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274 volume VI os16
Script e sorgenti del kernel 275
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1750019 | proc_table[pid].wakeup_timer--;
1750020 | if (proc_table[pid].wakeup_timer == 0)
1750021 | {
1750022 | proc_table[pid].status = PROC_READY;
1750023 | }
1750024 | }
1750025 | }
1750026 | }
1750027 | previous_time = current_time;
1750028 |}
104.9.11 kernel/proc/proc_scheduler.c
Si veda la sezione 103.8.11.
1760001 |#include
1760002 |#include
1760003 |#include
1760004 |//----------------------------------------------------------------------
1760005 |extern uint16_t _ksp;
1760006 |//----------------------------------------------------------------------
1760007 |void
1760008 |proc_scheduler (uint16_t *sp, segment_t *segment_d)
1760009 |{
1760010 | //
1760011 | // The process is identified from the data and stack segment.
1760012 | //
1760013 | pid_t prev;
1760014 | pid_t next;
1760015 | //
1760016 | static unsigned long int previous_clock;
1760017 | unsigned long int current_clock;
1760018 | //
1760019 | // Check if current data segments are right.
1760020 | //
1760021 | if (es () != ds () || ss () != ds ())
1760022 | {
1760023 | k_printf ("\n");
1760024 | k_printf ("Kernel panic: ES, DS, SS are different!\n");
1760025 | k_exit (0);
1760026 | }
1760027 | //
1760028 | // Search the data segment inside the process table.
1760029 | // Must be done here, because the subsequent call to
1760030 | // proc_sch_signals() will remove the segment numbers
1760031 | // from a zombie process.
1760032 | //
1760033 | prev = proc_find (*segment_d);
1760034 | //
1760035 | // Take care of sleeping processes: wake up if sleeping time
1760036 | // elapsed.
1760037 | //
1760038 | proc_sch_timers ();
1760039 | //
1760040 | // Take care of pending signals.
1760041 | //
1760042 | proc_sch_signals ();
1760043 | //
1760044 | // Take care input from terminals.
1760045 | //
1760046 | proc_sch_terminals ();
1760047 | //
1760048 | // Update the CPU time usage.
1760049 | //
1760050 | current_clock = k_clock ();
1760051 | proc_table[prev].usage += current_clock - previous_clock;
1760052 | previous_clock = current_clock;
1760053 | //
1760054 | // Scan for a next process.
1760055 | //
1760056 | for (next = prev+1; next != prev; next++)
1760057 | {
1760058 | if (next >= PROCESS_MAX)
1760059 | {
1760060 | next = -1; // At the next loop, ‘next’ will be zero.
1760061 | continue;
1760062 | }
1760063 | if (proc_table[next].status == PROC_EMPTY)
1760064 | {
1760065 | continue;
1760066 | }
1760067 | else if (proc_table[next].status == PROC_CREATED)
1760068 | {
1760069 | continue;
1760070 | }
1760071 | else if (proc_table[next].status == PROC_READY)
1760072 | {
1760073 | if (proc_table[prev].status == PROC_RUNNING)
1760074 | {
1760075 | proc_table[prev].status = PROC_READY;
1760076 | }
1760077 | proc_table[prev].sp = *sp;
1760078 | proc_table[next].status = PROC_RUNNING;
1760079 | proc_table[next].ret = 0;
1760080 | *segment_d = proc_table[next].segment_d;
1760081 | *sp = proc_table[next].sp;
1760082 | break;
1760083 | }
1760084 | else if (proc_table[next].status == PROC_RUNNING)
1760085 | {
1760086 | if (proc_table[prev].status == PROC_RUNNING)
1760087 | {
1760088 | k_printf ("Kernel alert: process %i ", prev);
1760089 | k_printf ("and %i \"running\"!\r", next);
1760090 | proc_table[prev].status = PROC_READY;
1760091 | }
1760092 | proc_table[prev].sp = *sp;
1760093 | proc_table[next].status = PROC_RUNNING;
1760094 | proc_table[next].ret = 0;
1760095 | *segment_d = proc_table[next].segment_d;
1760096 | *sp = proc_table[next].sp;
1760097 | break;
1760098 | }
1760099 | else if (proc_table[next].status == PROC_SLEEPING)
1760100 | {
1760101 | continue;
1760102 | }
1760103 | else if (proc_table[next].status == PROC_ZOMBIE)
1760104 | {
1760105 | continue;
1760106 | }
1760107 | }
1760108 | //
1760109 | // Check again if the next process is set to running, otherwise set
1760110 | // the kernel to such value!
