//! Register types and the core interface for armv8-M

use crate::architecture::arm::memory::adi_v5_memory_interface::ArmProbe;
use crate::architecture::arm::sequences::ArmDebugSequence;
use crate::architecture::arm::ArmError;
use crate::core::RegisterFile;
use crate::error::Error;
use crate::memory::valid_32bit_address;
use crate::{architecture::arm::core::register, CoreStatus, HaltReason, MemoryInterface};
use crate::{Architecture, CoreInformation};
use crate::{CoreInterface, CoreType, InstructionSet, MemoryMappedRegister};
use crate::{RegisterId, RegisterValue};
use anyhow::Result;

use bitfield::bitfield;

use super::cortex_m::Mvfr0;
use super::{CortexMState, Dfsr, CORTEX_M_COMMON_REGS, CORTEX_M_WITH_FP_REGS};
use std::sync::Arc;
use std::{
    mem::size_of,
    time::{Duration, Instant},
};

/// The state of a core that can be used to persist core state across calls to multiple different cores.
pub struct Armv8m<'probe> {
    memory: Box<dyn ArmProbe + 'probe>,

    state: &'probe mut CortexMState,

    sequence: Arc<dyn ArmDebugSequence>,
}

impl<'probe> Armv8m<'probe> {
    pub(crate) fn new(
        mut memory: Box<dyn ArmProbe + 'probe>,
        state: &'probe mut CortexMState,
        sequence: Arc<dyn ArmDebugSequence>,
    ) -> Result<Self, Error> {
        if !state.initialized() {
            // determine current state
            let dhcsr = Dhcsr(memory.read_word_32(Dhcsr::ADDRESS)?);

            tracing::debug!("State when connecting: {:x?}", dhcsr);

            let core_state = if dhcsr.s_sleep() {
                CoreStatus::Sleeping
            } else if dhcsr.s_halt() {
                let dfsr = Dfsr(memory.read_word_32(Dfsr::ADDRESS)?);

                let reason = dfsr.halt_reason();

                tracing::debug!("Core was halted when connecting, reason: {:?}", reason);

                CoreStatus::Halted(reason)
            } else {
                CoreStatus::Running
            };

            // Clear DFSR register. The bits in the register are sticky,
            // so we clear them here to ensure that that none are set.
            let dfsr_clear = Dfsr::clear_all();

            memory.write_word_32(Dfsr::ADDRESS, dfsr_clear.into())?;

            state.current_state = core_state;
            state.fp_present = Mvfr0(memory.read_word_32(Mvfr0::ADDRESS)?).fp_present();

            state.initialize();
        }

        Ok(Self {
            memory,
            state,
            sequence,
        })
    }
}

impl<'probe> CoreInterface for Armv8m<'probe> {
    fn wait_for_core_halted(&mut self, timeout: Duration) -> Result<(), Error> {
        // Wait until halted state is active again.
        let start = Instant::now();

        while start.elapsed() < timeout {
            if self.core_halted()? {
                return Ok(());
            }

            std::thread::sleep(Duration::from_millis(1));
        }
        Err(Error::Arm(ArmError::Timeout))
    }

    fn core_halted(&mut self) -> Result<bool, Error> {
        // Wait until halted state is active again.
        Ok(self.status()?.is_halted())
    }

    fn halt(&mut self, timeout: Duration) -> Result<CoreInformation, Error> {
        let mut value = Dhcsr(0);
        value.set_c_halt(true);
        value.set_c_debugen(true);
        value.enable_write();

        self.memory.write_word_32(Dhcsr::ADDRESS, value.into())?;

        self.wait_for_core_halted(timeout)?;

        // Update core status
        let _ = self.status()?;

        // try to read the program counter
        let pc_value = self.read_core_reg(register::PC.id)?;

        // get pc
        Ok(CoreInformation {
            pc: pc_value.try_into()?,
        })
    }

    fn run(&mut self) -> Result<(), Error> {
        // Before we run, we always perform a single instruction step, to account for possible breakpoints that might get us stuck on the current instruction.
        self.step()?;

        let mut value = Dhcsr(0);
        value.set_c_halt(false);
        value.set_c_debugen(true);
        value.enable_write();

        self.memory.write_word_32(Dhcsr::ADDRESS, value.into())?;
        self.memory.flush()?;

        // We assume that the core is running now
        self.state.current_state = CoreStatus::Running;

        Ok(())
    }

    fn reset(&mut self) -> Result<(), Error> {
        self.sequence
            .reset_system(&mut *self.memory, crate::CoreType::Armv8m, None)?;
        Ok(())
    }

    fn reset_and_halt(&mut self, _timeout: Duration) -> Result<CoreInformation, Error> {
        // Set the vc_corereset bit in the DEMCR register.
        // This will halt the core after reset.

