/*
  limits.c - code pertaining to limit-switches and performing the homing cycle
  Part of Grbl

  Copyright (c) 2012-2016 Sungeun K. Jeon for Gnea Research LLC
  Copyright (c) 2009-2011 Simen Svale Skogsrud

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Grbl is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "grbl.h"

// Homing axis search distance multiplier. Computed by this value times the cycle travel.
#ifndef HOMING_AXIS_SEARCH_SCALAR
#define HOMING_AXIS_SEARCH_SCALAR 1.5 // Must be > 1 to ensure limit switch will be engaged.
#endif
#ifndef HOMING_AXIS_LOCATE_SCALAR
#define HOMING_AXIS_LOCATE_SCALAR 5.0 // Must be > 1 to ensure limit switch is cleared.
#endif

#ifdef ENABLE_DUAL_AXIS
// Flags for dual axis async limit trigger check.
#define DUAL_AXIS_CHECK_DISABLE   0 // Must be zero
#define DUAL_AXIS_CHECK_ENABLE    bit(0)
#define DUAL_AXIS_CHECK_TRIGGER_1 bit(1)
#define DUAL_AXIS_CHECK_TRIGGER_2 bit(2)
#endif

void limits_init() {
    LIMIT_DDR &= ~(LIMIT_MASK); // Set as input pins

#ifdef DISABLE_LIMIT_PIN_PULL_UP
    LIMIT_PORT &= ~(LIMIT_MASK); // Normal low operation. Requires external pull-down.
#else
    LIMIT_PORT |= (LIMIT_MASK); // Enable internal pull-up resistors. Normal high operation.
#endif

    if (bit_istrue(settings.flags, BITFLAG_HARD_LIMIT_ENABLE)) {
        LIMIT_PCMSK |= LIMIT_MASK; // Enable specific pins of the Pin Change Interrupt
        PCICR |= (1 << LIMIT_INT); // Enable Pin Change Interrupt
    } else {
        limits_disable();
    }

#ifdef ENABLE_SOFTWARE_DEBOUNCE
    MCUSR &= ~(1 << WDRF);
    WDTCSR |= (1 << WDCE) | (1 << WDE);
    WDTCSR = (1 << WDP0); // Set time-out at ~32msec.
#endif
}

// Disables hard limits.
void limits_disable() {
    LIMIT_PCMSK &= ~LIMIT_MASK; // Disable specific pins of the Pin Change Interrupt
    PCICR &= ~(1 << LIMIT_INT); // Disable Pin Change Interrupt
}

// Returns limit state as a bit-wise uint8 variable. Each bit indicates an axis limit, where
// triggered is 1 and not triggered is 0. Invert mask is applied. Axes are defined by their
// number in bit position, i.e. Z_AXIS is (1<<2) or bit 2, and Y_AXIS is (1<<1) or bit 1.
uint8_t limits_get_state() {
    uint8_t limit_state = 0;
    uint8_t pin = (LIMIT_PIN & LIMIT_MASK);
#ifdef INVERT_LIMIT_PIN_MASK
    pin ^= INVERT_LIMIT_PIN_MASK;
#endif
    if (bit_isfalse(settings.flags, BITFLAG_INVERT_LIMIT_PINS)) {
        pin ^= LIMIT_MASK;
    }
    if (pin) {
        uint8_t idx;
        for (idx = 0; idx < N_AXIS; idx++) {
            if (pin & get_limit_pin_mask(idx)) {
                limit_state |= (1 << idx);
            }
        }
#ifdef ENABLE_DUAL_AXIS
        if (pin & (1 << DUAL_LIMIT_BIT)) {
            limit_state |= (1 << N_AXIS);
        }
#endif
    }
    return (limit_state);
}

