/*

** Copyright (C) 1999-2017 Erik de Castro Lopo <erikd@mega-nerd.com>

**

** This program 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 program 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 program; if not, write to the Free Software

** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

*/

#include "sfconfig.h"

#include <stdio.h>

#include <stdlib.h>

#include <fcntl.h>

#include <string.h>

#include <ctype.h>

#include <math.h>

#include "sndfile.h"

#include "sfendian.h"

#include "common.h"

/*------------------------------------------------------------------------------

** Macros to handle big/little endian issues.

*/

#define FAP_MARKER  (MAKE_MARKER ('f', 'a', 'p', ' '))

#define PAF_MARKER  (MAKE_MARKER (' ', 'p', 'a', 'f'))

/*------------------------------------------------------------------------------

** Other defines.

*/

#define PAF_HEADER_LENGTH       2048

#define PAF24_SAMPLES_PER_BLOCK   10

#define PAF24_BLOCK_SIZE      32

/*------------------------------------------------------------------------------

** Typedefs.

*/

typedef struct

{ int version ;

  int endianness ;

  int samplerate ;

  int format ;

  int channels ;

  int source ;

} PAF_FMT ;

typedef struct

{ int       max_blocks, channels, blocksize ;

  int       read_block, write_block, read_count, write_count ;

  sf_count_t    sample_count ;

  int       *samples ;

  int       *block ;

  int       data [] ; /* ISO C99 struct flexible array. */

} PAF24_PRIVATE ;

/*------------------------------------------------------------------------------

** Private static functions.

*/

static int paf24_init (SF_PRIVATE *psf) ;

static int  paf_read_header (SF_PRIVATE *psf) ;

static int  paf_write_header (SF_PRIVATE *psf, int calc_length) ;

static sf_count_t paf24_read_s (SF_PRIVATE *psf, short *ptr, sf_count_t len) ;

static sf_count_t paf24_read_i (SF_PRIVATE *psf, int *ptr, sf_count_t len) ;

static sf_count_t paf24_read_f (SF_PRIVATE *psf, float *ptr, sf_count_t len) ;

static sf_count_t paf24_read_d (SF_PRIVATE *psf, double *ptr, sf_count_t len) ;

static sf_count_t paf24_write_s (SF_PRIVATE *psf, const short *ptr, sf_count_t len) ;

static sf_count_t paf24_write_i (SF_PRIVATE *psf, const int *ptr, sf_count_t len) ;

static sf_count_t paf24_write_f (SF_PRIVATE *psf, const float *ptr, sf_count_t len) ;

static sf_count_t paf24_write_d (SF_PRIVATE *psf, const double *ptr, sf_count_t len) ;

static sf_count_t paf24_seek (SF_PRIVATE *psf, int mode, sf_count_t offset) ;

enum

{ PAF_PCM_16 = 0,

  PAF_PCM_24 = 1,

  PAF_PCM_S8 = 2

} ;

/*------------------------------------------------------------------------------

** Public function.

*/

int

paf_open  (SF_PRIVATE *psf)

{ int   subformat, error, endian ;

  psf->dataoffset = PAF_HEADER_LENGTH ;

  if (psf->file.mode == SFM_READ || (psf->file.mode == SFM_RDWR && psf->filelength > 0))

  { if ((error = paf_read_header (psf)))

      return error ;

    } ;

  subformat = SF_CODEC (psf->sf.format) ;

  if (psf->file.mode == SFM_WRITE || psf->file.mode == SFM_RDWR)

  { if ((SF_CONTAINER (psf->sf.format)) != SF_FORMAT_PAF)

      return  SFE_BAD_OPEN_FORMAT ;

    endian = SF_ENDIAN (psf->sf.format) ;

    /* PAF is by default big endian. */

    psf->endian = SF_ENDIAN_BIG ;

    if (endian == SF_ENDIAN_LITTLE || (CPU_IS_LITTLE_ENDIAN && (endian == SF_ENDIAN_CPU)))

      psf->endian = SF_ENDIAN_LITTLE ;

    if ((error = paf_write_header (psf, SF_FALSE)))

      return error ;

    psf->write_header = paf_write_header ;

