1 files changed, 121 insertions, 0 deletions
diff --git a/third_party/aom/av1/decoder/laplace_decoder.c b/third_party/aom/av1/decoder/laplace_decoder.c
new file mode 100644
index 000000000..b6cf50bc7
--- /dev/null
+++ b/third_party/aom/av1/decoder/laplace_decoder.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2001-2016, 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.
+ */
+/* clang-format off */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdio.h>
+
+#include "aom_dsp/bitreader.h"
+#include "av1/common/pvq.h"
+#include "pvq_decoder.h"
+
+#define aom_decode_pvq_split(r, adapt, sum, ctx, ACCT_STR_NAME) \
+  aom_decode_pvq_split_(r, adapt, sum, ctx ACCT_STR_ARG(ACCT_STR_NAME))
+
+static int aom_decode_pvq_split_(aom_reader *r, od_pvq_codeword_ctx *adapt,
+ int sum, int ctx ACCT_STR_PARAM) {
+  int shift;
+  int count;
+  int msbs;
+  int fctx;
+  count = 0;
+  if (sum == 0) return 0;
+  shift = OD_MAXI(0, OD_ILOG(sum) - 3);
+  fctx = 7*ctx + (sum >> shift) - 1;
+  msbs = aom_read_symbol_pvq(r, adapt->pvq_split_cdf[fctx], (sum >> shift) + 1,
+      ACCT_STR_NAME);
+  if (shift) count = aom_read_literal(r, shift, ACCT_STR_NAME);
+  count += msbs << shift;
+  if (count > sum) {
+    count = sum;
+#if CONFIG_DAALA_EC
+    r->ec.error = 1;
+#else
+# error "CONFIG_PVQ currently requires CONFIG_DAALA_EC."
+#endif
+  }
+  return count;
+}
+
+void aom_decode_band_pvq_splits(aom_reader *r, od_pvq_codeword_ctx *adapt,
+ od_coeff *y, int n, int k, int level) {
+  int mid;
+  int count_right;
+  if (n == 1) {
+    y[0] = k;
+  }
+  else if (k == 0) {
+    OD_CLEAR(y, n);
+  }
+  else if (k == 1 && n <= 16) {
+    int cdf_id;
+    int pos;
+    cdf_id = od_pvq_k1_ctx(n, level == 0);
+    OD_CLEAR(y, n);
+    pos = aom_read_symbol_pvq(r, adapt->pvq_k1_cdf[cdf_id], n, "pvq:k1");
+    y[pos] = 1;
+  }
+  else {
+    mid = n >> 1;
+    count_right = aom_decode_pvq_split(r, adapt, k, od_pvq_size_ctx(n),
+     "pvq:split");
+    aom_decode_band_pvq_splits(r, adapt, y, mid, k - count_right, level + 1);
+    aom_decode_band_pvq_splits(r, adapt, y + mid, n - mid, count_right,
+     level + 1);
+  }
+}
+
+/** Decodes the tail of a Laplace-distributed variable, i.e. it doesn't
+ * do anything special for the zero case.
+ *
+ * @param [dec] range decoder
+ * @param [decay] decay factor of the distribution, i.e. pdf ~= decay^x
+ *
+ * @retval decoded variable x
+ */
+int aom_laplace_decode_special_(aom_reader *r, unsigned decay ACCT_STR_PARAM) {
+  int pos;
+  int shift;
+  int xs;
+  int sym;
+  const uint16_t *cdf;
+  shift = 0;
+  /* We don't want a large decay value because that would require too many
+     symbols. */
+  while (decay > 235) {
+    decay = (decay*decay + 128) >> 8;
+    shift++;
+  }
+  decay = OD_MINI(decay, 254);
+  decay = OD_MAXI(decay, 2);
+  cdf = EXP_CDF_TABLE[(decay + 1) >> 1];
+  OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "decay = %d\n", decay));
+  xs = 0;
+  do {
+    sym = OD_MINI(xs, 15);
+    {
+      int i;
+      OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "%d %d %d", xs, shift, sym));
+      for (i = 0; i < 16; i++) {
+        OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "%d ", cdf[i]));
+      }
+      OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "\n"));
+    }
+    sym = aom_read_cdf(r, cdf, 16, ACCT_STR_NAME);
+    xs += sym;
+  } while (sym >= 15);
+  if (shift) pos = (xs << shift) + aom_read_literal(r, shift, ACCT_STR_NAME);
+  else pos = xs;
+  return pos;
+}