// This is the Limit Pin Change Interrupt, which handles the hard limit feature. A bouncing
// limit switch can cause a lot of problems, like false readings and multiple interrupt calls.
// If a switch is triggered at all, something bad has happened and treat it as such, regardless
// if a limit switch is being disengaged. It's impossible to reliably tell the state of a
// bouncing pin because the Arduino microcontroller does not retain any state information when
// detecting a pin change. If we poll the pins in the ISR, you can miss the correct reading if the
// switch is bouncing.
// NOTE: Do not attach an e-stop to the limit pins, because this interrupt is disabled during
// homing cycles and will not respond correctly. Upon user request or need, there may be a
// special pinout for an e-stop, but it is generally recommended to just directly connect
// your e-stop switch to the Arduino reset pin, since it is the most correct way to do this.
#ifndef ENABLE_SOFTWARE_DEBOUNCE
ISR(LIMIT_INT_vect) // DEFAULT: Limit pin change interrupt process.
{
    // Ignore limit switches if already in an alarm state or in-process of executing an alarm.
    // When in the alarm state, Grbl should have been reset or will force a reset, so any pending
    // moves in the planner and serial buffers are all cleared and newly sent blocks will be
    // locked out until a homing cycle or a kill lock command. Allows the user to disable the hard
    // limit setting if their limits are constantly triggering after a reset and move their axes.
    if (sys.state != STATE_ALARM) {
        if (!(sys_rt_exec_alarm)) {
#ifdef HARD_LIMIT_FORCE_STATE_CHECK
            // Check limit pin state.
            if (limits_get_state()) {
                mc_reset();                                   // Initiate system kill.
                system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
            }
#else
            mc_reset();                                   // Initiate system kill.
            system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
#endif
        }
    }
}
#else // OPTIONAL: Software debounce limit pin routine.
// Upon limit pin change, enable watchdog timer to create a short delay.
ISR(LIMIT_INT_vect) {
    if (!(WDTCSR & (1 << WDIE))) {
        WDTCSR |= (1 << WDIE);
    }
}

ISR(WDT_vect) // Watchdog timer ISR
{
    WDTCSR &= ~(1 << WDIE);         // Disable watchdog timer.
    if (sys.state != STATE_ALARM) { // Ignore if already in alarm state.
        if (!(sys_rt_exec_alarm)) {
            // Check limit pin state.
            if (limits_get_state()) {
                mc_reset();                                   // Initiate system kill.
                system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
            }
        }
    }
}
#endif

// Homes the specified cycle axes, sets the machine position, and performs a pull-off motion after
// completing. Homing is a special motion case, which involves rapid uncontrolled stops to locate
// the trigger point of the limit switches. The rapid stops are handled by a system level axis lock
// mask, which prevents the stepper algorithm from executing step pulses. Homing motions typically
// circumvent the processes for executing motions in normal operation.
// NOTE: Only the abort realtime command can interrupt this process.
// TODO: Move limit pin-specific calls to a general function for portability.
void limits_go_home(uint8_t cycle_mask) {
    if (sys.abort) {
        return;
    } // Block if system reset has been issued.

    // Initialize plan data struct for homing motion. Spindle and coolant are disabled.
    plan_line_data_t  plan_data;
    plan_line_data_t *pl_data = &plan_data;
    memset(pl_data, 0, sizeof(plan_line_data_t));
    pl_data->condition = (PL_COND_FLAG_SYSTEM_MOTION | PL_COND_FLAG_NO_FEED_OVERRIDE);
#ifdef USE_LINE_NUMBERS
    pl_data->line_number = HOMING_CYCLE_LINE_NUMBER;
#endif