    } ;

  switch (subformat)

  { case SF_FORMAT_PCM_S8 :

          psf->bytewidth = 1 ;

          error = pcm_init (psf) ;

          break ;

    case SF_FORMAT_PCM_16 :

          psf->bytewidth = 2 ;

          error = pcm_init (psf) ;

          break ;

    case SF_FORMAT_PCM_24 :

          /* No bytewidth because of whacky 24 bit encoding. */

          error = paf24_init (psf) ;

          break ;

    default : return SFE_PAF_UNKNOWN_FORMAT ;

    } ;

  return error ;

} /* paf_open */

/*------------------------------------------------------------------------------

*/

static int

paf_read_header (SF_PRIVATE *psf)

{ PAF_FMT   paf_fmt ;

  int     marker ;

  if (psf->filelength < PAF_HEADER_LENGTH)

    return SFE_PAF_SHORT_HEADER ;

  memset (&paf_fmt, 0, sizeof (paf_fmt)) ;

  psf_binheader_readf (psf, "pm", 0, &marker) ;

  psf_log_printf (psf, "Signature   : '%M'\n", marker) ;

  if (marker == PAF_MARKER)

  { psf_binheader_readf (psf, "E444444", &(paf_fmt.version), &(paf_fmt.endianness),

      &(paf_fmt.samplerate), &(paf_fmt.format), &(paf_fmt.channels), &(paf_fmt.source)) ;

    }

  else if (marker == FAP_MARKER)

  { psf_binheader_readf (psf, "e444444", &(paf_fmt.version), &(paf_fmt.endianness),

      &(paf_fmt.samplerate), &(paf_fmt.format), &(paf_fmt.channels), &(paf_fmt.source)) ;

    }

  else

    return SFE_PAF_NO_MARKER ;

  psf_log_printf (psf, "Version     : %d\n", paf_fmt.version) ;

  if (paf_fmt.version != 0)

  { psf_log_printf (psf, "*** Bad version number. should be zero.\n") ;

    return SFE_PAF_VERSION ;

    } ;

  psf_log_printf (psf, "Sample Rate : %d\n", paf_fmt.samplerate) ;

  psf_log_printf (psf, "Channels    : %d\n", paf_fmt.channels) ;

  psf_log_printf (psf, "Endianness  : %d => ", paf_fmt.endianness) ;

  if (paf_fmt.endianness)

  { psf_log_printf (psf, "Little\n", paf_fmt.endianness) ;

    psf->endian = SF_ENDIAN_LITTLE ;

    }

  else

  { psf_log_printf (psf, "Big\n", paf_fmt.endianness) ;

    psf->endian = SF_ENDIAN_BIG ;

    } ;

  if (paf_fmt.channels < 1 || paf_fmt.channels > SF_MAX_CHANNELS)

    return SFE_PAF_BAD_CHANNELS ;

  psf->datalength = psf->filelength - psf->dataoffset ;

  psf_binheader_readf (psf, "p", (int) psf->dataoffset) ;

  psf->sf.samplerate  = paf_fmt.samplerate ;

  psf->sf.channels  = paf_fmt.channels ;

  /* Only fill in type major. */

  psf->sf.format = SF_FORMAT_PAF ;

  psf_log_printf (psf, "Format      : %d => ", paf_fmt.format) ;

  /* PAF is by default big endian. */

  psf->sf.format |= paf_fmt.endianness ? SF_ENDIAN_LITTLE : SF_ENDIAN_BIG ;

  switch (paf_fmt.format)

