From aa8d179b2df2ce031a84172a70be88697dfda7c4 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Thu, 6 Jan 2022 23:20:04 -0800
Subject: Rewrote scheduler in Assembly

---
 include/sys/core.h     | 14 ++++++++++
 include/sys/schedule.h | 75 ++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 75 insertions(+), 14 deletions(-)

(limited to 'include')

diff --git a/include/sys/core.h b/include/sys/core.h
index 361ffb1..eb1f1e6 100644
--- a/include/sys/core.h
+++ b/include/sys/core.h
@@ -21,6 +21,20 @@ static inline void delay(unsigned long cycles)
 			: "=r"(cycles): [cycles]"0"(cycles) : "cc");
 }
 
+static inline void* getlr(void)
+{
+	void* out;
+	asm volatile ("mov %0, lr" : "=r"(out));
+	return out;
+}
+
+static inline void* getpc(void)
+{
+	void* out;
+	asm volatile ("mov %0, pc" : "=r"(out));
+	return out;
+}
+
 static inline void* getsp(void)
 {
 	void* out;
diff --git a/include/sys/schedule.h b/include/sys/schedule.h
index 38c6632..c3c748b 100644
--- a/include/sys/schedule.h
+++ b/include/sys/schedule.h
@@ -14,27 +14,43 @@ enum ThreadStatus {
 	THREAD_FINISHED,
 };
 
+struct cpu_context {
+	unsigned long r4;
+	unsigned long r5;
+	unsigned long r6;
+	unsigned long r7;
+	unsigned long r8;
+	unsigned long r9;
+	unsigned long r10;
+	unsigned long r11;
+	unsigned long r12;
+	unsigned long lr;
+};
+
 struct ThreadData {
+	unsigned char priority;
+	unsigned char preempt_count;
 	unsigned short status;
 	void* mutex_waiting;
 	unsigned long pid;
-	unsigned char priority;
-	unsigned char preempt_count;
+	struct cpu_context cpu_context;
 };
 
 struct Thread {
-	struct ThreadData data;
-	void (*thread)(void);
+	//void (*thread)(void);
+	void* thread;
 	void* stack;
 	void* stack_base;
+	struct ThreadData data;
 };
 
 #define MAX_THREADS 0x100
 #define STACK_SIZE 0x1000
 #define PRIORITIES 6
 struct Scheduler {
-	struct LL tlist[PRIORITIES];
 	struct LL* rthread_ll;
+	struct cpu_context* ctx;
+	struct LL tlist[PRIORITIES];
 };
 
 #ifndef SYS_SCHEDULE_C
@@ -44,24 +60,27 @@ extern struct Scheduler scheduler;
 
 void init_scheduler(void);
 void add_thread(void (*thread_fxn)(void), unsigned char priority);
-void schedule(void);
+extern void schedule(void);
+void schedule_c(void);
 void schedule_irq(void);
-void remove_running_thread(void);
+void cleanup(void);
+void sched_info(void);
+void yield(void);
 
-static inline void preservestack(struct Thread* thread)
+static inline void preserve_stack(struct Thread* thread)
 {
 	// Get current mode
 	unsigned long mode = getmode();
 	// Set supervisor mode - "User mode"
 	setsvc();
 	// Store the stack pointer
-	void* ssp = getsp();
+	void* ssp = getsp() + 4*4; // Ignore 4 words pushed on by (schedule)
 	thread->stack = ssp;
 	// Restore mode
 	setmode(mode);
 }
 
-static inline void restorestack(struct Thread* thread)
+static inline void restore_stack(struct Thread* thread)
 {
 	// Get current mode
 	unsigned long mode = getmode();
@@ -73,7 +92,7 @@ static inline void restorestack(struct Thread* thread)
 	setmode(mode);
 }
 
-static inline void preservesysstack(unsigned long* sp)
+static inline void preserve_sys_stack(unsigned long* sp)
 {
 	if (*sp == 0) {
 		unsigned long mode = getmode();
@@ -83,7 +102,7 @@ static inline void preservesysstack(unsigned long* sp)
 	}
 }
 
-static inline void restoresysstack(unsigned long* sp)
+static inline void restore_sys_stack(unsigned long* sp)
 {
 	if (*sp) {
 		unsigned long mode = getmode();
@@ -94,9 +113,37 @@ static inline void restoresysstack(unsigned long* sp)
 	}
 }
 
-static inline void preservepc(struct Thread* t)
+static inline void preserve_pc(struct Thread* t)
+{
+	t->thread = (void*)t->data.cpu_context.lr;
+}
+
+static inline void preserve_ctx(struct cpu_context* cpuctx)
+{
+	asm volatile ("mov %0, r4" : "=r"(cpuctx->r4));
+	asm volatile ("mov %0, r5" : "=r"(cpuctx->r5));
+	asm volatile ("mov %0, r6" : "=r"(cpuctx->r6));
+	asm volatile ("mov %0, r7" : "=r"(cpuctx->r7));
+	asm volatile ("mov %0, r8" : "=r"(cpuctx->r8));
+	asm volatile ("mov %0, r9" : "=r"(cpuctx->r9));
+	asm volatile ("mov %0, r10" : "=r"(cpuctx->r10));
+	asm volatile ("mov %0, r11" : "=r"(cpuctx->r11));
+	asm volatile ("mov %0, r12" : "=r"(cpuctx->r12));
+	asm volatile ("mov %0, lr" : "=r"(cpuctx->lr));
+}
+
+static inline void restore_ctx(struct cpu_context* cpuctx)
 {
-	asm volatile ("mov %0, lr" : "=r"(t->thread));
+	asm volatile ("mov r4,  %0" :: "r"(cpuctx->r4));
+	asm volatile ("mov r5,  %0" :: "r"(cpuctx->r5));
+	asm volatile ("mov r6,  %0" :: "r"(cpuctx->r6));
+	asm volatile ("mov r7,  %0" :: "r"(cpuctx->r7));
+	asm volatile ("mov r8,  %0" :: "r"(cpuctx->r8));
+	asm volatile ("mov r9,  %0" :: "r"(cpuctx->r9));
+	asm volatile ("mov r10, %0" :: "r"(cpuctx->r10));
+	asm volatile ("mov r11, %0" :: "r"(cpuctx->r11));
+	asm volatile ("mov r12, %0" :: "r"(cpuctx->r12));
+	asm volatile ("mov lr,  %0" :: "r"(cpuctx->lr));
 }
 
 #endif
-- 
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