From e0ee9dc3ad3ca254ae0b441748d12ad6b8fabcc7 Mon Sep 17 00:00:00 2001
From: Sylvie <35663410+Rangi42@users.noreply.github.com>
Date: Sun, 24 Nov 2024 19:30:49 -0500
Subject: [PATCH] Add `reverse_1bit` RGBGFX test (#1555)

Fixes a bug to always use 2bpp `_data` in `TileData`
---
 src/gfx/process.cpp           |  16 ++++++++++++----
 test/gfx/reverse_1bit.1bpp    |   1 +
 test/gfx/reverse_1bit.attrmap | Bin 0 -> 4 bytes
 test/gfx/reverse_1bit.flags   |   3 +++
 test/gfx/reverse_1bit.tilemap | Bin 0 -> 4 bytes
 5 files changed, 16 insertions(+), 4 deletions(-)
 create mode 100644 test/gfx/reverse_1bit.1bpp
 create mode 100644 test/gfx/reverse_1bit.attrmap
 create mode 100644 test/gfx/reverse_1bit.flags
 create mode 100644 test/gfx/reverse_1bit.tilemap

diff --git a/src/gfx/process.cpp b/src/gfx/process.cpp
index 21db52e8..9bcb64e5 100644
--- a/src/gfx/process.cpp
+++ b/src/gfx/process.cpp
@@ -712,6 +712,9 @@ static void hashBitplanes(uint16_t bitplanes, uint16_t &hash) {
 }
 
 class TileData {
+	// Importantly, `TileData` is **always** 2bpp.
+	// If the active bit depth is 1bpp, all tiles are processed as 2bpp nonetheless, but emitted as 1bpp.
+	// This massively simplifies internal processing, since bit depth is always identical outside of I/O / serialization boundaries.
 	std::array<uint8_t, 16> _data;
 	// The hash is a bit lax: it's the XOR of all lines, and every other nibble is identical
 	// if horizontal mirroring is in effect. It should still be a reasonable tie-breaker in
@@ -755,9 +758,7 @@ public:
 			hashBitplanes(bitplanes, _hash);
 
 			_data[writeIndex++] = bitplanes & 0xFF;
-			if (options.bitDepth == 2) {
-				_data[writeIndex++] = bitplanes >> 8;
-			}
+			_data[writeIndex++] = bitplanes >> 8;
 		}
 	}
 
@@ -1032,7 +1033,14 @@ static void outputTileData(UniqueTiles const &tiles) {
 		TileData const *tile = *iter;
 		assume(tile->tileID == tileID);
 		++tileID;
-		output->sputn(reinterpret_cast<char const *>(tile->data().data()), options.bitDepth * 8);
+		if (options.bitDepth == 2) {
+			output->sputn(reinterpret_cast<char const *>(tile->data().data()), 16);
+		} else {
+			assume(options.bitDepth == 1);
+			for (size_t y = 0; y < 8; ++y) {
+				output->sputc(tile->data()[y * 2]);
+			}
+		}
 	}
 }
 
diff --git a/test/gfx/reverse_1bit.1bpp b/test/gfx/reverse_1bit.1bpp
new file mode 100644
index 00000000..76ffa732
--- /dev/null
+++ b/test/gfx/reverse_1bit.1bpp
@@ -0,0 +1 @@
+ @LŒŒ€€€‰F@ 
\ No newline at end of file
diff --git a/test/gfx/reverse_1bit.attrmap b/test/gfx/reverse_1bit.attrmap
new file mode 100644
index 0000000000000000000000000000000000000000..ba58dcb8efa5e18a3b5f04f10268a4efd512e846
GIT binary patch
literal 4
LcmZQjU{C-60E7TR

literal 0
HcmV?d00001

diff --git a/test/gfx/reverse_1bit.flags b/test/gfx/reverse_1bit.flags
new file mode 100644
index 00000000..4e003469
--- /dev/null
+++ b/test/gfx/reverse_1bit.flags
@@ -0,0 +1,3 @@
+-m
+-t reverse_1bit.tilemap
+-a reverse_1bit.attrmap
diff --git a/test/gfx/reverse_1bit.tilemap b/test/gfx/reverse_1bit.tilemap
new file mode 100644
index 0000000000000000000000000000000000000000..dee9c4c8adafc2e6af2ee0379ef082b7b43cd95f
GIT binary patch
literal 4
LcmZQzU}OXU00#gA

literal 0
HcmV?d00001