From 4047f9b7644ece47f0f4c7240641b7e9b4c52cd4 Mon Sep 17 00:00:00 2001
From: Ariel A <24759293+aarant@users.noreply.github.com>
Date: Wed, 25 Dec 2024 19:48:54 -0500
Subject: [PATCH] feat: added FadeScreenHardware utility

---
 include/field_weather.h |  1 +
 include/palette.h       |  2 +-
 src/field_weather.c     | 29 +++++++++++++++++++++++++++++
 src/palette.c           |  5 +++--
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/include/field_weather.h b/include/field_weather.h
index d741bdd2b0..a8550845cc 100644
--- a/include/field_weather.h
+++ b/include/field_weather.h
@@ -152,6 +152,7 @@ void SetCurrentAndNextWeatherNoDelay(u8 weather);
 void ApplyWeatherColorMapIfIdle(s8 colorMapIndex);
 void ApplyWeatherColorMapIfIdle_Gradual(u8 colorMapIndex, u8 targetColorMapIndex, u8 colorMapStepDelay);
 void FadeScreen(u8 mode, s8 delay);
+u16 FadeScreenHardware(u8 mode, s8 delay);
 bool8 IsWeatherNotFadingIn(void);
 void UpdateSpritePaletteWithWeather(u8 spritePaletteIndex, bool8 allowFog);
 void ApplyWeatherColorMapToPal(u8 paletteIndex);
diff --git a/include/palette.h b/include/palette.h
index f86ab00a63..30592a4ecb 100644
--- a/include/palette.h
+++ b/include/palette.h
@@ -99,7 +99,7 @@ void InvertPlttBuffer(u32 selectedPalettes);
 void TintPlttBuffer(u32 selectedPalettes, s8 r, s8 g, s8 b);
 void UnfadePlttBuffer(u32 selectedPalettes);
 void BeginFastPaletteFade(u8 submode);
-void BeginHardwarePaletteFade(u8 blendCnt, u8 delay, u8 y, u8 targetY, u8 shouldResetBlendRegisters);
+void BeginHardwarePaletteFade(u16 blendCnt, u8 delay, u8 y, u8 targetY, u8 shouldResetBlendRegisters);
 void BlendPalettes(u32 selectedPalettes, u8 coeff, u16 color);
 void BlendPalettesFine(u32 palettes, u16 *src, u16 *dst, u32 coeff, u32 color);
 void BlendPalettesUnfaded(u32 selectedPalettes, u8 coeff, u16 color);
diff --git a/src/field_weather.c b/src/field_weather.c
index 9f41014ff3..2bcaa2f857 100644
--- a/src/field_weather.c
+++ b/src/field_weather.c
@@ -815,6 +815,35 @@ void FadeScreen(u8 mode, s8 delay)
     }
 }
 
+// fades screen using BLDY
+// Note: This enables blending in all windows;
+// These bits may need to be disabled later
+u16 FadeScreenHardware(u8 mode, s8 delay) {
+    u16 bldCnt = GetGpuReg(REG_OFFSET_BLDCNT) & BLDCNT_TGT2_ALL;
+    bldCnt |= BLDCNT_TGT1_ALL;
+    // enable blend in all windows
+    SetGpuRegBits(REG_OFFSET_WININ, WININ_WIN0_CLR | WININ_WIN1_CLR);
+    SetGpuRegBits(REG_OFFSET_WINOUT, WINOUT_WIN01_CLR);
+
+    switch (mode)
+    {
+    case FADE_FROM_BLACK:
+        BeginHardwarePaletteFade(bldCnt | BLDCNT_EFFECT_DARKEN, delay, 16, 0, TRUE);
+        break;
+    case FADE_TO_BLACK:
+        BeginHardwarePaletteFade(bldCnt | BLDCNT_EFFECT_DARKEN, delay, 0, 16, FALSE);
+        break;
+    case FADE_FROM_WHITE:
+        BeginHardwarePaletteFade(bldCnt | BLDCNT_EFFECT_LIGHTEN, delay, 16, 0, TRUE);
+        break;
+    case FADE_TO_WHITE:
+        BeginHardwarePaletteFade(bldCnt | BLDCNT_EFFECT_LIGHTEN, delay, 0, 16, FALSE);
+        break;
+    }
+
+    return 0;
+}
+
 bool8 IsWeatherNotFadingIn(void)
 {
     return (gWeatherPtr->palProcessingState != WEATHER_PAL_STATE_SCREEN_FADING_IN);
diff --git a/src/palette.c b/src/palette.c
index ddc0688209..3ea2a08195 100644
--- a/src/palette.c
+++ b/src/palette.c
@@ -896,7 +896,7 @@ static u8 UpdateFastPaletteFade(void)
     return gPaletteFade.active ? PALETTE_FADE_STATUS_ACTIVE : PALETTE_FADE_STATUS_DONE;
 }
 
-void BeginHardwarePaletteFade(u8 blendCnt, u8 delay, u8 y, u8 targetY, u8 shouldResetBlendRegisters)
+void BeginHardwarePaletteFade(u16 blendCnt, u8 delay, u8 y, u8 targetY, u8 shouldResetBlendRegisters)
 {
     gPaletteFade_blendCnt = blendCnt;
     gPaletteFade.delayCounter = delay;
@@ -950,7 +950,8 @@ static u8 UpdateHardwarePaletteFade(void)
     {
         if (gPaletteFade.shouldResetBlendRegisters)
         {
-            gPaletteFade_blendCnt = 0;
+            // clear TGT1
+            gPaletteFade_blendCnt &= ~0xFF;
             gPaletteFade.y = 0;
         }
         gPaletteFade.shouldResetBlendRegisters = FALSE;