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| <title>Using as: i386-Float</title> |
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| <a name="i386_002dFloat"></a> |
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| <p> |
| Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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| <hr> |
| <a name="Floating-Point-9"></a> |
| <h4 class="subsection">9.15.10 Floating Point</h4> |
| |
| <a name="index-i386-floating-point"></a> |
| <a name="index-floating-point_002c-i386"></a> |
| <a name="index-x86_002d64-floating-point"></a> |
| <a name="index-floating-point_002c-x86_002d64"></a> |
| <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. |
| </p> |
| <a name="index-float-directive_002c-i386"></a> |
| <a name="index-single-directive_002c-i386"></a> |
| <a name="index-double-directive_002c-i386"></a> |
| <a name="index-tfloat-directive_002c-i386"></a> |
| <a name="index-float-directive_002c-x86_002d64"></a> |
| <a name="index-single-directive_002c-x86_002d64"></a> |
| <a name="index-double-directive_002c-x86_002d64"></a> |
| <a name="index-tfloat-directive_002c-x86_002d64"></a> |
| <ul> |
| <li> Floating point constructors are ‘<samp>.float</samp>’ or ‘<samp>.single</samp>’, |
| ‘<samp>.double</samp>’, and ‘<samp>.tfloat</samp>’ for 32-, 64-, and 80-bit formats. |
| These correspond to instruction mnemonic suffixes ‘<samp>s</samp>’, ‘<samp>l</samp>’, |
| and ‘<samp>t</samp>’. ‘<samp>t</samp>’ stands for 80-bit (ten byte) real. The 80387 |
| only supports this format via the ‘<samp>fldt</samp>’ (load 80-bit real to stack |
| top) and ‘<samp>fstpt</samp>’ (store 80-bit real and pop stack) instructions. |
| |
| </li><li> <a name="index-word-directive_002c-i386"></a> |
| <a name="index-long-directive_002c-i386"></a> |
| <a name="index-int-directive_002c-i386"></a> |
| <a name="index-quad-directive_002c-i386"></a> |
| <a name="index-word-directive_002c-x86_002d64"></a> |
| <a name="index-long-directive_002c-x86_002d64"></a> |
| <a name="index-int-directive_002c-x86_002d64"></a> |
| <a name="index-quad-directive_002c-x86_002d64"></a> |
| Integer constructors are ‘<samp>.word</samp>’, ‘<samp>.long</samp>’ or ‘<samp>.int</samp>’, and |
| ‘<samp>.quad</samp>’ for the 16-, 32-, and 64-bit integer formats. The |
| corresponding instruction mnemonic suffixes are ‘<samp>s</samp>’ (single), |
| ‘<samp>l</samp>’ (long), and ‘<samp>q</samp>’ (quad). As with the 80-bit real format, |
| the 64-bit ‘<samp>q</samp>’ format is only present in the ‘<samp>fildq</samp>’ (load |
| quad integer to stack top) and ‘<samp>fistpq</samp>’ (store quad integer and pop |
| stack) instructions. |
| </li></ul> |
| |
| <p>Register to register operations should not use instruction mnemonic suffixes. |
| ‘<samp>fstl %st, %st(1)</samp>’ will give a warning, and be assembled as if you |
| wrote ‘<samp>fst %st, %st(1)</samp>’, since all register to register operations |
| use 80-bit floating point operands. (Contrast this with ‘<samp>fstl %st, mem</samp>’, |
| which converts ‘<samp>%st</samp>’ from 80-bit to 64-bit floating point format, |
| then stores the result in the 4 byte location ‘<samp>mem</samp>’) |
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| Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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