drivers/media/v4l2-core/v4l2-h264.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * V4L2 H264 helpers.
   4  *
   5  * Copyright (C) 2019 Collabora, Ltd.
   6  *
   7  * Author: Boris Brezillon <boris.brezillon@collabora.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/sort.h>
  12
  13 #include <media/v4l2-h264.h>
  14
  15 /**
  16  * v4l2_h264_init_reflist_builder() - Initialize a P/B0/B1 reference list
  17  *                                    builder
  18  *
  19  * @b: the builder context to initialize
  20  * @dec_params: decode parameters control
  21  * @sps: SPS control
  22  * @dpb: DPB to use when creating the reference list
  23  */
  24 void
  25 v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
  26                 const struct v4l2_ctrl_h264_decode_params *dec_params,
  27                 const struct v4l2_ctrl_h264_sps *sps,
  28                 const struct v4l2_h264_dpb_entry dpb[V4L2_H264_NUM_DPB_ENTRIES])
  29 {
  30         int cur_frame_num, max_frame_num;
  31         unsigned int i;
  32
  33         max_frame_num = 1 << (sps->log2_max_frame_num_minus4 + 4);
  34         cur_frame_num = dec_params->frame_num;
  35
  36         memset(b, 0, sizeof(*b));
  37         if (!(dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC))
  38                 b->cur_pic_order_count = min(dec_params->bottom_field_order_cnt,
  39                                              dec_params->top_field_order_cnt);
  40         else if (dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD)
  41                 b->cur_pic_order_count = dec_params->bottom_field_order_cnt;
  42         else
  43                 b->cur_pic_order_count = dec_params->top_field_order_cnt;
  44
  45         for (i = 0; i < V4L2_H264_NUM_DPB_ENTRIES; i++) {
  46                 u32 pic_order_count;
  47
  48                 if (!(dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
  49                         continue;
  50
  51                 b->refs[i].pic_num = dpb[i].pic_num;
  52                 if (dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM)
  53                         b->refs[i].longterm = true;
  54
  55                 /*
  56                  * Handle frame_num wraparound as described in section
  57                  * '8.2.4.1 Decoding process for picture numbers' of the spec.
  58                  * TODO: This logic will have to be adjusted when we start
  59                  * supporting interlaced content.
  60                  */
  61                 if (dpb[i].frame_num > cur_frame_num)
  62                         b->refs[i].frame_num = (int)dpb[i].frame_num -
  63                                                max_frame_num;
  64                 else
  65                         b->refs[i].frame_num = dpb[i].frame_num;
  66
  67                 if (dpb[i].fields == V4L2_H264_FRAME_REF)
  68                         pic_order_count = min(dpb[i].top_field_order_cnt,
  69                                               dpb[i].bottom_field_order_cnt);
  70                 else if (dpb[i].fields & V4L2_H264_BOTTOM_FIELD_REF)
  71                         pic_order_count = dpb[i].bottom_field_order_cnt;
  72                 else
  73                         pic_order_count = dpb[i].top_field_order_cnt;
  74
  75                 b->refs[i].pic_order_count = pic_order_count;
  76                 b->unordered_reflist[b->num_valid] = i;
  77                 b->num_valid++;
  78         }
  79
  80         for (i = b->num_valid; i < ARRAY_SIZE(b->unordered_reflist); i++)
  81                 b->unordered_reflist[i] = i;
  82 }
  83 EXPORT_SYMBOL_GPL(v4l2_h264_init_reflist_builder);
  84
  85 static int v4l2_h264_p_ref_list_cmp(const void *ptra, const void *ptrb,
  86                                     const void *data)
  87 {
  88         const struct v4l2_h264_reflist_builder *builder = data;
  89         u8 idxa, idxb;
  90
  91         idxa = *((u8 *)ptra);
  92         idxb = *((u8 *)ptrb);
  93
  94         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
  95                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
  96                 return 1;
  97
  98         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
  99                 /* Short term pics first. */
 100                 if (!builder->refs[idxa].longterm)
 101                         return -1;
 102                 else
 103                         return 1;
 104         }
 105
 106         /*
 107          * Short term pics in descending pic num order, long term ones in
 108          * ascending order.
 109          */
 110         if (!builder->refs[idxa].longterm)
 111                 return builder->refs[idxb].frame_num <
 112                        builder->refs[idxa].frame_num ?
 113                        -1 : 1;
 114
 115         return builder->refs[idxa].pic_num < builder->refs[idxb].pic_num ?
 116                -1 : 1;
 117 }
 118
 119 static int v4l2_h264_b0_ref_list_cmp(const void *ptra, const void *ptrb,
 120                                      const void *data)
 121 {
 122         const struct v4l2_h264_reflist_builder *builder = data;
 123         s32 poca, pocb;
 124         u8 idxa, idxb;
 125
 126         idxa = *((u8 *)ptra);
 127         idxb = *((u8 *)ptrb);
 128
 129         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
 130                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
 131                 return 1;
 132
 133         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
 134                 /* Short term pics first. */
 135                 if (!builder->refs[idxa].longterm)
 136                         return -1;
 137                 else
 138                         return 1;
 139         }
 140
 141         /* Long term pics in ascending pic num order. */
 142         if (builder->refs[idxa].longterm)
 143                 return builder->refs[idxa].pic_num <
 144                        builder->refs[idxb].pic_num ?