    // Initialize variables used for homing computations.
    uint8_t n_cycle = (2 * N_HOMING_LOCATE_CYCLE + 1);
    uint8_t step_pin[N_AXIS];
#ifdef ENABLE_DUAL_AXIS
    uint8_t step_pin_dual;
    uint8_t dual_axis_async_check;
    int32_t dual_trigger_position;
#if (DUAL_AXIS_SELECT == X_AXIS)
    float fail_distance = (-DUAL_AXIS_HOMING_FAIL_AXIS_LENGTH_PERCENT / 100.0) * settings.max_travel[Y_AXIS];
#else
    float fail_distance = (-DUAL_AXIS_HOMING_FAIL_AXIS_LENGTH_PERCENT / 100.0) * settings.max_travel[X_AXIS];
#endif
    fail_distance = min(fail_distance, DUAL_AXIS_HOMING_FAIL_DISTANCE_MAX);
    fail_distance = max(fail_distance, DUAL_AXIS_HOMING_FAIL_DISTANCE_MIN);
    int32_t dual_fail_distance = trunc(fail_distance * settings.steps_per_mm[DUAL_AXIS_SELECT]);
    // int32_t dual_fail_distance =
    // trunc((DUAL_AXIS_HOMING_TRIGGER_FAIL_DISTANCE)*settings.steps_per_mm[DUAL_AXIS_SELECT]);
#endif
    float   target[N_AXIS];
    float   max_travel = 0.0;
    uint8_t idx;
    for (idx = 0; idx < N_AXIS; idx++) {
        // Initialize step pin masks
        step_pin[idx] = get_step_pin_mask(idx);
#ifdef COREXY
        if ((idx == A_MOTOR) || (idx == B_MOTOR)) {
            step_pin[idx] = (get_step_pin_mask(X_AXIS) | get_step_pin_mask(Y_AXIS));
        }
#endif

        if (bit_istrue(cycle_mask, bit(idx))) {
            // Set target based on max_travel setting. Ensure homing switches engaged with search scalar.
            // NOTE: settings.max_travel[] is stored as a negative value.
            max_travel = max(max_travel, (-HOMING_AXIS_SEARCH_SCALAR) * settings.max_travel[idx]);
        }
    }
#ifdef ENABLE_DUAL_AXIS
    step_pin_dual = (1 << DUAL_STEP_BIT);
#endif

    // Set search mode with approach at seek rate to quickly engage the specified cycle_mask limit switches.
    bool  approach = true;
    float homing_rate = settings.homing_seek_rate;

    uint8_t limit_state, axislock, n_active_axis;
    do {

        system_convert_array_steps_to_mpos(target, sys_position);

        // Initialize and declare variables needed for homing routine.
        axislock = 0;
#ifdef ENABLE_DUAL_AXIS
        sys.homing_axis_lock_dual = 0;
        dual_trigger_position = 0;
        dual_axis_async_check = DUAL_AXIS_CHECK_DISABLE;
#endif
        n_active_axis = 0;
        for (idx = 0; idx < N_AXIS; idx++) {
            // Set target location for active axes and setup computation for homing rate.
            if (bit_istrue(cycle_mask, bit(idx))) {
                n_active_axis++;
#ifdef COREXY
                if (idx == X_AXIS) {
                    int32_t axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
                    sys_position[A_MOTOR] = axis_position;
                    sys_position[B_MOTOR] = -axis_position;
                } else if (idx == Y_AXIS) {
                    int32_t axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
                    sys_position[A_MOTOR] = sys_position[B_MOTOR] = axis_position;
                } else {
                    sys_position[Z_AXIS] = 0;
                }
#else
                sys_position[idx] = 0;
#endif
                // Set target direction based on cycle mask and homing cycle approach state.
                // NOTE: This happens to compile smaller than any other implementation tried.
                if (bit_istrue(settings.homing_dir_mask, bit(idx))) {
                    if (approach) {
                        target[idx] = -max_travel;
                    } else {
                        target[idx] = max_travel;
                    }
                } else {
                    if (approach) {
                        target[idx] = max_travel;
                    } else {
                        target[idx] = -max_travel;
                    }
                }
                // Apply axislock to the step port pins active in this cycle.
                axislock |= step_pin[idx];
#ifdef ENABLE_DUAL_AXIS
                if (idx == DUAL_AXIS_SELECT) {
                    sys.homing_axis_lock_dual = step_pin_dual;
                }
#endif
            }
        }
        homing_rate *= sqrt(n_active_axis); // [sqrt(N_AXIS)] Adjust so individual axes all move at homing rate.
        sys.homing_axis_lock = axislock;

        // Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
        pl_data->feed_rate = homing_rate;  // Set current homing rate.
        plan_buffer_line(target, pl_data); // Bypass mc_line(). Directly plan homing motion.

        sys.step_control = STEP_CONTROL_EXECUTE_SYS_MOTION; // Set to execute homing motion and clear existing flags.
        st_prep_buffer();                                   // Prep and fill segment buffer from newly planned block.
        st_wake_up();                                       // Initiate motion
        do {
            if (approach) {
                // Check limit state. Lock out cycle axes when they change.
                limit_state = limits_get_state();
                for (idx = 0; idx < N_AXIS; idx++) {
                    if (axislock & step_pin[idx]) {
                        if (limit_state & (1 << idx)) {
#ifdef COREXY
                            if (idx == Z_AXIS) {
                                axislock &= ~(step_pin[Z_AXIS]);
                            } else {
                                axislock &= ~(step_pin[A_MOTOR] | step_pin[B_MOTOR]);
                            }
#else
                            axislock &= ~(step_pin[idx]);
#ifdef ENABLE_DUAL_AXIS
                            if (idx == DUAL_AXIS_SELECT) {
                                dual_axis_async_check |= DUAL_AXIS_CHECK_TRIGGER_1;
                            }
#endif
#endif
                        }
                    }
                }
                sys.homing_axis_lock = axislock;
#ifdef ENABLE_DUAL_AXIS
                if (sys.homing_axis_lock_dual) { // NOTE: Only true when homing dual axis.
                    if (limit_state & (1 << N_AXIS)) {
                        sys.homing_axis_lock_dual = 0;
                        dual_axis_async_check |= DUAL_AXIS_CHECK_TRIGGER_2;
                    }
                }

                // When first dual axis limit triggers, record position and begin checking distance until other limit
                // triggers. Bail upon failure.
                if (dual_axis_async_check) {
                    if (dual_axis_async_check & DUAL_AXIS_CHECK_ENABLE) {
                        if ((dual_axis_async_check & (DUAL_AXIS_CHECK_TRIGGER_1 | DUAL_AXIS_CHECK_TRIGGER_2)) ==
                            (DUAL_AXIS_CHECK_TRIGGER_1 | DUAL_AXIS_CHECK_TRIGGER_2)) {
                            dual_axis_async_check = DUAL_AXIS_CHECK_DISABLE;
                        } else {
                            if (abs(dual_trigger_position - sys_position[DUAL_AXIS_SELECT]) > dual_fail_distance) {
                                system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_DUAL_APPROACH);
                                mc_reset();
                                protocol_execute_realtime();
                                return;
                            }
                        }
                    } else {
                        dual_axis_async_check |= DUAL_AXIS_CHECK_ENABLE;
                        dual_trigger_position = sys_position[DUAL_AXIS_SELECT];
                    }
                }
#endif
            }

            st_prep_buffer(); // Check and prep segment buffer. NOTE: Should take no longer than 200us.

            // Exit routines: No time to run protocol_execute_realtime() in this loop.
            if (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET | EXEC_CYCLE_STOP)) {
                uint8_t rt_exec = sys_rt_exec_state;
                // Homing failure condition: Reset issued during cycle.
                if (rt_exec & EXEC_RESET) {
                    system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_RESET);
                }
                // Homing failure condition: Safety door was opened.
                if (rt_exec & EXEC_SAFETY_DOOR) {
                    system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_DOOR);
                }
                // Homing failure condition: Limit switch still engaged after pull-off motion
                if (!approach && (limits_get_state() & cycle_mask)) {
                    system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_PULLOFF);
                }
                // Homing failure condition: Limit switch not found during approach.
                if (approach && (rt_exec & EXEC_CYCLE_STOP)) {
                    system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_APPROACH);
                }
                if (sys_rt_exec_alarm) {
                    mc_reset(); // Stop motors, if they are running.
                    protocol_execute_realtime();
                    return;
                } else {
                    // Pull-off motion complete. Disable CYCLE_STOP from executing.
                    system_clear_exec_state_flag(EXEC_CYCLE_STOP);
                    break;
                }
            }

#ifdef ENABLE_DUAL_AXIS
        } while ((STEP_MASK & axislock) || (sys.homing_axis_lock_dual));
#else
        } while (STEP_MASK & axislock);
#endif

        st_reset();                               // Immediately force kill steppers and reset step segment buffer.
        delay_ms(settings.homing_debounce_delay); // Delay to allow transient dynamics to dissipate.

