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FXAM
Compares two floating-point values (ST(0) and a source operand) and sets the floating-point status word flags based on the result of the comparison.
The following table covers what the source and destinations can be:
| source | destination(s) |
|---|---|
| f32/f64 | ST(0) |
| m32/m64 | ST(0) |
| ST(i) | ST(0) |
DO NOT support LOCK
This instruction is available in 64-bit mode, compatibility mode, and 32-bit mode. It operates exclusively on the x87 Floating-Point Unit (FPU) register stack.
The source operand must be a valid floating-point number. If the source is a memory operand, the size (m32 or m64) must match the precision of the comparison.
Using FXAM with an invalid operand or a signaling NaN SHALL trigger #I. If the comparison involves denormalized operands, #D MAY be signaled depending on the control word settings. Precision loss during the internal comparison process SHALL trigger #P.