Ensured Aligned Mutexes

6 files changed, 347 insertions, 0 deletions

diff --git a/later/schedule.S b/later/schedule.S
new file mode 100644
index 0000000..1811c7c
--- /dev/null
+++ b/later/schedule.S
@@ -0,0 +1,58 @@
+.section .text
+.globl preserveregs
+preserveregs:
+	str r4,  [r0, #0x10]
+	str r5,  [r0, #0x14]
+	str r6,  [r0, #0x18]
+	str r7,  [r0, #0x1c]
+	str r8,  [r0, #0x20]
+	str r9,  [r0, #0x24]
+	str r10, [r0, #0x28]
+	str r11, [r0, #0x2c]
+	bx lr
+
+.globl restoreregs
+restoreregs:
+	ldr r4,  [r0, #0x10]
+	ldr r5,  [r0, #0x14]
+	ldr r6,  [r0, #0x18]
+	ldr r7,  [r0, #0x1c]
+	ldr r8,  [r0, #0x20]
+	ldr r9,  [r0, #0x24]
+	ldr r10, [r0, #0x28]
+	ldr r11, [r0, #0x2c]
+	bx lr
+
+.globl exetask
+exetask:
+	push {r0, r4, r5, r6, r7, r8, r9, r10, r11, lr}
+	// Restore registers from context switch
+	ldr r4,  [r0, #0x10]
+	ldr r5,  [r0, #0x14]
+	ldr r6,  [r0, #0x18]
+	ldr r7,  [r0, #0x1c]
+	ldr r8,  [r0, #0x20]
+	ldr r9,  [r0, #0x24]
+	ldr r10, [r0, #0x28]
+	ldr r11, [r0, #0x2c]
+
+	// Preserve system stack
+	ldr r1,  =msp
+	str sp, [r1]
+	// Setup task's stack
+	ldr sp, [r0, #0x34]
+	// Switch to task
+	ldr lr, [r0, #0x3c]
+	blx lr
+	// Restore system stack
+	ldr r1, =msp
+	ldr sp, [r1]
+	pop {r0, r4, r5, r6, r7, r8, r9, r10, r11, pc}
+
+.section .data
+msp:
+	.space 4
+.section .data.stacks
+.globl stacks
+stacks:
+	.space 0x100000
diff --git a/later/schedule.c b/later/schedule.c
new file mode 100644
index 0000000..8cf2780
--- /dev/null
+++ b/later/schedule.c
@@ -0,0 +1,83 @@
+#include "../sys/schedule.h"
+#include "../lib/ll.h"
+#include "../lib/q.h"
+
+#ifdef IGNORE
+#ifdef FLAT
+static struct Task* task_list[256];
+
+static struct Scheduler scheduler = {
+	.tasks = task_list,
+};
+
+static unsigned int ntask_i = 0;
+
+void add_task(struct Task* t)
+{
+	scheduler.tasks[ntask_i] = t;
+	ntask_i += 1;
+	if (ntask_i > 256) {
+		ntask_i = 0;
+	}
+}
+
+unsigned int get_task_length(void)
+{
+	return ntask_i;
+}
+
+void execute_task(void)
+{
+	if (scheduler.tasks[ntask_i-1] != 0)
+		scheduler.tasks[ntask_i-1]->task();
+}
+#elseif LL
+static struct LL bl = {
+	.prev = 0,
+	.next = 0,
+};
+static struct Scheduler scheduler = {
+	.tasks = &bl,
+};
+#else
+static struct Q_base bq = {
+	.next = 0,
+	.last = 0,
+};
+static struct Scheduler  scheduler = {
+	.tasks = &bq,
+};
+
+void add_task(struct Task* t)
+{
+	pushq(scheduler.tasks, t);
+}
+
+unsigned int get_task_length(void)
+{
+	unsigned int length = 0;
+	if (scheduler.tasks->last == 0)
+		return length;
+	else if (scheduler.tasks->next == scheduler.tasks->last)
+		return 1;
+	else {
+		struct Q* q = scheduler.tasks->next;
+		length += 1;
+		while (q->next != 0) {
+			q = q->next;
+			length += 1;
+		}
+		return length;
+	}
+}
+
+void execute_task(void)
+{
+	if (scheduler.tasks->last != 0) {
+		struct Task* tsk = (struct Task*)scheduler.tasks->next->data;
+		(tsk->task)();
+		popq(scheduler.tasks);
+	}
+}
+#endif
+#endif
diff --git a/later/schedule.flat.c b/later/schedule.flat.c
new file mode 100644
index 0000000..6eb0d14
--- /dev/null
+++ b/later/schedule.flat.c
@@ -0,0 +1,32 @@
+#ifdef FLAT
+
+#include "../sys/schedule.h"
+static struct Task* task_list[256];
+
+static struct Scheduler scheduler = {
+	.tasks = task_list,
+};
+
+static unsigned int ntask_i = 0;
+
+void add_task(struct Task* t)
+{
+	scheduler.tasks[ntask_i] = t;
+	ntask_i += 1;
+	if (ntask_i > 256) {
+		ntask_i = 0;
+	}
+}
+
+unsigned int get_task_length(void)
+{
+	return ntask_i;
+}
+
+void execute_task(void)
+{
+	if (scheduler.tasks[ntask_i-1] != 0)
+		scheduler.tasks[ntask_i-1]->task();
+}
+
+#endif
diff --git a/later/schedule.h b/later/schedule.h
new file mode 100644
index 0000000..77da7eb
--- /dev/null
+++ b/later/schedule.h
@@ -0,0 +1,43 @@
+#ifndef SYS_SCHEDULE_H
+#define SYS_SCHEDULE_H
+
+#define S_WAITING 0
+#define S_READY 1
+
+#define STACK_SIZE 0x800
+struct Task {
+	unsigned char priority;
+	unsigned char status;