  { case PAF_PCM_S8 :

          psf_log_printf (psf, "8 bit linear PCM\n") ;

          psf->bytewidth = 1 ;

          psf->sf.format |= SF_FORMAT_PCM_S8 ;

          psf->blockwidth = psf->bytewidth * psf->sf.channels ;

          psf->sf.frames = psf->datalength / psf->blockwidth ;

          break ;

    case PAF_PCM_16 :

          psf_log_printf (psf, "16 bit linear PCM\n") ;

          psf->bytewidth = 2 ;

          psf->sf.format |= SF_FORMAT_PCM_16 ;

          psf->blockwidth = psf->bytewidth * psf->sf.channels ;

          psf->sf.frames = psf->datalength / psf->blockwidth ;

          break ;

    case PAF_PCM_24 :

          psf_log_printf (psf, "24 bit linear PCM\n") ;

          psf->bytewidth = 3 ;

          psf->sf.format |= SF_FORMAT_PCM_24 ;

          psf->blockwidth = 0 ;

          psf->sf.frames = PAF24_SAMPLES_PER_BLOCK * psf->datalength /

                      (PAF24_BLOCK_SIZE * psf->sf.channels) ;

          break ;

    default : psf_log_printf (psf, "Unknown\n") ;

          return SFE_PAF_UNKNOWN_FORMAT ;

          break ;

    } ;

  psf_log_printf (psf, "Source      : %d => ", paf_fmt.source) ;

  switch (paf_fmt.source)

  { case 1 : psf_log_printf (psf, "Analog Recording\n") ;

          break ;

    case 2 : psf_log_printf (psf, "Digital Transfer\n") ;

          break ;

    case 3 : psf_log_printf (psf, "Multi-track Mixdown\n") ;

          break ;

    case 5 : psf_log_printf (psf, "Audio Resulting From DSP Processing\n") ;

          break ;

    default : psf_log_printf (psf, "Unknown\n") ;

          break ;

    } ;

  return 0 ;

} /* paf_read_header */

static int

paf_write_header (SF_PRIVATE *psf, int UNUSED (calc_length))

{ int     paf_format ;

  /* PAF header already written so no need to re-write. */

  if (psf_ftell (psf) >= PAF_HEADER_LENGTH)

    return 0 ;

  psf->dataoffset = PAF_HEADER_LENGTH ;

  switch (SF_CODEC (psf->sf.format))

  { case SF_FORMAT_PCM_S8 :

          paf_format = PAF_PCM_S8 ;

          break ;

    case SF_FORMAT_PCM_16 :

          paf_format = PAF_PCM_16 ;

          break ;

    case SF_FORMAT_PCM_24 :

          paf_format = PAF_PCM_24 ;

          break ;

    default : return SFE_PAF_UNKNOWN_FORMAT ;

    } ;

  /* Reset the current header length to zero. */

  psf->header.ptr [0] = 0 ;

  psf->header.indx = 0 ;

  if (psf->endian == SF_ENDIAN_BIG)

  { /* Marker, version, endianness, samplerate */

    psf_binheader_writef (psf, "Em444", BHWm (PAF_MARKER), BHW4 (0), BHW4 (0), BHW4 (psf->sf.samplerate)) ;

    /* format, channels, source */

    psf_binheader_writef (psf, "E444", BHW4 (paf_format), BHW4 (psf->sf.channels), BHW4 (0)) ;

    }

  else if (psf->endian == SF_ENDIAN_LITTLE)

  { /* Marker, version, endianness, samplerate */

    psf_binheader_writef (psf, "em444", BHWm (FAP_MARKER), BHW4 (0), BHW4 (1), BHW4 (psf->sf.samplerate)) ;

    /* format, channels, source */

    psf_binheader_writef (psf, "e444", BHW4 (paf_format), BHW4 (psf->sf.channels), BHW4 (0)) ;

    } ;

  /* Zero fill to dataoffset. */

  psf_binheader_writef (psf, "z", BHWz ((size_t) (psf->dataoffset - psf->header.indx))) ;

  psf_fwrite (psf->header.ptr, psf->header.indx, 1, psf) ;

  return psf->error ;

} /* paf_write_header */

/*===============================================================================

