/* * H.26L/H.264/AVC/JVT/14496-10/... reference picture handling * Copyright (c) 2003 Michael Niedermayer * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * H.264 / AVC / MPEG4 part10 reference picture handling. * @author Michael Niedermayer */ #include "internal.h" #include "avcodec.h" #include "h264.h" #include "golomb.h" //#undef NDEBUG #include #define COPY_PICTURE(dst, src) \ do {\ *(dst) = *(src);\ (dst)->f.extended_data = (dst)->f.data;\ (dst)->tf.f = &(dst)->f;\ } while (0) static void pic_as_field(Picture *pic, const int parity){ int i; for (i = 0; i < 4; ++i) { if (parity == PICT_BOTTOM_FIELD) pic->f.data[i] += pic->f.linesize[i]; pic->reference = parity; pic->f.linesize[i] *= 2; } pic->poc= pic->field_poc[parity == PICT_BOTTOM_FIELD]; } static int split_field_copy(Picture *dest, Picture *src, int parity, int id_add){ int match = !!(src->reference & parity); if (match) { COPY_PICTURE(dest, src); if(parity != PICT_FRAME){ pic_as_field(dest, parity); dest->pic_id *= 2; dest->pic_id += id_add; } } return match; } static int build_def_list(Picture *def, Picture **in, int len, int is_long, int sel){ int i[2]={0}; int index=0; while(i[0]reference & sel))) i[0]++; while (i[1] < len && !(in[ i[1] ] && (in[ i[1] ]->reference & (sel^3)))) i[1]++; if(i[0] < len){ in[ i[0] ]->pic_id= is_long ? i[0] : in[ i[0] ]->frame_num; split_field_copy(&def[index++], in[ i[0]++ ], sel , 1); } if(i[1] < len){ in[ i[1] ]->pic_id= is_long ? i[1] : in[ i[1] ]->frame_num; split_field_copy(&def[index++], in[ i[1]++ ], sel^3, 0); } } return index; } static int add_sorted(Picture **sorted, Picture **src, int len, int limit, int dir){ int i, best_poc; int out_i= 0; for(;;){ best_poc= dir ? INT_MIN : INT_MAX; for(i=0; ipoc; if(((poc > limit) ^ dir) && ((poc < best_poc) ^ dir)){ best_poc= poc; sorted[out_i]= src[i]; } } if(best_poc == (dir ? INT_MIN : INT_MAX)) break; limit= sorted[out_i++]->poc - dir; } return out_i; } int ff_h264_fill_default_ref_list(H264Context *h){ int i, len; if(h->slice_type_nos==AV_PICTURE_TYPE_B){ Picture *sorted[32]; int cur_poc, list; int lens[2]; if(FIELD_PICTURE) cur_poc= h->cur_pic_ptr->field_poc[h->picture_structure == PICT_BOTTOM_FIELD]; else cur_poc= h->cur_pic_ptr->poc; for(list= 0; list<2; list++){ len= add_sorted(sorted , h->short_ref, h->short_ref_count, cur_poc, 1^list); len+=add_sorted(sorted+len, h->short_ref, h->short_ref_count, cur_poc, 0^list); assert(len<=32); len= build_def_list(h->default_ref_list[list] , sorted , len, 0, h->picture_structure); len+=build_def_list(h->default_ref_list[list]+len, h->long_ref, 16 , 1, h->picture_structure); assert(len<=32); if(len < h->ref_count[list]) memset(&h->default_ref_list[list][len], 0, sizeof(Picture)*(h->ref_count[list] - len)); lens[list]= len; } if(lens[0] == lens[1] && lens[1] > 1){ for (i = 0; h->default_ref_list[0][i].f.data[0] == h->default_ref_list[1][i].f.data[0] && i < lens[0]; i++); if (i == lens[0]) { Picture tmp; COPY_PICTURE(&tmp, &h->default_ref_list[1][0]); COPY_PICTURE(&h->default_ref_list[1][0], &h->default_ref_list[1][1]); COPY_PICTURE(&h->default_ref_list[1][1], &tmp); } } }else{ len = build_def_list(h->default_ref_list[0] , h->short_ref, h->short_ref_count, 0, h->picture_structure); len+= build_def_list(h->default_ref_list[0]+len, h-> long_ref, 