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sbc_primitives.c

/*
 *
 *  Bluetooth low-complexity, subband codec (SBC) library
 *
 *  Copyright (C) 2004-2009  Marcel Holtmann <marcel@holtmann.org>
 *  Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
 *  Copyright (C) 2005-2006  Brad Midgley <bmidgley@xmission.com>
 *
 *
 *  This library 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.
 *
 *  This library 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 this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <stdint.h>
#include <limits.h>
#include <string.h>
#include "sbc.h"
#include "sbc_math.h"
#include "sbc_tables.h"

#include "sbc_primitives.h"
#include "sbc_primitives_mmx.h"
#include "sbc_primitives_neon.h"

/*
 * A reference C code of analysis filter with SIMD-friendly tables
 * reordering and code layout. This code can be used to develop platform
 * specific SIMD optimizations. Also it may be used as some kind of test
 * for compiler autovectorization capabilities (who knows, if the compiler
 * is very good at this stuff, hand optimized assembly may be not strictly
 * needed for some platform).
 *
 * Note: It is also possible to make a simple variant of analysis filter,
 * which needs only a single constants table without taking care about
 * even/odd cases. This simple variant of filter can be implemented without
 * input data permutation. The only thing that would be lost is the
 * possibility to use pairwise SIMD multiplications. But for some simple
 * CPU cores without SIMD extensions it can be useful. If anybody is
 * interested in implementing such variant of a filter, sourcecode from
 * bluez versions 4.26/4.27 can be used as a reference and the history of
 * the changes in git repository done around that time may be worth checking.
 */

static inline void sbc_analyze_four_simd(const int16_t *in, int32_t *out,
                                          const FIXED_T *consts)
{
      FIXED_A t1[4];
      FIXED_T t2[4];
      int hop = 0;

      /* rounding coefficient */
      t1[0] = t1[1] = t1[2] = t1[3] =
            (FIXED_A) 1 << (SBC_PROTO_FIXED4_SCALE - 1);

      /* low pass polyphase filter */
      for (hop = 0; hop < 40; hop += 8) {
            t1[0] += (FIXED_A) in[hop] * consts[hop];
            t1[0] += (FIXED_A) in[hop + 1] * consts[hop + 1];
            t1[1] += (FIXED_A) in[hop + 2] * consts[hop + 2];
            t1[1] += (FIXED_A) in[hop + 3] * consts[hop + 3];
            t1[2] += (FIXED_A) in[hop + 4] * consts[hop + 4];
            t1[2] += (FIXED_A) in[hop + 5] * consts[hop + 5];
            t1[3] += (FIXED_A) in[hop + 6] * consts[hop + 6];
            t1[3] += (FIXED_A) in[hop + 7] * consts[hop + 7];
      }

      /* scaling */
      t2[0] = t1[0] >> SBC_PROTO_FIXED4_SCALE;
      t2[1] = t1[1] >> SBC_PROTO_FIXED4_SCALE;
      t2[2] = t1[2] >> SBC_PROTO_FIXED4_SCALE;
      t2[3] = t1[3] >> SBC_PROTO_FIXED4_SCALE;

      /* do the cos transform */
      t1[0]  = (FIXED_A) t2[0] * consts[40 + 0];
      t1[0] += (FIXED_A) t2[1] * consts[40 + 1];
      t1[1]  = (FIXED_A) t2[0] * consts[40 + 2];
      t1[1] += (FIXED_A) t2[1] * consts[40 + 3];
      t1[2]  = (FIXED_A) t2[0] * consts[40 + 4];
      t1[2] += (FIXED_A) t2[1] * consts[40 + 5];
      t1[3]  = (FIXED_A) t2[0] * consts[40 + 6];
      t1[3] += (FIXED_A) t2[1] * consts[40 + 7];

