/************************************************************************** * * Copyright 2013 Advanced Micro Devices, Inc. * All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sub license, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice (including the * next paragraph) shall be included in all copies or substantial portions * of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * **************************************************************************/ /* * Authors: * Christian König <christian.koenig@amd.com> * */ /* * Functions for reading the raw byte sequence payload of H.264 */ #ifndef vl_rbsp_h #define vl_rbsp_h #include "vl/vl_vlc.h" struct vl_rbsp { struct vl_vlc nal; unsigned escaped; }; /** * Initialize the RBSP object */ static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits) { unsigned bits_left = vl_vlc_bits_left(nal); /* copy the position */ rbsp->nal = *nal; rbsp->escaped = 0; /* search for the end of the NAL unit */ while (vl_vlc_search_byte(nal, num_bits, 0x00)) { if (vl_vlc_peekbits(nal, 24) == 0x000001 || vl_vlc_peekbits(nal, 32) == 0x00000001) { vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal)); return; } vl_vlc_eatbits(nal, 8); } } /** * Make at least 16 more bits available */ static inline void vl_rbsp_fillbits(struct vl_rbsp *rbsp) { unsigned valid = vl_vlc_valid_bits(&rbsp->nal); unsigned i, bits; /* abort if we still have enough bits */ if (valid >= 32) return; vl_vlc_fillbits(&rbsp->nal); /* abort if we have less than 24 bits left in this nal */ if (vl_vlc_bits_left(&rbsp->nal) < 24) return; /* check that we have enough bits left from the last fillbits */ assert(valid >= rbsp->escaped); /* handle the already escaped bits */ valid -= rbsp->escaped; /* search for the emulation prevention three byte */ rbsp->escaped = 16; bits = vl_vlc_valid_bits(&rbsp->nal); for (i = valid + 24; i <= bits; i += 8) { if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) { vl_vlc_removebits(&rbsp->nal, i - 8, 8); rbsp->escaped = bits - i; bits -= 8; i += 8; } } } /** * Return an unsigned integer from the first n bits */ static inline unsigned vl_rbsp_u(struct vl_rbsp *rbsp, unsigned n) { if (n == 0) return 0; vl_rbsp_fillbits(rbsp); return vl_vlc_get_uimsbf(&rbsp->nal, n); } /** * Return an unsigned exponential Golomb encoded integer */ static inline unsigned vl_rbsp_ue(struct vl_rbsp *rbsp) { unsigned bits = 0; vl_rbsp_fillbits(rbsp); while (!vl_vlc_get_uimsbf(&rbsp->nal, 1)) ++bits; return (1 << bits) - 1 + vl_rbsp_u(rbsp, bits); } /** * Return an signed exponential Golomb encoded integer */ static inline signed vl_rbsp_se(struct vl_rbsp *rbsp) { signed codeNum = vl_rbsp_ue(rbsp); if (codeNum & 1) return (codeNum + 1) >> 1; else return -(codeNum >> 1); } /** * Are more data available in the RBSP ? */ static inline bool vl_rbsp_more_data(struct vl_rbsp *rbsp) { unsigned bits, value; if (vl_vlc_bits_left(&rbsp->nal) > 8) return TRUE; bits = vl_vlc_valid_bits(&rbsp->nal); value = vl_vlc_peekbits(&rbsp->nal, bits); if (value == 0 || value == (1 << (bits - 1))) return FALSE; return TRUE; } #endif /* vl_rbsp_h */