zext.h
Zero-extend halfword
This instruction is defined by:
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anyOf:
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B, version >= 0
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Zbb, version >= 0
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This instruction is included in the following profiles:
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RVA22U64 (Mandatory)
Synopsis
This instruction zero-extends the least-significant halfword of the source to XLEN by inserting 0’s into all of the bits more significant than 15.
The zext.h instruction is a pseudo-op for pack when Zbkb is implemented and XLEN == 32.
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The zext.h instruction is a pseudo-op for packw when Zbkb is implemented and XLEN == 64.
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Decode Variables
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RV32
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RV64
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];Execution
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IDL
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Sail
if (implemented?(ExtensionName::B) && (CSR[misa].B == 1'b0)) {
raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
X[rd] = X[rs1][15:0];{
let rs1_val = X(rs1);
let result : xlenbits = match op {
RISCV_SEXTB => sign_extend(rs1_val[7..0]),
RISCV_SEXTH => sign_extend(rs1_val[15..0]),
RISCV_ZEXTH => zero_extend(rs1_val[15..0])
};
X(rd) = result;
RETIRE_SUCCESS
}