Use BROTLI_MAX_STATIC_CONTEXTS instead of magic constants in encode.c

PiperOrigin-RevId: 615332290

c/enc/encode.c

diff --git a/c/enc/encode.c b/c/enc/encode.c
index 6b39707..491361b 100644
--- a/c/enc/encode.c
+++ b/c/enc/encode.c
@@ -351,7 +351,7 @@
     size_t sink;
     size_t i;
     ContextLut utf8_lut = BROTLI_CONTEXT_LUT(CONTEXT_UTF8);
-    memset(arena, 0, sizeof(arena[0]) * 32 * 14);
+    memset(arena, 0, sizeof(arena[0]) * 32 * (BROTLI_MAX_STATIC_CONTEXTS + 1));
     for (; start_pos + 64 <= end_pos; start_pos += 4096) {
       const size_t stride_end_pos = start_pos + 64;
       uint8_t prev2 = input[start_pos & mask];
@@ -372,7 +372,7 @@
     }
     entropy[1] = ShannonEntropy(combined_histo, 32, &sink);
     entropy[2] = 0;
-    for (i = 0; i < 13; ++i) {
+    for (i = 0; i < BROTLI_MAX_STATIC_CONTEXTS; ++i) {
       entropy[2] += ShannonEntropy(context_histo + (i << 5), 32, &sink);
     }
     entropy[0] = 1.0 / (double)total;
@@ -388,7 +388,7 @@
     if (entropy[2] > 3.0 || entropy[1] - entropy[2] < 0.2) {
       return BROTLI_FALSE;
     } else {
-      *num_literal_contexts = 13;
+      *num_literal_contexts = BROTLI_MAX_STATIC_CONTEXTS;
       *literal_context_map = kStaticContextMapComplexUTF8;
       return BROTLI_TRUE;
     }
@@ -532,7 +532,8 @@
       const uint32_t* literal_context_map = NULL;
       if (!params->disable_literal_context_modeling) {
         /* TODO(eustas): pull to higher level and reuse. */
-        uint32_t* arena = BROTLI_ALLOC(m, uint32_t, 14 * 32);
+        uint32_t* arena =
+            BROTLI_ALLOC(m, uint32_t, 32 * (BROTLI_MAX_STATIC_CONTEXTS + 1));
         if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(arena)) return;
         DecideOverLiteralContextModeling(
             data, wrapped_last_flush_pos, bytes, mask, params->quality,

c/enc/metablock.c

diff --git a/c/enc/metablock.c b/c/enc/metablock.c
index 0c5c078..5fe43a5 100644
--- a/c/enc/metablock.c
+++ b/c/enc/metablock.c
@@ -298,8 +298,6 @@
 #include "metablock_inc.h"  /* NOLINT(build/include) */
 #undef FN
 
-#define BROTLI_MAX_STATIC_CONTEXTS 13
-
 /* Greedy block splitter for one block category (literal, command or distance).
    Gathers histograms for all context buckets. */
 typedef struct ContextBlockSplitter {

c/enc/metablock.h

diff --git a/c/enc/metablock.h b/c/enc/metablock.h
index db38f8f..e574bae 100644
--- a/c/enc/metablock.h
+++ b/c/enc/metablock.h
@@ -24,6 +24,8 @@
 extern "C" {
 #endif
 
+#define BROTLI_MAX_STATIC_CONTEXTS 13
+
 typedef struct MetaBlockSplit {
   BlockSplit literal_split;
   BlockSplit command_split;