697 lines
22 KiB
HTML
697 lines
22 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="en">
|
|
<head>
|
|
<meta charset="utf-8">
|
|
<title>Expression Evaluator</title>
|
|
<style>
|
|
:root {
|
|
font-family: Arial, sans-serif;
|
|
font-size : 16px;
|
|
text-align : justify;
|
|
-webkit-text-size-adjust: none;
|
|
}
|
|
a { text-decoration : underline; }
|
|
a.ext { text-decoration-style: dotted; }
|
|
body { margin : 8px; }
|
|
circle, path, rect {
|
|
fill : none;
|
|
paint-order : markers fill stroke;
|
|
stroke-width: 1.5;
|
|
}
|
|
code, pre, .mono { font-family: Consolas, monospace; }
|
|
h1 {
|
|
border-radius: 8px;
|
|
font-size : 20px;
|
|
font-weight : normal;
|
|
padding : 4px 8px;
|
|
}
|
|
h1.top {
|
|
font-weight: bold;
|
|
font-size : 24px;
|
|
text-align : center;
|
|
}
|
|
h1.bottom {
|
|
font-size : 16px;
|
|
padding : 6px 8px;
|
|
text-align: right;
|
|
}
|
|
h2 {
|
|
font-size : 18px;
|
|
font-weight: bold;
|
|
margin-top : 32px;
|
|
}
|
|
sup, .small { font-size: 10px; }
|
|
table {
|
|
border : none;
|
|
border-spacing: 0px;
|
|
}
|
|
td, th { padding-right : 12px; }
|
|
tr { vertical-align: top; }
|
|
.b {
|
|
border-style: solid;
|
|
border-width: 0;
|
|
font-size : 1px;
|
|
height : 4px;
|
|
padding : 0;
|
|
width : 16px;
|
|
}
|
|
.bb { border-bottom-width: 1px; }
|
|
.bc, .bd, .be {
|
|
font-size : 12px;
|
|
height : 32px;
|
|
position : relative;
|
|
text-align: center;
|
|
}
|
|
.bd { height: 48px; }
|
|
.be { height: 72px; }
|
|
.bh {
|
|
font-size : 10px;
|
|
padding : 2px 0;
|
|
text-align: center;
|
|
}
|
|
.bl { border-left-width : 1px; }
|
|
.br { border-right-width : 1px; }
|
|
.bs, .by, .bz {
|
|
box-sizing : border-box;
|
|
height : 17px;
|
|
left : 17px;
|
|
line-height : 17px;
|
|
margin-left : -1px;
|
|
position : absolute;
|
|
text-align : center;
|
|
top : -4px;
|
|
transform : rotate(90deg);
|
|
transform-origin: 0 0;
|
|
white-space : nowrap;
|
|
width : 41px;
|
|
}
|
|
.by {
|
|
font-size: 10px;
|
|
width : 82px;
|
|
}
|
|
.bz {
|
|
font-size: 10px;
|
|
width : 57px;
|
|
}
|
|
.bt { border-top-width : 1px; }
|
|
.center { text-align : center; }
|
|
.ednote {
|
|
border-radius: 8px;
|
|
border-style : solid;
|
|
border-width : 1px;
|
|
font-style : italic;
|
|
margin-left : 16px;
|
|
margin-right : 16px;
|
|
padding : 4px 8px;
|
|
}
|
|
.indent { margin-left : 16px; }
|
|
.middle { vertical-align: middle; }
|
|
.minor { font-size : 14px; }
|
|
.nowrap { white-space : nowrap; }
|
|
.narrow { width : 1px; }
|
|
.outdent { margin-left : -16px; }
|
|
.right { text-align : right; }
|
|
|
|
:root { color : #000000; }
|
|
a { color : #0099ff; }
|
|
a.ext { color : #00bb66; }
|
|
a.redlink { color : #ff3366; }
|
|
body { background : #ffffff; }
|
|
h1, .shade { background : #d4d4d4; }
|
|
.b { border-color: #666666; }
|
|
.ednote { border-color: #999999; color: #666666; }
|
|
.fill { fill : #ffffff; }
|
|
.stroke { stroke : #666666; }
|
|
|
|
.bordered {
|
|
border-style: solid;
|
|
border-color: #999999;
|
|
border-width: 1px 0 0 1px;
|
|
}
|
|
|
|
.bordered td {
|
|
border-style: solid;
|
|
border-color: #999999;
|
|
border-width: 0 1px 1px 0;
|
|
}
|
|
|
|
.bordered tr > :first-child {
|
|
padding: 1px 12px 1px 12px;
|
|
text-align: center;
|
|
}
|
|
|
|
.bordered td.open { border-bottom: none; }
|
|
|
|
</style>
|
|
</head>
|
|
<body>
|
|
|
|
<h1 class="top">Expression Evaluator</h1>
|
|
<p>
|
|
The emulator is capable of evaluating expressions within breakpoint
|
|
conditions and Go To prompts. These expressions inspect the current emulation
|
|
state and can be used to dynamically process registers, variables and other
|
|
data elements that may change from one invocation to the next.