        self.sequence
            .reset_catch_set(&mut *self.memory, crate::CoreType::Armv8m, None)?;
        self.sequence
            .reset_system(&mut *self.memory, crate::CoreType::Armv8m, None)?;

        // Update core status
        let _ = self.status()?;

        const XPSR_THUMB: u32 = 1 << 24;
        let xpsr_value: u32 = self.read_core_reg(register::XPSR.id)?.try_into()?;
        if xpsr_value & XPSR_THUMB == 0 {
            self.write_core_reg(register::XPSR.id, (xpsr_value | XPSR_THUMB).into())?;
        }

        self.sequence
            .reset_catch_clear(&mut *self.memory, crate::CoreType::Armv8m, None)?;

        // try to read the program counter
        let pc_value = self.read_core_reg(register::PC.id)?;

        // get pc
        Ok(CoreInformation {
            pc: pc_value.try_into()?,
        })
    }

    fn step(&mut self) -> Result<CoreInformation, Error> {
        // First check if we stopped on a breakpoint, because this requires special handling before we can continue.
        let pc_before_step = self.read_core_reg(self.registers().program_counter().id)?;
        let was_breakpoint = if matches!(
            self.state.current_state,
            CoreStatus::Halted(HaltReason::Breakpoint(_))
        ) {
            self.enable_breakpoints(false)?;
            true
        } else {
            false
        };

        let mut value = Dhcsr(0);
        // Leave halted state.
        // Step one instruction.
        value.set_c_step(true);
        value.set_c_halt(false);
        value.set_c_debugen(true);
        value.set_c_maskints(true);
        value.enable_write();

        self.memory.write_word_32(Dhcsr::ADDRESS, value.into())?;
        self.memory.flush()?;

        self.wait_for_core_halted(Duration::from_millis(100))?;

        // Try to read the new program counter.
        let mut pc_after_step = self.read_core_reg(self.registers().program_counter().id)?;

        // Re-enable breakpoints before we continue.
        if was_breakpoint {
            // If we were stopped on a software breakpoint, then we need to manually advance the PC, or else we will be stuck here forever.
            if pc_before_step == pc_after_step
                && !self
                    .hw_breakpoints()?
                    .contains(&pc_before_step.try_into().ok())
            {
                tracing::debug!("Encountered a breakpoint instruction @ {}. We need to manually advance the program counter to the next instruction.", pc_after_step);
                // Advance the program counter by the architecture specific byte size of the BKPT instruction.
                pc_after_step.incremenet_address(2)?;
                self.write_core_reg(self.registers().program_counter().id, pc_after_step)?;
            }
            self.enable_breakpoints(true)?;
        }

        Ok(CoreInformation {
            pc: pc_after_step.try_into()?,
        })
    }

    fn read_core_reg(&mut self, address: RegisterId) -> Result<RegisterValue, Error> {
        if self.state.current_state.is_halted() {
            let value = super::cortex_m::read_core_reg(&mut *self.memory, address)?;
            Ok(value.into())
        } else {
            Err(Error::Arm(ArmError::CoreNotHalted))
        }
    }

    fn write_core_reg(&mut self, address: RegisterId, value: RegisterValue) -> Result<(), Error> {
        if self.state.current_state.is_halted() {
            super::cortex_m::write_core_reg(&mut *self.memory, address, value.try_into()?)?;
            Ok(())
        } else {
            Err(Error::Arm(ArmError::CoreNotHalted))
        }
    }

    fn available_breakpoint_units(&mut self) -> Result<u32, Error> {
        let raw_val = self.memory.read_word_32(FpCtrl::ADDRESS)?;

        let reg = FpCtrl::from(raw_val);

        Ok(reg.num_code())
    }

    fn enable_breakpoints(&mut self, state: bool) -> Result<(), Error> {
        let mut val = FpCtrl::from(0);
        val.set_key(true);
        val.set_enable(state);

        self.memory.write_word_32(FpCtrl::ADDRESS, val.into())?;
        self.memory.flush()?;

        self.state.hw_breakpoints_enabled = state;

        Ok(())
    }

    fn set_hw_breakpoint(&mut self, bp_unit_index: usize, addr: u64) -> Result<(), Error> {
        let addr = valid_32bit_address(addr)?;

        let mut val = FpCompN::from(0);

        // clear bits which cannot be set and shift into position
        let comp_val = (addr & 0xff_ff_ff_fe) >> 1;

        val.set_bp_addr(comp_val);
        val.set_enable(true);

        let reg_addr = FpCompN::ADDRESS + (bp_unit_index * size_of::<u32>()) as u64;

        self.memory.write_word_32(reg_addr, val.into())?;

