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BEXTR
Extracts a contiguous range of bits from the source operand, starting at the index specified by the control operand, and writes the result to the destination operand. The destination is zero-extended to the size of the operand.
The following table covers what the source and destinations can be:
| source | destination(s) |
|---|---|
| reg | reg |
| mN | reg |
DO NOT support LOCK
BEXTR is available only in 64-bit mode or 32-bit mode (via BMI1). It is NOT supported in 16-bit compatibility mode.
The control operand (reg or mN) MUST provide the start index in bits 7:0 and the length in bits 15:8. If the start index or the length exceeds the size of the source operand, the instruction SHALL return 0. The result is always zero-extended, meaning bits higher than the extracted length are cleared.