Merge "Add a placeholder forward buffered ANS coder." into nextgenv2
diff --git a/vp10/encoder/buf_ans.h b/vp10/encoder/buf_ans.h
new file mode 100644
index 0000000..ae76873
--- /dev/null
+++ b/vp10/encoder/buf_ans.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2016 The WebM project authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef VP10_ENCODER_BUF_ANS_H_
+#define VP10_ENCODER_BUF_ANS_H_
+// Buffered forward ANS writer.
+// Symbols are written to the writer in forward (decode) order and serialzed
+// backwards due to ANS's stack like behavior.
+
+#include <assert.h>
+#include "./vpx_config.h"
+#include "vpx/vpx_integer.h"
+#include "vpx_ports/mem_ops.h"
+#include "vp10/common/ans.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+#define ANS_METHOD_UABS 0
+#define ANS_METHOD_RANS 1
+
+struct buffered_ans_symbol {
+ uint8_t method; // one of ANS_METHOD_UABS or ANS_METHOD_RANS
+ // TODO(aconverse): Should be possible to write this interms of start for ABS
+ AnsP8 val_start; // Boolean value for ABS, start in symbol cycle for Rans
+ AnsP8 prob; // Probability of this symbol
+};
+
+struct BufAnsCoder {
+ struct buffered_ans_symbol *buf;
+ int size;
+ int offset;
+};
+
+static INLINE void buf_ans_write_init(struct BufAnsCoder *const c,
+ struct buffered_ans_symbol *sym_arr,
+ int size) {
+ c->buf = sym_arr;
+ c->size = size;
+ c->offset = 0;
+}
+
+static INLINE void buf_uabs_write(struct BufAnsCoder *const c,
+ uint8_t val, AnsP8 prob) {
+ assert(c->offset < c->size);
+ c->buf[c->offset].method = ANS_METHOD_UABS;
+ c->buf[c->offset].val_start = val;
+ c->buf[c->offset].prob = prob;
+ ++c->offset;
+}
+
+static INLINE void buf_rans_write(struct BufAnsCoder *const c,
+ const struct rans_sym *const sym) {
+ assert(c->offset < c->size);
+ c->buf[c->offset].method = ANS_METHOD_RANS;
+ c->buf[c->offset].val_start = sym->cum_prob;
+ c->buf[c->offset].prob = sym->prob;
+ ++c->offset;
+}
+
+static INLINE void buf_ans_flush(const struct BufAnsCoder *const c,
+ struct AnsCoder *ans) {
+ int offset;
+ for (offset = c->offset - 1; offset >= 0; --offset) {
+ if (c->buf[offset].method == ANS_METHOD_RANS) {
+ struct rans_sym sym;
+ sym.prob = c->buf[offset].prob;
+ sym.cum_prob = c->buf[offset].val_start;
+ rans_write(ans, &sym);
+ } else {
+ uabs_write(ans, c->buf[offset].val_start, c->buf[offset].prob);
+ }
+ }
+}
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
+#endif // VP10_ENCODER_BUF_ANS_H_