        Ok(())
    }

    fn registers(&self) -> &'static RegisterFile {
        if self.state.fp_present {
            &CORTEX_M_WITH_FP_REGS
        } else {
            &CORTEX_M_COMMON_REGS
        }
    }

    fn clear_hw_breakpoint(&mut self, bp_unit_index: usize) -> Result<(), Error> {
        let mut val = FpCompN::from(0);
        val.set_enable(false);
        val.set_bp_addr(0);

        let reg_addr = FpCompN::ADDRESS + (bp_unit_index * size_of::<u32>()) as u64;

        self.memory.write_word_32(reg_addr, val.into())?;

        Ok(())
    }

    fn hw_breakpoints_enabled(&self) -> bool {
        self.state.hw_breakpoints_enabled
    }

    fn architecture(&self) -> Architecture {
        Architecture::Arm
    }

    fn core_type(&self) -> CoreType {
        CoreType::Armv8m
    }

    fn instruction_set(&mut self) -> Result<InstructionSet, Error> {
        Ok(InstructionSet::Thumb2)
    }

    fn status(&mut self) -> Result<crate::core::CoreStatus, Error> {
        let dhcsr = Dhcsr(self.memory.read_word_32(Dhcsr::ADDRESS)?);

        if dhcsr.s_lockup() {
            tracing::warn!(
                "The core is in locked up status as a result of an unrecoverable exception"
            );

            self.state.current_state = CoreStatus::LockedUp;

            return Ok(CoreStatus::LockedUp);
        }

        if dhcsr.s_sleep() {
            // Check if we assumed the core to be halted
            if self.state.current_state.is_halted() {
                tracing::warn!("Expected core to be halted, but core is running");
            }

            self.state.current_state = CoreStatus::Sleeping;

            return Ok(CoreStatus::Sleeping);
        }

        // TODO: Handle lockup

        if dhcsr.s_halt() {
            let dfsr = Dfsr(self.memory.read_word_32(Dfsr::ADDRESS)?);

            let reason = dfsr.halt_reason();

            // Clear bits from Dfsr register
            self.memory
                .write_word_32(Dfsr::ADDRESS, Dfsr::clear_all().into())?;

            // If the core was halted before, we cannot read the halt reason from the chip,
            // because we clear it directly after reading.
            if self.state.current_state.is_halted() {
                // There shouldn't be any bits set, otherwise it means
                // that the reason for the halt has changed. No bits set
                // means that we have an unkown HaltReason.
                if reason == HaltReason::Unknown {
                    tracing::debug!("Cached halt reason: {:?}", self.state.current_state);
                    return Ok(self.state.current_state);
                }

                tracing::debug!(
                    "Reason for halt has changed, old reason was {:?}, new reason is {:?}",
                    &self.state.current_state,
                    &reason
                );
            }

            self.state.current_state = CoreStatus::Halted(reason);

            return Ok(CoreStatus::Halted(reason));
        }

        // Core is neither halted nor sleeping, so we assume it is running.
        if self.state.current_state.is_halted() {
            tracing::warn!("Core is running, but we expected it to be halted");
        }

        self.state.current_state = CoreStatus::Running;

        Ok(CoreStatus::Running)
    }

    /// See docs on the [`CoreInterface::hw_breakpoints`] trait
    fn hw_breakpoints(&mut self) -> Result<Vec<Option<u64>>, Error> {
        let mut breakpoints = vec![];
        let num_hw_breakpoints = self.available_breakpoint_units()? as usize;
        for bp_unit_index in 0..num_hw_breakpoints {
            let reg_addr = FpCompN::ADDRESS + (bp_unit_index * size_of::<u32>()) as u64;
            // The raw breakpoint address as read from memory
            let register_value = self.memory.read_word_32(reg_addr)?;
            // The breakpoint address after it has been adjusted for FpRev 1 or 2
            if FpCompN::from(register_value).enable() {
                let breakpoint = FpCompN::from(register_value).bp_addr() << 1;
                breakpoints.push(Some(breakpoint as u64));
            } else {
                breakpoints.push(None);
            }
        }
        Ok(breakpoints)
    }

    fn fpu_support(&mut self) -> Result<bool, crate::error::Error> {
        Ok(self.state.fp_present)
    }
}

impl<'probe> MemoryInterface for Armv8m<'probe> {
    fn supports_native_64bit_access(&mut self) -> bool {
        self.memory.supports_native_64bit_access()
    }
    fn read_word_32(&mut self, address: u64) -> Result<u32, Error> {
        self.memory
            .read_word_32(address)
            .map_err(From::<ArmError>::from)
    }
    fn read_word_8(&mut self, address: u64) -> Result<u8, Error> {
        self.memory
            .read_word_8(address)
            .map_err(From::<ArmError>::from)
    }

