From 3fec9c7ecbe279eeb7c7312321a813d871ed7168 Mon Sep 17 00:00:00 2001
From: Charlie Birks <charlie@daft.games>
Date: Sun, 8 Oct 2023 17:30:57 +0100
Subject: [PATCH] R/B swap for picovision

---
 32blit/CMakeLists.txt |  2 ++
 core/DMGDisplay.cpp   | 24 ++++++++++++++++++------
 core/DMGDisplay.h     |  2 +-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/32blit/CMakeLists.txt b/32blit/CMakeLists.txt
index fda12bc..348674d 100644
--- a/32blit/CMakeLists.txt
+++ b/32blit/CMakeLists.txt
@@ -13,6 +13,8 @@ target_link_libraries(DaftBoy32 DaftBoyCore DUH)
 if(32BLIT_PICO)
     if(${PICO_BOARD} STREQUAL "pimoroni_picosystem")
         target_compile_definitions(DaftBoy32 PRIVATE -DDISPLAY_RGB565)
+    elseif(${PICO_ADDON} STREQUAL "pimoroni_picovision")
+        target_compile_definitions(DaftBoy32 PRIVATE -DDISPLAY_RB_SWAP)
     endif()
 else()
     set_target_properties(DaftBoy32 PROPERTIES INTERPROCEDURAL_OPTIMIZATION TRUE)
diff --git a/core/DMGDisplay.cpp b/core/DMGDisplay.cpp
index 1ed9451..d6c685c 100644
--- a/core/DMGDisplay.cpp
+++ b/core/DMGDisplay.cpp
@@ -463,7 +463,7 @@ bool DMGDisplay::writeReg(uint16_t addr, uint8_t data)
 
             auto bcps = mem.readIOReg(IO_BCPS);
 
-#ifdef DISPLAY_RGB565
+#if defined(DISPLAY_RGB565) || defined(DISPLAY_RB_SWAP)
             reinterpret_cast<uint8_t *>(bgPaletteRaw)[bcps & 0x3F] = data;
             bgPaletteDirty = true;
 #else
@@ -485,7 +485,7 @@ bool DMGDisplay::writeReg(uint16_t addr, uint8_t data)
 
             auto ocps = mem.readIOReg(IO_OCPS);
 
-#ifdef DISPLAY_RGB565
+#if defined(DISPLAY_RGB565) || defined(DISPLAY_RB_SWAP)
             reinterpret_cast<uint8_t *>(objPaletteRaw)[ocps & 0x3F] = data;
             objPaletteDirty = true;
 #else
@@ -639,12 +639,24 @@ void DMGDisplay::drawScanLine(int y)
     const bool isColour = cpu.getColourMode();
 
 // sync palettes
+#if defined(DISPLAY_RGB565) || defined(DISPLAY_RB_SWAP)
+
+    const auto convert = [](uint16_t col)
+    {
+#ifdef DISPLAY_RB_SWAP
+        col = col << 10 | (col & 0x3E0) | (col << 1) >> 11;
+#endif
 #ifdef DISPLAY_RGB565
+    col = (col & 0x1F)  | (col & 0x7FE0) << 1;
+#endif
+        return col;
+    };
+
     if(bgPaletteDirty)
     {
         auto outCol = bgPalette;
-        for(auto &col : bgPaletteRaw)
-            *outCol++ = (col & 0x1F)  | (col & 0x7FE0) << 1;
+        for(auto col : bgPaletteRaw)
+            *outCol++ = convert(col);
 
         bgPaletteDirty = false;
     }
@@ -652,8 +664,8 @@ void DMGDisplay::drawScanLine(int y)
     if(objPaletteDirty)
     {
         auto outCol = objPalette;
-        for(auto &col : objPaletteRaw)
-            *outCol++ = (col & 0x1F)  | (col & 0x7FE0) << 1;
+        for(auto col : objPaletteRaw)
+            *outCol++ = convert(col);
 
         objPaletteDirty = false;
     }
diff --git a/core/DMGDisplay.h b/core/DMGDisplay.h
index a5e8537..1cfcfd2 100644
--- a/core/DMGDisplay.h
+++ b/core/DMGDisplay.h
@@ -59,7 +59,7 @@ class DMGDisplay
     // GBC
     uint16_t bgPalette[8 * 4], objPalette[8 * 4];
 
-#ifdef DISPLAY_RGB565
+#if defined(DISPLAY_RGB565) || defined(DISPLAY_RB_SWAP)
     uint16_t bgPaletteRaw[8 * 4], objPaletteRaw[8 * 4];
     bool bgPaletteDirty = false, objPaletteDirty = false;
 #endif