"""
 mbed CMSIS-DAP debugger
 Copyright (c) 2015-2017 ARM Limited

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
"""

from .provider import (Breakpoint, BreakpointProvider)
from ...core import exceptions
from ...core.target import Target
import logging

class SoftwareBreakpoint(Breakpoint):
    def __init__(self, provider):
        super(SoftwareBreakpoint, self).__init__(provider)
        self.type = Target.BREAKPOINT_SW

class SoftwareBreakpointProvider(BreakpointProvider):
    ## BKPT #0 instruction.
    BKPT_INSTR = 0xbe00

    def __init__(self, core):
        super(SoftwareBreakpointProvider, self).__init__()
        self._core = core
        self._breakpoints = {}

    def init(self):
        pass

    def bp_type(self):
        return Target.BREAKPOINT_SW

    @property
    def do_filter_memory(self):
        return True

    def available_breakpoints(self):
        return -1

    def find_breakpoint(self, addr):
        return self._breakpoints.get(addr, None)

    def set_breakpoint(self, addr):
        assert self._core.memory_map.get_region_for_address(addr).is_ram
        assert (addr & 1) == 0

        try:
            # Read original instruction.
            instr = self._core.read16(addr)

            # Insert BKPT #0 instruction.
            self._core.write16(addr, self.BKPT_INSTR)

            # Create bp object.
            bp = SoftwareBreakpoint(self)
            bp.enabled = True
            bp.addr = addr
            bp.original_instr = instr

            # Save this breakpoint.
            self._breakpoints[addr] = bp
            return bp
        except exceptions.TransferError:
            logging.debug("Failed to set sw bp at 0x%x" % addr)
            return None

    def remove_breakpoint(self, bp):
        assert bp is not None and isinstance(bp, Breakpoint)

        try:
            # Restore original instruction.
            self._core.write16(bp.addr, bp.original_instr)

            # Remove from our list.
            del self._breakpoints[bp.addr]
        except exceptions.TransferError:
            logging.debug("Failed to remove sw bp at 0x%x" % bp.addr)

    def filter_memory(self, addr, size, data):
        for bp in self._breakpoints.values():
            if size == 8:
                if bp.addr == addr:
                    data = bp.original_instr & 0xff
                elif bp.addr + 1 == addr:
                    data = bp.original_instr >> 8
            elif size == 16:
                if bp.addr == addr:
                    data = bp.original_instr
            elif size == 32:
                if bp.addr == addr:
                    data = (data & 0xffff0000) | bp.original_instr
                elif bp.addr == addr + 2:
                    data = (data & 0xffff) | (bp.original_instr << 16)

        return data