    fn read_64(&mut self, address: u64, data: &mut [u64]) -> Result<(), crate::error::Error> {
        self.memory
            .read_64(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn read_32(&mut self, address: u64, data: &mut [u32]) -> Result<(), Error> {
        self.memory
            .read_32(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn read_8(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
        self.memory
            .read_8(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn read_word_64(&mut self, address: u64) -> Result<u64, crate::error::Error> {
        self.memory
            .read_word_64(address)
            .map_err(From::<ArmError>::from)
    }

    fn write_word_64(&mut self, address: u64, data: u64) -> Result<(), crate::error::Error> {
        self.memory
            .write_word_64(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write_word_32(&mut self, address: u64, data: u32) -> Result<(), Error> {
        self.memory
            .write_word_32(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write_word_8(&mut self, address: u64, data: u8) -> Result<(), Error> {
        self.memory
            .write_word_8(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write_64(&mut self, address: u64, data: &[u64]) -> Result<(), crate::error::Error> {
        self.memory
            .write_64(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write_32(&mut self, address: u64, data: &[u32]) -> Result<(), Error> {
        self.memory
            .write_32(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write_8(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
        self.memory
            .write_8(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn write(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
        self.memory
            .write(address, data)
            .map_err(From::<ArmError>::from)
    }

    fn supports_8bit_transfers(&self) -> Result<bool, Error> {
        self.memory
            .supports_8bit_transfers()
            .map_err(From::<ArmError>::from)
    }

    fn flush(&mut self) -> Result<(), Error> {
        self.memory.flush().map_err(From::<ArmError>::from)
    }
}

/*
pub const REGISTERS: BasicRegisterAddresses = BasicRegisterAddresses {
    R0: CoreRegisterAddress(0b0_0000),
    R1: CoreRegisterAddress(0b0_0001),
    R2: CoreRegisterAddress(0b0_0010),
    R3: CoreRegisterAddress(0b0_0011),
    R4: CoreRegisterAddress(0b0_0100),
    R5: CoreRegisterAddress(0b0_0101),
    R6: CoreRegisterAddress(0b0_0110),
    R7: CoreRegisterAddress(0b0_0111),
    R8: CoreRegisterAddress(0b0_1000),
    R9: CoreRegisterAddress(0b0_1001),
    PC: CoreRegisterAddress(0b0_1111),
    SP: CoreRegisterAddress(0b0_1101),
    LR: CoreRegisterAddress(0b0_1110),
    XPSR: CoreRegisterAddress(0b1_0000),
};
*/