        // Reverse direction and reset homing rate for locate cycle(s).
        approach = !approach;

        // After first cycle, homing enters locating phase. Shorten search to pull-off distance.
        if (approach) {
            max_travel = settings.homing_pulloff * HOMING_AXIS_LOCATE_SCALAR;
            homing_rate = settings.homing_feed_rate;
        } else {
            max_travel = settings.homing_pulloff;
            homing_rate = settings.homing_seek_rate;
        }

    } while (n_cycle-- > 0);

    // The active cycle axes should now be homed and machine limits have been located. By
    // default, Grbl defines machine space as all negative, as do most CNCs. Since limit switches
    // can be on either side of an axes, check and set axes machine zero appropriately. Also,
    // set up pull-off maneuver from axes limit switches that have been homed. This provides
    // some initial clearance off the switches and should also help prevent them from falsely
    // triggering when hard limits are enabled or when more than one axes shares a limit pin.
    int32_t set_axis_position;
    // Set machine positions for homed limit switches. Don't update non-homed axes.
    for (idx = 0; idx < N_AXIS; idx++) {
        // NOTE: settings.max_travel[] is stored as a negative value.
        if (cycle_mask & bit(idx)) {
#ifdef HOMING_FORCE_SET_ORIGIN
            set_axis_position = 0;
#else
            if (bit_istrue(settings.homing_dir_mask, bit(idx))) {
                set_axis_position =
                    lround((settings.max_travel[idx] + settings.homing_pulloff) * settings.steps_per_mm[idx]);
            } else {
                set_axis_position = lround(-settings.homing_pulloff * settings.steps_per_mm[idx]);
            }
#endif

#ifdef COREXY
            if (idx == X_AXIS) {
                int32_t off_axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
                sys_position[A_MOTOR] = set_axis_position + off_axis_position;
                sys_position[B_MOTOR] = set_axis_position - off_axis_position;
            } else if (idx == Y_AXIS) {
                int32_t off_axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
                sys_position[A_MOTOR] = off_axis_position + set_axis_position;
                sys_position[B_MOTOR] = off_axis_position - set_axis_position;
            } else {
                sys_position[idx] = set_axis_position;
            }
#else
            sys_position[idx] = set_axis_position;
#endif
        }
    }
    sys.step_control = STEP_CONTROL_NORMAL_OP; // Return step control to normal operation.
}

// Performs a soft limit check. Called from mc_line() only. Assumes the machine has been homed,
// the workspace volume is in all negative space, and the system is in normal operation.
// NOTE: Used by jogging to limit travel within soft-limit volume.
void limits_soft_check(float *target) {
    if (system_check_travel_limits(target)) {
        sys.soft_limit = true;
        // Force feed hold if cycle is active. All buffered blocks are guaranteed to be within
        // workspace volume so just come to a controlled stop so position is not lost. When complete
        // enter alarm mode.
        if (sys.state == STATE_CYCLE) {
            system_set_exec_state_flag(EXEC_FEED_HOLD);
            do {
                protocol_execute_realtime();
                if (sys.abort) {
                    return;
                }
            } while (sys.state != STATE_IDLE);
        }
        mc_reset();                                   // Issue system reset and ensure spindle and coolant are shutdown.
        system_set_exec_alarm(EXEC_ALARM_SOFT_LIMIT); // Indicate soft limit critical event
        protocol_execute_realtime();                  // Execute to enter critical event loop and system abort
        return;
    }
}