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dload_3=41       Stack: ... ->
..., word1, word2&nbsp;&nbsp;from vars[3] &amp; vars[4]</TT>
</BLOCKQUOTE>
<H5>Load Object from Local Variable</H5>
<BLOCKQUOTE>
<TT>aload=25 vindex&nbsp;&nbsp;Stack: ...
-&gt; ..., object&nbsp;&nbsp;from vars[vindex]<BR>
aload_0=42&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: ... -&gt;
..., object&nbsp;&nbsp;from vars[0]<BR>
aload_1=43&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: ... -&gt;
..., object&nbsp;&nbsp;from vars[1]<BR>
aload_2=44&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: ... -&gt;
..., object&nbsp;&nbsp;from vars[2]<BR>
aload_3=45&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: ... -&gt;
..., object&nbsp;&nbsp;from vars[3]</TT>
</BLOCKQUOTE>
<H5>Store Integer into Local Variable</H5>
<BLOCKQUOTE>
<TT>istore=54 vindex Stack: ..., INT -&gt;
...&nbsp;&nbsp;into vars[vindex]<BR>
istore_0=59&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., INT
-&gt; ...&nbsp;&nbsp;into vars[0]<BR>
istore_1=60&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., INT
-&gt; ...&nbsp;&nbsp;into vars[1]<BR>
istore_2=61&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., INT
-&gt; ...&nbsp;&nbsp;into vars[2]<BR>
istore_3=62&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., INT
-&gt; ...&nbsp;&nbsp;into vars[3]</TT>
</BLOCKQUOTE>
<H5>Store Long Integer into Local Variable</H5>
<BLOCKQUOTE>
<TT>lstore=55 vindex Stack: ..., word1, word2
-&gt; ...&nbsp;&nbsp;into vars[vindex] &amp; vars[vindex+1]<BR>
lstore_0=63&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[0] &amp; vars[1]<BR>
lstore_1=64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[1] &amp; vars[2]<BR>
lstore_2=65&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[2] &amp; vars[3]<BR>
lstore_3=66&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[3] &amp; vars[4]</TT>
</BLOCKQUOTE>
<H5>Store Float into Local Variable</H5>
<BLOCKQUOTE>
<TT>fstore=56 vindex Stack: ..., FLOAT -&gt;
...&nbsp;&nbsp;into vars[vindex]<BR>
fstore_0=67&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., FLOAT
-&gt; ...&nbsp;&nbsp;into vars[0]<BR>
fstore_1=68&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., FLOAT
-&gt; ...&nbsp;&nbsp;into vars[1]<BR>
fstore_2=69&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., FLOAT
-&gt; ...&nbsp;&nbsp;into vars[2]<BR>
fstore_3=70&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., FLOAT
-&gt; ...&nbsp;&nbsp;into vars[3]</TT>
</BLOCKQUOTE>
<H5>Store Double into Local Variable</H5>
<BLOCKQUOTE>
<TT>dstore=57 vindex Stack: ..., word1, word2
-&gt; ...&nbsp;&nbsp;into vars[vindex] &amp; vars[vindex+1]<BR>
dstore_0=71&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[0] &amp; vars[1]<BR>
dstore_1=72&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[1] &amp; vars[2]<BR>
dstore_2=73&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[2] &amp; vars[3]<BR>
dstore_3=74&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., word1,
word2 -&gt; ...&nbsp;&nbsp;into vars[3] &amp; vars[4]</TT>
</BLOCKQUOTE>
<H5>Store Object into Local Variable</H5>
<BLOCKQUOTE>
<TT>istore=58 vindex Stack: ..., OBJ -&gt;
...&nbsp;&nbsp;into vars[vindex]<BR>
istore_0=75&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., OBJ
-&gt; ...&nbsp;&nbsp;into vars[0]<BR>
istore_1=76&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., OBJ
-&gt; ...&nbsp;&nbsp;into vars[1]<BR>
istore_2=77&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., OBJ
-&gt; ...&nbsp;&nbsp;into vars[2]<BR>
istore_3=78&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., OBJ
-&gt; ...&nbsp;&nbsp;into vars[3]</TT>
</BLOCKQUOTE>
<H5>Increment Local Variable </H5>
<P>
This applies only to integers.
<BLOCKQUOTE>
<TT>iinc=132 vindex constant&nbsp;&nbsp;&nbsp;Stack:
... -&gt; ...&nbsp;&nbsp;vars[vindex] += constant</TT>
</BLOCKQUOTE>
<H4>Managing Arrays</H4>
<UL>
<LI>Arrays are treated as objects, but as you learned in <A HREF="Ch10.htm" >Chapter 10</A>,
they don't use a method table pointer. Because of this uniqueness,
arrays have special bytecodes to create and access them.