 145                        -1 : 1;
 146
 147         poca = builder->refs[idxa].pic_order_count;
 148         pocb = builder->refs[idxb].pic_order_count;
 149
 150         /*
 151          * Short term pics with POC < cur POC first in POC descending order
 152          * followed by short term pics with POC > cur POC in POC ascending
 153          * order.
 154          */
 155         if ((poca < builder->cur_pic_order_count) !=
 156              (pocb < builder->cur_pic_order_count))
 157                 return poca < pocb ? -1 : 1;
 158         else if (poca < builder->cur_pic_order_count)
 159                 return pocb < poca ? -1 : 1;
 160
 161         return poca < pocb ? -1 : 1;
 162 }
 163
 164 static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
 165                                      const void *data)
 166 {
 167         const struct v4l2_h264_reflist_builder *builder = data;
 168         s32 poca, pocb;
 169         u8 idxa, idxb;
 170
 171         idxa = *((u8 *)ptra);
 172         idxb = *((u8 *)ptrb);
 173
 174         if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
 175                     idxb >= V4L2_H264_NUM_DPB_ENTRIES))
 176                 return 1;
 177
 178         if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
 179                 /* Short term pics first. */
 180                 if (!builder->refs[idxa].longterm)
 181                         return -1;
 182                 else
 183                         return 1;
 184         }
 185
 186         /* Long term pics in ascending pic num order. */
 187         if (builder->refs[idxa].longterm)
 188                 return builder->refs[idxa].pic_num <
 189                        builder->refs[idxb].pic_num ?
 190                        -1 : 1;
 191
 192         poca = builder->refs[idxa].pic_order_count;
 193         pocb = builder->refs[idxb].pic_order_count;
 194
 195         /*
 196          * Short term pics with POC > cur POC first in POC ascending order
 197          * followed by short term pics with POC < cur POC in POC descending
 198          * order.
 199          */
 200         if ((poca < builder->cur_pic_order_count) !=
 201             (pocb < builder->cur_pic_order_count))
 202                 return pocb < poca ? -1 : 1;
 203         else if (poca < builder->cur_pic_order_count)
 204                 return pocb < poca ? -1 : 1;
 205
 206         return poca < pocb ? -1 : 1;
 207 }
 208
 209 /**
 210  * v4l2_h264_build_p_ref_list() - Build the P reference list
 211  *
 212  * @builder: reference list builder context
 213  * @reflist: 16-bytes array used to store the P reference list. Each entry
 214  *           is an index in the DPB
 215  *
 216  * This functions builds the P reference lists. This procedure is describe in
 217  * section '8.2.4 Decoding process for reference picture lists construction'
 218  * of the H264 spec. This function can be used by H264 decoder drivers that
 219  * need to pass a P reference list to the hardware.
 220  */
 221 void
 222 v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
 223                            u8 *reflist)
 224 {
 225         memcpy(reflist, builder->unordered_reflist,
 226                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 227         sort_r(reflist, builder->num_valid, sizeof(*reflist),
 228                v4l2_h264_p_ref_list_cmp, NULL, builder);
 229 }
 230 EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
 231
 232 /**
 233  * v4l2_h264_build_b_ref_lists() - Build the B0/B1 reference lists
 234  *
 235  * @builder: reference list builder context
 236  * @b0_reflist: 16-bytes array used to store the B0 reference list. Each entry
 237  *              is an index in the DPB
 238  * @b1_reflist: 16-bytes array used to store the B1 reference list. Each entry
 239  *              is an index in the DPB
 240  *
 241  * This functions builds the B0/B1 reference lists. This procedure is described
 242  * in section '8.2.4 Decoding process for reference picture lists construction'
 243  * of the H264 spec. This function can be used by H264 decoder drivers that
 244  * need to pass B0/B1 reference lists to the hardware.
 245  */
 246 void
 247 v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
 248                             u8 *b0_reflist, u8 *b1_reflist)
 249 {
 250         memcpy(b0_reflist, builder->unordered_reflist,
 251                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 252         sort_r(b0_reflist, builder->num_valid, sizeof(*b0_reflist),
 253                v4l2_h264_b0_ref_list_cmp, NULL, builder);
 254
 255         memcpy(b1_reflist, builder->unordered_reflist,
 256                sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 257         sort_r(b1_reflist, builder->num_valid, sizeof(*b1_reflist),
 258                v4l2_h264_b1_ref_list_cmp, NULL, builder);
 259
 260         if (builder->num_valid > 1 &&
 261             !memcmp(b1_reflist, b0_reflist, builder->num_valid))
 262                 swap(b1_reflist[0], b1_reflist[1]);
 263 }
 264 EXPORT_SYMBOL_GPL(v4l2_h264_build_b_ref_lists);
 265
 266 MODULE_LICENSE("GPL");
 267 MODULE_DESCRIPTION("V4L2 H264 Helpers");
 268 MODULE_AUTHOR("Boris Brezillon <boris.brezillon@collabora.com>");