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<a name="i386_002dFloat"></a>Next:&nbsp;<a rel="next" accesskey="n" href="i386_002dSIMD.html#i386_002dSIMD">i386-SIMD</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="i386_002dJumps.html#i386_002dJumps">i386-Jumps</a>,
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<h4 class="subsection">9.13.10 Floating Point</h4>
<p><a name="index-i386-floating-point-923"></a><a name="index-floating-point_002c-i386-924"></a><a name="index-x86_002d64-floating-point-925"></a><a name="index-floating-point_002c-x86_002d64-926"></a>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.
<p><a name="index-_0040code_007bfloat_007d-directive_002c-i386-927"></a><a name="index-_0040code_007bsingle_007d-directive_002c-i386-928"></a><a name="index-_0040code_007bdouble_007d-directive_002c-i386-929"></a><a name="index-_0040code_007btfloat_007d-directive_002c-i386-930"></a><a name="index-_0040code_007bfloat_007d-directive_002c-x86_002d64-931"></a><a name="index-_0040code_007bsingle_007d-directive_002c-x86_002d64-932"></a><a name="index-_0040code_007bdouble_007d-directive_002c-x86_002d64-933"></a><a name="index-_0040code_007btfloat_007d-directive_002c-x86_002d64-934"></a>
<ul>
<li>Floating point constructors are <span class="samp">.float</span> or <span class="samp">.single</span>,
<span class="samp">.double</span>, and <span class="samp">.tfloat</span> for 32-, 64-, and 80-bit formats.
These correspond to instruction mnemonic suffixes <span class="samp">s</span>, <span class="samp">l</span>,
and <span class="samp">t</span>. <span class="samp">t</span> stands for 80-bit (ten byte) real. The 80387
only supports this format via the <span class="samp">fldt</span> (load 80-bit real to stack
top) and <span class="samp">fstpt</span> (store 80-bit real and pop stack) instructions.
<p><a name="index-_0040code_007bword_007d-directive_002c-i386-935"></a><a name="index-_0040code_007blong_007d-directive_002c-i386-936"></a><a name="index-_0040code_007bint_007d-directive_002c-i386-937"></a><a name="index-_0040code_007bquad_007d-directive_002c-i386-938"></a><a name="index-_0040code_007bword_007d-directive_002c-x86_002d64-939"></a><a name="index-_0040code_007blong_007d-directive_002c-x86_002d64-940"></a><a name="index-_0040code_007bint_007d-directive_002c-x86_002d64-941"></a><a name="index-_0040code_007bquad_007d-directive_002c-x86_002d64-942"></a><li>Integer constructors are <span class="samp">.word</span>, <span class="samp">.long</span> or <span class="samp">.int</span>, and
<span class="samp">.quad</span> for the 16-, 32-, and 64-bit integer formats. The
corresponding instruction mnemonic suffixes are <span class="samp">s</span> (single),
<span class="samp">l</span> (long), and <span class="samp">q</span> (quad). As with the 80-bit real format,
the 64-bit <span class="samp">q</span> format is only present in the <span class="samp">fildq</span> (load
quad integer to stack top) and <span class="samp">fistpq</span> (store quad integer and pop
stack) instructions.
</ul>
<p>Register to register operations should not use instruction mnemonic suffixes.
<span class="samp">fstl %st, %st(1)</span> will give a warning, and be assembled as if you
wrote <span class="samp">fst %st, %st(1)</span>, since all register to register operations
use 80-bit floating point operands. (Contrast this with <span class="samp">fstl %st, mem</span>,
which converts <span class="samp">%st</span> from 80-bit to 64-bit floating point format,
then stores the result in the 4 byte location <span class="samp">mem</span>)
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