📄 v850-opcodes.html

📁 gcc手册
💻 HTML
字号:
<html lang="en">

<head>

<title>Using as</title>

<meta http-equiv="Content-Type" content="text/html">

<meta name="description" content="Using as">

<meta name="generator" content="makeinfo 4.3">

<link href="http://www.gnu.org/software/texinfo/" rel="generator-home">

</head>

<body>

<div class="node">

<p>

Node:<a name="V850%20Opcodes">V850 Opcodes</a>,

Previous:<a rel="previous" accesskey="p" href="V850-Directives.html#V850%20Directives">V850 Directives</a>,

Up:<a rel="up" accesskey="u" href="V850-Dependent.html#V850-Dependent">V850-Dependent</a>

<hr><br>

</div>



<h4 class="section">Opcodes</h4>



   <p><code>as</code> implements all the standard V850 opcodes.



   <p><code>as</code> also implements the following pseudo ops:



     <dl>



     <br><dt><code>hi0()</code>

     <dd>Computes the higher 16 bits of the given expression and stores it into

the immediate operand field of the given instruction.  For example:



     <p><code>mulhi hi0(here - there), r5, r6</code>



     <p>computes the difference between the address of labels 'here' and

'there', takes the upper 16 bits of this difference, shifts it down 16

bits and then mutliplies it by the lower 16 bits in register 5, putting

the result into register 6.



     <br><dt><code>lo()</code>

     <dd>Computes the lower 16 bits of the given expression and stores it into

the immediate operand field of the given instruction.  For example:



     <p><code>addi lo(here - there), r5, r6</code>



     <p>computes the difference between the address of labels 'here' and

'there', takes the lower 16 bits of this difference and adds it to

register 5, putting the result into register 6.



     <br><dt><code>hi()</code>

     <dd>Computes the higher 16 bits of the given expression and then adds the

value of the most significant bit of the lower 16 bits of the expression

and stores the result into the immediate operand field of the given

instruction.  For example the following code can be used to compute the

address of the label 'here' and store it into register 6:



     <p><code>movhi hi(here), r0, r6</code>

    <code>movea lo(here), r6, r6</code>



     <p>The reason for this special behaviour is that movea performs a sign

extention on its immediate operand.  So for example if the address of

'here' was 0xFFFFFFFF then without the special behaviour of the hi()

pseudo-op the movhi instruction would put 0xFFFF0000 into r6, then the

movea instruction would takes its immediate operand, 0xFFFF, sign extend

it to 32 bits, 0xFFFFFFFF, and then add it into r6 giving 0xFFFEFFFF

which is wrong (the fifth nibble is E).  With the hi() pseudo op adding

in the top bit of the lo() pseudo op, the movhi instruction actually

stores 0 into r6 (0xFFFF + 1 = 0x0000), so that the movea instruction

stores 0xFFFFFFFF into r6 - the right value.



     <br><dt><code>hilo()</code>

     <dd>Computes the 32 bit value of the given expression and stores it into

the immediate operand field of the given instruction (which must be a

mov instruction).  For example:



     <p><code>mov hilo(here), r6</code>



     <p>computes the absolute address of label 'here' and puts the result into

register 6.



     <br><dt><code>sdaoff()</code>

     <dd>Computes the offset of the named variable from the start of the Small

Data Area (whoes address is held in register 4, the GP register) and

stores the result as a 16 bit signed value in the immediate operand

field of the given instruction.  For example:



     <p><code>ld.w sdaoff(_a_variable)[gp],r6</code>



     <p>loads the contents of the location pointed to by the label '_a_variable'

into register 6, provided that the label is located somewhere within +/-

32K of the address held in the GP register.  [Note the linker assumes

that the GP register contains a fixed address set to the address of the

label called '__gp'.  This can either be set up automatically by the

linker, or specifically set by using the <code>--defsym __gp=&lt;value&gt;</code>

command line option].



     <br><dt><code>tdaoff()</code>

     <dd>Computes the offset of the named variable from the start of the Tiny

Data Area (whoes address is held in register 30, the EP register) and

stores the result as a 4,5, 7 or 8 bit unsigned value in the immediate

operand field of the given instruction.  For example:



     <p><code>sld.w tdaoff(_a_variable)[ep],r6</code>



     <p>loads the contents of the location pointed to by the label '_a_variable'

into register 6, provided that the label is located somewhere within +256

bytes of the address held in the EP register.  [Note the linker assumes

that the EP register contains a fixed address set to the address of the

label called '__ep'.  This can either be set up automatically by the

linker, or specifically set by using the <code>--defsym __ep=&lt;value&gt;</code>

command line option].



     <br><dt><code>zdaoff()</code>

     <dd>Computes the offset of the named variable from address 0 and stores the

result as a 16 bit signed value in the immediate operand field of the

given instruction.  For example:



     <p><code>movea zdaoff(_a_variable),zero,r6</code>



     <p>puts the address of the label '_a_variable' into register 6, assuming

that the label is somewhere within the first 32K of memory.  (Strictly

speaking it also possible to access the last 32K of memory as well, as

the offsets are signed).



     <br><dt><code>ctoff()</code>

     <dd>Computes the offset of the named variable from the start of the Call

Table Area (whoes address is helg in system register 20, the CTBP

register) and stores the result a 6 or 16 bit unsigned value in the

immediate field of then given instruction or piece of data.  For

example:



     <p><code>callt ctoff(table_func1)</code>



     <p>will put the call the function whoes address is held in the call table

at the location labeled 'table_func1'.



   </dl>



   <p>For information on the V850 instruction set, see <cite>V850

Family 32-/16-Bit single-Chip Microcontroller Architecture Manual</cite> from NEC. 

Ltd.



   </body></html>
⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -