The Tor Browser: media/libvpx/vp9/encoder/vp9_tokenize.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_tokenize.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_tokenize.c

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /*
  *  Copyright (c) 2010 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 <math.h>
 #include <stdio.h>
 #include <string.h>
 #include <assert.h>
 #include "vp9/encoder/vp9_onyx_int.h"
 #include "vp9/encoder/vp9_tokenize.h"
 #include "vpx_mem/vpx_mem.h"
 #include "vp9/common/vp9_pred_common.h"
 #include "vp9/common/vp9_seg_common.h"
 #include "vp9/common/vp9_entropy.h"
 static TOKENVALUE dct_value_tokens[DCT_MAX_VALUE * 2];
 const TOKENVALUE *vp9_dct_value_tokens_ptr;
 static int dct_value_cost[DCT_MAX_VALUE * 2];
 const int *vp9_dct_value_cost_ptr;
 static void fill_value_tokens() {
   TOKENVALUE *const t = dct_value_tokens + DCT_MAX_VALUE;
   const vp9_extra_bit *const e = vp9_extra_bits;
   int i = -DCT_MAX_VALUE;
   int sign = 1;
   do {
     if (!i)
       sign = 0;
     {
       const int a = sign ? -i : i;
       int eb = sign;
       if (a > 4) {
         int j = 4;
         while (++j < 11  &&  e[j].base_val <= a) {}
         t[i].token = --j;
         eb |= (a - e[j].base_val) << 1;
       } else {
         t[i].token = a;
       }
       t[i].extra = eb;
     }
     // initialize the cost for extra bits for all possible coefficient value.
     {
       int cost = 0;
       const vp9_extra_bit *p = &vp9_extra_bits[t[i].token];
       if (p->base_val) {
         const int extra = t[i].extra;
         const int length = p->len;
         if (length)
           cost += treed_cost(p->tree, p->prob, extra >> 1, length);
         cost += vp9_cost_bit(vp9_prob_half, extra & 1); /* sign */
         dct_value_cost[i + DCT_MAX_VALUE] = cost;
       }
     }
   } while (++i < DCT_MAX_VALUE);
   vp9_dct_value_tokens_ptr = dct_value_tokens + DCT_MAX_VALUE;
   vp9_dct_value_cost_ptr = dct_value_cost + DCT_MAX_VALUE;
 }
 struct tokenize_b_args {
   VP9_COMP *cpi;
   MACROBLOCKD *xd;
   TOKENEXTRA **tp;
   TX_SIZE tx_size;
   uint8_t *token_cache;
 };
 static void set_entropy_context_b(int plane, int block, BLOCK_SIZE plane_bsize,
                                   TX_SIZE tx_size, void *arg) {
   struct tokenize_b_args* const args = arg;
   MACROBLOCKD *const xd = args->xd;
   struct macroblockd_plane *pd = &xd->plane[plane];
   int aoff, loff;
   txfrm_block_to_raster_xy(plane_bsize, tx_size, block, &aoff, &loff);
   set_contexts(xd, pd, plane_bsize, tx_size, pd->eobs[block] > 0, aoff, loff);
 }
 static void tokenize_b(int plane, int block, BLOCK_SIZE plane_bsize,
                        TX_SIZE tx_size, void *arg) {
   struct tokenize_b_args* const args = arg;
   VP9_COMP *cpi = args->cpi;
   MACROBLOCKD *xd = args->xd;
   TOKENEXTRA **tp = args->tp;
   uint8_t *token_cache = args->token_cache;
   struct macroblockd_plane *pd = &xd->plane[plane];
   MB_MODE_INFO *mbmi = &xd->mi_8x8[0]->mbmi;
   int pt; /* near block/prev token context index */
   int c = 0, rc = 0;
   TOKENEXTRA *t = *tp;        /* store tokens starting here */
   const int eob = pd->eobs[block];
   const PLANE_TYPE type = pd->plane_type;
   const int16_t *qcoeff_ptr = BLOCK_OFFSET(pd->qcoeff, block);
   const int segment_id = mbmi->segment_id;
   const int16_t *scan, *nb;
   vp9_coeff_count *const counts = cpi->coef_counts[tx_size];
   vp9_coeff_probs_model *const coef_probs = cpi->common.fc.coef_probs[tx_size];
   const int ref = is_inter_block(mbmi);
