Hi all, I have Javabytecode from decompiling COD (blackberry) file

who can teach me how to read this code :

[PHP]
static public final boolean checkRegCode( java.lang.String ); // address: 0
{
enter
ldc literal_77:"203A1E5B"
astore_1
invokestatic_lib int getDeviceId( ) // DeviceInfo
invokestatic_lib java.lang.String toHexString( int ) // Integer
invokenonvirtual_lib java.lang.String.toUpperCase // pc=1
astore_1
aload_1
invokenonvirtual_lib java.lang.String.toCharArray // pc=1
astore_2
iconst_0
istore_3
aload_2
arraylength
bipush 10
if_icmpgt Label31
iconst_0
istore_4
goto Label26
Label19:
iload_3
aload_2
iload_4
caload
iadd
istore_3
iinc 4 1
Label26:
iload_4
aload_2
arraylength
if_icmplt Label19
goto Label61
Label31:
iconst_0
istore_4
goto Label41
Label34:
iload_3
aload_2
iload_4
caload
iadd
istore_3
iinc 4 1
Label41:
iload_4
bipush 5
if_icmplt Label34
aload_2
arraylength
bipush 5
isub
istore_5
goto Label57
Label50:
iload_3
aload_2
iload_5
caload
iadd
istore_3
iinc 5 1
Label57:
iload_5
aload_2
arraylength
if_icmplt Label50
Label61:
iload_3
bipush 8
ishl
sipush 872
iadd
istore_3
iload_3
iipush 65535
iand
istore_4
iload_4
invokestatic_lib java.lang.String toString( int ) // Integer
astore_5
aload_5
bipush 5
bipush 48
invokestatic java.lang.String prepad( java.lang.String, int, char ) // SnapScreen
astore_6
aload_0
aload_6
invokevirtual_short .equals // idx=1 pc=2
ifeq Label85
iconst_1
ireturn
Label85:
iconst_0
ireturn
}


[/PHP]

thx..