      t1[0] += (FIXED_A) t2[2] * consts[40 + 8];
      t1[0] += (FIXED_A) t2[3] * consts[40 + 9];
      t1[1] += (FIXED_A) t2[2] * consts[40 + 10];
      t1[1] += (FIXED_A) t2[3] * consts[40 + 11];
      t1[2] += (FIXED_A) t2[2] * consts[40 + 12];
      t1[2] += (FIXED_A) t2[3] * consts[40 + 13];
      t1[3] += (FIXED_A) t2[2] * consts[40 + 14];
      t1[3] += (FIXED_A) t2[3] * consts[40 + 15];

      out[0] = t1[0] >>
            (SBC_COS_TABLE_FIXED4_SCALE - SCALE_OUT_BITS);
      out[1] = t1[1] >>
            (SBC_COS_TABLE_FIXED4_SCALE - SCALE_OUT_BITS);
      out[2] = t1[2] >>
            (SBC_COS_TABLE_FIXED4_SCALE - SCALE_OUT_BITS);
      out[3] = t1[3] >>
            (SBC_COS_TABLE_FIXED4_SCALE - SCALE_OUT_BITS);
}

static inline void sbc_analyze_eight_simd(const int16_t *in, int32_t *out,
                                          const FIXED_T *consts)
{
      FIXED_A t1[8];
      FIXED_T t2[8];
      int i, hop;

      /* rounding coefficient */
      t1[0] = t1[1] = t1[2] = t1[3] = t1[4] = t1[5] = t1[6] = t1[7] =
            (FIXED_A) 1 << (SBC_PROTO_FIXED8_SCALE-1);

      /* low pass polyphase filter */
      for (hop = 0; hop < 80; hop += 16) {
            t1[0] += (FIXED_A) in[hop] * consts[hop];
            t1[0] += (FIXED_A) in[hop + 1] * consts[hop + 1];
            t1[1] += (FIXED_A) in[hop + 2] * consts[hop + 2];
            t1[1] += (FIXED_A) in[hop + 3] * consts[hop + 3];
            t1[2] += (FIXED_A) in[hop + 4] * consts[hop + 4];
            t1[2] += (FIXED_A) in[hop + 5] * consts[hop + 5];
            t1[3] += (FIXED_A) in[hop + 6] * consts[hop + 6];
            t1[3] += (FIXED_A) in[hop + 7] * consts[hop + 7];
            t1[4] += (FIXED_A) in[hop + 8] * consts[hop + 8];
            t1[4] += (FIXED_A) in[hop + 9] * consts[hop + 9];
            t1[5] += (FIXED_A) in[hop + 10] * consts[hop + 10];
            t1[5] += (FIXED_A) in[hop + 11] * consts[hop + 11];
            t1[6] += (FIXED_A) in[hop + 12] * consts[hop + 12];
            t1[6] += (FIXED_A) in[hop + 13] * consts[hop + 13];
            t1[7] += (FIXED_A) in[hop + 14] * consts[hop + 14];
            t1[7] += (FIXED_A) in[hop + 15] * consts[hop + 15];
      }

      /* scaling */
      t2[0] = t1[0] >> SBC_PROTO_FIXED8_SCALE;
      t2[1] = t1[1] >> SBC_PROTO_FIXED8_SCALE;
      t2[2] = t1[2] >> SBC_PROTO_FIXED8_SCALE;
      t2[3] = t1[3] >> SBC_PROTO_FIXED8_SCALE;
      t2[4] = t1[4] >> SBC_PROTO_FIXED8_SCALE;
      t2[5] = t1[5] >> SBC_PROTO_FIXED8_SCALE;
      t2[6] = t1[6] >> SBC_PROTO_FIXED8_SCALE;
      t2[7] = t1[7] >> SBC_PROTO_FIXED8_SCALE;


      /* do the cos transform */
      t1[0] = t1[1] = t1[2] = t1[3] = t1[4] = t1[5] = t1[6] = t1[7] = 0;

      for (i = 0; i < 4; i++) {
            t1[0] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 0];
            t1[0] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 1];
            t1[1] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 2];
            t1[1] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 3];
            t1[2] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 4];
            t1[2] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 5];
            t1[3] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 6];
            t1[3] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 7];
            t1[4] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 8];
            t1[4] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 9];
            t1[5] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 10];
            t1[5] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 11];
            t1[6] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 12];
            t1[6] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 13];
            t1[7] += (FIXED_A) t2[i * 2 + 0] * consts[80 + i * 16 + 14];
            t1[7] += (FIXED_A) t2[i * 2 + 1] * consts[80 + i * 16 + 15];
      }

      for (i = 0; i < 8; i++)
            out[i] = t1[i] >>
                  (SBC_COS_TABLE_FIXED8_SCALE - SCALE_OUT_BITS);
}

static inline void sbc_analyze_4b_4s_simd(int16_t *x,
                                    int32_t *out, int out_stride)
{
      /* Analyze blocks */
      sbc_analyze_four_simd(x + 12, out, analysis_consts_fixed4_simd_odd);
      out += out_stride;
      sbc_analyze_four_simd(x + 8, out, analysis_consts_fixed4_simd_even);
      out += out_stride;
      sbc_analyze_four_simd(x + 4, out, analysis_consts_fixed4_simd_odd);
      out += out_stride;
      sbc_analyze_four_simd(x + 0, out, analysis_consts_fixed4_simd_even);
}

static inline void sbc_analyze_4b_8s_simd(int16_t *x,
                                int32_t *out, int out_stride)
{
      /* Analyze blocks */
      sbc_analyze_eight_simd(x + 24, out, analysis_consts_fixed8_simd_odd);
      out += out_stride;
      sbc_analyze_eight_simd(x + 16, out, analysis_consts_fixed8_simd_even);
      out += out_stride;
      sbc_analyze_eight_simd(x + 8, out, analysis_consts_fixed8_simd_odd);
      out += out_stride;
      sbc_analyze_eight_simd(x + 0, out, analysis_consts_fixed8_simd_even);
}

static inline int16_t unaligned16_be(const uint8_t *ptr)
{
      return (int16_t) ((ptr[0] << 8) | ptr[1]);
}

static inline int16_t unaligned16_le(const uint8_t *ptr)
{
      return (int16_t) (ptr[0] | (ptr[1] << 8));
}

/*
 * Internal helper functions for input data processing. In order to get
 * optimal performance, it is important to have "nsamples", "nchannels"
 * and "big_endian" arguments used with this inline function as compile
 * time constants.
 */

static SBC_ALWAYS_INLINE int sbc_encoder_process_input_s4_internal(
      int position,
      const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
      int nsamples, int nchannels, int big_endian)
{
      /* handle X buffer wraparound */
      if (position < nsamples) {
            if (nchannels > 0)
                  memcpy(&X[0][SBC_X_BUFFER_SIZE - 36], &X[0][position],
                                          36 * sizeof(int16_t));
            if (nchannels > 1)
                  memcpy(&X[1][SBC_X_BUFFER_SIZE - 36], &X[1][position],
                                          36 * sizeof(int16_t));
            position = SBC_X_BUFFER_SIZE - 36;
      }

      #define PCM(i) (big_endian ? \
            unaligned16_be(pcm + (i) * 2) : unaligned16_le(pcm + (i) * 2))

      /* copy/permutate audio samples */
      while ((nsamples -= 8) >= 0) {
            position -= 8;
            if (nchannels > 0) {
                  int16_t *x = &X[0][position];
                  x[0]  = PCM(0 + 7 * nchannels);
                  x[1]  = PCM(0 + 3 * nchannels);
                  x[2]  = PCM(0 + 6 * nchannels);
                  x[3]  = PCM(0 + 4 * nchannels);
                  x[4]  = PCM(0 + 0 * nchannels);
                  x[5]  = PCM(0 + 2 * nchannels);
                  x[6]  = PCM(0 + 1 * nchannels);
                  x[7]  = PCM(0 + 5 * nchannels);
            }
            if (nchannels > 1) {
                  int16_t *x = &X[1][position];
                  x[0]  = PCM(1 + 7 * nchannels);
                  x[1]  = PCM(1 + 3 * nchannels);
                  x[2]  = PCM(1 + 6 * nchannels);
                  x[3]  = PCM(1 + 4 * nchannels);
                  x[4]  = PCM(1 + 0 * nchannels);
                  x[5]  = PCM(1 + 2 * nchannels);
                  x[6]  = PCM(1 + 1 * nchannels);
                  x[7]  = PCM(1 + 5 * nchannels);
            }
            pcm += 16 * nchannels;
      }
      #undef PCM