</UL>
<H5>Allocate a New Array</H5>
<BLOCKQUOTE>
<TT>newarray=188 type Stack: ..., size -&gt;
..., OBJ</TT>
</BLOCKQUOTE>
<H5>Allocate a New Array of Objects</H5>
<BLOCKQUOTE>
<TT>anewarray=189 classindex1 classindex2
Stack: ..., size -&gt; ..., OBJ</TT>
</BLOCKQUOTE>
<H5>Allocate a New Multi-Dimensional Array</H5>
<BLOCKQUOTE>
<TT>newarray=197 indexbyte1 indexbyte1 indexbyte2&nbsp;&nbsp;Stack:
..., size1, size2, etc -&gt; ..., OBJ</TT>
</BLOCKQUOTE>
<H5>Get the Array Length</H5>
<BLOCKQUOTE>
<TT>arraylength=190 Stack: ..., OBJ -&gt;
..., length</TT>
</BLOCKQUOTE>
<H5>Load Primitives from the Array</H5>
<BLOCKQUOTE>
<TT>iaload=46 Stack: ..., OBJ, index -&gt;
..., INT<BR>
laload=47 Stack: ..., OBJ, index -&gt; ..., LONG1, LONG2<BR>
faload=48 Stack: ..., OBJ, index -&gt; ..., FLOAT<BR>
daload=49 Stack: ..., OBJ, index -&gt; ..., DOUBLE1, DOUBLE2<BR>
aaload=50 Stack: ..., OBJ, index -&gt; ..., OBJ<BR>
baload=51 Stack: ..., OBJ, index -&gt; ..., BYTE<BR>
caload=52 Stack: ..., OBJ, index -&gt; ..., CHAR<BR>
saload=53 Stack: ..., OBJ, index -&gt; ..., SHORT</TT>
</BLOCKQUOTE>
<H5>Store Primitives into the Array</H5>
<BLOCKQUOTE>
<TT>iastore-79 Stack: ..., OBJ, index, INT
-&gt; ...<BR>
lastore=80 Stack: ..., OBJ, index, LONG1, LONG2 -&gt; ...<BR>
fastore=81 Stack: ..., OBJ, index, FLOAT -&gt; ...<BR>
dastore=82 Stack: ..., OBJ, index, DOUBLE1, DOUBLE2 -&gt; ...
<BR>
aastore=83 Stack: ..., OBJ, index, OBJ -&gt; ...<BR>
bastore=84 Stack: ..., OBJ, index, BYTE -&gt; ...<BR>
castore=85 Stack: ..., OBJ, index, CHAR -&gt; ...<BR>
sastore=86 Stack: ..., OBJ, index, SHORT -&gt; ...</TT>
</BLOCKQUOTE>
<H4>Generic Stack Instructions</H4>
<P>
These are basic operations that alter the stack:
<H5>Do Nothing</H5>
<BLOCKQUOTE>
<TT>nop=0&nbsp;&nbsp;&nbsp;Stack: ... -&gt;
...</TT>
</BLOCKQUOTE>
<H5>Pop Stack Values</H5>
<BLOCKQUOTE>
<TT>pop=87&nbsp;&nbsp;Stack: ..., VAL -&gt;
...<BR>
pop2=88&nbsp;&nbsp;Stack: ..., VAL1, VAL2 -&gt; ...</TT>
</BLOCKQUOTE>
<H5>Duplicate Stack Values and Possibly Insert Below Stack Top
</H5>
<BLOCKQUOTE>
<TT>dup=89&nbsp;&nbsp;&nbsp;&nbsp; Stack:
..., V -&gt; ..., V, V<BR>
dup2=92&nbsp;&nbsp;&nbsp;&nbsp;Stack: ..., V1, V2 -&gt; ..., V1,
V2, V1, V2<BR>
dup_x1=90&nbsp;&nbsp;Stack: ..., V1, V2 -&gt; ..., V2, V1, V2
<BR>
dup2_x1=93 Stack: ..., V1, V2, V3 -&gt; ..., V2, V3, V1, V2, V3
<BR>
dup_x2=91&nbsp;&nbsp;Stack: ..., V1, V2, V3 -&gt; ..., V3, V1,
V2, V3<BR>
dup2_x2=94 Stack: ..., V1, V2, V3, V4 -&gt; ..., V3, V4, V1, V2,
V3, V4</TT>
</BLOCKQUOTE>
<H5>Swap Two-Stack Items</H5>
<BLOCKQUOTE>
<TT>swap=95&nbsp;&nbsp;&nbsp;&nbsp;Stack:
..., V1, V2 -&gt; ..., V2, V1</TT>
</BLOCKQUOTE>
<H4>Arithmetic and Logical Instructions</H4>
<P>
All the arithmetic operations operate on four possible types:
integer, long, float, or double. Logical instructions operate
only on integer and long types.
