1 files changed, 69 insertions, 0 deletions
diff --git a/third_party/aom/av1/encoder/hash.c b/third_party/aom/av1/encoder/hash.c
new file mode 100644
index 000000000..89c5bd8a3
--- /dev/null
+++ b/third_party/aom/av1/encoder/hash.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2016, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include "av1/encoder/hash.h"
+
+static void crc_calculator_process_data(CRC_CALCULATOR *p_crc_calculator,
+                                        uint8_t *pData, uint32_t dataLength) {
+  for (uint32_t i = 0; i < dataLength; i++) {
+    const uint8_t index =
+        (p_crc_calculator->remainder >> (p_crc_calculator->bits - 8)) ^
+        pData[i];
+    p_crc_calculator->remainder <<= 8;
+    p_crc_calculator->remainder ^= p_crc_calculator->table[index];
+  }
+}
+
+void crc_calculator_reset(CRC_CALCULATOR *p_crc_calculator) {
+  p_crc_calculator->remainder = 0;
+}
+
+static uint32_t crc_calculator_get_crc(CRC_CALCULATOR *p_crc_calculator) {
+  return p_crc_calculator->remainder & p_crc_calculator->final_result_mask;
+}
+
+static void crc_calculator_init_table(CRC_CALCULATOR *p_crc_calculator) {
+  const uint32_t high_bit = 1 << (p_crc_calculator->bits - 1);
+  const uint32_t byte_high_bit = 1 << (8 - 1);
+
+  for (uint32_t value = 0; value < 256; value++) {
+    uint32_t remainder = 0;
+    for (uint8_t mask = byte_high_bit; mask != 0; mask >>= 1) {
+      if (value & mask) {
+        remainder ^= high_bit;
+      }
+
+      if (remainder & high_bit) {
+        remainder <<= 1;
+        remainder ^= p_crc_calculator->trunc_poly;
+      } else {
+        remainder <<= 1;
+      }
+    }
+    p_crc_calculator->table[value] = remainder;
+  }
+}
+
+void av1_crc_calculator_init(CRC_CALCULATOR *p_crc_calculator, uint32_t bits,
+                             uint32_t truncPoly) {
+  p_crc_calculator->remainder = 0;
+  p_crc_calculator->bits = bits;
+  p_crc_calculator->trunc_poly = truncPoly;
+  p_crc_calculator->final_result_mask = (1 << bits) - 1;
+  crc_calculator_init_table(p_crc_calculator);
+}
+
+uint32_t av1_get_crc_value(CRC_CALCULATOR *p_crc_calculator, uint8_t *p,
+                           int length) {
+  crc_calculator_reset(p_crc_calculator);
+  crc_calculator_process_data(p_crc_calculator, p, length);
+  return crc_calculator_get_crc(p_crc_calculator);
+}