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-rw-r--r--third_party/aom/aom_dsp/binary_codes_reader.c117
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;
+}