1760111 | //
1760112 | next = proc_find (*segment_d);
1760113 | if (proc_table[next].status != PROC_RUNNING)
1760114 | {
1760115 | proc_table[0].status = PROC_RUNNING;
1760116 | *segment_d = proc_table[0].segment_d;
1760117 | *sp = proc_table[0].sp;
1760118 | }
1760119 | //
1760120 | // Save kernel stack pointer.
1760121 | //
1760122 | _ksp = proc_table[0].sp;
1760123 | //
1760124 | // At the end, must inform the PIC 1, with message «EOI».
1760125 | //
1760126 | out_8 (0x20, 0x20);
1760127 |}
104.9.12 kernel/proc/proc_sig_chld.c
Si veda la sezione 103.8.12.
1770001 |#include
1770002 |//----------------------------------------------------------------------
1770003 |void
1770004 |proc_sig_chld (pid_t parent, int sig)
1770005 |{
1770006 | pid_t child;
1770007 | //
1770008 | // Please note that ‘sig’ should be SIGCHLD and nothing else.
1770009 | // So, the following test, means to verify if the parent process
1770010 | // has received a SIGCHLD already.
1770011 | //
1770012 | if (proc_sig_status (parent, sig))
1770013 | {
1770014 | if ( (!proc_sig_ignore (parent, sig))
1770015 | && (proc_table[parent].status == PROC_SLEEPING)
1770016 | && (proc_table[parent].wakeup_events & WAKEUP_EVENT_SIGNAL)
1770017 | && (proc_table[parent].wakeup_signal == sig))
1770018 | {
1770019 | //
1770020 | // The signal is not ignored from the parent process;
1770021 | // the parent process is sleeping;
1770022 | // the parent process is waiting for a signal;
1770023 | // the parent process is waiting for current signal.
1770024 | // So, just wake it up.
1770025 | //
1770026 | proc_table[parent].status = PROC_READY;
1770027 | proc_table[parent].wakeup_events ^= WAKEUP_EVENT_SIGNAL;
1770028 | proc_table[parent].wakeup_signal = 0;
1770029 | }
1770030 | else
1770031 | {
1770032 | //
1770033 | // All other cases, means to remove all dead children.
1770034 | //
1770035 | for (child = 1; child < PROCESS_MAX; child++)
1770036 | {
1770037 | if ( proc_table[child].ppid == parent
1770038 | && proc_table[child].status == PROC_ZOMBIE)
1770039 | {
1770040 | proc_available (child);
1770041 | }
1770042 | }
1770043 | }
1770044 | proc_sig_off (parent, sig);
1770045 | }
1770046 |}
104.9.13 kernel/proc/proc_sig_cont.c
Si veda la sezione 103.8.13.
1780001 |#include
1780002 |//----------------------------------------------------------------------
1780003 |void
1780004 |proc_sig_cont (pid_t pid, int sig)
1780005 |{
1780006 | //
1780007 | // The value for argument ‘sig’ should be SIGCONT.
1780008 | //
1780009 | if (proc_sig_status (pid, sig))
1780010 | {
1780011 | if (proc_sig_ignore (pid, sig))
1780012 | {
1780013 | proc_sig_off (pid, sig);
1780014 | }
1780015 | else
1780016 | {
1780017 | proc_table[pid].status = PROC_READY;
1780018 | proc_sig_off (pid, sig);
1780019 | }
1780020 | }
1780021 |}
104.9.14 kernel/proc/proc_sig_core.c
Si veda la sezione 103.8.14.
1790001 |#include
1790002 |//----------------------------------------------------------------------
1790003 |void
1790004 |proc_sig_core (pid_t pid, int sig)
1790005 |{
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