Problem - Kevin Tafuro

eak;
case SPC_ARRAY_FOLD:
index = (idx / num_row) + (a->split * (idx % num_row) );
break;
case SPC_ARRAY_FLAT:
index = subarray + (a->split * (idx % num_row));
break;
}
return (index >= a->num_elem ? -1 : index);
}
/* Get a pointer to element 'idx' in array 'subarray' */
void *spc_array_get(spc_array_t *a, int subarray, int idx) {
int index;
if (!a || (index = array_index(a, subarray, idx)) = = -1) return 0;
return (void *)(a->data + (a->sz_elem * index));
}
/* Set element 'idx' in array 'subarray' to the data pointed to by 'src' --
* note that the sz_elem used to initialize the array is used here to copy
* the correct amount of data.
*/
int spc_array_set(spc_array_t *a, int subarray, int idx, void *src) {
int index;
if (!a || !src || (index = array_index(a, subarray, idx)) = = -1)
return 0;
memcpy(a->data + (a->sz_elem * index), src, a->sz_elem);
return 1;
}
/* Free an spc_array_t, including its table of elements */
int spc_array_free(spc_array_t *a) {
if (a) free(a);
return !!a;
}
The function spc_array_split( ) creates a two-dimensional array that is accessed as
if it were an array of a single dimension; all odd-numbered elements are stored in the
first half of the array, and all even-numbered elements are stored in the second half.
For example, an array of five elements with indices numbered zero through four is
conceptually broken up into two arrays where the second and fourth elements are
stored in the first array, and the first, third, and fifth elements are stored in the second
array. The two conceptual arrays are actually stored contiguously in memory.
The effect is a simple reordering of the elements as illustrated in Figure 12-1.
The function spc_array_merge( ) creates a single-dimensional array whose elements
are indexed as if they were two separate arrays; the elements are referenced by an
array number (0 or 1) and an index into that array. The ratio of the size between the
two arrays is used to determine the placement of each element, so that the arrays are
stored in memory as illustrated in Figure 12-2.
This is the Title of the Book, eMatter Edition
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Restructuring Arrays | 675