<<<
[#insns-c_sext_b,reftext="Sign extend byte, 16-bit encoding"]
=== c.sext.b

Synopsis::
Sign extend byte, 16-bit encoding

Mnemonic::
c.sext.b _rd'/rs1'_

Encoding (RV32, RV64)::
[wavedrom, , svg]
....
{reg:[
    { bits:  2, name: 0x1, attr: ['C1'] },
    { bits:  3, name: 0x1, attr: ['C.SEXT.B'] },
    { bits:  2, name: 0x3, attr: ['FUNCT2'] },
    { bits:  3, name: 'rd\'/rs1\'', attr: ['SRCDST'] },
    { bits:  3, name: 0x7 },
    { bits:  3, name: 0x4, attr: ['FUNCT3'] },
],config:{bits:16}}
....

Description::
This instruction takes a single source/destination operand. 
It sign-extends the least-significant byte in the operand to XLEN bits by copying the most-significant bit
in the byte (i.e., bit 7) to all of the more-significant bits.

[NOTE]
  _rd'/rs1'_ is from the standard 8-register set x8-x15.

Prerequisites::
Zbb is also required.

32-bit equivalent::
<<insns-sext_b>> from Zbb

[NOTE]

  The SAIL module variable for _rd'/rs1'_ is called _rsdc_.

Operation::
[source,sail]
--
X(rsdc) = EXTS(X(rsdc)[7..0]);
--

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