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/* ****************************************************************** */
/* This file specifies the instructions in the 'Zicsr' extension. */
/* ****************************************************************** */
union clause ast = CSR : (bits(12), regbits, regbits, bool, csrop)
mapping encdec_csrop : csrop <-> bits(2) = {
CSRRW <-> 0b01,
CSRRS <-> 0b10,
CSRRC <-> 0b11
}
mapping clause encdec = CSR(csr, rs1, rd, is_imm, op)
<-> csr @ rs1 @ bool_bits(is_imm) @ encdec_csrop(op) @ rd @ 0b1110011
function readCSR csr : csreg -> xlenbits = {
let res : xlenbits =
match (csr, sizeof(xlen)) {
/* machine mode */
(0xF11, _) => EXTZ(mvendorid),
(0xF12, _) => marchid,
(0xF13, _) => mimpid,
(0xF14, _) => mhartid,
(0x300, _) => mstatus.bits(),
(0x301, _) => misa.bits(),
(0x302, _) => medeleg.bits(),
(0x303, _) => mideleg.bits(),
(0x304, _) => mie.bits(),
(0x305, _) => mtvec.bits(),
(0x306, _) => EXTZ(mcounteren.bits()),
(0x340, _) => mscratch,
(0x341, _) => get_xret_target(Machine) & pc_alignment_mask(),
(0x342, _) => mcause.bits(),
(0x343, _) => mtval,
(0x344, _) => mip.bits(),
(0x3A0, _) => pmpcfg0,
(0x3B0, _) => pmpaddr0,
/* machine mode counters */
(0xB00, _) => mcycle[(sizeof(xlen) - 1) .. 0],
(0xB02, _) => minstret[(sizeof(xlen) - 1) .. 0],
(0xB80, 32) => mcycle[63 .. 32],
(0xB82, 32) => minstret[63 .. 32],
/* trigger/debug */
(0x7a0, _) => ~(tselect), /* this indicates we don't have any trigger support */
/* supervisor mode */
(0x100, _) => lower_mstatus(mstatus).bits(),
(0x102, _) => sedeleg.bits(),
(0x103, _) => sideleg.bits(),
(0x104, _) => lower_mie(mie, mideleg).bits(),
(0x105, _) => stvec.bits(),
(0x106, _) => EXTZ(scounteren.bits()),
(0x140, _) => sscratch,
(0x141, _) => get_xret_target(Supervisor) & pc_alignment_mask(),
(0x142, _) => scause.bits(),
(0x143, _) => stval,
(0x144, _) => lower_mip(mip, mideleg).bits(),
(0x180, _) => satp,
/* user mode counters */
(0xC00, _) => mcycle[(sizeof(xlen) - 1) .. 0],
(0xC01, _) => mtime[(sizeof(xlen) - 1) .. 0],
(0xC02, _) => minstret[(sizeof(xlen) - 1) .. 0],
(0xC80, 32) => mcycle[63 .. 32],
(0xC81, 32) => mtime[63 .. 32],
(0xC82, 32) => minstret[63 .. 32],
_ => /* check extensions */
match read_UExt_CSR(csr) {
Some(res) => res,
None() => { print_bits("unhandled read to CSR ", csr);
EXTZ(0x0) }
}
};
print_reg("CSR " ^ csr ^ " -> " ^ BitStr(res));
res
}
function writeCSR (csr : csreg, value : xlenbits) -> unit = {
let res : option(xlenbits) =
match (csr, sizeof(xlen)) {
/* machine mode */
(0x300, _) => { mstatus = legalize_mstatus(mstatus, value); Some(mstatus.bits()) },
(0x301, _) => { misa = legalize_misa(misa, value); Some(misa.bits()) },
(0x302, _) => { medeleg = legalize_medeleg(medeleg, value); Some(medeleg.bits()) },
(0x303, _) => { mideleg = legalize_mideleg(mideleg, value); Some(mideleg.bits()) },
(0x304, _) => { mie = legalize_mie(mie, value); Some(mie.bits()) },
(0x305, _) => { mtvec = legalize_tvec(mtvec, value); Some(mtvec.bits()) },
(0x306, _) => { mcounteren = legalize_mcounteren(mcounteren, value); Some(EXTZ(mcounteren.bits())) },
(0x340, _) => { mscratch = value; Some(mscratch) },
