boo/soxr/src/fifo.h

/* SoX Resampler Library      Copyright (c) 2007-13 robs@users.sourceforge.net
 * Licence for this file: LGPL v2.1                  See LICENCE for details. */

#ifndef fifo_included
#define fifo_included

#if !defined FIFO_SIZE_T
#define FIFO_SIZE_T size_t
#endif

#if !defined FIFO_REALLOC
  #define FIFO_REALLOC(a,b,c) realloc(a,b)
  #undef FIFO_FREE
  #define FIFO_FREE free
  #undef FIFO_MALLOC
  #define FIFO_MALLOC malloc
#endif

typedef struct {
  char * data;
  size_t allocation;   /* Number of bytes allocated for data. */
  size_t item_size;    /* Size of each item in data */
  size_t begin;        /* Offset of the first byte to read. */
  size_t end;          /* 1 + Offset of the last byte byte to read. */
} fifo_t;

#if !defined FIFO_MIN
  #define FIFO_MIN 0x4000
#endif

#if !defined UNUSED
  #define UNUSED
#endif

UNUSED static void fifo_clear(fifo_t * f)
{
  f->end = f->begin = 0;
}

UNUSED static void * fifo_reserve(fifo_t * f, FIFO_SIZE_T n0)
{
  size_t n = (size_t)n0;
  n *= f->item_size;

  if (f->begin == f->end)
    fifo_clear(f);

  while (1) {
    if (f->end + n <= f->allocation) {
      void *p = f->data + f->end;

      f->end += n;
      return p;
    }
    if (f->begin > FIFO_MIN) {
      memmove(f->data, f->data + f->begin, f->end - f->begin);
      f->end -= f->begin;
      f->begin = 0;
      continue;
    }
    f->data = FIFO_REALLOC(f->data, f->allocation + n, f->allocation);
    f->allocation += n;
    if (!f->data)
      return 0;
  }
}

UNUSED static void * fifo_write(fifo_t * f, FIFO_SIZE_T n0, void const * data)
{
  size_t n = (size_t)n0;
  void * s = fifo_reserve(f, n0);
  if (data)
    memcpy(s, data, n * f->item_size);
  return s;
}

UNUSED static void fifo_trim_to(fifo_t * f, FIFO_SIZE_T n0)
{
  size_t n = (size_t)n0;
  n *= f->item_size;
  f->end = f->begin + n;
}

UNUSED static void fifo_trim_by(fifo_t * f, FIFO_SIZE_T n0)
{
  size_t n = (size_t)n0;
  n *= f->item_size;
  f->end -= n;
}

UNUSED static FIFO_SIZE_T fifo_occupancy(fifo_t * f)
{
  return (FIFO_SIZE_T)((f->end - f->begin) / f->item_size);
}

UNUSED static void * fifo_read(fifo_t * f, FIFO_SIZE_T n0, void * data)
{
  size_t n = (size_t)n0;
  char * ret = f->data + f->begin;
  n *= f->item_size;
  if (n > (f->end - f->begin))
    return NULL;
  if (data)
    memcpy(data, ret, (size_t)n);
  f->begin += n;
  return ret;
}

#define fifo_read_ptr(f) fifo_read(f, (FIFO_SIZE_T)0, NULL)

UNUSED static void fifo_delete(fifo_t * f)
{
  FIFO_FREE(f->data);
}

UNUSED static int fifo_create(fifo_t * f, FIFO_SIZE_T item_size)
{
  f->item_size = (size_t)item_size;
  f->allocation = FIFO_MIN;
  fifo_clear(f);
  return !(f->data = FIFO_MALLOC(f->allocation));
}

#endif