1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/sched.c	Mon Aug 01 06:45:29 2011 +0300
     1.3 @@ -0,0 +1,154 @@
     1.4 +#include <stdio.h>
     1.5 +#include "sched.h"
     1.6 +#include "proc.h"
     1.7 +#include "intr.h"
     1.8 +#include "asmops.h"
     1.9 +#include "config.h"
    1.10 +
    1.11 +#define EMPTY(q)	((q).head == 0)
    1.12 +
    1.13 +struct proc_list {
    1.14 +	struct process *head, *tail;
    1.15 +};
    1.16 +
    1.17 +static void ins_back(struct proc_list *q, struct process *proc);
    1.18 +static void ins_front(struct proc_list *q, struct process *proc);
    1.19 +static void remove(struct proc_list *q, struct process *proc);
    1.20 +
    1.21 +static struct proc_list runq;
    1.22 +static struct proc_list waitq;
    1.23 +static struct proc_list zombieq;
    1.24 +
    1.25 +void schedule(void)
    1.26 +{
    1.27 +	if(EMPTY(runq)) {
    1.28 +		/* idle "process".
    1.29 +		 * make sure interrupts are enabled before halting
    1.30 +		 */
    1.31 +		enable_intr();
    1.32 +		halt_cpu();
    1.33 +		/* this won't return, it'll just wake up in an interrupt later */
    1.34 +	}
    1.35 +
    1.36 +	disable_intr();
    1.37 +
    1.38 +	/* if the current process exhausted its timeslice,
    1.39 +	 * move it to the back of the queue.
    1.40 +	 */
    1.41 +	if(runq.head->ticks_left <= 0) {
    1.42 +		if(runq.head->next) {
    1.43 +			struct process *proc = runq.head;
    1.44 +			remove(&runq, proc);
    1.45 +			ins_back(&runq, proc);
    1.46 +		}
    1.47 +
    1.48 +		/* start a new timeslice */
    1.49 +		runq.head->ticks_left = TIMESLICE_TICKS;
    1.50 +	}
    1.51 +
    1.52 +	/* no need to re-enable interrupts, they will be enabled with the iret */
    1.53 +	context_switch(runq.head->id);
    1.54 +}
    1.55 +
    1.56 +int add_proc(int pid, enum proc_state state)
    1.57 +{
    1.58 +	int istate;
    1.59 +	struct proc_list *q;
    1.60 +	struct process *proc = get_process(pid);
    1.61 +
    1.62 +	istate = get_intr_state();
    1.63 +	disable_intr();
    1.64 +
    1.65 +	q = state == STATE_RUNNING ? &runq : &waitq;
    1.66 +
    1.67 +	ins_back(q, proc);
    1.68 +	proc->state = state;
    1.69 +
    1.70 +	set_intr_state(istate);
    1.71 +	return 0;
    1.72 +}
    1.73 +
    1.74 +int block_proc(int pid)
    1.75 +{
    1.76 +	int istate;
    1.77 +	struct process *proc = get_process(pid);
    1.78 +
    1.79 +	if(proc->state != STATE_RUNNING) {
    1.80 +		printf("block_proc: process %d not running\n", pid);
    1.81 +		return -1;
    1.82 +	}
    1.83 +
    1.84 +	istate = get_intr_state();
    1.85 +	disable_intr();
    1.86 +
    1.87 +	remove(&runq, proc);
    1.88 +	ins_back(&waitq, proc);
    1.89 +	proc->state = STATE_BLOCKED;
    1.90 +
    1.91 +	set_intr_state(istate);
    1.92 +	return 0;
    1.93 +}
    1.94 +
    1.95 +int unblock_proc(int pid)
    1.96 +{
    1.97 +	int istate;
    1.98 +	struct process *proc = get_process(pid);
    1.99 +
   1.100 +	if(proc->state != STATE_BLOCKED) {
   1.101 +		printf("unblock_proc: process %d not blocked\n", pid);
   1.102 +		return -1;
   1.103 +	}
   1.104 +
   1.105 +	istate = get_intr_state();
   1.106 +	disable_intr();
   1.107 +
   1.108 +	remove(&waitq, proc);
   1.109 +	ins_back(&runq, proc);
   1.110 +	proc->state = STATE_RUNNING;
   1.111 +
   1.112 +	set_intr_state(istate);
   1.113 +	return 0;
   1.114 +}
   1.115 +
   1.116 +
   1.117 +static void ins_back(struct proc_list *q, struct process *proc)
   1.118 +{
   1.119 +	if(EMPTY(*q)) {
   1.120 +		q->head = proc;
   1.121 +	} else {
   1.122 +		q->tail->next = proc;
   1.123 +	}
   1.124 +
   1.125 +	proc->next = 0;
   1.126 +	proc->prev = q->tail;
   1.127 +	q->tail = proc;
   1.128 +}
   1.129 +
   1.130 +static void ins_front(struct proc_list *q, struct process *proc)
   1.131 +{
   1.132 +	if(EMPTY(*q)) {
   1.133 +		q->tail = proc;
   1.134 +	} else {
   1.135 +		q->head->prev = proc;
   1.136 +	}
   1.137 +
   1.138 +	proc->next = q->head;
   1.139 +	proc->prev = 0;
   1.140 +	q->head = proc;
   1.141 +}
   1.142 +
   1.143 +static void remove(struct proc_list *q, struct process *proc)
   1.144 +{
   1.145 +	if(proc->prev) {
   1.146 +		proc->prev->next = proc->next;
   1.147 +	}
   1.148 +	if(proc->next) {
   1.149 +		proc->next->prev = proc->prev;
   1.150 +	}
   1.151 +	if(q->head == proc) {
   1.152 +		q->head = proc->next;
   1.153 +	}
   1.154 +	if(q->tail == proc) {
   1.155 +		q->tail = proc->prev;
   1.156 +	}
   1.157 +}