**  24 bit PAF files have a really weird encoding.

**  For a mono file, 10 samples (each being 3 bytes) are packed into a 32 byte

**  block. The 8 ints in this 32 byte block are then endian swapped (as ints)

**  if necessary before being written to disk.

**  For a stereo file, blocks of 10 samples from the same channel are encoded

**  into 32 bytes as for the mono case. The 32 byte blocks are then interleaved

**  on disk.

**  Reading has to reverse the above process :-).

**  Weird!!!

**

**  The code below attempts to gain efficiency while maintaining readability.

*/

static int paf24_read_block (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24) ;

static int paf24_write_block (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24) ;

static int paf24_close (SF_PRIVATE *psf) ;

static int

paf24_init (SF_PRIVATE *psf)

{ PAF24_PRIVATE *ppaf24 ;

  int paf24size ;

  paf24size = sizeof (PAF24_PRIVATE) + psf->sf.channels *

          (PAF24_BLOCK_SIZE + PAF24_SAMPLES_PER_BLOCK * sizeof (int)) ;

  /*

  **  Not exactly sure why this needs to be here but the tests

  **  fail without it.

  */

  psf->last_op = 0 ;

  if (! (psf->codec_data = calloc (1, paf24size)))

    return SFE_MALLOC_FAILED ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  ppaf24->channels  = psf->sf.channels ;

  ppaf24->samples   = ppaf24->data ;

  ppaf24->block   = ppaf24->data + PAF24_SAMPLES_PER_BLOCK * ppaf24->channels ;

  ppaf24->blocksize = PAF24_BLOCK_SIZE * ppaf24->channels ;

  if (psf->file.mode == SFM_READ || psf->file.mode == SFM_RDWR)

  { paf24_read_block (psf, ppaf24) ;  /* Read first block. */

    psf->read_short   = paf24_read_s ;

    psf->read_int   = paf24_read_i ;

    psf->read_float   = paf24_read_f ;

    psf->read_double  = paf24_read_d ;

    } ;

  if (psf->file.mode == SFM_WRITE || psf->file.mode == SFM_RDWR)

  { psf->write_short  = paf24_write_s ;

    psf->write_int    = paf24_write_i ;

    psf->write_float  = paf24_write_f ;

    psf->write_double = paf24_write_d ;

    } ;

  psf->seek = paf24_seek ;

  psf->container_close  = paf24_close ;

  psf->filelength = psf_get_filelen (psf) ;

  psf->datalength = psf->filelength - psf->dataoffset ;

  if (psf->datalength % PAF24_BLOCK_SIZE)

  { if (psf->file.mode == SFM_READ)

      psf_log_printf (psf, "*** Warning : file seems to be truncated.\n") ;

    ppaf24->max_blocks = psf->datalength / ppaf24->blocksize + 1 ;

    }

  else

    ppaf24->max_blocks = psf->datalength / ppaf24->blocksize ;

  ppaf24->read_block = 0 ;

  if (psf->file.mode == SFM_RDWR)

    ppaf24->write_block = ppaf24->max_blocks ;

  else

    ppaf24->write_block = 0 ;

  psf->sf.frames = PAF24_SAMPLES_PER_BLOCK * ppaf24->max_blocks ;

  ppaf24->sample_count = psf->sf.frames ;

  return 0 ;

} /* paf24_init */

static sf_count_t

paf24_seek (SF_PRIVATE *psf, int mode, sf_count_t offset)

{ PAF24_PRIVATE *ppaf24 ;

  int       newblock, newsample ;

  if (psf->codec_data == NULL)

  { psf->error = SFE_INTERNAL ;

    return PSF_SEEK_ERROR ;

    } ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  if (mode == SFM_READ && ppaf24->write_count > 0)

    paf24_write_block (psf, ppaf24) ;

  newblock  = offset / PAF24_SAMPLES_PER_BLOCK ;

  newsample = offset % PAF24_SAMPLES_PER_BLOCK ;

  switch (mode)

  { case SFM_READ :

        if (psf->last_op == SFM_WRITE && ppaf24->write_count)

          paf24_write_block (psf, ppaf24) ;

        psf_fseek (psf, psf->dataoffset + newblock * ppaf24->blocksize, SEEK_SET) ;

        ppaf24->read_block = newblock ;

        paf24_read_block (psf, ppaf24) ;

        ppaf24->read_count = newsample ;

        break ;

    case SFM_WRITE :

        if (offset > ppaf24->sample_count)

