/*

 *  Copyright (c) 2011 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.

 */

#include <assert.h>

#include <stdlib.h>

#include "vpx_config.h"

#include "lookahead.h"

#include "vp8/common/extend.h"

#define MAX_LAG_BUFFERS (CONFIG_REALTIME_ONLY ? 1 : 25)

struct lookahead_ctx {

  unsigned int max_sz;         /* Absolute size of the queue */

  unsigned int sz;             /* Number of buffers currently in the queue */

  unsigned int read_idx;       /* Read index */

  unsigned int write_idx;      /* Write index */

  struct lookahead_entry *buf; /* Buffer list */

};

/* Return the buffer at the given absolute index and increment the index */

static struct lookahead_entry *pop(struct lookahead_ctx *ctx,

                                   unsigned int *idx) {

  unsigned int index = *idx;

  struct lookahead_entry *buf = ctx->buf + index;

  assert(index < ctx->max_sz);

  if (++index >= ctx->max_sz) index -= ctx->max_sz;

  *idx = index;

  return buf;

}

void vp8_lookahead_destroy(struct lookahead_ctx *ctx) {

  if (ctx) {

    if (ctx->buf) {

      unsigned int i;

      for (i = 0; i < ctx->max_sz; ++i) {

        vp8_yv12_de_alloc_frame_buffer(&ctx->buf[i].img);

      }

      free(ctx->buf);

    }

    free(ctx);

  }

}

struct lookahead_ctx *vp8_lookahead_init(unsigned int width,

                                         unsigned int height,

                                         unsigned int depth) {

  struct lookahead_ctx *ctx = NULL;

  unsigned int i;

  /* Clamp the lookahead queue depth */

  if (depth < 1) {

    depth = 1;

  } else if (depth > MAX_LAG_BUFFERS) {

    depth = MAX_LAG_BUFFERS;

  }

  /* Keep last frame in lookahead buffer by increasing depth by 1.*/

  depth += 1;

  /* Align the buffer dimensions */

  width = (width + 15) & ~15;

  height = (height + 15) & ~15;

  /* Allocate the lookahead structures */

  ctx = calloc(1, sizeof(*ctx));

  if (ctx) {

    ctx->max_sz = depth;

    ctx->buf = calloc(depth, sizeof(*ctx->buf));

    if (!ctx->buf) goto bail;

    for (i = 0; i < depth; ++i) {

      if (vp8_yv12_alloc_frame_buffer(&ctx->buf[i].img, width, height,

                                      VP8BORDERINPIXELS)) {

        goto bail;

      }

    }

  }

  return ctx;

bail:

  vp8_lookahead_destroy(ctx);

  return NULL;

}

int vp8_lookahead_push(struct lookahead_ctx *ctx, YV12_BUFFER_CONFIG *src,

                       int64_t ts_start, int64_t ts_end, unsigned int flags,

                       unsigned char *active_map) {

  struct lookahead_entry *buf;

  int row, col, active_end;

  int mb_rows = (src->y_height + 15) >> 4;

  int mb_cols = (src->y_width + 15) >> 4;

  if (ctx->sz + 2 > ctx->max_sz) return 1;

  ctx->sz++;

  buf = pop(ctx, &ctx->write_idx);

  /* Only do this partial copy if the following conditions are all met:

   * 1. Lookahead queue has has size of 1.

   * 2. Active map is provided.

   * 3. This is not a key frame, golden nor altref frame.

   */

  if (ctx->max_sz == 1 && active_map && !flags) {

    for (row = 0; row < mb_rows; ++row) {

      col = 0;

      while (1) {

        /* Find the first active macroblock in this row. */

        for (; col < mb_cols; ++col) {

          if (active_map[col]) break;

        }

        /* No more active macroblock in this row. */

        if (col == mb_cols) break;

        /* Find the end of active region in this row. */

        active_end = col;

        for (; active_end < mb_cols; ++active_end) {

          if (!active_map[active_end]) break;

        }

        /* Only copy this active region. */

        vp8_copy_and_extend_frame_with_rect(src, &buf->img, row << 4, col << 4,

                                            16, (active_end - col) << 4);

        /* Start again from the end of this active region. */

        col = active_end;

      }

      active_map += mb_cols;

    }

  } else {

    vp8_copy_and_extend_frame(src, &buf->img);

  }

  buf->ts_start = ts_start;

  buf->ts_end = ts_end;

  buf->flags = flags;

  return 0;

}

struct lookahead_entry *vp8_lookahead_pop(struct lookahead_ctx *ctx,

                                          int drain) {

  struct lookahead_entry *buf = NULL;

  assert(ctx != NULL);

  if (ctx->sz && (drain || ctx->sz == ctx->max_sz - 1)) {

    buf = pop(ctx, &ctx->read_idx);

    ctx->sz--;

  }

  return buf;

}

struct lookahead_entry *vp8_lookahead_peek(struct lookahead_ctx *ctx,

                                           unsigned int index, int direction) {

  struct lookahead_entry *buf = NULL;

  if (direction == PEEK_FORWARD) {

    assert(index < ctx->max_sz - 1);

    if (index < ctx->sz) {

      index += ctx->read_idx;

      if (index >= ctx->max_sz) index -= ctx->max_sz;

      buf = ctx->buf + index;

    }

  } else if (direction == PEEK_BACKWARD) {

    assert(index == 1);

    if (ctx->read_idx == 0) {

      index = ctx->max_sz - 1;

    } else {

      index = ctx->read_idx - index;

    }

    buf = ctx->buf + index;

  }

  return buf;

}

unsigned int vp8_lookahead_depth(struct lookahead_ctx *ctx) { return ctx->sz; }