1 files changed, 45 insertions, 37 deletions

diff --git a/Source/Core/VideoBackends/Software/TextureSampler.cpp b/Source/Core/VideoBackends/Software/TextureSampler.cpp
index 353fe6c8ac..f54002bdb5 100644
--- a/Source/Core/VideoBackends/Software/TextureSampler.cpp
+++ b/Source/Core/VideoBackends/Software/TextureSampler.cpp
@@ -18,29 +18,36 @@
 
 namespace TextureSampler
 {
-static inline void WrapCoord(int* coordp, WrapMode wrapMode, int imageSize)
+static inline void WrapCoord(int* coordp, WrapMode wrap_mode, int image_size)
 {
   int coord = *coordp;
-  switch (wrapMode)
+  switch (wrap_mode)
   {
   case WrapMode::Clamp:
-    coord = (coord > imageSize) ? imageSize : (coord < 0) ? 0 : coord;
+    coord = std::clamp(coord, 0, image_size - 1);
     break;
   case WrapMode::Repeat:
-    coord = coord % (imageSize + 1);
-    coord = (coord < 0) ? imageSize + coord : coord;
+    // Per YAGCD's info on TX_SETMODE1_I0 (et al.), mirror "requires the texture size to be a power
+    // of two. (wrapping is implemented by a logical AND (SIZE-1))".  So though this doesn't wrap
+    // nicely for non-power-of-2 sizes, that's how hardware does it.
+    coord = coord & (image_size - 1);
     break;
   case WrapMode::Mirror:
   {
-    const int sizePlus1 = imageSize + 1;
-    const int div = coord / sizePlus1;
-    coord = coord - (div * sizePlus1);
-    coord = (coord < 0) ? -coord : coord;
-    coord = (div & 1) ? imageSize - coord : coord;
+    // YAGCD doesn't mention this, but this seems to be the check used to implement mirroring.
+    // With power-of-2 sizes, this correctly checks if it's an even-numbered repeat or an
+    // odd-numbered one, and thus can decide whether to reflect.  It fails in unusual ways
+    // with non-power-of-2 sizes, but seems to match what happens on actual hardware.
+    if ((coord & image_size) != 0)
+      coord = ~coord;
+    coord = coord & (image_size - 1);
     break;
   }
   default:
-    PanicAlertFmt("Invalid wrap mode: {}", wrapMode);
+    // Hardware testing indicates that wrap_mode set to 3 behaves the same as clamp.
+    PanicAlertFmt("Invalid wrap mode: {}", wrap_mode);
+    coord = std::clamp(coord, 0, image_size - 1);
+    break;
   }
   *coordp = coord;
 }
@@ -131,8 +138,8 @@ void SampleMip(s32 s, s32 t, s32 mip, bool linear, u8 texmap, u8* sample)
     imageSrc = Memory::GetPointer(imageBase);
   }
 
-  int imageWidth = ti0.width;
-  int imageHeight = ti0.height;
+  int image_width_minus_1 = ti0.width;
+  int image_height_minus_1 = ti0.height;
 
   const int tlutAddress = texTlut.tmem_offset << 9;
   const u8* tlut = &texMem[tlutAddress];
@@ -141,15 +148,15 @@ void SampleMip(s32 s, s32 t, s32 mip, bool linear, u8 texmap, u8* sample)
   // move texture pointer to mip location
   if (mip)
   {
-    int mipWidth = imageWidth + 1;
-    int mipHeight = imageHeight + 1;
+    int mipWidth = image_width_minus_1 + 1;
+    int mipHeight = image_height_minus_1 + 1;
 
     const int fmtWidth = TexDecoder_GetBlockWidthInTexels(texfmt);
     const int fmtHeight = TexDecoder_GetBlockHeightInTexels(texfmt);
     const int fmtDepth = TexDecoder_GetTexelSizeInNibbles(texfmt);
 
-    imageWidth >>= mip;
-    imageHeight >>= mip;
+    image_width_minus_1 >>= mip;
+    image_height_minus_1 >>= mip;
     s >>= mip;
     t >>= mip;
 