        { psf->error = SFE_BAD_SEEK ;

          return PSF_SEEK_ERROR ;

          } ;

        if (psf->last_op == SFM_WRITE && ppaf24->write_count)

          paf24_write_block (psf, ppaf24) ;

        psf_fseek (psf, psf->dataoffset + newblock * ppaf24->blocksize, SEEK_SET) ;

        ppaf24->write_block = newblock ;

        paf24_read_block (psf, ppaf24) ;

        ppaf24->write_count = newsample ;

        break ;

    default :

        psf->error = SFE_BAD_SEEK ;

        return PSF_SEEK_ERROR ;

    } ;

  return newblock * PAF24_SAMPLES_PER_BLOCK + newsample ;

} /* paf24_seek */

static int

paf24_close (SF_PRIVATE *psf)

{ PAF24_PRIVATE *ppaf24 ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  if (psf->file.mode == SFM_WRITE || psf->file.mode == SFM_RDWR)

  { if (ppaf24->write_count > 0)

      paf24_write_block (psf, ppaf24) ;

    } ;

  return 0 ;

} /* paf24_close */

/*---------------------------------------------------------------------------

*/

static int

paf24_read_block (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24)

{ int       k, channel ;

  unsigned char *cptr ;

  ppaf24->read_block ++ ;

  ppaf24->read_count = 0 ;

  if (ppaf24->read_block * PAF24_SAMPLES_PER_BLOCK > ppaf24->sample_count)

  { memset (ppaf24->samples, 0, PAF24_SAMPLES_PER_BLOCK * ppaf24->channels) ;

    return 1 ;

    } ;

  /* Read the block. */

  if ((k = (int) psf_fread (ppaf24->block, 1, ppaf24->blocksize, psf)) != ppaf24->blocksize)

    psf_log_printf (psf, "*** Warning : short read (%d != %d).\n", k, ppaf24->blocksize) ;

  /* Do endian swapping if necessary. */

  if ((CPU_IS_BIG_ENDIAN && psf->endian == SF_ENDIAN_LITTLE) || (CPU_IS_LITTLE_ENDIAN && psf->endian == SF_ENDIAN_BIG))

    endswap_int_array (ppaf24->block, 8 * ppaf24->channels) ;

  /* Unpack block. */

  for (k = 0 ; k < PAF24_SAMPLES_PER_BLOCK * ppaf24->channels ; k++)

  { channel = k % ppaf24->channels ;

    cptr = ((unsigned char *) ppaf24->block) + PAF24_BLOCK_SIZE * channel + 3 * (k / ppaf24->channels) ;

    ppaf24->samples [k] = (cptr [0] << 8) | (cptr [1] << 16) | (((unsigned) cptr [2]) << 24) ;

    } ;

  return 1 ;

} /* paf24_read_block */

static int

paf24_read (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24, int *ptr, int len)

{ int count, total = 0 ;

  while (total < len)

  { if (ppaf24->read_block * PAF24_SAMPLES_PER_BLOCK >= ppaf24->sample_count)

    { memset (&(ptr [total]), 0, (len - total) * sizeof (int)) ;

      return total ;

      } ;

    if (ppaf24->read_count >= PAF24_SAMPLES_PER_BLOCK)

      paf24_read_block (psf, ppaf24) ;

    count = (PAF24_SAMPLES_PER_BLOCK - ppaf24->read_count) * ppaf24->channels ;

    count = (len - total > count) ? count : len - total ;

    memcpy (&(ptr [total]), &(ppaf24->samples [ppaf24->read_count * ppaf24->channels]), count * sizeof (int)) ;

    total += count ;

    ppaf24->read_count += count / ppaf24->channels ;

    } ;

  return total ;

} /* paf24_read */

static sf_count_t

paf24_read_s (SF_PRIVATE *psf, short *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, readcount, count ;

  sf_count_t    total = 0 ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { readcount = (len >= bufferlen) ? bufferlen : (int) len ;

    count = paf24_read (psf, ppaf24, iptr, readcount) ;

    for (k = 0 ; k < readcount ; k++)

      ptr [total + k] = iptr [k] >> 16 ;

    total += count ;

    len -= readcount ;

