envelope(gb);
+        }
     }
     
     if ((gb->apu.div_divider & 1) == 1) {
-        unrolled for (unsigned i = GB_SQUARE_2 + 1; i--;) {
+        unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
             if (gb->apu.square_channels[i].length_enabled) {
                 if (gb->apu.square_channels[i].pulse_length) {
                     if (!--gb->apu.square_channels[i].pulse_length) {
@@ -718,13 +743,13 @@ void GB_apu_div_event(GB_gameboy_t *gb)
     }
 }
 
-void GB_apu_div_secondary_event(GB_gameboy_t *gb)
+noinline void GB_apu_div_secondary_event(GB_gameboy_t *gb)
 {
     GB_apu_run(gb, true);
     gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
 
     if (!gb->apu.global_enable) return;
-    unrolled for (unsigned i = GB_SQUARE_2 + 1; i--;) {
+    unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
         uint8_t nrx2 = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
         if (gb->apu.is_active[i] && gb->apu.square_channels[i].volume_countdown == 0) {
             set_envelope_clock(&gb->apu.square_channels[i].envelope_clock,
diff --git a/Core/apu.h b/Core/apu.h
@@ -152,6 +152,7 @@ typedef struct
     uint8_t pcm_mask[2]; // For CGB-0 to CGB-C PCM read glitch
     
     bool apu_cycles_in_2mhz; // For compatibility with 0.16.x save states
+    bool pending_envelope_tick;
 } GB_apu_t;
 
 typedef enum {
@@ -230,6 +231,7 @@ internal void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value);
 internal uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg);
 internal void GB_apu_div_event(GB_gameboy_t *gb);
 internal void GB_apu_div_secondary_event(GB_gameboy_t *gb);
+internal void GB_apu_delayed_envelope_tick(GB_gameboy_t *gb);
 internal void GB_apu_init(GB_gameboy_t *gb);
 internal void GB_apu_run(GB_gameboy_t *gb, bool force);
 #endif
diff --git a/Core/timing.c b/Core/timing.c
@@ -279,6 +279,9 @@ static void timers_run(GB_gameboy_t *gb, uint8_t cycles)
         gb->apu.apu_cycles += 1 << !gb->cgb_double_speed;
         gb->apu_output.sample_cycles += (gb->apu_output.sample_rate << !gb->cgb_double_speed) << 1;
         GB_SLEEP(gb, div, 2, 4);
+        if (unlikely(gb->apu.pending_envelope_tick)) {
+            GB_apu_delayed_envelope_tick(gb);
+        }
     }
 }
 

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