   const uint8_t *const band_translate = get_band_translate(tx_size);
   const int seg_eob = get_tx_eob(&cpi->common.seg, segment_id, tx_size);
   int aoff, loff;
   txfrm_block_to_raster_xy(plane_bsize, tx_size, block, &aoff, &loff);
   assert((!type && !plane) || (type && plane));
   pt = get_entropy_context(tx_size, pd->above_context + aoff,
                                     pd->left_context + loff);
   get_scan(xd, tx_size, type, block, &scan, &nb);
   c = 0;
   do {
     const int band = band_translate[c];
     int token;
     int v = 0;
     rc = scan[c];
     if (c)
       pt = get_coef_context(nb, token_cache, c);
     if (c < eob) {
       v = qcoeff_ptr[rc];
       assert(-DCT_MAX_VALUE <= v  &&  v < DCT_MAX_VALUE);
       t->extra = vp9_dct_value_tokens_ptr[v].extra;
       token    = vp9_dct_value_tokens_ptr[v].token;
     } else {
       token = DCT_EOB_TOKEN;
     }
     t->token = token;
     t->context_tree = coef_probs[type][ref][band][pt];
     t->skip_eob_node = (c > 0) && (token_cache[scan[c - 1]] == 0);
     assert(vp9_coef_encodings[t->token].len - t->skip_eob_node > 0);
     ++counts[type][ref][band][pt][token];
     if (!t->skip_eob_node)
       ++cpi->common.counts.eob_branch[tx_size][type][ref][band][pt];
     token_cache[rc] = vp9_pt_energy_class[token];
     ++t;
   } while (c < eob && ++c < seg_eob);
   *tp = t;
   set_contexts(xd, pd, plane_bsize, tx_size, c > 0, aoff, loff);
 }
 struct is_skippable_args {
   MACROBLOCKD *xd;
   int *skippable;
 };
 static void is_skippable(int plane, int block,
                          BLOCK_SIZE plane_bsize, TX_SIZE tx_size,
                          void *argv) {
   struct is_skippable_args *args = argv;
   args->skippable[0] &= (!args->xd->plane[plane].eobs[block]);
 }
 int vp9_sb_is_skippable(MACROBLOCKD *xd, BLOCK_SIZE bsize) {
   int result = 1;
   struct is_skippable_args args = {xd, &result};
   foreach_transformed_block(xd, bsize, is_skippable, &args);
   return result;
 }
 int vp9_is_skippable_in_plane(MACROBLOCKD *xd, BLOCK_SIZE bsize,
                               int plane) {
   int result = 1;
   struct is_skippable_args args = {xd, &result};
   foreach_transformed_block_in_plane(xd, bsize, plane, is_skippable, &args);
   return result;
 }
 void vp9_tokenize_sb(VP9_COMP *cpi, TOKENEXTRA **t, int dry_run,
                      BLOCK_SIZE bsize) {
   VP9_COMMON *const cm = &cpi->common;
   MACROBLOCKD *const xd = &cpi->mb.e_mbd;
   MB_MODE_INFO *const mbmi = &xd->mi_8x8[0]->mbmi;
   TOKENEXTRA *t_backup = *t;
   const int mb_skip_context = vp9_get_pred_context_mbskip(xd);
   const int skip_inc = !vp9_segfeature_active(&cm->seg, mbmi->segment_id,
                                               SEG_LVL_SKIP);
   struct tokenize_b_args arg = {cpi, xd, t, mbmi->tx_size, cpi->mb.token_cache};
   mbmi->skip_coeff = vp9_sb_is_skippable(xd, bsize);
   if (mbmi->skip_coeff) {
     if (!dry_run)
       cm->counts.mbskip[mb_skip_context][1] += skip_inc;
     reset_skip_context(xd, bsize);
     if (dry_run)
       *t = t_backup;
     return;
   }
   if (!dry_run) {
     cm->counts.mbskip[mb_skip_context][0] += skip_inc;
     foreach_transformed_block(xd, bsize, tokenize_b, &arg);
   } else {
     foreach_transformed_block(xd, bsize, set_entropy_context_b, &arg);
     *t = t_backup;
   }
 }
 void vp9_tokenize_initialize() {
   fill_value_tokens();
 }

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media/libvpx/vp9/encoder/vp9_tokenize.c@ac0c01689b40 (annotated)

media/libvpx/vp9/encoder/vp9_tokenize.c