From 4b0f2ea43929cbce781a4a8f84acb6aa041234ed Mon Sep 17 00:00:00 2001
From: fgsfds <derp.primus@gmail.com>
Date: Sun, 20 Aug 2023 17:26:11 +0200
Subject: [PATCH] port: unswizzle pre-swizzled textures

---
 port/src/preprocess.c            | 10 ++++-
 src/game/texdecompress.c         | 71 +++++++++++++++++++++++++++++++-
 src/include/game/texdecompress.h |  4 ++
 3 files changed, 82 insertions(+), 3 deletions(-)

diff --git a/port/src/preprocess.c b/port/src/preprocess.c
index ce5d76d41..1349254f2 100644
--- a/port/src/preprocess.c
+++ b/port/src/preprocess.c
@@ -8,9 +8,10 @@
 #include "platform.h"
 #include "data.h"
 #include "bss.h"
+#include "game/setuputils.h"
+#include "game/texdecompress.h"
 #include "preprocess.h"
 #include "romdata.h"
-#include "game/setuputils.h"
 
 static inline f32 swapF32(f32 x) { *(u32 *)&x = PD_BE32(*(u32 *)&x); return x; }
 static inline u32 swapU32(u32 x) { return PD_BE32(x); }
@@ -1050,6 +1051,13 @@ void preprocessModel(u8 *base, u32 ofs)
 		struct textureconfig *texconfigs = PD_PTR_BASEOFS(mdl->texconfigs, base, ofs);
 		for (s16 i = 0; i < mdl->numtexconfigs; ++i) {
 			PD_SWAP_VAL(texconfigs[i].texturenum);
+			if ((texconfigs[i].texturenum & 0xf000000) == 0x5000000) {
+				// embedded texture; we need to unswizzle this
+				u8 *texdata = PD_PTR_BASEOFS(texconfigs[i].texturenum, base, ofs);
+				// figure out the format and unswizzle
+				const s32 format = texConfigToFormat(&texconfigs[i]);
+				texSwapAltRowBytesInternal(texdata, texconfigs[i].width, texconfigs[i].height, format);
+			}
 		}
 	}
 
diff --git a/src/game/texdecompress.c b/src/game/texdecompress.c
index 8e70e5ec8..70a04f684 100644
--- a/src/game/texdecompress.c
+++ b/src/game/texdecompress.c
@@ -1907,9 +1907,77 @@ s32 texInflateLookupFromBuffer(u8 *src, s32 width, s32 height, u8 *dst, u8 *look
  * For textures with 32-bit colour values (in GBI format), swap every pair
  * within each word. For all other textures, swap every byte within each pair.
  */
+#ifdef PLATFORM_N64
+void texSwapAltRowBytes(u8 *dst, s32 width, s32 height, s32 format)
+#else
+s32 texConfigToFormat(const struct textureconfig *tex)
+{
+	switch (tex->format) {
+		case G_IM_FMT_I:
+			switch (tex->depth) {
+				case G_IM_SIZ_4b:
+					return TEXFORMAT_I4;
+				case G_IM_SIZ_8b:
+					return TEXFORMAT_I8;
+				default:
+					break;
+			}
+			break;
+		case G_IM_FMT_IA:
+			switch (tex->depth) {
+				case G_IM_SIZ_4b:
+					return TEXFORMAT_IA4;
+				case G_IM_SIZ_8b:
+					return TEXFORMAT_IA8;
+				case G_IM_SIZ_16b:
+					return TEXFORMAT_IA16;
+				default:
+					break;
+			}
+			break;
+		case G_IM_FMT_CI:
+			switch (tex->depth) {
+				case G_IM_SIZ_4b:
+					return TEXFORMAT_IA16_CI4;
+				case G_IM_SIZ_8b:
+					return TEXFORMAT_IA16_CI8;
+				default:
+					break;
+			}
+			break;
+		case G_IM_FMT_RGBA:
+			switch (tex->depth) {
+				case G_IM_SIZ_4b:
+					return TEXFORMAT_RGBA16_CI4;
+				case G_IM_SIZ_8b:
+					return TEXFORMAT_RGBA16_CI8;
+				case G_IM_SIZ_16b:
+					return TEXFORMAT_RGBA16;
+				case G_IM_SIZ_32b:
+					return TEXFORMAT_RGBA32;
+				default:
+					break;
+			}
+			break;
+		default:
+			break;
+	}
+
+	return TEXFORMAT_I8;
+}
+
 void texSwapAltRowBytes(u8 *dst, s32 width, s32 height, s32 format)
 {
-#ifdef PLATFORM_N64 // the N64 GPU wants interleaved data, we don't
+	/**
+	 * The N64 GPU wants swizzled textures, we don't.
+	 * Thus this function is stubbed out, but its functionality is still made
+	 * available for unswizzling the embedded textures in preprocess.c.
+	 */
+}
+
+void texSwapAltRowBytesInternal(u8 *dst, s32 width, s32 height, s32 format)
+#endif
+{
 	s32 x;
 	s32 y;
 	s32 alignedwidth;
@@ -1967,7 +2035,6 @@ void texSwapAltRowBytes(u8 *dst, s32 width, s32 height, s32 format)
 			row += alignedwidth * 2;
 		}
 	}
-#endif
 }
 
 /**
diff --git a/src/include/game/texdecompress.h b/src/include/game/texdecompress.h
index 5c2c70d5d..d82a670e3 100644
--- a/src/include/game/texdecompress.h
+++ b/src/include/game/texdecompress.h
@@ -35,5 +35,9 @@ void texLoadFromDisplayList(Gfx *gdl, struct texpool *pool, s32 arg2);
 void texLoad(texnum_t *updateword, struct texpool *pool, bool arg2);
 void texLoadFromConfigs(struct textureconfig *configs, s32 numconfigs, struct texpool *pool, s32 arg3);
 void texLoadFromTextureNum(u32 arg0, struct texpool *pool);
+#ifndef PLATFORM_N64
+void texSwapAltRowBytesInternal(u8 *dst, s32 width, s32 height, s32 format);
+s32 texConfigToFormat(const struct textureconfig *tex);
+#endif
 
 #endif