From 4811199406d566d350294cd4b1ac94e174714bcf Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Sun, 4 Feb 2024 13:48:23 +0100
Subject: [PATCH] feat(ricepp): another 15% decode speedup

---
 ricepp/include/ricepp/bitstream_reader.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/ricepp/include/ricepp/bitstream_reader.h b/ricepp/include/ricepp/bitstream_reader.h
index 4c81cee0..5068530b 100644
--- a/ricepp/include/ricepp/bitstream_reader.h
+++ b/ricepp/include/ricepp/bitstream_reader.h
@@ -65,6 +65,10 @@ class bitstream_reader final {
   size_t find_first_set() {
     size_t zeros = 0;
     if (bit_pos_ != 0) [[likely]] {
+      if (peek_bit()) [[likely]] {
+        skip_bits(1);
+        return zeros;
+      }
       size_t const remaining_bits = kBitsTypeBits - bit_pos_;
       bits_type const bits = peek_bits(remaining_bits);
       size_t const ffs = std::countr_zero(bits);
@@ -107,6 +111,11 @@ class bitstream_reader final {
     }
   }
 
+  bool peek_bit() {
+    assert(bit_pos_ > 0 && bit_pos_ < kBitsTypeBits);
+    return (data_ & (static_cast<bits_type>(1) << bit_pos_)) != 0;
+  }
+
   bits_type peek_bits(size_t num_bits) {
     assert(bit_pos_ + num_bits <= kBitsTypeBits);
     if (bit_pos_ == 0) [[unlikely]] {