|
|
</p>
|
|
<p>
|
|
Expressions are organized into series of tokens with three main modes of
|
|
significance:
|
|
</p>
|
|
<table class="indent">
|
|
<tr>
|
|
<td class="narrow nowrap">• Value</td>
|
|
<td>
|
|
Numeric value that can be used in computation. This may take the form of
|
|
a literal number provided directly in the expression, or one of the
|
|
named symbols that represent things in the CPU state, current
|
|
instruction and/or current memory access.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="narrow nowrap">• Operator</td>
|
|
<td>
|
|
Modifies one or two values through a given operation. Unary operators
|
|
modify only the value on their right, while binary operators consider the
|
|
values on their left and right and produce a new value as the result.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• Group</td>
|
|
<td>
|
|
Operand groups, mainly through the use of parentheses <code>()</code>,
|
|
override the default order of operations. Anything enclosed in a group
|
|
is processed before any operations adjacent to that group.
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<p>
|
|
Expressions are case-insensitive.
|
|
</p>
|
|
|
|
|
|
|
|
<h2>Values</h2>
|
|
<p>
|
|
Values come in two forms:
|
|
</p>
|
|
<table class="indent">
|
|
<tr>
|
|
<td class="narrow nowrap">• Literal</td>
|
|
<td>Provided directly by the expression.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• Symbol</td>
|
|
<td>Refers to something in the current emulation state.</td>
|
|
</tr>
|
|
</table>
|
|
<p>
|
|
Values may be one of four data types:
|
|
</p>
|
|
<table class="indent">
|
|
<tr>
|
|
<td class="narrow nowrap">• Signed Word</td>
|
|
<td>
|
|
32-bit, two's complement integer.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• Unsigned Word</td>
|
|
<td>
|
|
32-bit, unsigned integer.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• Float</td>
|
|
<td>
|
|
32-bit floating short in IEEE-754 format.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• Boolean</td>
|
|
<td>
|
|
1-bit value representing whether a condition is true or false.
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<p>
|
|
Signed word and unsigned word are represented as sequences of character
|
|
digits. A numeric token that begins with the characters <code>0x</code>
|
|
will be interpreted as hexadecimal, allowing letters <code>A</code> through
|
|
<code>F</code> to be used as digits as well. If the given value can be
|
|
represented in the signed word data type, the token is a signed word.
|
|
Otherwise, if it can be represented in the unsigned word data type, the token
|
|
is an unsigned word. If the value cannot be represented in either data type,
|
|
a parsing error occurs.
|
|
</p>
|
|
<p>
|
|
Floats, like words, are represented as sequences of character digits. They
|
|
are differentiated from words by the presence of a dot <code>.</code>
|
|
character somewhere within the sequence. Only one dot may be present in a
|
|
float literal, and dots cannot be used in hexadecimal literals. If the given
|
|
value cannot be represented in the float data type, a parsing error occurs.
|
|
Float values in the expression evaluator are subjected to the same
|
|
restrictions as on the Virtual Boy's CPU: if the result of any float
|
|
operation is NaN, an infinity, a denormal number or negative zero, it will be
|
|
changed to positive zero.
|
|
</p>
|
|
<p>
|
|
Booleans are mechanically identical to signed words, but the semantics are
|
|
slightly different. When used in a numeric operation, a boolean will use the
|
|
value <code>0</code> if false or the value <code>1</code> if true. Boolean
|
|
literals are specified with the named values <code>true</code> and
|
|
<code>false</code> within the expression. In a boolean operation, any result
|
|
that is zero is considered false, and any non-zero value is considered true.
|
|
</p>
|
|
<p>
|
|
Operators exist for converting between data types (see Operators below). A
|
|
Go To expression will only be valid if its final data type is signed word or
|
|
unsigned word.
