09.01.2013 Views

AMD x86-64 Architecture Programmer's Manual, Volume 4, 128-Bit ...

AMD x86-64 Architecture Programmer's Manual, Volume 4, 128-Bit ...

AMD x86-64 Architecture Programmer's Manual, Volume 4, 128-Bit ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

26568—Rev. 3.05—September 2003 <strong>AMD</strong><strong>64</strong> Technology<br />

COMISS Compare Ordered Scalar Single-Precision<br />

Floating-Point<br />

Performs an ordered comparison of the single-precision floating-point value in the<br />

low-order 32 bits of an XMM register with the single-precision floating-point value in<br />

the low-order 32 bits of another XMM register or a 32-bit memory location and sets the<br />

ZF, PF, and CF bits in the rFLAGS register to reflect the result of the comparison. The<br />

result is unordered if one or both of the operand values is a NaN. The OF, AF, and SF<br />

bits in rFLAGS are set to zero.<br />

If the instruction causes an unmasked SIMD floating-point exception (#XF), the<br />

rFLAGS bits are not updated.<br />

Mnemonic Opcode Description<br />

COMISS xmm1, xmm2/mem32 0F 2F /r Compares single-precision floating-point values in an XMM register<br />

and an XMM register or 32-bit memory location. Sets rFLAGS.<br />

xmm1 xmm2/mem32<br />

127 31 0 127 31<br />

0<br />

63<br />

0<br />

31<br />

compare<br />

rFLAGS<br />

Result of Compare ZF PF CF<br />

Unordered 1 1 1<br />

Greater Than 0 0 0<br />

Less Than 0 0 1<br />

Equal 1 0 0<br />

0<br />

comiss.eps<br />

COMISS 39

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!