16 , 1, h->picture_structure); assert(len <= 32); if(len < h->ref_count[0]) memset(&h->default_ref_list[0][len], 0, sizeof(Picture)*(h->ref_count[0] - len)); } #ifdef TRACE for (i=0; iref_count[0]; i++) { tprintf(h->avctx, "List0: %s fn:%d 0x%p\n", (h->default_ref_list[0][i].long_ref ? "LT" : "ST"), h->default_ref_list[0][i].pic_id, h->default_ref_list[0][i].f.data[0]); } if(h->slice_type_nos==AV_PICTURE_TYPE_B){ for (i=0; iref_count[1]; i++) { tprintf(h->avctx, "List1: %s fn:%d 0x%p\n", (h->default_ref_list[1][i].long_ref ? "LT" : "ST"), h->default_ref_list[1][i].pic_id, h->default_ref_list[1][i].f.data[0]); } } #endif return 0; } static void print_short_term(H264Context *h); static void print_long_term(H264Context *h); /** * Extract structure information about the picture described by pic_num in * the current decoding context (frame or field). Note that pic_num is * picture number without wrapping (so, 0<=pic_numpicture_structure; if(FIELD_PICTURE){ if (!(pic_num & 1)) /* opposite field */ *structure ^= PICT_FRAME; pic_num >>= 1; } return pic_num; } int ff_h264_decode_ref_pic_list_reordering(H264Context *h){ int list, index, pic_structure, i; print_short_term(h); print_long_term(h); for(list=0; listlist_count; list++){ for (i = 0; i < h->ref_count[list]; i++) COPY_PICTURE(&h->ref_list[list][i], &h->default_ref_list[list][i]); if(get_bits1(&h->gb)){ int pred= h->curr_pic_num; for(index=0; ; index++){ unsigned int reordering_of_pic_nums_idc= get_ue_golomb_31(&h->gb); unsigned int pic_id; int i; Picture *ref = NULL; if(reordering_of_pic_nums_idc==3) break; if(index >= h->ref_count[list]){ av_log(h->avctx, AV_LOG_ERROR, "reference count overflow\n"); return -1; } if(reordering_of_pic_nums_idc<3){ if(reordering_of_pic_nums_idc<2){ const unsigned int abs_diff_pic_num= get_ue_golomb(&h->gb) + 1; int frame_num; if(abs_diff_pic_num > h->max_pic_num){ av_log(h->avctx, AV_LOG_ERROR, "abs_diff_pic_num overflow\n"); return -1; } if(reordering_of_pic_nums_idc == 0) pred-= abs_diff_pic_num; else pred+= abs_diff_pic_num; pred &= h->max_pic_num - 1; frame_num = pic_num_extract(h, pred, &pic_structure); for(i= h->short_ref_count-1; i>=0; i--){ ref = h->short_ref[i]; assert(ref->reference); assert(!ref->long_ref); if( ref->frame_num == frame_num && (ref->reference & pic_structure) ) break; } if(i>=0) ref->pic_id= pred; }else{ int long_idx; pic_id= get_ue_golomb(&h->gb); //long_term_pic_idx long_idx= pic_num_extract(h, pic_id, &pic_structure); if(long_idx>31){ av_log(h->avctx, AV_LOG_ERROR, "long_term_pic_idx overflow\n"); return -1; } ref = h->long_ref[long_idx]; assert(!(ref && !ref->reference)); if (ref && (ref->reference & pic_structure)) { ref->pic_id= pic_id; assert(ref->long_ref); i=0; }else{ i=-1; } } if (i < 0) { av_log(h->avctx, AV_LOG_ERROR, "reference picture missing during reorder\n"); memset(&h->ref_list[list][index], 0, sizeof(Picture)); //FIXME } else { for(i=index; i+1ref_count[list]; i++){ if(ref->long_ref == h->ref_list[list][i].long_ref && ref->pic_id == h->ref_list[list][i].pic_id) break; } for(; i > index; i--){ COPY_PICTURE(&h->ref_list[list][i], &h->ref_list[list][i - 1]); } COPY_PICTURE(&h->ref_list[list][index], ref); if (FIELD_PICTURE){ pic_as_field(&h->ref_list[list][index], pic_structure); } } }else{ av_log(h->avctx, AV_LOG_ERROR, "illegal reordering_of_pic_nums_idc\n"); return -1; } } } } for(list=0; listlist_count; list++){ for(index= 0; index < h->ref_count[list]; index++){ if (!h->ref_list[list][index].f.data[0]) { av_log(h->avctx, AV_LOG_ERROR, "Missing reference picture\n"); if (h->default_ref_list[list][0].f.data[0]) COPY_PICTURE(&h->ref_list[list][index], &h->default_ref_list[list][0]); else return -1; } } } return 0; } void ff_h264_fill_mbaff_ref_list(H264Context *h){ int list, i, j; for(list=0; list<2; list++){ //FIXME try list_count for(i=0; iref_count[list]; i++){ Picture *frame = &h->ref_list[list][i]; Picture *field = &h->ref_list[list][16+2*i]; COPY_PICTURE(field, frame); for(j=0; j<3; j++) field[0].f.linesize[j] <<= 1; field[0].reference = PICT_TOP_FIELD; field[0].poc= field[0].field_poc[0]; COPY_PICTURE(field + 1, field); for(j=0; j<3; j++) field[1].f.data[j] += frame->f.linesize[j]; field[1].reference = PICT_BOTTOM_FIELD; field[1].poc= field[1].field_poc[1]; h->luma_weight[16+2*i][list][0] = h->luma_weight[16+2*i+1][list][0] = h->luma_weight[i][list][0]; h->luma_weight[16+2*i][list][1] = h->luma_weight[16+2*i+1][list][1] = h->luma_weight[i][list][1]; for(j=0; j<2; j++){ h->chroma_weight[16+2*i][list][j][0] = h->chroma_weight[16+2*i+1][list][j][0] = h->chroma_weight[i][list][j][0]; h->chroma_weight[16+2*i][list][j][1] = h->chroma_weight[16+2*i+1][list][j][1] = h->chroma_weight[i][list][j][1]; } } } } /** * Mark a picture as no longer needed for reference. The refmask * argument allows unreferencing of individual fields or the whole frame. * If the picture becomes entirely unreferenced, but is being held for * display purposes, it is marked as such. * @param refmask mask of fields to unreference; the mask is bitwise * anded with the reference marking of pic * @return non-zero if pic becomes entirely unreferenced (except possibly * for display purposes) zero if one of the fields remains in * reference */ static inline int unreference_pic(H264Context *h, Picture *pic, int refmask){ int i; if (pic->reference &= refmask) { return 0; } else { for(i = 0; h->delayed_pic[i]; i++) if(pic == h->delayed_pic[i]){ pic->reference = DELAYED_PIC_REF; break; } return 1; } } /** * Find a Picture in the short term reference list by frame number. * @param frame_num frame number to search for * @param idx the index into h->short_ref where returned picture is found * undefined if no picture found. * @return pointer to the found picture, or NULL if no pic with the provided * frame number is found */ static Picture * find_short(H264Context *h, int frame_num, int *idx){ int i; for(i=0; ishort_ref_count; i++){ Picture *pic= h->short_ref[i]; if(h->avctx->debug&FF_DEBUG_MMCO) av_log(h->avctx, AV_LOG_DEBUG, "%d %d %p\n", i, pic->frame_num, pic); if(pic->frame_num == frame_num) { *idx = i; return pic; } } return NULL; } /** * Remove a picture from the short term reference list by its index in * that list. This does no checking on the provided index; it is assumed * to be valid. Other list entries are shifted down. * @param i index into h->short_ref of picture to remove. */ static void remove_short_at_index(H264Context *h, int i){ assert(i >= 0 && i < h->short_ref_count); h->short_ref[i]= NULL; if (--h->short_ref_count) memmove(&h->short_ref[i], &h->short_ref[i+1], (h->short_ref_count - i)*sizeof(Picture*)); } /** * * @return the removed picture or NULL if an error occurs */ static Picture * remove_short(H264Context *h, int frame_num, int ref_mask){ Picture *pic; int i; if(h->avctx->debug&FF_DEBUG_MMCO) av_log(h->avctx, AV_LOG_DEBUG, "remove short %d count %d\n", frame_num, h->short_ref_count); pic = find_short(h, frame_num, &i); if (pic){ if(unreference_pic(h, pic, ref_mask)) remove_short_at_index(h, i); } return pic; } /** * Remove a picture from the long term reference list by its index in * that list. * @return the removed picture or NULL if an error occurs */ static Picture * remove_long(H264Context *h, int i, int ref_mask){ Picture *pic; pic= h->long_ref[i]; if (pic){ if(unreference_pic(h, pic, ref_mask)){ assert(h->long_ref[i]->long_ref == 1); h->long_ref[i]->long_ref= 0; h->long_ref[i]= NULL; h->long_ref_count--; } } return pic; } void ff_h264_remove_all_refs(H264Context *h){ int i; for(i=0; i<16; i++){ remove_long(h, i, 0); } assert(h->long_ref_count==0); for(i=0; ishort_ref_count; i++){ unreference_pic(h, h->short_ref[i], 0); h->short_ref[i]= NULL; } h->short_ref_count=0; } /** * print short term list */ static void print_short_term(H264Context *h) { uint32_t i; if(h->avctx->debug&FF_DEBUG_MMCO) { av_log(h->avctx, AV_LOG_DEBUG, "short term list:\n"); for(i=0; ishort_ref_count; i++){ Picture *pic= h->short_ref[i]; av_log(h->avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->f.data[0]); } } } /** * print long term list */ static void print_long_term(H264Context *h) { uint32_t i; if(h->avctx->debug&FF_DEBUG_MMCO) { av_log(h->avctx, AV_LOG_DEBUG, "long term list:\n"); for(i = 0; i < 16; i++){ Picture *pic= h->long_ref[i]; if (pic) { av_log(h->avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->f.data[0]); } } } } static int check_opcodes(MMCO *mmco1, MMCO *mmco2, int n_mmcos) { int i; for (i = 0; i < n_mmcos; i++) { if (mmco1[i].opcode != mmco2[i].opcode) return -1; } return 0; } int ff_generate_sliding_window_mmcos(H264Context *h, int first_slice) { MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = first_slice ? h->mmco : mmco_temp; int mmco_index = 0, i; assert(h->long_ref_count + h->short_ref_count <= h->sps.ref_frame_count); if (h->short_ref_count && h->long_ref_count + h->short_ref_count == h->sps.ref_frame_count && !(FIELD_PICTURE && !h->first_field && h->cur_pic_ptr->reference)) { mmco[0].opcode = MMCO_SHORT2UNUSED; mmco[0].short_pic_num = h->short_ref[h->short_ref_count - 1]->frame_num; mmco_index = 1; if (FIELD_PICTURE) { mmco[0].short_pic_num *= 2; mmco[1].opcode = MMCO_SHORT2UNUSED; mmco[1].short_pic_num = mmco[0].short_pic_num + 1; mmco_index = 2; } } if (first_slice) { h->mmco_index = mmco_index; } else if (!first_slice && mmco_index >= 0 && (mmco_index != h->mmco_index || (i = check_opcodes(h->mmco, mmco_temp, mmco_index)))) { av_log(h->avctx, AV_LOG_ERROR, "Inconsistent MMCO state between slices [%d, %d, %d]\n", mmco_index, h->mmco_index, i); return AVERROR_INVALIDDATA; } return 0; } int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count){ int i, av_uninit(j); int current_ref_assigned=0, err=0; Picture *av_uninit(pic); if((h->avctx->debug&FF_DEBUG_MMCO) && mmco_count==0) av_log(h->avctx, AV_LOG_DEBUG, "no