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<h4 class="section">Floating Point</h4>



   <p>All 80387 floating point types except packed BCD are supported. 

(BCD support may be added without much difficulty).  These data

types are 16-, 32-, and 64- bit integers, and single (32-bit),

double (64-bit), and extended (80-bit) precision floating point. 

Each supported type has an instruction mnemonic suffix and a constructor

associated with it.  Instruction mnemonic suffixes specify the operand's

data type.  Constructors build these data types into memory.



     <ul>

<li>Floating point constructors are <code>.float</code> or <code>.single</code>,

<code>.double</code>, and <code>.tfloat</code> for 32-, 64-, and 80-bit formats. 

These correspond to instruction mnemonic suffixes <code>s</code>, <code>l</code>,

and <code>t</code>. <code>t</code> stands for 80-bit (ten byte) real.  The 80387

only supports this format via the <code>fldt</code> (load 80-bit real to stack

top) and <code>fstpt</code> (store 80-bit real and pop stack) instructions.



     <li>Integer constructors are <code>.word</code>, <code>.long</code> or <code>.int</code>, and

<code>.quad</code> for the 16-, 32-, and 64-bit integer formats.  The

corresponding instruction mnemonic suffixes are <code>s</code> (single),

<code>l</code> (long), and <code>q</code> (quad).  As with the 80-bit real format,

the 64-bit <code>q</code> format is only present in the <code>fildq</code> (load

quad integer to stack top) and <code>fistpq</code> (store quad integer and pop

stack) instructions. 

</ul>



   <p>Register to register operations should not use instruction mnemonic suffixes. 

<code>fstl %st, %st(1)</code> will give a warning, and be assembled as if you

wrote <code>fst %st, %st(1)</code>, since all register to register operations

use 80-bit floating point operands. (Contrast this with <code>fstl %st, mem</code>,

which converts <code>%st</code> from 80-bit to 64-bit floating point format,

then stores the result in the 4 byte location <code>mem</code>)



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