      return position;
}

static SBC_ALWAYS_INLINE int sbc_encoder_process_input_s8_internal(
      int position,
      const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
      int nsamples, int nchannels, int big_endian)
{
      /* handle X buffer wraparound */
      if (position < nsamples) {
            if (nchannels > 0)
                  memcpy(&X[0][SBC_X_BUFFER_SIZE - 72], &X[0][position],
                                          72 * sizeof(int16_t));
            if (nchannels > 1)
                  memcpy(&X[1][SBC_X_BUFFER_SIZE - 72], &X[1][position],
                                          72 * sizeof(int16_t));
            position = SBC_X_BUFFER_SIZE - 72;
      }

      #define PCM(i) (big_endian ? \
            unaligned16_be(pcm + (i) * 2) : unaligned16_le(pcm + (i) * 2))

      /* copy/permutate audio samples */
      while ((nsamples -= 16) >= 0) {
            position -= 16;
            if (nchannels > 0) {
                  int16_t *x = &X[0][position];
                  x[0]  = PCM(0 + 15 * nchannels);
                  x[1]  = PCM(0 + 7 * nchannels);
                  x[2]  = PCM(0 + 14 * nchannels);
                  x[3]  = PCM(0 + 8 * nchannels);
                  x[4]  = PCM(0 + 13 * nchannels);
                  x[5]  = PCM(0 + 9 * nchannels);
                  x[6]  = PCM(0 + 12 * nchannels);
                  x[7]  = PCM(0 + 10 * nchannels);
                  x[8]  = PCM(0 + 11 * nchannels);
                  x[9]  = PCM(0 + 3 * nchannels);
                  x[10] = PCM(0 + 6 * nchannels);
                  x[11] = PCM(0 + 0 * nchannels);
                  x[12] = PCM(0 + 5 * nchannels);
                  x[13] = PCM(0 + 1 * nchannels);
                  x[14] = PCM(0 + 4 * nchannels);
                  x[15] = PCM(0 + 2 * nchannels);
            }
            if (nchannels > 1) {
                  int16_t *x = &X[1][position];
                  x[0]  = PCM(1 + 15 * nchannels);
                  x[1]  = PCM(1 + 7 * nchannels);
                  x[2]  = PCM(1 + 14 * nchannels);
                  x[3]  = PCM(1 + 8 * nchannels);
                  x[4]  = PCM(1 + 13 * nchannels);
                  x[5]  = PCM(1 + 9 * nchannels);
                  x[6]  = PCM(1 + 12 * nchannels);
                  x[7]  = PCM(1 + 10 * nchannels);
                  x[8]  = PCM(1 + 11 * nchannels);
                  x[9]  = PCM(1 + 3 * nchannels);
                  x[10] = PCM(1 + 6 * nchannels);
                  x[11] = PCM(1 + 0 * nchannels);
                  x[12] = PCM(1 + 5 * nchannels);
                  x[13] = PCM(1 + 1 * nchannels);
                  x[14] = PCM(1 + 4 * nchannels);
                  x[15] = PCM(1 + 2 * nchannels);
            }
            pcm += 32 * nchannels;
      }
      #undef PCM

      return position;
}

/*
 * Input data processing functions. The data is endian converted if needed,
 * channels are deintrleaved and audio samples are reordered for use in
 * SIMD-friendly analysis filter function. The results are put into "X"
 * array, getting appended to the previous data (or it is better to say
 * prepended, as the buffer is filled from top to bottom). Old data is
 * discarded when neededed, but availability of (10 * nrof_subbands)
 * contiguous samples is always guaranteed for the input to the analysis
 * filter. This is achieved by copying a sufficient part of old data
 * to the top of the buffer on buffer wraparound.
 */