mmco here\n"); for(i=0; iavctx->debug&FF_DEBUG_MMCO) av_log(h->avctx, AV_LOG_DEBUG, "mmco:%d %d %d\n", h->mmco[i].opcode, h->mmco[i].short_pic_num, h->mmco[i].long_arg); if( mmco[i].opcode == MMCO_SHORT2UNUSED || mmco[i].opcode == MMCO_SHORT2LONG){ frame_num = pic_num_extract(h, mmco[i].short_pic_num, &structure); pic = find_short(h, frame_num, &j); if(!pic){ if(mmco[i].opcode != MMCO_SHORT2LONG || !h->long_ref[mmco[i].long_arg] || h->long_ref[mmco[i].long_arg]->frame_num != frame_num) { av_log(h->avctx, AV_LOG_ERROR, "mmco: unref short failure\n"); err = AVERROR_INVALIDDATA; } continue; } } switch(mmco[i].opcode){ case MMCO_SHORT2UNUSED: if(h->avctx->debug&FF_DEBUG_MMCO) av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref short %d count %d\n", h->mmco[i].short_pic_num, h->short_ref_count); remove_short(h, frame_num, structure ^ PICT_FRAME); break; case MMCO_SHORT2LONG: if (h->long_ref[mmco[i].long_arg] != pic) remove_long(h, mmco[i].long_arg, 0); remove_short_at_index(h, j); h->long_ref[ mmco[i].long_arg ]= pic; if (h->long_ref[ mmco[i].long_arg ]){ h->long_ref[ mmco[i].long_arg ]->long_ref=1; h->long_ref_count++; } break; case MMCO_LONG2UNUSED: j = pic_num_extract(h, mmco[i].long_arg, &structure); pic = h->long_ref[j]; if (pic) { remove_long(h, j, structure ^ PICT_FRAME); } else if(h->avctx->debug&FF_DEBUG_MMCO) av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref long failure\n"); break; case MMCO_LONG: // Comment below left from previous code as it is an interresting note. /* First field in pair is in short term list or * at a different long term index. * This is not allowed; see 7.4.3.3, notes 2 and 3. * Report the problem and keep the pair where it is, * and mark this field valid. */ if (h->long_ref[mmco[i].long_arg] != h->cur_pic_ptr) { remove_long(h, mmco[i].long_arg, 0); h->long_ref[ mmco[i].long_arg ]= h->cur_pic_ptr; h->long_ref[ mmco[i].long_arg ]->long_ref=1; h->long_ref_count++; } h->cur_pic_ptr->reference |= h->picture_structure; current_ref_assigned=1; break; case MMCO_SET_MAX_LONG: assert(mmco[i].long_arg <= 16); // just remove the long term which index is greater than new max for(j = mmco[i].long_arg; j<16; j++){ remove_long(h, j, 0); } break; case MMCO_RESET: while(h->short_ref_count){ remove_short(h, h->short_ref[0]->frame_num, 0); } for(j = 0; j < 16; j++) { remove_long(h, j, 0); } h->frame_num= h->cur_pic_ptr->frame_num= 0; h->mmco_reset = 1; h->cur_pic_ptr->mmco_reset=1; break; default: assert(0); } } if (!current_ref_assigned) { /* Second field of complementary field pair; the first field of * which is already referenced. If short referenced, it * should be first entry in short_ref. If not, it must exist * in long_ref; trying to put it on the short list here is an * error in the encoded bit stream (ref: 7.4.3.3, NOTE 2 and 3). */ if (h->short_ref_count && h->short_ref[0] == h->cur_pic_ptr) { /* Just mark the second field valid */ h->cur_pic_ptr->reference = PICT_FRAME; } else if (h->cur_pic_ptr->long_ref) { av_log(h->avctx, AV_LOG_ERROR, "illegal short term reference " "assignment for second field " "in complementary field pair " "(first field is long term)\n"); err = AVERROR_INVALIDDATA; } else { pic= remove_short(h, h->cur_pic_ptr->frame_num, 0); if(pic){ av_log(h->avctx, AV_LOG_ERROR, "illegal short term buffer state detected\n"); err = AVERROR_INVALIDDATA; } if(h->short_ref_count) memmove(&h->short_ref[1], &h->short_ref[0], h->short_ref_count*sizeof(Picture*)); h->short_ref[0]= h->cur_pic_ptr; h->short_ref_count++; h->cur_pic_ptr->reference |= h->picture_structure; } } if (h->long_ref_count + h->short_ref_count - (h->short_ref[0] == h->cur_pic_ptr) > h->sps.ref_frame_count){ /* We have too many reference frames, probably due to corrupted * stream. Need to discard one frame. Prevents overrun of the * short_ref and long_ref buffers. */ av_log(h->avctx, AV_LOG_ERROR, "number of reference frames (%d+%d) exceeds max (%d; probably " "corrupt input), discarding one\n", h->long_ref_count, h->short_ref_count, h->sps.ref_frame_count); err = AVERROR_INVALIDDATA; if (h->long_ref_count && !h->short_ref_count) { for (i = 0; i < 16; ++i) if (h->long_ref[i]) break; assert(i < 16); remove_long(h, i, 0); } else { pic = h->short_ref[h->short_ref_count - 1]; remove_short(h, pic->frame_num, 0); } } print_short_term(h); print_long_term(h); return (h->avctx->err_recognition & AV_EF_EXPLODE) ? err : 0; } int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb, int first_slice) { int i, ret; MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = first_slice ? h->mmco : mmco_temp; int mmco_index = 0; if (h->nal_unit_type == NAL_IDR_SLICE){ // FIXME fields skip_bits1(gb); // broken_link if (get_bits1(gb)){ mmco[0].opcode = MMCO_LONG; mmco[0].long_arg = 0; mmco_index = 1; } } else { if (get_bits1(gb)) { // adaptive_ref_pic_marking_mode_flag for (i = 0; i < MAX_MMCO_COUNT; i++) { MMCOOpcode opcode = get_ue_golomb_31(gb); mmco[i].opcode = opcode; if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG){ mmco[i].short_pic_num = (h->curr_pic_num - get_ue_golomb(gb) - 1) & (h->max_pic_num - 1); #if 0 if (mmco[i].short_pic_num >= h->short_ref_count || h->short_ref[ mmco[i].short_pic_num ] == NULL){ av_log(s->avctx, AV_LOG_ERROR, "illegal short ref in memory management control " "operation %d\n", mmco); return -1; } #endif } if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED || opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG) { unsigned int long_arg = get_ue_golomb_31(gb); if (long_arg >= 32 || (long_arg >= 16 && !(opcode == MMCO_SET_MAX_LONG && long_arg == 16) && !(opcode == MMCO_LONG2UNUSED && FIELD_PICTURE))){ av_log(h->avctx, AV_LOG_ERROR, "illegal long ref in memory management control " "operation %d\n", opcode); return -1; } mmco[i].long_arg = long_arg; } if (opcode > (unsigned) MMCO_LONG){ av_log(h->avctx, AV_LOG_ERROR, "illegal memory management control operation %d\n", opcode); return -1; } if (opcode == MMCO_END) break; } mmco_index = i; } else { if (first_slice) { ret = ff_generate_sliding_window_mmcos(h, first_slice); if (ret < 0 && h->avctx->err_recognition & AV_EF_EXPLODE) return ret; } mmco_index = -1; } } if (first_slice && mmco_index != -1) { h->mmco_index = mmco_index; } else if (!first_slice && mmco_index >= 0 && (mmco_index != h->mmco_index || (i = check_opcodes(h->mmco, mmco_temp, mmco_index)))) { av_log(h->avctx, AV_LOG_ERROR, "Inconsistent MMCO state between slices [%d, %d, %d]\n", mmco_index, h->mmco_index, i); return AVERROR_INVALIDDATA; } return 0; }