| commit | d3950433008cc524f0d93882f057026f88e346d8 | [log] [tgz] |
|---|---|---|
| author | Jim Lin <jim@andestech.com> | Fri Jun 06 09:02:18 2025 +0800 |
| committer | GitHub <noreply@github.com> | Fri Jun 06 09:02:18 2025 +0800 |
| tree | f766bd02f1be607ba3031fbb78f1a47600895332 | |
| parent | a23bd179cce86c8635bc20b813ee84ebfeed8f5f [diff] |
[RISCV] Select unsigned bitfield insert for XAndesPerf (#142737)
The XAndesPerf extension includes unsigned bitfield extraction
instruction `NDS.BFOZ`, which can extract the bits from 0 to Len -1,
place them starting at bit Msb, and zero-fills the remaining bits.
This patch handles the cases where Msb < Lsb for `NDS.BFOZ`.
Instruction Sytax:
nds.bfoz Rd, Rs1, Msb, Lsb
The operation is:
if Msb < Lsb:
Lenm1 = Lsb - Msb;
Rd[Lsb:Msb] = Rs1[Lenm1:0];
if (Lsb < (XLen -1)) Rd[XLen-1:Lsb+1]=0;
Rd[Msb-1:0]=0;
When Len == 1, it is a special case where the Msb is set to 0 instead of
being equal to the Lsb.
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