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FIST
Stores the truncated integer part of the ST(0) floating-point value into the specified destination. The instruction rounds the value toward zero.
The following table covers what the source and destinations can be:
| source | destination(s) |
|---|---|
| ST(0) | m16, m32 |
| ST(0) | r16, r32 |
DO NOT support LOCK
FIST is only available in x86-64 when executing in compatibility mode. It is not supported in 64-bit mode.
The destination must be a 16-bit or 32-bit register or memory location; attempting to use a 64-bit destination will result in an invalid operand. If the value in ST(0) is not representable as a signed integer of the destination size, the instruction SHALL trigger an #O exception. The value in ST(0) remains unchanged after execution.