fix edge case in decoder when very first op is QOI_OP_RUN

wx257osn2 · Feb 24, 2024 · 6d50faa · 6d50faa
1 parent 7a946d1
commit 6d50faa
Showing 1 changed file with 11 additions and 2 deletions.
diff --git a/include/qoixx.hpp b/include/qoixx.hpp
@@ -11,6 +11,7 @@
 #include<bit>
 #include<numeric>
 #include<array>
+#include<utility>
 
 #ifndef QOIXX_NO_SIMD
 #if defined(__ARM_FEATURE_SVE)
@@ -1146,7 +1147,7 @@ class qoi{
     static constexpr auto hash_diff_table = luma_hash_diff_table.data() + hash_table_offset;
     )
 
-    const auto f = [&pixels, &p, &px_len, &size, &px, &index QOIXX_HPP_WITH_TABLES(, &hash)]{
+    const auto f = [&pixels, &p, &px_len, &size, &px, &index QOIXX_HPP_WITH_TABLES(, &hash)](bool first){
       static constexpr std::uint32_t mask_tail_6 = 0b0011'1111u;
       [[maybe_unused]] static constexpr std::uint32_t mask_tail_4 = 0b0000'1111u;
       [[maybe_unused]] static constexpr std::uint32_t mask_tail_2 = 0b0000'0011u;
@@ -1187,6 +1188,13 @@ class qoi{
             run = px_len;
           px_len -= run;
           QOIXX_HPP_DECODE_RUN(px, run)
+          if(first)[[unlikely]]{
+            QOIXX_HPP_WITH_TABLES(hash = (0*3+0*5+0*7+255*11) % index_size;)
+            if constexpr(std::is_same<rgba_t, qoi::rgba_t>::value)
+              index[QOIXX_HPP_WITH_TABLES(hash) QOIXX_HPP_WITHOUT_TABLES((0*3+0*5+0*7+255*11) % index_size)] = px;
+            else
+              efficient_memcpy<Channels>(index + QOIXX_HPP_WITH_TABLES(hash) QOIXX_HPP_WITHOUT_TABLES((0*3+0*5+0*7+255*11) % index_size), &px);
+          }
           return;
         }
         if(b1 == chunk_tag::rgb){
@@ -1271,8 +1279,9 @@ class qoi{
       push<Channels>(pixels, &px);
     };
 
+    bool first = true;
     while(px_len--)[[likely]]{
-      f();
+      f(std::exchange(first, false));
       if(size < sizeof(padding))[[unlikely]]{
         throw std::runtime_error("qoixx::qoi::decode: insufficient input data");
       }