|
|
</p>
|
|
<p>
|
|
The following symbols may be used for accessing information about the current
|
|
instruction being executed:
|
|
</p>
|
|
<table class="indent">
|
|
<tr>
|
|
<td class="mono narrow">address</td>
|
|
<td>Current memory access's address.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">break</td>
|
|
<td>
|
|
Identifies what type of break scenario is being considered. See below for
|
|
a list of identifiers.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">code</td>
|
|
<td>Current exception's exception code.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">cond</td>
|
|
<td>
|
|
Condition code for <code>Bcond</code> and <code>SETF</code>
|
|
instructions. See below for a list of conditions.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">disp</td>
|
|
<td>Displacement offset for jumps and memory accesses.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">fetch</td>
|
|
<td>
|
|
Data unit index during a fetch operation, or <code>-1</code> if the read
|
|
operation is not a fetch.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">format</td>
|
|
<td>Current instruction's encoding format.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">id</td>
|
|
<td>
|
|
Identifies which specific instruction is being executed, considering
|
|
<code>opcode</code> and, where applicable, <code>subopcode</code>. See
|
|
below for a list of identifiers.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">imm</td>
|
|
<td>Immediate operand.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">opcode</td>
|
|
<td>Current instruction's top-level opcode.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">reg1</td>
|
|
<td>Source register index.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">reg2</td>
|
|
<td>Destination register index.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">regid</td>
|
|
<td>
|
|
System register index in <code>LDSR</code> and <code>STSR</code>
|
|
instructions.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">size</td>
|
|
<td>Number of bytes occupied by the current instruction.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">subopcode</td>
|
|
<td>Current instruction's secondary opcode.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">type</td>
|
|
<td>Data type of the current memory access.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">value</td>
|
|
<td>Value read by the current memory access.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">vector</td>
|
|
<td>Vector for <code>TRAP</code> instructions.</td>
|
|
</tr>
|
|
</table>
|
|
<p>
|
|
The following symbols may be used in conjunction with the <code>break</code>
|
|
symbol:
|
|
</p>
|
|
<div class="indent mono" style="column-width: 75px;">
|
|
<div>exception</div><div>execute</div><div>read</div><div>write</div>
|
|
</div>
|
|
<p>
|
|
The following symbols may be used in conjunction with the <code>cond</code>
|
|
symbol:
|
|
</p>
|
|
<div class="indent mono" style="column-width: 75px;">
|
|
<div>c </div><div>e </div><div>f </div><div>ge</div><div>gt</div>
|
|
<div>h </div><div>l </div><div>le</div><div>lt</div><div>n </div>
|
|
<div>nc</div><div>ne</div><div>nh</div><div>nl</div><div>nv</div>
|
|
<div>nz</div><div>p </div><div>t </div><div>v </div><div>z </div>
|
|
</div>
|
|
<p>
|
|
The following symbols may be used in conjunction with the <code>id</code>
|
|
symbol:
|
|
</p>
|
|
<div class="indent mono" style="column-width: 75px;">
|
|
<div>illegal</div><div>add_imm</div><div>add_reg</div><div>addf.s </div>
|
|
<div>addi </div><div>and </div><div>andbsu </div><div>andi </div>
|
|
<div>andnbsu</div><div>bcond </div><div>caxi </div><div>cli </div>
|
|
<div>cmp_imm</div><div>cmp_reg</div><div>cmpf.s </div><div>cvt.sw </div>
|
|
<div>cvt.ws </div><div>div </div><div>divf.s </div><div>divu </div>
|
|
<div>halt </div><div>in.b </div><div>in.h </div><div>in.w </div>
|
|
<div>jal </div><div>jmp </div><div>jr </div><div>ld.b </div>
|
|