@@ -186,45 +193,45 @@ void SampleMip(s32 s, s32 t, s32 mip, bool linear, u8 texmap, u8* sample)
     u8 sampledTex[4];
     u32 texel[4];
 
-    WrapCoord(&imageS, tm0.wrap_s, imageWidth);
-    WrapCoord(&imageT, tm0.wrap_t, imageHeight);
-    WrapCoord(&imageSPlus1, tm0.wrap_s, imageWidth);
-    WrapCoord(&imageTPlus1, tm0.wrap_t, imageHeight);
+    WrapCoord(&imageS, tm0.wrap_s, image_width_minus_1 + 1);
+    WrapCoord(&imageT, tm0.wrap_t, image_height_minus_1 + 1);
+    WrapCoord(&imageSPlus1, tm0.wrap_s, image_width_minus_1 + 1);
+    WrapCoord(&imageTPlus1, tm0.wrap_t, image_height_minus_1 + 1);
 
     if (!(texfmt == TextureFormat::RGBA8 && texUnit.texImage1[subTexmap].cache_manually_managed))
     {
-      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageT, imageWidth, texfmt, tlut,
-                             tlutfmt);
+      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageT, image_width_minus_1, texfmt,
+                             tlut, tlutfmt);
       SetTexel(sampledTex, texel, (128 - fractS) * (128 - fractT));
 
-      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageT, imageWidth, texfmt, tlut,
-                             tlutfmt);
+      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageT, image_width_minus_1, texfmt,
+                             tlut, tlutfmt);
       AddTexel(sampledTex, texel, (fractS) * (128 - fractT));
 
-      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageTPlus1, imageWidth, texfmt, tlut,
-                             tlutfmt);
+      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageTPlus1, image_width_minus_1, texfmt,
+                             tlut, tlutfmt);
       AddTexel(sampledTex, texel, (128 - fractS) * (fractT));
 
-      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageTPlus1, imageWidth, texfmt,
-                             tlut, tlutfmt);
+      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageTPlus1, image_width_minus_1,
+                             texfmt, tlut, tlutfmt);
       AddTexel(sampledTex, texel, (fractS) * (fractT));
     }
     else
     {
       TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageS, imageT,
-                                          imageWidth);
+                                          image_width_minus_1);
       SetTexel(sampledTex, texel, (128 - fractS) * (128 - fractT));
 
       TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageSPlus1, imageT,
-                                          imageWidth);
+                                          image_width_minus_1);
       AddTexel(sampledTex, texel, (fractS) * (128 - fractT));
 
       TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageS, imageTPlus1,
-                                          imageWidth);
+                                          image_width_minus_1);
       AddTexel(sampledTex, texel, (128 - fractS) * (fractT));
 
       TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageSPlus1,
-                                          imageTPlus1, imageWidth);
+                                          imageTPlus1, image_width_minus_1);
       AddTexel(sampledTex, texel, (fractS) * (fractT));
     }
 
@@ -240,14 +247,15 @@ void SampleMip(s32 s, s32 t, s32 mip, bool linear, u8 texmap, u8* sample)
     int imageT = t >> 7;
 
     // nearest neighbor sampling
-    WrapCoord(&imageS, tm0.wrap_s, imageWidth);
-    WrapCoord(&imageT, tm0.wrap_t, imageHeight);
+    WrapCoord(&imageS, tm0.wrap_s, image_width_minus_1 + 1);
+    WrapCoord(&imageT, tm0.wrap_t, image_height_minus_1 + 1);
 
     if (!(texfmt == TextureFormat::RGBA8 && texUnit.texImage1[subTexmap].cache_manually_managed))
-      TexDecoder_DecodeTexel(sample, imageSrc, imageS, imageT, imageWidth, texfmt, tlut, tlutfmt);
+      TexDecoder_DecodeTexel(sample, imageSrc, imageS, imageT, image_width_minus_1, texfmt, tlut,
+                             tlutfmt);
     else
       TexDecoder_DecodeTexelRGBA8FromTmem(sample, imageSrc, imageSrcOdd, imageS, imageT,
-                                          imageWidth);
+                                          image_width_minus_1);
   }
 }
 }  // namespace TextureSampler