<H5>Addition</H5>
<BLOCKQUOTE>
<TT>iadd=96&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; ..., INT1+INT2<BR>
ladd=97&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ...,
L1+L2 (high), L1+L2 (low)<BR>
fadd=98&nbsp;&nbsp;Stack: ..., FLOAT1, FLOAT2 -&gt; ..., FLOAT1+FLOAT2
<BR>
dadd=99&nbsp;&nbsp;Stack: ..., D1_1, D1_2, D2_1, D2_2 -&gt; ...,
D1+D2 (high), D1+D2 (low)</TT>
</BLOCKQUOTE>
<H5>Subtraction</H5>
<BLOCKQUOTE>
<TT>isub=100 Stack: ..., INT1, INT2 -&gt;
..., INT1-INT2<BR>
lsub=101 Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ..., L1-L2 (high),
L1-L2 (low)<BR>
fsub=102 Stack: ..., FLOAT1, FLOAT2 -&gt; ..., FLOAT1-FLOAT2<BR>
dsub=103 Stack: ..., D1_1, D1_2, D2_1, D2_2 -&gt; ..., D1-D2 (high),
D1-D2 (low)</TT>
</BLOCKQUOTE>
<H5>Multiplication</H5>
<BLOCKQUOTE>
<TT>imul=104&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; ..., INT1*INT2<BR>
lmul=105&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ...,
L1*L2 (high), L1*L2 (low)<BR>
fmul=106&nbsp;&nbsp;Stack: ..., FLOAT1, FLOAT2 -&gt; ..., FLOAT1*FLOAT2
<BR>
dmul=107&nbsp;&nbsp;Stack: ..., D1_1, D1_2, D2_1, D2_2 -&gt; ...,
D1*D2 (high), D1*D2 (low)</TT>
</BLOCKQUOTE>
<H5>Division</H5>
<BLOCKQUOTE>
<TT>idiv=108&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; ..., INT1/INT2<BR>
ldiv=109&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ...,
L1/L2 (high), L1/L2 (low)<BR>
fdiv=110&nbsp;&nbsp;Stack: ..., FLOAT1, FLOAT2 -&gt; ..., FLOAT1/FLOAT2
<BR>
ddiv=111&nbsp;&nbsp;Stack: ..., D1_1, D1_2, D2_1, D2_2 -&gt; ...,
D1/D2 (high), D1/D2 (low)</TT>
</BLOCKQUOTE>
<H5>Remainder</H5>
<BLOCKQUOTE>
<TT>irem=112&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; ..., INT1%INT2<BR>
lrem=113&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ...,
L1%L2 (high), L1%L2 (low)<BR>
frem=114&nbsp;&nbsp;Stack: ..., FLOAT1, FLOAT2 -&gt; ..., FLOAT1%FLOAT2
<BR>
drem=115&nbsp;&nbsp;Stack: ..., D1_1, D1_2, D2_1, D2_2 -&gt; ...,
D1%D2 (high), D1%D2 (low)</TT>
</BLOCKQUOTE>
<H5>Negation</H5>
<BLOCKQUOTE>
<TT>ineg=116&nbsp;&nbsp;Stack: ..., INT -&gt;
..., -INT<BR>
lneg=117&nbsp;&nbsp;Stack: ..., LONG1, LONG2 -&gt; ..., -LONG1,
-LONG2<BR>
fneg=118&nbsp;&nbsp;Stack: ..., FLOAT -&gt; ..., -FLOAT<BR>
dneg=119&nbsp;&nbsp;Stack: ..., DOUBLE1, DOUBLE2 -&gt; ..., -DOUBLE1,
-DOUBLE2</TT>
</BLOCKQUOTE>
<H5>Integer Logical Instructions </H5>
<P>
<TT>&gt;&gt;&gt;</TT> denotes an unsigned
right shift.
<BLOCKQUOTE>
<TT>ishl=120&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; INT1&lt;&lt;(INT2 &amp; 0x1f)<BR>
ishr=122&nbsp;&nbsp;Stack: ..., INT1, INT2 -&gt; INT1&gt;&gt;(INT2
&amp; 0x1f)<BR>
iushr=124 Stack: ..., INT1, INT2 -&gt; INT1&gt;&gt;&gt;(INT2 &amp;
0x1f)</TT>
</BLOCKQUOTE>
<H5>Long Integer Logical Instructions</H5>
<P>
<TT>&gt;&gt;&gt;</TT> denotes an unsigned
right shift.