static int sbc_enc_process_input_4s_le(int position,
            const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
            int nsamples, int nchannels)
{
      if (nchannels > 1)
            return sbc_encoder_process_input_s4_internal(
                  position, pcm, X, nsamples, 2, 0);
      else
            return sbc_encoder_process_input_s4_internal(
                  position, pcm, X, nsamples, 1, 0);
}

static int sbc_enc_process_input_4s_be(int position,
            const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
            int nsamples, int nchannels)
{
      if (nchannels > 1)
            return sbc_encoder_process_input_s4_internal(
                  position, pcm, X, nsamples, 2, 1);
      else
            return sbc_encoder_process_input_s4_internal(
                  position, pcm, X, nsamples, 1, 1);
}

static int sbc_enc_process_input_8s_le(int position,
            const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
            int nsamples, int nchannels)
{
      if (nchannels > 1)
            return sbc_encoder_process_input_s8_internal(
                  position, pcm, X, nsamples, 2, 0);
      else
            return sbc_encoder_process_input_s8_internal(
                  position, pcm, X, nsamples, 1, 0);
}

static int sbc_enc_process_input_8s_be(int position,
            const uint8_t *pcm, int16_t X[2][SBC_X_BUFFER_SIZE],
            int nsamples, int nchannels)
{
      if (nchannels > 1)
            return sbc_encoder_process_input_s8_internal(
                  position, pcm, X, nsamples, 2, 1);
      else
            return sbc_encoder_process_input_s8_internal(
                  position, pcm, X, nsamples, 1, 1);
}

/* Supplementary function to count the number of leading zeros */

static inline int sbc_clz(uint32_t x)
{
#ifdef __GNUC__
      return __builtin_clz(x);
#else
      /* TODO: this should be replaced with something better if good
       * performance is wanted when using compilers other than gcc */
      int cnt = 0;
      while (x) {
            cnt++;
            x >>= 1;
      }
      return 32 - cnt;
#endif
}

static void sbc_calc_scalefactors(
      int32_t sb_sample_f[16][2][8],
      uint32_t scale_factor[2][8],
      int blocks, int channels, int subbands)
{
      int ch, sb, blk;
      for (ch = 0; ch < channels; ch++) {
            for (sb = 0; sb < subbands; sb++) {
                  uint32_t x = 1 << SCALE_OUT_BITS;
                  for (blk = 0; blk < blocks; blk++) {
                        int32_t tmp = fabs(sb_sample_f[blk][ch][sb]);
                        if (tmp != 0)
                              x |= tmp - 1;
                  }
                  scale_factor[ch][sb] = (31 - SCALE_OUT_BITS) -
                        sbc_clz(x);
            }
      }
}

/*
 * Detect CPU features and setup function pointers
 */
void sbc_init_primitives(struct sbc_encoder_state *state)
{
      /* Default implementation for analyze functions */
      state->sbc_analyze_4b_4s = sbc_analyze_4b_4s_simd;
      state->sbc_analyze_4b_8s = sbc_analyze_4b_8s_simd;

      /* Default implementation for input reordering / deinterleaving */
      state->sbc_enc_process_input_4s_le = sbc_enc_process_input_4s_le;
      state->sbc_enc_process_input_4s_be = sbc_enc_process_input_4s_be;
      state->sbc_enc_process_input_8s_le = sbc_enc_process_input_8s_le;
      state->sbc_enc_process_input_8s_be = sbc_enc_process_input_8s_be;

      /* Default implementation for scale factors calculation */
      state->sbc_calc_scalefactors = sbc_calc_scalefactors;
      state->implementation_info = "Generic C";

      /* X86/AMD64 optimizations */
#ifdef SBC_BUILD_WITH_MMX_SUPPORT
      sbc_init_primitives_mmx(state);
#endif

      /* ARM optimizations */
#ifdef SBC_BUILD_WITH_NEON_SUPPORT
      sbc_init_primitives_neon(state);
#endif
}

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