    } ;

  return total ;

} /* paf24_read_s */

static sf_count_t

paf24_read_i (SF_PRIVATE *psf, int *ptr, sf_count_t len)

{ PAF24_PRIVATE *ppaf24 ;

  int       total ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  total = paf24_read (psf, ppaf24, ptr, len) ;

  return total ;

} /* paf24_read_i */

static sf_count_t

paf24_read_f (SF_PRIVATE *psf, float *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, readcount, count ;

  sf_count_t    total = 0 ;

  float     normfact ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  normfact = (psf->norm_float == SF_TRUE) ? (1.0 / 0x80000000) : (1.0 / 0x100) ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { readcount = (len >= bufferlen) ? bufferlen : (int) len ;

    count = paf24_read (psf, ppaf24, iptr, readcount) ;

    for (k = 0 ; k < readcount ; k++)

      ptr [total + k] = normfact * iptr [k] ;

    total += count ;

    len -= readcount ;

    } ;

  return total ;

} /* paf24_read_f */

static sf_count_t

paf24_read_d (SF_PRIVATE *psf, double *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, readcount, count ;

  sf_count_t    total = 0 ;

  double      normfact ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  normfact = (psf->norm_double == SF_TRUE) ? (1.0 / 0x80000000) : (1.0 / 0x100) ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { readcount = (len >= bufferlen) ? bufferlen : (int) len ;

    count = paf24_read (psf, ppaf24, iptr, readcount) ;

    for (k = 0 ; k < readcount ; k++)

      ptr [total + k] = normfact * iptr [k] ;

    total += count ;

    len -= readcount ;

    } ;

  return total ;

} /* paf24_read_d */

/*---------------------------------------------------------------------------

*/

static int

paf24_write_block (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24)

{ int       k, nextsample, channel ;

  unsigned char *cptr ;

  /* First pack block. */

  if (CPU_IS_LITTLE_ENDIAN)

  { for (k = 0 ; k < PAF24_SAMPLES_PER_BLOCK * ppaf24->channels ; k++)

    { channel = k % ppaf24->channels ;

      cptr = ((unsigned char *) ppaf24->block) + PAF24_BLOCK_SIZE * channel + 3 * (k / ppaf24->channels) ;

      nextsample = ppaf24->samples [k] >> 8 ;

      cptr [0] = nextsample ;

      cptr [1] = nextsample >> 8 ;

      cptr [2] = nextsample >> 16 ;

      } ;

    /* Do endian swapping if necessary. */

    if (psf->endian == SF_ENDIAN_BIG)

      endswap_int_array (ppaf24->block, 8 * ppaf24->channels) ;

    }

  else if (CPU_IS_BIG_ENDIAN)

  { /* This is correct. */

    for (k = 0 ; k < PAF24_SAMPLES_PER_BLOCK * ppaf24->channels ; k++)

    { channel = k % ppaf24->channels ;

      cptr = ((unsigned char *) ppaf24->block) + PAF24_BLOCK_SIZE * channel + 3 * (k / ppaf24->channels) ;

      nextsample = ppaf24->samples [k] >> 8 ;

      cptr [0] = nextsample ;

      cptr [1] = nextsample >> 8 ;

      cptr [2] = nextsample >> 16 ;

      } ;

    if (psf->endian == SF_ENDIAN_LITTLE)

      endswap_int_array (ppaf24->block, 8 * ppaf24->channels) ;

    } ;

  /* Write block to disk. */

  if ((k = (int) psf_fwrite (ppaf24->block, 1, ppaf24->blocksize, psf)) != ppaf24->blocksize)

    psf_log_printf (psf, "*** Warning : short write (%d != %d).\n", k, ppaf24->blocksize) ;

  if (ppaf24->sample_count < ppaf24->write_block * PAF24_SAMPLES_PER_BLOCK + ppaf24->write_count)

    ppaf24->sample_count = ppaf24->write_block * PAF24_SAMPLES_PER_BLOCK + ppaf24->write_count ;

  if (ppaf24->write_count == PAF24_SAMPLES_PER_BLOCK)