bitfield! {
    /// Debug Halting Control and Status Register, DHCSR (see armv8-M Architecture Reference Manual D1.2.38)
    ///
    /// To write this register successfully, you need to set the debug key via [`Dhcsr::enable_write`] first!
    #[derive(Copy, Clone)]
    pub struct Dhcsr(u32);
    impl Debug;
    /// Restart sticky status. Indicates the PE has processed a request to clear DHCSR.C_HALT to 0. That is, either
    /// a write to DHCSR that clears DHCSR.C_HALT from 1 to 0, or an External Restart Request.
    ///
    /// The possible values of this bit are:
    ///
    /// `0`: PE has not left Debug state since the last read of DHCSR.\
    /// `1`: PE has left Debug state since the last read of DHCSR.
    ///
    /// If the PE is not halted when `C_HALT` is cleared to zero, it is UNPREDICTABLE whether this bit is set to `1`. If
    /// `DHCSR.C_DEBUGEN == 0` this bit reads as an UNKNOWN value.
    ///
    /// This bit clears to zero when read.
    ///
    /// **Note**
    ///
    /// If the request to clear C_HALT is made simultaneously with a request to set C_HALT, for example
    /// a restart request and external debug request occur together, then the
    pub s_restart_st, _ : 26;
    ///  Indicates whether the processor has been reset since the last read of DHCSR:
    ///
    /// `0`: No reset since last DHCSR read.\
    /// `1`: At least one reset since last DHCSR read.
    ///
    /// This is a sticky bit, that clears to `0` on a read of DHCSR.
    pub s_reset_st, _: 25;
    /// When not in Debug state, indicates whether the processor has completed
    /// the execution of an instruction since the last read of DHCSR:
    ///
    /// `0`: No instruction has completed since last DHCSR read.\
    /// `1`: At least one instructions has completed since last DHCSR read.
    ///
    /// This is a sticky bit, that clears to `0` on a read of DHCSR.
    ///
    /// This bit is UNKNOWN:
    ///
    /// - after a Local reset, but is set to `1` as soon as the processor completes
    /// execution of an instruction.
    /// - when S_LOCKUP is set to `1`.
    /// - when S_HALT is set to `1`.
    ///
    /// When the processor is not in Debug state, a debugger can check this bit to
    /// determine if the processor is stalled on a load, store or fetch access.
    pub s_retire_st, _: 24;
    /// Floating-point registers Debuggable.
    /// Indicates that FPSCR, VPR, and the Floating-point registers are RAZ/WI in the current PE state when accessed via DCRSR. This reflects !CanDebugAccessFP().
    /// The possible values of this bit are:
    ///
    /// `0`: Floating-point registers accessible.\
    /// `1`: Floating-point registers are RAZ/WI.
    ///
    /// If version Armv8.1-M of the architecture is not implemented, this bit is RES0
    pub s_fpd, _: 23;
    /// Secure unprivileged halting debug enabled. Indicates whether Secure unprivileged-only halting debug is allowed or active.
    /// The possible values of this bit are:
    ///
    /// `0`: Secure invasive halting debug prohibited or not restricted to an unprivileged mode.\
    /// `1`: Unprivileged Secure invasive halting debug enabled.
    ///
    /// If the PE is in Non-debug state, this bit reflects the value of `UnprivHaltingDebugAllowed(TRUE) && !SecureHaltingDebugAllowed()`.
    ///
    /// The value of this bit does not change whilst the PE remains in Debug state.
    ///
    /// If the Security Extension is not implemented, this bit is RES0.
    /// If version Armv8.1 of the architecture and UDE are not implemented, this bit is RES0.
    pub s_suide, _: 22;
    /// Non-secure unprivileged halting debug enabled. Indicates whether Non-secure unprivileged-only halting debug is allowed or active.
    ///
    /// The possible values of this bit are:
    ///
    /// `0`: Non-secure invasive halting debug prohibited or not restricted to an unprivileged mode.\
    /// `1`: Unprivileged Non-secure invasive halting debug enabled.
    ///
    /// If the PE is in Non-debug state, this bit reflects the value of `UnprivHaltingDebugAllowed(FALSE) &&
    /// !HaltingDebugAllowed()`.
    ///
    /// The value of this bit does not change whilst the PE remains in Debug state.
    /// If version Armv8.1 of the architecture and UDE are not implemented, this bit is RES0
    pub s_nsuide, _: 21;
    /// Secure debug enabled. Indicates whether Secure invasive debug is allowed.
    /// The possible values of this bit are:
    ///
    /// `0`: Secure invasive debug prohibited.\
    /// `1`: Secure invasive debug allowed.
    ///
    /// If the PE is in Non-debug state, this bit reflects the value of SecureHaltingDebugAllowed() or UnprivHaltingDebugAllowed(TRUE).
    ///
    /// The value of this bit does not change while the PE remains in Debug state.
    ///
    /// If the Security Extension is not implemented, this bit is RES0.
    pub s_sde, _: 20;
    /// Indicates whether the processor is locked up because of an unrecoverable
    /// exception:
    ///
    /// `0` Not locked up.\
    /// `1` Locked up.
    /// See Unrecoverable exception cases on page B1-206 for more
    /// information.
    ///
    /// This bit can only read as `1` when accessed by a remote debugger using the
    /// DAP. The value of `1` indicates that the processor is running but locked up.
    /// The bit clears to `0` when the processor enters Debug state.
    pub s_lockup, _: 19;
    /// Indicates whether the processor is sleeping:
    ///
