From 9236a2a01060760b75ef635850026e1db3a1dd6f Mon Sep 17 00:00:00 2001
From: Adrian Siekierka <kontakt@asie.pl>
Date: Thu, 2 Jan 2025 11:30:47 +0100
Subject: [PATCH 1/2] Round down colors evenly in reduce_color() (#55)

---
 src/Color.h |  5 +++++
 src/Mode.h  | 24 ++++++++++++------------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/Color.h b/src/Color.h
index e299b54..e7ea850 100644
--- a/src/Color.h
+++ b/src/Color.h
@@ -73,6 +73,11 @@ constexpr channel_t scale_up(channel_t value, unsigned shift) {
   }
 }
 
+// scale down value, rounding evenly
+constexpr channel_t scale_down(channel_t value, unsigned shift) {
+  return (value + (1 << (shift - 1))) >> shift;
+}
+
 //
 // rgba_color / hsva_color
 //
diff --git a/src/Mode.h b/src/Mode.h
index 27590d3..ad99671 100644
--- a/src/Mode.h
+++ b/src/Mode.h
@@ -334,9 +334,9 @@ inline rgba_t reduce_color(const rgba_t color, Mode to_mode) {
       return transparent_color;
     } else {
       rgba_color c(color);
-      c.r >>= 3;
-      c.g >>= 3;
-      c.b >>= 3;
+      c.r = scale_down(c.r, 3);
+      c.g = scale_down(c.g, 3);
+      c.b = scale_down(c.b, 3);
       rgba_t scaled = c;
       return (scaled & 0x00ffffff) + 0xff000000;
     }
@@ -372,18 +372,18 @@ inline rgba_t reduce_color(const rgba_t color, Mode to_mode) {
       return transparent_color;
     } else {
       rgba_color c(color);
-      c.r >>= 5;
-      c.g >>= 5;
-      c.b >>= 5;
+      c.r = scale_down(c.r, 5);
+      c.g = scale_down(c.g, 5);
+      c.b = scale_down(c.b, 5);
       rgba_t scaled = c;
       return (scaled & 0x00ffffff) + 0xff000000;
     }
     break;
   case Mode::sms: {
     rgba_color c(color);
-    c.r >>= 6;
-    c.g >>= 6;
-    c.b >>= 6;
+    c.r = scale_down(c.r, 6);
+    c.g = scale_down(c.g, 6);
+    c.b = scale_down(c.b, 6);
     rgba_t scaled = c;
     return (scaled & 0x00ffffff) + 0xff000000;
   }
@@ -395,9 +395,9 @@ inline rgba_t reduce_color(const rgba_t color, Mode to_mode) {
       return transparent_color;
     } else {
       rgba_color c(color);
-      c.r >>= 4;
-      c.g >>= 4;
-      c.b >>= 4;
+      c.r = scale_down(c.r, 4);
+      c.g = scale_down(c.g, 4);
+      c.b = scale_down(c.b, 4);
       rgba_t scaled = c;
       return (scaled & 0x00ffffff) + 0xff000000;
     }

From 3691d8c87969f4b7eb3d5389b707b5129146285d Mon Sep 17 00:00:00 2001
From: undisbeliever <undisbeliever@users.noreply.github.com>
Date: Thu, 2 Jan 2025 20:37:44 +1000
Subject: [PATCH 2/2] Fix remap_tiles_for_output() for -W16 (#57)

This commit fixes a bug where the tile data output was squished and
missing even columns when converting a SNES tileset with a `-W 16`
argument.

This commit also fixes a segfault when converting a snes tileset with
`-W 8 -H 16` (when _tile_width is 8 `(cells_per_tile_h - 2)` underflows).
---
 src/Tiles.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Tiles.cpp b/src/Tiles.cpp
index 156ff2d..3f0ca2c 100644
--- a/src/Tiles.cpp
+++ b/src/Tiles.cpp
@@ -240,7 +240,7 @@ std::vector<Tile> Tileset::remap_tiles_for_output(const std::vector<Tile>& tiles
 
     for (unsigned i = 0; i < tiles.size(); ++i) {
       unsigned base_pos =
-        (((i / tiles_per_row) * cells_per_tile_v) * cells_per_row) + ((i % tiles_per_row) << (cells_per_tile_h - 2));
+        (((i / tiles_per_row) * cells_per_tile_v) * cells_per_row) + ((i % tiles_per_row) * cells_per_tile_h);
       const auto ct = tiles[i].crops(8, 8);
       for (unsigned cy = 0; cy < cells_per_tile_v; ++cy) {
         for (unsigned cx = 0; cx < cells_per_tile_h; ++cx) {