  { ppaf24->write_block ++ ;

    ppaf24->write_count = 0 ;

    } ;

  return 1 ;

} /* paf24_write_block */

static int

paf24_write (SF_PRIVATE *psf, PAF24_PRIVATE *ppaf24, const int *ptr, int len)

{ int   count, total = 0 ;

  while (total < len)

  { count = (PAF24_SAMPLES_PER_BLOCK - ppaf24->write_count) * ppaf24->channels ;

    if (count > len - total)

      count = len - total ;

    memcpy (&(ppaf24->samples [ppaf24->write_count * ppaf24->channels]), &(ptr [total]), count * sizeof (int)) ;

    total += count ;

    ppaf24->write_count += count / ppaf24->channels ;

    if (ppaf24->write_count >= PAF24_SAMPLES_PER_BLOCK)

      paf24_write_block (psf, ppaf24) ;

    } ;

  return total ;

} /* paf24_write */

static sf_count_t

paf24_write_s (SF_PRIVATE *psf, const short *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, writecount = 0, count ;

  sf_count_t    total = 0 ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { writecount = (len >= bufferlen) ? bufferlen : (int) len ;

    for (k = 0 ; k < writecount ; k++)

      iptr [k] = ptr [total + k] << 16 ;

    count = paf24_write (psf, ppaf24, iptr, writecount) ;

    total += count ;

    len -= writecount ;

    if (count != writecount)

      break ;

    } ;

  return total ;

} /* paf24_write_s */

static sf_count_t

paf24_write_i (SF_PRIVATE *psf, const int *ptr, sf_count_t len)

{ PAF24_PRIVATE   *ppaf24 ;

  int       writecount, count ;

  sf_count_t    total = 0 ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  while (len > 0)

  { writecount = (len > 0x10000000) ? 0x10000000 : (int) len ;

    count = paf24_write (psf, ppaf24, ptr, writecount) ;

    total += count ;

    len -= count ;

    if (count != writecount)

      break ;

    } ;

  return total ;

} /* paf24_write_i */

static sf_count_t

paf24_write_f (SF_PRIVATE *psf, const float *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, writecount = 0, count ;

  sf_count_t    total = 0 ;

  float     normfact ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  normfact = (psf->norm_float == SF_TRUE) ? (1.0 * 0x7FFFFFFF) : (1.0 / 0x100) ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { writecount = (len >= bufferlen) ? bufferlen : (int) len ;

    for (k = 0 ; k < writecount ; k++)

      iptr [k] = psf_lrintf (normfact * ptr [total + k]) ;

    count = paf24_write (psf, ppaf24, iptr, writecount) ;

    total += count ;

    len -= writecount ;

    if (count != writecount)

      break ;

    } ;

  return total ;

} /* paf24_write_f */

static sf_count_t

paf24_write_d (SF_PRIVATE *psf, const double *ptr, sf_count_t len)

{ BUF_UNION   ubuf ;

  PAF24_PRIVATE   *ppaf24 ;

  int       *iptr ;

  int       k, bufferlen, writecount = 0, count ;

  sf_count_t    total = 0 ;

  double      normfact ;

  if (psf->codec_data == NULL)

    return 0 ;

  ppaf24 = (PAF24_PRIVATE*) psf->codec_data ;

  normfact = (psf->norm_double == SF_TRUE) ? (1.0 * 0x7FFFFFFF) : (1.0 / 0x100) ;

  iptr = ubuf.ibuf ;

  bufferlen = ARRAY_LEN (ubuf.ibuf) ;

  while (len > 0)

  { writecount = (len >= bufferlen) ? bufferlen : (int) len ;

    for (k = 0 ; k < writecount ; k++)

      iptr [k] = psf_lrint (normfact * ptr [total+k]) ;

    count = paf24_write (psf, ppaf24, iptr, writecount) ;

    total += count ;

    len -= writecount ;

    if (count != writecount)

      break ;

    } ;

  return total ;

} /* paf24_write_d */