(0x341, _) => { Some(set_xret_target(Machine, value)) },
(0x342, _) => { mcause->bits() = value; Some(mcause.bits()) },
(0x343, _) => { mtval = value; Some(mtval) },
(0x344, _) => { mip = legalize_mip(mip, value); Some(mip.bits()) },
(0x3A0, _) => { pmpcfg0 = value; Some(pmpcfg0) }, /* FIXME: legalize */
(0x3B0, _) => { pmpaddr0 = value; Some(pmpaddr0) }, /* FIXME: legalize */
/* machine mode counters */
(0xB00, _) => { mcycle[(sizeof(xlen) - 1) .. 0] = value; Some(value) },
(0xB02, _) => { minstret[(sizeof(xlen) - 1) .. 0] = value; minstret_written = true; Some(value) },
(0xB80, 32) => { mcycle[63 .. 32] = value; Some(value) },
(0xB82, 32) => { minstret[63 .. 32] = value; minstret_written = true; Some(value) },
/* trigger/debug */
(0x7a0, _) => { tselect = value; Some(tselect) },
/* supervisor mode */
(0x100, _) => { mstatus = legalize_sstatus(mstatus, value); Some(mstatus.bits()) },
(0x102, _) => { sedeleg = legalize_sedeleg(sedeleg, value); Some(sedeleg.bits()) },
(0x103, _) => { sideleg->bits() = value; Some(sideleg.bits()) }, /* TODO: does this need legalization? */
(0x104, _) => { mie = legalize_sie(mie, mideleg, value); Some(mie.bits()) },
(0x105, _) => { stvec = legalize_tvec(stvec, value); Some(stvec.bits()) },
(0x106, _) => { scounteren = legalize_scounteren(scounteren, value); Some(EXTZ(scounteren.bits())) },
(0x140, _) => { sscratch = value; Some(sscratch) },
(0x141, _) => { Some(set_xret_target(Supervisor, value)) },
(0x142, _) => { scause->bits() = value; Some(scause.bits()) },
(0x143, _) => { stval = value; Some(stval) },
(0x144, _) => { mip = legalize_sip(mip, mideleg, value); Some(mip.bits()) },
(0x180, _) => { satp = legalize_satp(cur_Architecture(), satp, value); Some(satp) },
_ => None()
};
match res {
Some(v) => print_reg("CSR " ^ csr ^ " <- " ^ BitStr(v) ^ " (input: " ^ BitStr(value) ^ ")"),
None() => { /* check extensions */
if write_UExt_CSR(csr, value)
then ()
else print_bits("unhandled write to CSR ", csr)
}
}
}
function clause execute CSR(csr, rs1, rd, is_imm, op) = {
let rs1_val : xlenbits = if is_imm then EXTZ(rs1) else X(rs1);
let isWrite : bool = match op {
CSRRW => true,
_ => if is_imm then unsigned(rs1_val) != 0 else unsigned(rs1) != 0
};
if ~ (check_CSR(csr, cur_privilege, isWrite))
then { handle_illegal(); false }
else {
let csr_val = readCSR(csr); /* could have side-effects, so technically shouldn't perform for CSRW[I] with rd == 0 */
if isWrite then {
let new_val : xlenbits = match op {
CSRRW => rs1_val,
CSRRS => csr_val | rs1_val,
CSRRC => csr_val & ~(rs1_val)
};
writeCSR(csr, new_val)
};
X(rd) = csr_val;
true
}
}
mapping maybe_i : bool <-> string = {
true <-> "i",
false <-> ""
}
mapping csr_mnemonic : csrop <-> string = {
CSRRW <-> "csrrw",
CSRRS <-> "csrrs",
CSRRC <-> "csrrc"
}
mapping clause assembly = CSR(csr, rs1, rd, true, op)
<-> csr_mnemonic(op) ^ "i" ^ spc() ^ reg_name(rd) ^ sep() ^ hex_bits_5(rs1) ^ sep() ^ csr_name_map(csr)
mapping clause assembly = CSR(csr, rs1, rd, false, op)
<-> csr_mnemonic(op) ^ spc() ^ reg_name(rd) ^ sep() ^ reg_name(rs1) ^ sep() ^ csr_name_map(csr)
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