/*
 * Copyright(C) 1999-2022 National Technology & Engineering Solutions
 * of Sandia, LLC (NTESS).  Under the terms of Contract DE-NA0003525 with
 * NTESS, the U.S. Government retains certain rights in this software.
 *
 * See packages/seacas/LICENSE for details
 */

#include "elb_allo.h"
#include <cstdarg> // for va_end, va_arg, va_list, etc
#include <cstddef> // for size_t
#include <cstdio>  // for stderr
#include <cstdlib> // for exit, malloc
#include <fmt/ostream.h>

static void *smalloc(size_t n);

/******************************************************************************
 *
 *                    Dynamic Allocation of Multidimensional Arrays
 *-----------------------------------------------------------------------------
 *
 * Example Usage:
 *
 *     typedef  struct
 *       {      int     bus1;
 *              int     bus2;
 *              int     dest;
 *      }       POINT;
 *
 *      POINT    **points, corner;
 *
 *      points = (POINT **) array_alloc (2, x, y, sizeof(POINT));
 *                                       ^  ^  ^
 *                                       |  |  |
 *                 number of dimensions--+  |  |
 *                   first dimension max----+  |
 *                   second dimension max------+
 *
 *         (points may be now be used as if it were declared
 *          POINT points[x][y])
 *
 *          This particular version is limited to dimensions of 3 or less.
 *
 *      corner = points[2][3]; (refer to the structure as you would any array)
 *
 *      free (points); (frees the entire structure in one fell swoop)
 *
 *****************************************************************************/
/*****************************************************************************/
/*****************************************************************************/
void *array_alloc(int numdim, ...)
{
  struct dim
  {
    size_t index; /* Number of elements in the dimension        */
    size_t total; /* Total number of elements           */
    size_t size;  /* Size of a single element in bytes  */
    size_t off;   /* offset from beginning of array     */
  } dim[3];       /* Info about each dimension          */
  va_list va;     /* Current pointer in the argument list       */

  va_start(va, numdim);

  if (numdim <= 0) {
    fmt::print(stderr, "array_alloc ERROR: number of dimensions, {}, is <=0\n", numdim);
    va_end(va);
    return nullptr;
  }
  if (numdim > 3) {
    fmt::print(stderr, "array_alloc ERROR: number of dimensions, {}, is > 3\n", numdim);
    va_end(va);
    return nullptr;
  }

  dim[0].index = va_arg(va, size_t);

  if (dim[0].index == 0) {
    va_end(va);
    return nullptr;
  }

  dim[0].total = dim[0].index;
  dim[0].size  = sizeof(void *);
  dim[0].off   = 0;
  for (int i = 1; i < numdim; i++) {
    dim[i].index = va_arg(va, size_t);
    if (dim[i].index == 0) {
      va_end(va);
      return nullptr;
    }

    dim[i].total = dim[i - 1].total * dim[i].index;
    dim[i].size  = sizeof(void *);
    dim[i].off   = dim[i - 1].off + dim[i - 1].total * dim[i - 1].size;
  }
  dim[numdim - 1].size = va_arg(va, size_t);
  va_end(va);

  /* Round up the last offset value so data is properly aligned. */
  dim[numdim - 1].off = dim[numdim - 1].size *
                        ((dim[numdim - 1].off + dim[numdim - 1].size - 1) / dim[numdim - 1].size);

  size_t total = dim[numdim - 1].off + dim[numdim - 1].total * dim[numdim - 1].size;

  void *dfield = smalloc(total);
  char *field  = reinterpret_cast<char *>(dfield);

  for (int i = 0; i < numdim - 1; i++) {
    char **ptr  = reinterpret_cast<char **>(field + dim[i].off);
    char  *data = (field + dim[i + 1].off);
    for (size_t j = 0; j < dim[i].total; j++) {
      ptr[j] = data + j * dim[i + 1].size * dim[i + 1].index;
    }
  }
  return (dfield);
}

/* Safe version of malloc.  Does not initialize memory .*/

/*****************************************************************************/
/*****************************************************************************/
/*****************************************************************************/
static void *smalloc(size_t n)
{
  void *pntr = nullptr; /* return value */

  if (n == 0) {
    pntr = nullptr;
  }
  else {
    pntr = malloc(n);
  }

  if (pntr == nullptr && n != 0) {
    fmt::print(stderr,
               "smalloc: Out of space - number of bytes "
               "requested = {}\n",
               fmt::group_digits(n));
    exit(0);
  }
  return (pntr);
}

/*****************************************************************************/
/*                       END of elb_allo.c                                   */
/*****************************************************************************/