From f1672b6c7816f2d35eb82d174a91a6858bd4176c Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Mon, 5 Feb 2024 21:52:03 +0100
Subject: [PATCH] feat(ricepp): some minor speed improvements

---
 ricepp/include/ricepp/detail/decode.h | 8 ++++----
 ricepp/include/ricepp/detail/encode.h | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/ricepp/include/ricepp/detail/decode.h b/ricepp/include/ricepp/detail/decode.h
index 0a6dfee2..5225c4e7 100644
--- a/ricepp/include/ricepp/detail/decode.h
+++ b/ricepp/include/ricepp/detail/decode.h
@@ -50,20 +50,20 @@ void decode_block(V block, BitstreamReader& reader, PixelTraits const& traits,
   if (fsp1 == 0) [[unlikely]] {
     std::fill(block.begin(), block.end(), traits.write(last));
   } else if (fsp1 > kFsMax) [[unlikely]] {
-    for (size_t i = 0; i < block.size(); ++i) {
-      block[i] = reader.template read_bits<pixel_value_type>(kPixelBits);
+    for (auto& b : block) {
+      b = reader.template read_bits<pixel_value_type>(kPixelBits);
     }
     last = traits.read(block.back());
   } else {
     auto const fs = fsp1 - 1;
-    for (size_t i = 0; i < block.size(); ++i) {
+    for (auto& b : block) {
       pixel_value_type diff = reader.find_first_set() << fs;
       if (fs > 0) {
         diff |= reader.template read_bits<pixel_value_type>(fs);
       }
       last += static_cast<std::make_signed_t<pixel_value_type>>(
           (diff & 1) ? ~(diff >> 1) : (diff >> 1));
-      block[i] = traits.write(last);
+      b = traits.write(last);
     }
   }
 
diff --git a/ricepp/include/ricepp/detail/encode.h b/ricepp/include/ricepp/detail/encode.h
index 19e249d7..98412cfb 100644
--- a/ricepp/include/ricepp/detail/encode.h
+++ b/ricepp/include/ricepp/detail/encode.h
@@ -125,8 +125,8 @@ void encode_block(V block, BitstreamWriter& writer, PixelTraits const& traits,
       // the input pixel data. This is really unlikely, so reading the input
       // pixels again is fine.
       writer.write_bits(kFsMax + 1, kFsBits);
-      for (size_t i = 0; i < block.size(); ++i) {
-        writer.write_bits(block[i], kPixelBits);
+      for (auto& b : block) {
+        writer.write_bits(b, kPixelBits);
       }
     } else {
       // Encode the difference values using Rice entropy coding.
@@ -134,7 +134,7 @@ void encode_block(V block, BitstreamWriter& writer, PixelTraits const& traits,
       for (size_t i = 0; i < block.size(); ++i) {
         pixel_value_type const diff = delta[i];
         pixel_value_type const top = diff >> fs;
-        if (top > 0) {
+        if (top > 0) [[unlikely]] {
           writer.write_bit(0, top);
         }
         writer.write_bit(1);