+	unsigned long pid;
+	void (*task)(void);
+	unsigned long reg[16];
+	unsigned long stacki;
+	void* stack;
+};
+
+#ifdef FLAT
+struct Scheduler {
+	unsigned long running_pid;
+	struct Task** tasks;
+};
+#elseif LL
+#include "../lib/ll.h"
+struct Scheduler {
+	unsigned long running_pid;
+	struct LL* tasks;
+};
+#else
+#include "../lib/q.h"
+struct Scheduler {
+	unsigned long running_pid;
+	struct Q_base* tasks;
+};
+#endif
+
+void add_fxn(void (*task)(void), unsigned char priority);
+unsigned char exists(void (*task)(void));
+void add_no_repeat(void (*task)(void), unsigned char priority);
+unsigned int get_task_length(void);
+void execute_task(void);
+
+#endif
diff --git a/later/schedule.ll.c b/later/schedule.ll.c
new file mode 100644
index 0000000..d9ab954
--- /dev/null
+++ b/later/schedule.ll.c
@@ -0,0 +1,13 @@
+#ifdef LL
+
+#include "../sys/schedule.h"
+#include "../lib/ll.h"
+static struct LL bl = {
+	.prev = 0,
+	.next = 0,
+};
+static struct Scheduler scheduler = {
+	.tasks = &bl,
+};
+
+#endif
diff --git a/later/schedule.q.c b/later/schedule.q.c
new file mode 100644
index 0000000..4a5ff85
--- /dev/null
+++ b/later/schedule.q.c
@@ -0,0 +1,118 @@
+#if !(defined(LL) || defined(FLAT))
+#include "../sys/schedule.h"
+#include "../lib/q.h"
+#include "../lib/mem.h"
+#include "../drivers/uart.h"
+
+extern void preserveregs(void*);
+extern void restoreregs(void*);
+extern void exetask(void*);
+
+static unsigned long next_pid = 3;
+unsigned char table[256] = {0, };
+
+static struct __attribute__((packed,align(4))) Q_base bq = {
+	.next = 0,
+	.last = 0,
+};
+struct __attribute__((packed,align(4))) Scheduler scheduler = {
+	.running_pid = 0,
+	.tasks = &bq,
+};
+
+extern unsigned long __stacks_start;
+
+unsigned long getstack(void)
+{
+	for(unsigned int i = 0; i < 256; i++) {
+		if (table[i] == 0) {
+			table[i] = 1;
+			return i;
+		}
+	}
+	return -1;
+}
+
+void add_fxn(void (*task)(void), unsigned char priority)
+{
+	struct Task* t = (struct Task*)malloc(sizeof(struct Task));
+	// Allocate a stack frame and space for registers to be preserved on context switches
+	t->priority = priority;
+	t->task = task;
+	t->stacki = getstack();
+	t->pid = next_pid;
+	next_pid += 1;
+	if(t->stacki > 256)
+		t->stack = 0;
+	else
+		t->stack = (void*)(__stacks_start + STACK_SIZE*t->stacki);
+	t->status = S_READY;
+	for(unsigned char i = 0; i < 13; i++)
+		t->reg[i] = 0;
+	t->reg[13] = (unsigned long)t->stack;
+	t->reg[14] = 0; // LR
+	t->reg[15] = (unsigned long)task; // PC
+	pushq(scheduler.tasks, t);
+}
+
+unsigned char exists(void (*task)(void))
+{
+	if (scheduler.tasks->next == 0)
+		return 0;
+	struct Q* q = scheduler.tasks->next;
+	while (q != 0) {
+		struct Task* t = q->data;
+		if (t->task == task)
+			return 1;
+		q = q->next;
+	}
+	return 0;
+}
+
+void add_no_repeat(void (*task)(void), unsigned char priority)
+{
+	if (!(exists(task)))
+		add_fxn(task, priority);
+}
+
+unsigned int get_task_length(void)
+{
+	unsigned int length = 0;
+	if (scheduler.tasks->last == 0)
+		return length;
+	else if (scheduler.tasks->next == scheduler.tasks->last)
+		return 1;
+	else {
+		struct Q* q = scheduler.tasks->next;
+		length += 1;
+		while (q->next != 0) {
+			q = q->next;
+			length += 1;
+		}
+		return length;
+	}
+}
+void execute_task(void)
+{
+	// Preserve Current Running PID's Data
+	if (scheduler.tasks->last != 0) {
+		struct Q* q = (struct Q*)scheduler.tasks->next;
+		while (((struct Task*)q->data)->status == S_WAITING) {
+			q = q->next;
+		}
+		struct Task* tsk = (struct Task*)q->data;
+		// Restore registers 
+		//  Including program counter as the entry point
+		//  Including allocated stack position
+		//  Set lr to the return address to restore system stack
+		//preserveregs(tsk->reg);
+		//restoreregs(tsk->reg);
+		scheduler.running_pid = tsk->pid;
+		exetask(tsk->reg);
+		scheduler.running_pid = 0;
+		table[tsk->stacki] = 0;
+		popq(scheduler.tasks);
+	}
+}
+
+#endif