    /// `0` Not sleeping.
    /// `1` Sleeping.
    ///
    /// The debugger must set the DHCSR.C_HALT bit to `1` to gain control, or
    /// wait for an interrupt or other wakeup event to wakeup the system
    pub s_sleep, _: 18;
    /// Indicates whether the processor is in Debug state:
    ///
    /// `0`: Not in Debug state.\
    /// `1`: In Debug state.
    pub s_halt, _: 17;
    /// A handshake flag for transfers through the DCRDR:
    ///
    /// - Writing to DCRSR clears the bit to `0`.\
    /// - Completion of the DCRDR transfer then sets the bit to `1`.
    ///
    /// For more information about DCRDR transfers see Debug Core Register
    /// Data Register, DCRDR on page C1-292.
    ///
    /// `0`: There has been a write to the DCRDR, but the transfer is not complete.\
    /// `1` The transfer to or from the DCRDR is complete.
    ///
    /// This bit is only valid when the processor is in Debug state, otherwise the
    /// bit is UNKNOWN.
    pub s_regrdy, _: 16;
    /// Halt on PMU overflow control. Request entry to Debug state when a PMU counter overflows.
    ///
    /// The possible values of this bit are:
    ///
    /// `0`: No action.\
    /// `1`: If C_DEBUGEN is set to `1`, then when a PMU counter is configured to generate an interrupt overflows,
    /// the PE sets DHCSR.C_HALT to `1` and DFSR.PMU to `1`.
    ///
    /// PMU_OVSSET and PMU_OVSCLR indicate which counter or counters triggered the halt.
    ///
    /// If the Main Extension is not implemented, this bit is RES0.
    ///
    /// If version Armv8.1 of the architecture and PMU are not implemented, this bit is RES0.
    ///
    /// This bit resets to zero on a Cold reset.
    pub c_pmov, set_c_pmov: 6;
    /// Allow imprecise entry to Debug state. The actions on writing to this bit are:
    ///
    /// `0`: No action.\
    /// `1`: Allow imprecise entry to Debug state, for example by forcing any stalled load
    /// or store instruction to complete.
    ///
    /// Setting this bit to `1` allows a debugger to request imprecise entry to Debug state.
    ///
    /// The effect of setting this bit to `1` is UNPREDICTABLE unless the DHCSR write also sets
    /// C_DEBUGEN and C_HALT to `1`. This means that if the processor is not already in Debug
    /// state it enters Debug state when the stalled instruction completes.
    ///
    /// Writing `1` to this bit makes the state of the memory system UNPREDICTABLE. Therefore, if a
    /// debugger writes `1` to this bit it must reset the processor before leaving Debug state.
    ///
    /// **Note**
    ///
    /// - A debugger can write to the DHCSR to clear this bit to `0`. However, this does not
    /// remove the UNPREDICTABLE state of the memory system caused by setting C_SNAPSTALL to `1`.
    /// - The architecture does not guarantee that setting this bit to 1 will force entry to Debug
    /// state.
    /// - Arm strongly recommends that a value of `1` is never written to C_SNAPSTALL when
    /// the processor is in Debug state.
    ///
    /// A power-on reset sets this bit to `0`.
    pub c_snapstall, set_c_snapstall: 5;
    /// When debug is enabled, the debugger can write to this bit to mask
    /// PendSV, SysTick and external configurable interrupts:
    ///
    /// `0`: Do not mask.\
    /// `1` Mask PendSV, SysTick and external configurable interrupts.
    /// The effect of any attempt to change the value of this bit is UNPREDICTABLE
    /// unless both:
    /// - before the write to DHCSR, the value of the C_HALT bit is `1`.
    /// - the write to the DHCSR that changes the C_MASKINTS bit also
    /// writes `1` to the C_HALT bit.
    ///
    /// This means that a single write to DHCSR cannot set the C_HALT to `0` and
    /// change the value of the C_MASKINTS bit.
    ///
    /// The bit does not affect NMI. When DHCSR.C_DEBUGEN is set to `0`, the
    /// value of this bit is UNKNOWN.
    ///
    /// For more information about the use of this bit see Table C1-9 on
    /// page C1-282.
    ///
    /// This bit is UNKNOWN after a power-on reset.
    pub c_maskints, set_c_maskints: 3;
    /// Processor step bit. The effects of writes to this bit are:
    ///
    /// `0`: Single-stepping disabled.\
    /// `1`: Single-stepping enabled.
    ///
    /// For more information about the use of this bit see Table C1-9 on page C1-282.
    ///
    /// This bit is UNKNOWN after a power-on reset.
    pub c_step, set_c_step: 2;
    /// Processor halt bit. The effects of writes to this bit are:
    ///
    /// `0`: Request a halted processor to run.\
    /// `1`: Request a running processor to halt.
    ///
    /// Table C1-9 on page C1-282 shows the effect of writes to this bit when the
    /// processor is in Debug state.
    ///
    /// This bit is 0 after a System reset
    pub c_halt, set_c_halt: 1;
    /// Halting debug enable bit:
    /// `0`: Halting debug disabled.\
    /// `1`: Halting debug enabled.
    ///
    /// If a debugger writes to DHCSR to change the value of this bit from `0` to
    /// `1`, it must also write 0 to the C_MASKINTS bit, otherwise behavior is UNPREDICTABLE.
    ///
    /// This bit can only be written from the DAP. Access to the DHCSR from
    /// software running on the processor is IMPLEMENTATION DEFINED.
    ///
    /// However, writes to this bit from software running on the processor are ignored.
    ///
    /// This bit is `0` after a power-on reset.
    pub c_debugen, set_c_debugen: 0;
}

