diff mupdf-source/thirdparty/brotli/c/enc/prefix.h @ 2:b50eed0cc0ef upstream

ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/brotli/c/enc/prefix.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,54 @@
+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Functions for encoding of integers into prefix codes the amount of extra
+   bits, and the actual values of the extra bits. */
+
+#ifndef BROTLI_ENC_PREFIX_H_
+#define BROTLI_ENC_PREFIX_H_
+
+#include <brotli/types.h>
+
+#include "../common/constants.h"
+#include "../common/platform.h"
+#include "fast_log.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+/* Here distance_code is an intermediate code, i.e. one of the special codes or
+   the actual distance increased by BROTLI_NUM_DISTANCE_SHORT_CODES - 1. */
+static BROTLI_INLINE void PrefixEncodeCopyDistance(size_t distance_code,
+                                                   size_t num_direct_codes,
+                                                   size_t postfix_bits,
+                                                   uint16_t* code,
+                                                   uint32_t* extra_bits) {
+  if (distance_code < BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes) {
+    *code = (uint16_t)distance_code;
+    *extra_bits = 0;
+    return;
+  } else {
+    size_t dist = ((size_t)1 << (postfix_bits + 2u)) +
+        (distance_code - BROTLI_NUM_DISTANCE_SHORT_CODES - num_direct_codes);
+    size_t bucket = Log2FloorNonZero(dist) - 1;
+    size_t postfix_mask = (1u << postfix_bits) - 1;
+    size_t postfix = dist & postfix_mask;
+    size_t prefix = (dist >> bucket) & 1;
+    size_t offset = (2 + prefix) << bucket;
+    size_t nbits = bucket - postfix_bits;
+    *code = (uint16_t)((nbits << 10) |
+        (BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes +
+         ((2 * (nbits - 1) + prefix) << postfix_bits) + postfix));
+    *extra_bits = (uint32_t)((dist - offset) >> postfix_bits);
+  }
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}  /* extern "C" */
+#endif
+
+#endif  /* BROTLI_ENC_PREFIX_H_ */