/*
 * binres.c
 *
 * Summary:  Read or write a binary restart file.
 *
 * Author:  David Hardy
 */

#include <stdio.h>
#include "binres.h"
#include "mdtypes.h"
#include "error.h"


#undef  START
#define START 1
#undef  VEC
#define VEC   2


int binres_init(Binres *b)
{
  /* init everything */
  b->f = NULL;
  b->nelem = 0;
  b->elemsize = 0;
  b->access = 0;
  b->state = 0;
  b->status = 0;
  return 0;
}


void binres_destroy(Binres *b)
{
  /* clear everything */
  b->f = NULL;
  b->nelem = 0;
  b->elemsize = 0;
  b->access = 0;
  b->state = 0;
  b->status = 0;
}


int binres_open(Binres *b, const char *fname, int access, int type)
{
  switch (type) {
  case MD_FVEC:
    b->elemsize = sizeof(MD_Fvec);
    break;
  case MD_DVEC:
    b->elemsize = sizeof(MD_Dvec);
    break;
  default:
    mdio_fatal("illegal type, file %s, line %d\n", __FILE__, __LINE__);
  }

  switch (access) {
  case BINRES_READ:
    b->f = fopen(fname, "rb");
    break;
  case BINRES_WRITE:
    b->f = fopen(fname, "wb");
    break;
  default:
    mdio_fatal("illegal access, file %s, line %d\n", __FILE__, __LINE__);
  }
  MDIO_ASSERT(b->f != NULL);
  b->access = access;
  b->state = START;
  return 0;
}


int binres_close(Binres *b)
{
  int ret;

  ret = fclose(b->f);
  MDIO_ASSERT(ret == 0);
  return ret;
}


int binres_read(Binres *b, void *vec, int len, int *num, int *max)
{
  int n;

  MDIO_ASSERT(b->access == BINRES_READ);
  switch (b->state) {
  case START:
    fread((void *) max, sizeof(int), 1, b->f);
    b->nelem = 0;
    b->state = VEC;
    /* fall through */
  case VEC:
    n = *max - b->nelem;
    if (n > 0) {
      if (n > len)  n = len;
      fread(vec, b->elemsize, n, b->f);
      b->nelem += n;
    }
    *num = n;
    break;
  default:
    mdio_fatal("illegal state, file %s, line %d\n", __FILE__, __LINE__);
  }
  return (b->nelem < *max);
}


int binres_write(Binres *b, const void *vec, int num, int max)
{
  MDIO_ASSERT(b->access == BINRES_WRITE);
  switch (b->state) {
  case START:
    fwrite((void *) &max, sizeof(int), 1, b->f);
    b->nelem = 0;
    b->state = VEC;
    /* fall through */
  case VEC:
    MDIO_ASSERT(b->nelem + num <= max);
    fwrite(vec, b->elemsize, num, b->f);
    b->nelem += num;
    break;
  default:
    mdio_fatal("illegal state, file %s, line %d\n", __FILE__, __LINE__);
  }
  return (b->nelem < max);
}