array-length
Purpose
Store in the given destination register the length of the indicated array,
in entries.
Details
| Op & Format |
Mnemonic / Syntax |
Arguments |
| 21 12x |
array-length vA, vB |
A: destination register (4 bits)
B: array reference-bearing register (4 bits) |
Constraints
-
Both A and B must be valid register indices for the current stack frame.
-
Register vB must contain a reference to an array.
Behavior
-
The length of the array referenced by vB is stored in vA, that is
vA' = length(vB).
-
If register v(A-1) is the lower half of a register pair, register v(A-1)'
becomes undefined.
-
If register v(A+1) is the upper half of a register pair, register v(A+1)'
becomes undefined.
Exceptions
-
NullPointerException is thrown if the value of register vB is null.