Import aom library

This is the reference implementation for the Alliance for Open Media's av1 video code.

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

1 files changed, 117 insertions, 0 deletions

diff --git a/third_party/aom/aom_dsp/binary_codes_reader.c b/third_party/aom/aom_dsp/binary_codes_reader.c
new file mode 100644
index 000000000..96c4cb436
--- /dev/null
+++ b/third_party/aom/aom_dsp/binary_codes_reader.c
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2017, 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 "aom_dsp/bitreader.h"
+
+#include "av1/common/common.h"
+
+// Inverse recenters a non-negative literal v around a reference r
+static uint16_t inv_recenter_nonneg(uint16_t r, uint16_t v) {
+  if (v > (r << 1))
+    return v;
+  else if ((v & 1) == 0)
+    return (v >> 1) + r;
+  else
+    return r - ((v + 1) >> 1);
+}
+
+// Inverse recenters a non-negative literal v in [0, n-1] around a
+// reference r also in [0, n-1]
+static uint16_t inv_recenter_finite_nonneg(uint16_t n, uint16_t r, uint16_t v) {
+  if ((r << 1) <= n) {
+    return inv_recenter_nonneg(r, v);
+  } else {
+    return n - 1 - inv_recenter_nonneg(n - 1 - r, v);
+  }
+}
+
+int16_t aom_read_primitive_symmetric(aom_reader *r, unsigned int mag_bits) {
+  if (aom_read_bit(r, NULL)) {
+    int s = aom_read_bit(r, NULL);
+    int16_t x = aom_read_literal(r, mag_bits, NULL) + 1;
+    return (s > 0 ? -x : x);
+  } else {
+    return 0;
+  }
+}
+
+uint16_t aom_read_primitive_quniform(aom_reader *r, uint16_t n) {
+  if (n <= 1) return 0;
+  const int l = get_msb(n - 1) + 1;
+  const int m = (1 << l) - n;
+  const int v = aom_read_literal(r, l - 1, NULL);
+  return v < m ? v : (v << 1) - m + aom_read_bit(r, NULL);
+}
+
+uint16_t aom_read_primitive_refbilevel(aom_reader *r, uint16_t n, uint16_t p,
+                                       uint16_t ref) {
+  if (n <= 1) return 0;
+  assert(p > 0 && p <= n);
+  assert(ref < n);
+  int lolimit = ref - p / 2;
+  const int hilimit = lolimit + p - 1;
+  if (lolimit < 0) {
+    lolimit = 0;
+  } else if (hilimit >= n) {
+    lolimit = n - p;
+  }
+  int v;
+  if (aom_read_bit(r, NULL)) {
+    v = aom_read_primitive_quniform(r, p) + lolimit;
+  } else {
+    v = aom_read_primitive_quniform(r, n - p);
+    if (v >= lolimit) v += p;
+  }
+  return v;
+}
+
+// Decode finite subexponential code that for a symbol v in [0, n-1] with
+// parameter k
+uint16_t aom_read_primitive_subexpfin(aom_reader *r, uint16_t n, uint16_t k) {
+  int i = 0;
+  int mk = 0;
+  uint16_t v;
+  while (1) {
+    int b = (i ? k + i - 1 : k);
+    int a = (1 << b);
+    if (n <= mk + 3 * a) {
+      v = aom_read_primitive_quniform(r, n - mk) + mk;
+      break;
+    } else {
+      if (aom_read_bit(r, NULL)) {
+        i = i + 1;
+        mk += a;
+      } else {
+        v = aom_read_literal(r, b, NULL) + mk;
+        break;
+      }
+    }
+  }
+  return v;
+}
+
+// Decode finite subexponential code that for a symbol v in [0, n-1] with
+// parameter k
+// based on a reference ref also in [0, n-1].
+uint16_t aom_read_primitive_refsubexpfin(aom_reader *r, uint16_t n, uint16_t k,
+                                         uint16_t ref) {
+  return inv_recenter_finite_nonneg(n, ref,
+                                    aom_read_primitive_subexpfin(r, n, k));
+}
+
+// Decode finite subexponential code that for a symbol v in [-(n-1), n-1] with
+// parameter k based on a reference ref also in [-(n-1), n-1].
+int16_t aom_read_signed_primitive_refsubexpfin(aom_reader *r, uint16_t n,
+                                               uint16_t k, int16_t ref) {
+  ref += n - 1;
+  const uint16_t scaled_n = (n << 1) - 1;
+  return aom_read_primitive_refsubexpfin(r, scaled_n, k, ref) - n + 1;
+}