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/**
* @file task.h
* Provides multitasking functionality
*
* Copyright (C) 2018 Clyne Sullivan
*
* This program 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.
*
* This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef TASK_H_
#define TASK_H_
#include <stdint.h>
#define WIFEXITED(w) (w & (1 << 8))
#define WEXITSTATUS(w) (w & 0xFF)
typedef uint16_t pid_t;
/**
* A structure to contain task data.
*/
typedef struct task_t {
struct task_t *next; /**< pointer to the next task_t instance */
uint32_t *sp; /**< pointer to the task's last sp register value */
uint32_t *stack; /**< pointer to the task's stack */
uint32_t *heap;
pid_t pid; /**< Task (Process) ID */
pid_t pgid; /**< Process Group ID */
struct {
uint32_t state : 8;
uint32_t value : 24;
} status;
} task_t;
enum TASK_STATUS_FLAGS {
TASK_RUNNING, /**< Task is actively running */
TASK_SLEEPING, /**< Task is sleeping for task_t.sleep ms */
TASK_EXITED, /**< Task has exited, task_t.sleep has code */
TASK_ZOMBIE /**< Task exited, accounted for, ready to go bye bye */
};
/**
* Enters multitasking mode. The given function acts as the initial thread.
* This task is given a 4kb stack.
* @param init the initial thread to run
*/
void task_init(void (*init)(void), uint16_t stackSize);
/**
* Starts a new task.
* @param task the code to run
* @param stackSize how many bytes of stack to give the thread
*/
void task_start(void (*task)(void), uint16_t stackSize);
/**
* Allows task switching to be disabled, for low-level/time-critical operations.
* Multiple holds can be placed, and all must be removed to continue task
* switching.
* @param hold non-zero for hold, zero to remove hold
*/
void task_hold(uint8_t hold);
/**
* Puts the task to sleep for the given duration.
* @param ms Milliseconds to sleep for
*/
void task_sleep(uint32_t ms);
/**
* Called by the task when it's ready to exit.
* @param code Task's exit code
*/
void task_exit(int code);
/**
* Forks the task into two processes.
*/
int task_fork(void);
/**
* Gets the task's PID.
*/
pid_t task_getpid(void);
/**
* Waits for a task to change state (TODO confirm).
*/
pid_t task_waitpid(pid_t pid, int *wstatus, int options);
/**
* TODO
*/
void *task_sbrk(uint32_t bytes);
#endif // TASK_H_
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