Method write

crates/virtual-machine/src/cpu/csr.rs:183–290

(&mut self, addr: u16, val: u64)

    }

    pub fn write(&mut self, addr: u16, val: u64) -> Result<(), VmError> {
        use addr::{
            CYCLE, FCSR, FFLAGS, FRM, INSTRET, MCAUSE, MCOUNTEREN, MEDELEG, MEPC, MHARTID, MIDELEG,
            MIE, MIP, MISA, MSCRATCH, MSTATUS, MTVAL, MTVEC, SATP, SCAUSE, SCOUNTEREN, SEPC, SIE,
            SIP, SSCRATCH, SSTATUS, STVAL, STVEC,
        };
        match addr {
            FFLAGS => {
                self.fflags = (val & 0x1F) as u8;
            }
            FRM => {
                self.frm = (val & 0x07) as u8;
            }
            FCSR => {
                self.fflags = (val & 0x1F) as u8;
                self.frm = ((val >> 5) & 0x07) as u8;
            }
            // Read-only counters; writes silently ignored.
            CYCLE | INSTRET | MHARTID | MISA => {}

            // sstatus write updates only the S-mode-visible bits of mstatus.
            SSTATUS => {
                self.mstatus = (self.mstatus & !SSTATUS_MASK) | (val & SSTATUS_MASK);
            }
            // sie write updates only the S-mode-visible interrupt-enable bits of mie.
            SIE => {
                self.mie = (self.mie & !S_IRQ_MASK) | (val & S_IRQ_MASK);
            }
            STVEC => {
                self.stvec = val;
            }
            // SCOUNTEREN: stub, ignore writes.
            SCOUNTEREN => {}
            SSCRATCH => {
                self.sscratch = val;
            }
            SEPC => {
                self.sepc = val & !0x3;
            }
            SCAUSE => {
                self.scause = val;
            }
            STVAL => {
                self.stval = val;
            }
            // sip write: only SSIP (bit 1) is software-writable from S-mode.
            SIP => {
                self.mip = (self.mip & !(1u64 << 1)) | (val & (1u64 << 1));
            }
            SATP => {
                let mode = (val >> 60) & 0xF;
                if mode == 0 || mode == 8 {
                    self.satp = val;
                } else {
                    // Unsupported mode: set Bare (mode=0) silently.
                    self.satp = val & !(0xFu64 << 60);
                }
            }