From 8cc7be498627cf9f79bd7ef1509b28fdb5fd4a10 Mon Sep 17 00:00:00 2001
From: Kp <kp@valhallalegends.com>
Date: Thu, 16 Jul 2020 02:31:04 +0000
Subject: [PATCH] Use std::bitset to track used colors

This reduces memory usage over using std::array<bool> for the same
number of bits.
---
 common/2d/bitmap.cpp | 4 ++--
 common/2d/bitmap.h   | 3 ++-
 similar/2d/font.cpp  | 7 ++++---
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/common/2d/bitmap.cpp b/common/2d/bitmap.cpp
index 6ed8b2db7..ca8658252 100644
--- a/common/2d/bitmap.cpp
+++ b/common/2d/bitmap.cpp
@@ -137,7 +137,7 @@ void gr_init_sub_bitmap (grs_bitmap &bm, grs_bitmap &bmParent, uint16_t x, uint1
 	bm.bm_data = &bmParent.bm_data[static_cast<uint32_t>((y*bmParent.bm_rowsize)+x)];
 }
 
-void decode_data(ubyte *data, uint_fast32_t num_pixels, std::array<color_t, 256> &colormap, std::array<bool, 256> &used)
+void decode_data(uint8_t *data, uint_fast32_t num_pixels, std::array<color_t, 256> &colormap, std::bitset<256> &used)
 {
 	const auto a = [&](uint8_t mapped) {
 		return used[mapped] = true, colormap[mapped];
@@ -169,7 +169,7 @@ void gr_remap_bitmap_good(grs_bitmap &bmp, palette_array_t &palette, uint_fast32
 	if (transparent_color < colormap.size())
 		colormap[transparent_color] = TRANSPARENCY_COLOR;
 
-	std::array<bool, 256> freq{};
+	std::bitset<256> freq{};
 	if (bmp.bm_w == bmp.bm_rowsize)
 		decode_data(bmp.get_bitmap_data(), bmp.bm_w * bmp.bm_h, colormap, freq );
 	else {
diff --git a/common/2d/bitmap.h b/common/2d/bitmap.h
index bccc782af..bf94e7ada 100644
--- a/common/2d/bitmap.h
+++ b/common/2d/bitmap.h
@@ -11,10 +11,11 @@
 #ifdef __cplusplus
 #include "palette.h"
 #include <array>
+#include <bitset>
 
 namespace dcx {
 void build_colormap_good(const palette_array_t &palette, std::array<color_t, 256> &colormap);
-void decode_data(ubyte *data, uint_fast32_t num_pixels, std::array<color_t, 256> &colormap, std::array<bool, 256> &used);
+void decode_data(uint8_t *data, uint_fast32_t num_pixels, std::array<color_t, 256> &colormap, std::bitset<256> &used);
 }
 
 #endif
diff --git a/similar/2d/font.cpp b/similar/2d/font.cpp
index 6e8c355ef..83b077069 100644
--- a/similar/2d/font.cpp
+++ b/similar/2d/font.cpp
@@ -1013,10 +1013,11 @@ static std::unique_ptr<grs_font> gr_internal_init_font(const char *fontname)
 		std::array<uint8_t, 256> colormap;
 		/* `freq` exists so that decode_data can write to it, but it is
 		 * otherwise unused.  `decode_data` is not guaranteed to write
-		 * to every element, so `freq` must not be read without first
-		 * adding an initialization step.
+		 * to every element, but the bitset constructor will initialize
+		 * the storage, so reading unwritten fields will always return
+		 * false.
 		 */
-		std::array<bool, 256> freq;
+		std::bitset<256> freq;
 
 		PHYSFS_read(fontfile,&palette[0],sizeof(palette[0]),palette.size());		//read the palette