impl Dhcsr {
    /// This function sets the bit to enable writes to this register.
    fn enable_write(&mut self) {
        self.0 &= !(0xffff << 16);
        self.0 |= 0xa05f << 16;
    }
}

impl From<u32> for Dhcsr {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl From<Dhcsr> for u32 {
    fn from(value: Dhcsr) -> Self {
        value.0
    }
}

impl MemoryMappedRegister for Dhcsr {
    const ADDRESS: u64 = 0xE000_EDF0;
    const NAME: &'static str = "DHCSR";
}

bitfield! {
    /// Application Interrupt and Reset Control Register, AIRCR (see armv8-M Architecture Reference Manual D1.2.3)
    ///
    /// [`Aircr::vectkey`] must be called before this register can effectively be written!
    #[derive(Copy, Clone)]
    pub struct Aircr(u32);
    impl Debug;
    /// Vector Key. The value `0x05FA` must be written to this register, otherwise
    /// the register write is UNPREDICTABLE.
    get_vectkeystat, set_vectkey: 31,16;
    /// Indicates the memory system data endianness:
    ///
    /// `0`: little endian.\
    /// `1` big endian.
    ///
    /// See Endian support on page A3-44 for more information.
    pub endianness, set_endianness: 15;
    /// Priority grouping, indicates the binary point position.
    /// For information about the use of this field see Priority grouping on page B1-527.
    ///
    /// This field resets to `0b000`.
    pub prigroup, set_prigroup: 10,8;
    /// System reset request Secure only. The value of this bit defines whether the SYSRESETREQ bit is functional for Non-secure use.
    /// This bit is not banked between Security states.
    /// The possible values of this bit are:
    ///
    /// `0`: SYSRESETREQ functionality is available to both Security states.\
    /// `1`: SYSRESETREQ functionality is only available to Secure state.
    ///
    /// This bit is RAZ/WI from Non-secure state.
    /// This bit resets to zero on a Warm reset
    pub sysresetreqs, set_sysresetreqs: 3;
    ///  System Reset Request:
    ///
    /// `0` do not request a reset.\
    /// `1` request reset.
    ///
    /// Writing 1 to this bit asserts a signal to request a reset by the external
    /// system. The system components that are reset by this request are
    /// IMPLEMENTATION DEFINED. A Local reset is required as part of a system
    /// reset request.
    ///
    /// A Local reset clears this bit to `0`.
    ///
    /// See Reset management on page B1-208 for more information
    pub sysresetreq, set_sysresetreq: 2;
    /// Clears all active state information for fixed and configurable exceptions:
    ///
    /// `0`: do not clear state information.\
    /// `1`: clear state information.
    ///
    /// The effect of writing a `1` to this bit if the processor is not halted in Debug
    /// state is UNPREDICTABLE.
    pub vectclractive, set_vectclractive: 1;
    /// Writing `1` to this bit causes a local system reset, see Reset management on page B1-559 for
    /// more information. This bit self-clears.
    ///
    /// The effect of writing a `1` to this bit if the processor is not halted in Debug state is
    /// UNPREDICTABLE.
    ///
    /// When the processor is halted in Debug state, if a write to the register writes a `1` to both
    /// VECTRESET and SYSRESETREQ, the behavior is UNPREDICTABLE.
    ///
    /// This bit is write only.
    pub vectreset, set_vectreset: 0;
}

impl From<u32> for Aircr {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl From<Aircr> for u32 {
    fn from(value: Aircr) -> Self {
        value.0
    }
}

impl Aircr {
    /// Must be called before writing the register.
    pub fn vectkey(&mut self) {
        self.set_vectkey(0x05FA);
    }

    /// Verifies that the vector key is correct (see [`Aircr::vectkey`])
    pub fn vectkeystat(&self) -> bool {
        self.get_vectkeystat() == 0xFA05
    }
}

impl MemoryMappedRegister for Aircr {
    const ADDRESS: u64 = 0xE000_ED0C;
    const NAME: &'static str = "AIRCR";
}

/// Debug Core Register Data Register, DCRDR (see armv8-M Architecture Reference Manual D1.2.32)
#[derive(Debug, Copy, Clone)]
pub struct Dcrdr(u32);

impl From<u32> for Dcrdr {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl From<Dcrdr> for u32 {
    fn from(value: Dcrdr) -> Self {
        value.0
    }
}

impl MemoryMappedRegister for Dcrdr {
    const ADDRESS: u64 = 0xE000_EDF8;
    const NAME: &'static str = "DCRDR";
}

