Assembly Language for Beginners

4.1. JAVA

The value to be written is set at offset 12.

iastoreat 13 writes the array’s element.

How it is an element accessed?

public static int get12 (int[][] in)

{

return in[1][2];

}

public static int get12(int[][]);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=2, locals=1, args_size=1

0: aload_0

1: iconst_1

2: aaload

3: iconst_2

4: iaload

5: ireturn

AReferenceto the array’s row is loaded at offset 2, the column is set at offset 3, thenialoadloads the
array’s element.

Three-dimensional arrays

Three-dimensional arrays are just one-dimensional arrays ofreferencesto one-dimensional arrays ofref-
erences.

public static void main(String[] args)

{

int[][][] a = new int[5][10][15];

a[1][2][3]=4;

get_elem(a);

}

public static void main(java.lang.String[]);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=3, locals=2, args_size=1

0: iconst_5

1: bipush 10

3: bipush 15

5: multianewarray #2, 3 // class "[[[I"

9: astore_1

10: aload_1

11: iconst_1

12: aaload

13: iconst_2

14: aaload

15: iconst_3

16: iconst_4

17: iastore

18: aload_1

19: invokestatic #3 // Method get_elem:([[[I)I

22: pop

23: return

Now it takes twoaaloadinstructions to find rightreference:

public static int get_elem (int[][][] a)

{

return a[1][2][3];

}