<div>ld.h </div><div>ld.w </div><div>ldsr </div><div>mov_imm</div>
|
|
<div>mov_reg</div><div>movbsu </div><div>movea </div><div>movhi </div>
|
|
<div>mpyhw </div><div>mul </div><div>mulf.s </div><div>mulu </div>
|
|
<div>not </div><div>notbsu </div><div>or </div><div>orbsu </div>
|
|
<div>ori </div><div>ornbsu </div><div>out.b </div><div>out.h </div>
|
|
<div>out.w </div><div>reti </div><div>rev </div><div>sar_imm</div>
|
|
<div>sar_reg</div><div>sch0bsd</div><div>sch0bsu</div><div>sch1bsd</div>
|
|
<div>sch1bsu</div><div>sei </div><div>setf </div><div>shl_imm</div>
|
|
<div>shl_reg</div><div>shr_imm</div><div>shr_reg</div><div>st.b </div>
|
|
<div>st.h </div><div>st.w </div><div>stsr </div><div>sub </div>
|
|
<div>subf.s </div><div>trap </div><div>trnc.sw</div><div>xb </div>
|
|
<div>xh </div><div>xor </div><div>xorbsu </div><div>xori </div>
|
|
<div>xornbsu</div>
|
|
</div>
|
|
<p>
|
|
The following symbols may be used to retrieve the contents of a CPU program
|
|
register:
|
|
</p>
|
|
<div class="indent mono" style="column-width: 75px;">
|
|
<div>r0 </div><div>r1 </div><div>r2 </div><div>r3 </div><div>r4 </div>
|
|
<div>r5 </div><div>r6 </div><div>r7 </div><div>r8 </div><div>r9 </div>
|
|
<div>r10</div><div>r11</div><div>r12</div><div>r13</div><div>r14</div>
|
|
<div>r15</div><div>r16</div><div>r17</div><div>r18</div><div>r19</div>
|
|
<div>r20</div><div>r21</div><div>r22</div><div>r23</div><div>r24</div>
|
|
<div>r25</div><div>r26</div><div>r27</div><div>r28</div><div>r29</div>
|
|
<div>r30</div><div>r31</div><div>gp </div><div>hp </div><div>lp </div>
|
|
<div>sp </div><div>tp </div>
|
|
</div>
|
|
<p>
|
|
The following symbols may be used to retrieve the contents of a CPU system
|
|
register:
|
|
</p>
|
|
<div class="indent mono" style="column-width: 75px;">
|
|
<div>adtre</div><div>chcw </div><div>ecr </div><div>eipc</div>
|
|
<div>eipsw</div><div>fepc </div><div>fepsw</div><div>pc </div>
|
|
<div>pir </div><div>psw </div><div>tkcw </div><div>sr29</div>
|
|
<div>sr30 </div><div>sr31 </div>
|
|
</div>
|
|
|
|
|
|
<h2>Operators</h2>
|
|
<p>
|
|
Operators may apply to one (unary) or two (binary) values. All unary
|
|
operators appear to the left of the value they modify (or another unary
|
|
operator). Binary operators appear between the values they modify. Each
|
|
operator considers the types of its operands in order to produce a new value
|
|
of the appropriate type.
|
|
</p>
|
|
<p>
|
|
If the operands of a binary operator have different types, one of the values
|
|
will be converted to the other type before performing the operation. The
|
|
conversion depends on the "greater" of the two types, in the following order
|
|
(higher is "greater"):
|
|
</p>
|
|
<table class="indent">
|
|
<tr><td class="center narrow">↑</td><td>Float</td></tr>
|
|
<tr><td class="center"></td><td>Unsigned word</td></tr>
|
|
<tr><td class="center"></td><td>Signed word</td></tr>
|
|
<tr><td class="center">↓</td><td>Boolean</td></tr>
|
|
</table>
|
|
<p>
|
|
For example, if an operation contains both a signed word and a float, the
|
|
signed word value is first converted to float.
|
|
</p>
|
|
<p>
|
|
Operators have assigned precedence that specifies the order of operations.
|
|
For example, in the expression <code>1 + 2 * 3</code>, the multiplication
|
|
happens before the addition because it has higher precedence. Parentheses
|
|
<code>()</code> may be used to encapsulate operations and guarantee that they
|
|
are evaluated first regardless of the relative precedence of the adjacent
|
|
operators. For example, in the expression <code>(1 + 2) * 3</code>, the
|
|
addition happens before the multiplication because it is enclosed in
|
|
parentheses.
|
|
</p>
|
|
<p>
|
|
The following operators may be used in expressions. Groups listed higher have
|
|
higher precedence and happen before groups listed lower. Operators within
|
|
groups have the same precedence and are processed in the order they appear in
|
|
the expression from left to right.