<BLOCKQUOTE>
<TT>lshl=121&nbsp;&nbsp;Stack: ..., L1, L2,
INT -&gt; L1&lt;&lt;(INT &amp; 0x3f), L2&lt;&lt;(INT &amp; 0x3f)
<BR>
lshr=123&nbsp;&nbsp;Stack: ..., L1, L2, INT -&gt; INT1&gt;&gt;(INT
&amp; 0x3f), L2&gt;&gt;(INT &amp; 0x03)<BR>
lushr=125 Stack: ..., L1, L2, INT -&gt; INT1&gt;&gt;&gt;(INT &amp;
0x3f), L2&gt;&gt;&gt;(INT &amp; 0x3f)</TT>
</BLOCKQUOTE>
<H5>Integer Boolean Operations</H5>
<BLOCKQUOTE>
<TT>iand=126&nbsp;&nbsp;Stack: ..., INT1,
INT2 -&gt; ..., INT1&amp;INT2<BR>
ior=128&nbsp;&nbsp;&nbsp;Stack: ..., INT1, INT2 -&gt; ..., INT1|INT2
<BR>
ixor=130&nbsp;&nbsp;Stack: ..., INT1, INT2 -&gt; ..., INT1^INT2</TT>
</BLOCKQUOTE>
<H5>Long Integer Boolean Operations</H5>
<BLOCKQUOTE>
<TT>land=127&nbsp;&nbsp;Stack: ..., L1_1,
L1_2, L2_1, L2_2 -&gt; ..., L1_1&amp;L2_1, L1_2&amp;L2_2<BR>
lor=129&nbsp;&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt;
..., L1_1|L2_1, L1_2|L2_2<BR>
lxor=131&nbsp;&nbsp;Stack: ..., L1_1, L1_2, L2_1, L2_2 -&gt; ...,
L1_1^L2_1. L1_2^L2_2</TT>
</BLOCKQUOTE>
<H4>Conversion Instructions</H4>
<P>
Because most of the previous bytecodes expect the stack to contain
a homogenous set of operands, Java uses conversion functions.
In code, you can add a float and an integer, but Java will first
convert the integer to a float type before performing the addition.
<H5>Integer Conversions</H5>
<BLOCKQUOTE>
<TT>i2l=133&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Stack: .., INT -&gt; ..., LONG1, LONG2<BR>
i2f=134&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., INT -&gt;
..., FLOAT<BR>
i2d=135&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., INT -&gt;
..., DOUBLE1, DOUBLE2<BR>
int2byte=145&nbsp;&nbsp;Stack: .., INT -&gt; ..., BYTE<BR>
int2char=146&nbsp;&nbsp;Stack: .., INT -&gt; ..., CHAR<BR>
int2short=147 Stack: .., INT -&gt; ..., SHORT</TT>
</BLOCKQUOTE>
<H5>Long Integer Conversions</H5>
<BLOCKQUOTE>
<TT>l2i=136&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Stack: .., LONG1, LONG2 -&gt; ..., INT<BR>
l2f=137&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., LONG1,
LONG2 -&gt; ..., FLOAT<BR>
l2d=138&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., LONG1,
LONG2 -&gt; ..., DOUBLE1, DOUBLE2</TT>
</BLOCKQUOTE>
<H5>Float Conversions</H5>
<BLOCKQUOTE>
<TT>f2i=139&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Stack: .., FLOAT -&gt; ..., INT<BR>
f2l=140&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., FLOAT -&gt;
..., LONG1, LONG2<BR>
f2d=141&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., FLOAT -&gt;
..., DOUBLE1, DOUBLE2</TT>
</BLOCKQUOTE>
<H5>Double Conversions</H5>
<BLOCKQUOTE>
<TT>d2i=142&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Stack: .., DOUBLE1, DOUBLE2 -&gt; ..., INT<BR>
d2l=143&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., DOUBLE1,
DOUBLE2 -&gt; ..., LONG1, LONG2<BR>
d2f=144&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stack: .., DOUBLE1,
DOUBLE2 -&gt; ..., FLOAT</TT>
</BLOCKQUOTE>
<H4>Control Transfer and Function Return</H4>
<P>
All branch indexes are signed 16-bit offsets from the current
<TT>pc</TT> register.
<H5>Comparisons with Zero</H5>
<BLOCKQUOTE>
<TT>ifeq=153 branch1 branch2&nbsp;&nbsp;&nbsp;Stack:
..., INT -&gt; ...<BR>
ifne=154 branch1 branch2&nbsp;&nbsp;&nbsp;Stack: ..., INT -&gt;
...<BR>
iflt=155 branch1 branch2&nbsp;&nbsp;&nbsp;Stack: ..., INT -&gt;
...<BR>
ifge=156 branch1 branch2&nbsp;&nbsp;&nbsp;Stack: ..., INT -&gt;
...<BR>
ifgt=157 branch1 branch2&nbsp;&nbsp;&nbsp;Stack: ..., INT -&gt;
...<BR>