/* wave.c
 *
 * MS Wave files store data 'little endian' sytle. These functions will only
 * work on 'little endian' machines. 09/02/01 P.Everett
 * note. both Acorn/RISC OS and PC/DOS are little endian.
 */
 
#include "g_includes.h"
#include "wave.h"

/* RISC OS specifics */
#define WAVE  0xfb1      /* Wave filetype */
#define DATA  0xffd      /* Data filetype */

/*
 * wave_close:
 * -----------
 */
void wave_close(config_t *config)
{
  if (config->wave.file != stdin)
    fclose(config->wave.file);
}

/*
 * wave_open:
 * ----------
 * Opens and verifies the header of the Input Wave file. The file pointer is
 * left pointing to the start of the samples.
 */
void wave_open(config_t *config)
{

  static char *channel_mappings[] = {NULL,"mono","stereo"};
  int i=0;

  /* Wave file headers can vary from this, but we're only intereseted in this format */
  struct wave_header
  {
    char riff[4];             /* "RIFF" */
    unsigned int size;       /* length of rest of file = size of rest of header(36) + data length */
    char wave[4];             /* "WAVE" */
    char fmt[4];              /* "fmt " */
    unsigned int fmt_len;    /* length of rest of fmt chunk = 16 */
    unsigned short tag;       /* MS PCM = 1 */
    unsigned short channels;  /* channels, mono = 1, stereo = 2 */
    unsigned int samp_rate;  /* samples per second = 44100 */
    unsigned int byte_rate;  /* bytes per second = samp_rate * byte_samp = 176400 */
    unsigned short byte_samp; /* block align (bytes per sample) = channels * bits_per_sample / 8 = 4 */
    unsigned short bit_samp;  /* bits per sample = 16 for MS PCM (format specific) */
    char data[4];             /* "data" */
    unsigned int length;     /* data length (bytes) */
  } header;

  // Read from stdin or file
  if (!strcmp(config->infile, "-"))
    config->wave.file = stdin;
  else if((config->wave.file = fopen(config->infile,"rb")) == NULL)
    error("Unable to open file");

    if (fread(&header, sizeof(header), 1, config->wave.file) != 1)
      error("Invalid Header");
    
    if(strncmp(header.riff,"RIFF",4) != 0) error("Not a MS-RIFF file");
    if(strncmp(header.wave,"WAVE",4) != 0) error("Not a WAVE audio");
    if(strncmp(header.fmt, "fmt ",4) != 0) error("Can't find format chunk");
    if(header.tag != 1)                    error("Unknown WAVE format");
    if(header.channels > 2)                error("More than 2 channels");
    if(header.bit_samp != 16)              error("Not 16 bit");
    if(strncmp(header.data,"data",4) != 0) error("Can't find data chunk");
    i = 0;

  

  config->wave.type          = WAVE_RIFF_PCM;
  config->wave.channels      = header.channels;
  config->wave.samplerate    = header.samp_rate;
  config->wave.bits          = header.bit_samp;
  config->wave.total_samples = header.length / header.byte_samp;
  config->wave.length        = header.length / header.byte_rate;

  if (!config->quiet)
    fprintf(stderr, "%s, %s %dHz %dbit, Length: %2ld:%2ld:%2ld\n", 
          "WAV PCM DATA",channel_mappings[header.channels],header.samp_rate,header.bit_samp,
          config->wave.length/3600,(config->wave.length/60)%60,config->wave.length%60);
}

/*
 * read_samples:
 * -------------
 */
int read_samples(short *sample_buffer, int frame_size, config_t *config)
{
  int samples_read=0;

  switch(config->wave.type)
  {
    case WAVE_RIFF_PCM :
      samples_read = fread(sample_buffer,sizeof(short),frame_size, config->wave.file);
  
      if(samples_read<frame_size && samples_read>0) /* Pad sample with zero's */
        while(samples_read<frame_size) sample_buffer[samples_read++] = 0;
      break;

    default:
      error("[read_samples], wave filetype not supported");
  }
  return samples_read;
}

/*
 * wave_get:
 * ---------
 * Expects an interleaved 16bit pcm stream from read_samples, which it
 * de-interleaves into buffer.
 */
int wave_get(short buffer[2][samp_per_frame], void *config_in)
{
  static short temp_buf[2304];
  int          samples_read;
  int          j;
  config_t *config=config_in;
    
  switch(config->mpeg.mode)
  {
    case MODE_MONO  :
      samples_read = read_samples(temp_buf,(int)config->mpeg.samples_per_frame, config);
      for(j=0;j<samp_per_frame;j++)
      {
        buffer[0][j] = temp_buf[j];
        buffer[1][j] = 0;
      }
      break;
      
    default: /* stereo */
      samples_read = read_samples(temp_buf,(int)config->mpeg.samples_per_frame<<1, config);
      for(j=0;j<samp_per_frame;j++)
      {
        buffer[0][j] = temp_buf[2*j];
        buffer[1][j] = temp_buf[2*j+1];
      }
  }
  return samples_read;
}