array.c

/*
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Copyright (C) 1999 Malin Space Science Systems.  All Rights Reserved.
*/
static char *sccsid = "@(#)array.c	1.1 10/04/99";
 
/*
    Auto-expanding array package
    Mike Caplinger, MOC GDS Design Scientist
    SCCS @(#)array.c	1.2 10/18/91

    Implements a simple auto-expanding array data structure.  Include
    "array.h" to use.
*/

#include "array.h"

/*
    Create a new array with an initial allocation of len (0 will work if
    you can't make a better guess) and return it.
*/
Array *array_new(len)
int len;
{
    Array *new = (Array *) malloc(sizeof(Array));

    if(new == 0) return 0;
    
    new->len = 0;
    new->free = len;
    new->data = (char *) malloc(len);

    if(new->data == 0) return 0;

    return new;
}

/*
    Append len bytes of data at the end of the array.  Returns 0 if the
    operation fails, otherwise a positive number.
*/
int array_append(a, data, len)
Array *a;
char *data;
int len;
{
    if(a->free < len) {
	/* expand array */
	a->data = (char *) realloc(a->data, len+(a->len+a->free)*2);
	if(a->data == 0) {
	    return 0;
	}
	a->free += len+(a->len+a->free);
    }

    bcopy(data, a->data+a->len, len);
    a->free -= len;
    a->len += len;
    return len;
}

/*
    Delete an entry from the array and shove the remaining contents,
    if any, down.  Returns 0 if the operation fails, otherwise a
    positive number.
*/
int array_slot_delete(a, slot, len)
Array *a;
int slot, len;
{
    if(a->len < (slot+1)*len) return 0;
    bcopy(&a->data[(slot+1)*len], &a->data[(slot)*len],
	  (a->len/len-slot-1)*len);
    a->free += len;
    a->len -= len;
    return 1;
}

/*
    Returns the current size of the array in bytes.
*/
int array_len(a)
Array *a;
{
    return a->len;
}

/*
    Returns the data contained in the array.  This is a contiguous vector
    of bytes guaranteed to be array_len(a) in size.
*/
char *array_data(a)
Array *a;
{
    return a->data;
}

/*
    Deallocate an array and its data.
*/
void array_free(a)
Array *a;
{
    free(a->data);
    free(a);
}

#ifdef TEST
main() {
    Array *t = array_new(0);

    array_append(t, "abcdef", 7);
    array_slot_delete(t, 0, 1);
    printf("%s\n", array_data(t));
    array_slot_delete(t, 2, 1);
    printf("%s\n", array_data(t));
    array_slot_delete(t, 3, 1);
    printf("%s\n", array_data(t));
    array_slot_delete(t, 3, 1);
    array_append(t, "1234", 5);
    printf("%s\n", array_data(t));
}
#endif