|
|
</p>
|
|
<table class="indent bordered">
|
|
<tr>
|
|
<td class="mono open">~</td>
|
|
<td class="open">Not Bitwise</td>
|
|
<td class="open">Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">!</td>
|
|
<td class="open">Not Logical</td>
|
|
<td class="open">Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">-</td>
|
|
<td class="open">Negate</td>
|
|
<td class="open">Cannot be used with an unsigned word value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">bool</td>
|
|
<td class="open">Cast to Boolean</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">ceil</td>
|
|
<td class="open">Round Up</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">float</td>
|
|
<td class="open">Cast to Float</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">floor</td>
|
|
<td class="open">Round Down</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">round</td>
|
|
<td class="open">Round to Nearest</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>s8</code>, <code>byte</code></td>
|
|
<td class="open">Cast to Signed Byte</td>
|
|
<td class="open">Result is of type signed word.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>s16</code>, <code>halfword</code></td>
|
|
<td class="open">Cast to Signed Halfword</td>
|
|
<td class="open">Result is of type signed word.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>s32</code>, <code>word</code></td>
|
|
<td class="open">Cast to Signed Word</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">trunc</td>
|
|
<td class="open">Truncate</td>
|
|
<td class="open">Removes any fraction.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code><code>u8</code>, ubyte</code></td>
|
|
<td class="open">Cast to Unsigned Byte</td>
|
|
<td class="open">Result is of type unsigned word.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>u16</code>, <code>uhalfword</code></td>
|
|
<td class="open">Cast to Unsigned Halfword</td>
|
|
<td class="open">Result is of type unsigned word.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>u32</code>, <code>uword</code></td>
|
|
<td class="open">Cast to Unsigned Word</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">xfloat</td>
|
|
<td class="open">Reinterpret as Float</td>
|
|
<td class="open">The binary value is not modified.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="open"><code>xs32</code>, <code>xword</code></td>
|
|
<td class="open">Reinterpret as Signed Word</td>
|
|
<td class="open">The binary value is not modified.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><code>xu32</code>, <code>xuword</code></td>
|
|
<td>Reinterpret as Unsgned Word</td>
|
|
<td>The binary value is not modified.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">/</td>
|
|
<td class="open">Divide</td>
|
|
<td class="open">Zero divisor yields zero as result.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">*</td>
|
|
<td class="open">Multiply</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">%</td>
|
|
<td>Remainder</td>
|
|
<td>Zero divisor yields zero as result.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">+</td>
|
|
<td class="open">Add</td>
|
|
<td class="open"></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">-</td>
|
|
<td>Subtract</td>
|
|
<td></td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open"><<</td>
|
|
<td class="open">Shift Left</td>
|
|
<td class="open">Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">>></td>
|
|
<td class="open">Shift Right Arithmetic</td>
|
|
<td class="open">Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">>>></td>
|
|
<td>Shift Right Logical</td>
|
|
<td>Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">></td>
|
|
<td class="open">Greater</td>
|
|
<td class="open">Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">>=</td>
|
|
<td class="open">Greater or Equal</td>
|
|
<td class="open">Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open"><</td>
|
|
<td class="open">Less</td>
|
|
<td class="open">Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono"><=</td>
|
|
<td>Less or Equal</td>
|
|
<td>Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono open">==</td>
|
|
<td class="open">Equal</td>
|
|
<td class="open">Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">!=</td>
|
|
<td>Not Equal</td>
|
|
<td>Always produces a boolean.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">&</td>
|
|
<td>And Bitwise</td>
|
|
<td>Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">^</td>
|
|
<td>Exclusive Or Bitwise</td>
|
|
<td>Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">|</td>
|
|
<td>Or Bitwise</td>
|
|
<td>Cannot be used with a float value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">&&</td>
|
|
<td>And Logical</td>
|
|
<td>If left is true, returns right; else returns left.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">^^</td>
|
|
<td>Exclusive Or Logical</td>
|
|
<td>If only one operand is true, returns the truthy value.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="mono">||</td>
|
|
<td>Or Logical</td>
|
|
<td>If left is true, returns left; else returns right.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
|
|
|
|
<h2>Memory Read</h2>
|
|
<p>
|
|
A value can be read from the memory bus of the emulation state. This is done
|
|
by enclosing the part of the expression that represents the address in square
|
|
brackets <code>[]</code>. This functions in an identical manner to
|
|
parentheses <code>()</code>, but will additionally perform the read
|
|
operation.
|
|
</p>
|
|
<p>
|
|
Under most circumstances, a signed word read is performed. Certain operators
|
|
can be placed in front of the group to alter how the read is performed:
|
|
</p>
|
|
<table class="indent">
|
|
<tr>
|
|
<td class="narrow nowrap">• <code>float</code></td>
|
|
<td>Behaves like <code>xfloat</code> instead.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• <code>s8</code>, <code>u8</code></td>
|
|
<td>Performs a byte read of the specified signedness.</td>
|
|
</tr>
|
|
<tr>
|
|
<td class="nowrap">• <code>s16</code>, <code>u16</code></td>
|
|
<td>Performs a halfword read of the specified signedness.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
</body>
|
|
</html>
|