bitfield! {
    /// /// Debug Exception and Monitor Control Register, DEMCR (see armv8-M Architecture Reference Manual D1.2.36)
    #[derive(Copy, Clone)]
    pub struct Demcr(u32);
    impl Debug;
    /// Global enable for DWT, PMU and ITM features
    pub trcena, set_trcena: 24;
    /// Monitor pending request key. Writes to the mon_pend and mon_en fields
    /// request are ignorend unless monprkey is set to zero concurrently.
    pub monprkey, set_monprkey: 23;
    /// Unprivileged monitor enable.
    pub umon_en, set_umon_en: 21;
    /// Secure DebugMonitor enable
    pub sdme, set_sdme: 20;
    /// DebugMonitor semaphore bit
    pub mon_req, set_mon_req: 19;
    /// Step the processor?
    pub mon_step, set_mon_step: 18;
    /// Sets or clears the pending state of the DebugMonitor exception
    pub mon_pend, set_mon_pend: 17;
    /// Enable the DebugMonitor exception
    pub mon_en, set_mon_en: 16;
    /// Enable halting debug on a SecureFault exception
    pub vc_sferr, set_vc_sferr: 11;
    /// Enable halting debug trap on a HardFault exception
    pub vc_harderr, set_vc_harderr: 10;
    /// Enable halting debug trap on a fault occurring during exception entry
    /// or exception return
    pub vc_interr, set_vc_interr: 9;
    /// Enable halting debug trap on a BusFault exception
    pub vc_buserr, set_vc_buserr: 8;
    /// Enable halting debug trap on a UsageFault exception caused by a state
    /// information error, for example an Undefined Instruction exception
    pub vc_staterr, set_vc_staterr: 7;
    /// Enable halting debug trap on a UsageFault exception caused by a
    /// checking error, for example an alignment check error
    pub vc_chkerr, set_vc_chkerr: 6;
    /// Enable halting debug trap on a UsageFault caused by an access to a
    /// Coprocessor
    pub vc_nocperr, set_vc_nocperr: 5;
    /// Enable halting debug trap on a MemManage exception.
    pub vc_mmerr, set_vc_mmerr: 4;
    /// Enable Reset Vector Catch
    pub vc_corereset, set_vc_corereset: 0;
}

impl From<u32> for Demcr {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl From<Demcr> for u32 {
    fn from(value: Demcr) -> Self {
        value.0
    }
}

impl MemoryMappedRegister for Demcr {
    const ADDRESS: u64 = 0xe000_edfc;
    const NAME: &'static str = "DEMCR";
}

bitfield! {
    /// Flash Patch Control Register, FP_CTRL (see armv8-M Architecture Reference Manual D1.2.108)
    #[derive(Copy,Clone)]
    pub struct FpCtrl(u32);
    impl Debug;
    /// Flash Patch breakpoint architecture revision:
    /// 0000 Flash Patch breakpoint version 1.
    /// 0001 Flash Patch breakpoint version 2. Supports breakpoints on any location in the 4GB address range.
    pub rev, _: 31, 28;
    num_code_1, _: 14, 12;
    /// The number of literal address comparators supported, starting from NUM_CODE upwards.
    /// UNK/SBZP if Flash Patch is not implemented. Flash Patch is not implemented if FP_REMAP[29] is 0.
    /// If this field is zero, the implementation does not support literal comparators.
    pub num_lit, _: 11, 8;
    num_code_0, _: 7, 4;
    /// On any write to FP_CTRL, this bit must be 1. A write to the register with this bit set to zero
    /// is ignored. The Flash Patch Breakpoint unit ignores the write unless this bit is 1.
    pub _, set_key: 1;
    /// Enable bit for the FPB:
    /// 0 Flash Patch breakpoint disabled.
    /// 1 Flash Patch breakpoint enabled.
    /// A power-on reset clears this bit to 0.
    pub enable, set_enable: 0;
}

impl FpCtrl {
    /// The number of instruction address comparators.
    /// If NUM_CODE is zero, the implementation does not support any instruction address comparators.
    pub fn num_code(&self) -> u32 {
        (self.num_code_1() << 4) | self.num_code_0()
    }
}

impl MemoryMappedRegister for FpCtrl {
    const ADDRESS: u64 = 0xE000_2000;
    const NAME: &'static str = "FP_CTRL";
}

impl From<u32> for FpCtrl {
    fn from(value: u32) -> Self {
        FpCtrl(value)
    }
}

impl From<FpCtrl> for u32 {
    fn from(value: FpCtrl) -> Self {
        value.0
    }
}

bitfield! {
    /// FP_COMPn, Flash Patch Comparator Register, n = 0 - 125 (see armv8-M Architecture Reference Manual D1.2.107)
    #[derive(Copy,Clone)]
    pub struct FpCompN(u32);
    impl Debug;
    /// BPADDR, bits[31:1] Breakpoint address. Specifies bits[31:1] of the breakpoint instruction address.
    /// If BE == 0, this field is Reserved, UNK/SBZP.
    /// The reset value of this field is UNKNOWN.
    pub bp_addr, set_bp_addr: 31, 1;
    /// Enable bit for breakpoint:
    /// 0 Breakpoint disabled.
    /// 1 Breakpoint enabled.
    /// The reset value of this bit is UNKNOWN.
    pub enable, set_enable: 0;
}

impl MemoryMappedRegister for FpCompN {
    const ADDRESS: u64 = 0xE000_2008;
    const NAME: &'static str = "FP_COMPn";
}

impl From<u32> for FpCompN {
    fn from(value: u32) -> Self {
        FpCompN(value)
    }
}

impl From<FpCompN> for u32 {
    fn from(value: FpCompN) -> Self {
        value.0
    }
}