From 4cf9e1ac0f0f6133baf4e8136e600ea51aaab65d Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Wed, 16 Mar 2022 11:11:42 -0700
Subject: Return if add is successful
---
src/sys/schedule.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
(limited to 'src')
diff --git a/src/sys/schedule.c b/src/sys/schedule.c
index 287091c..fe919e6 100644
--- a/src/sys/schedule.c
+++ b/src/sys/schedule.c
@@ -80,7 +80,7 @@ struct Thread* get_unused_thread(void)
return 0;
}
-void add_thread(void* pc, void* arg, unsigned char priority)
+unsigned char add_thread(void* pc, void* arg, unsigned char priority)
{
struct Thread* thread = get_unused_thread();
thread_table[thread->offset] = 1;
@@ -98,28 +98,36 @@ void add_thread(void* pc, void* arg, unsigned char priority)
if (nextpid < FIRST_AVAIL_PID) {
nextpid = FIRST_AVAIL_PID;
}
+ // Cap Priority Level
if (priority >= PRIORITIES)
thread->priority = PRIORITIES - 1;
else
thread->priority = priority;
+ // This thread is new
thread->old_priority = -1;
+ // Reserved for non-preemptible tasking
thread->preempt = 0;
// Get the Ready Queue
struct ThreadQueue* ready_queue = &scheduler.ready[thread->priority];
// Get the write pointer
struct ThreadEntryIterator* ready_write = &ready_queue->write;
- // TODO: Check if it is possible to add
- //if (ready_write->queue->thread == 0) {
+ if (ready_write->entry->thread == 0) {
// Add the thread to the write pointer
ready_write->entry->thread = thread;
// Move the write pointer to the next entry
ready_write->entry = ready_write->entry->next;
- //}
+ } else {
+ // Cannot add, mark the stack space as available
+ // so that it can be used on a subsequent add thread
+ thread_table[thread->offset] = 0;
+ return 1;
+ }
// Schedule if this was called in usermode
unsigned long mode = getmode() & 0x1F;
if (mode == 0x10) {
sys0(SYS_YIELD_HIGH);
}
+ return 0;
}
void uart_scheduler(void)
--
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