rp2040

commit 59737698a76411d4fd1d407846b70c03309d4125
parent f6681f83ad1eadc2f66a1ec907436afc33486fc9
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Tue, 12 Mar 2024 12:37:27 +0900

try to implement context switch.
find some weird error.

Diffstat:
M
ex3/main.c
 | 
50
+++++++++++++++++++++++++++++++++++++++-----------
M
ex3/memmap.ld
 | 
3
+++
M
ex3/proc.s
 | 
28
++++++++++++++++++++++++++++
M
ex3/start.s
 | 
5
+++++

4 files changed, 75 insertions(+), 11 deletions(-)
diff --git a/ex3/main.c b/ex3/main.c
@@ -4,9 +4,13 @@ void printh(void *);
 void set_alarm(unsigned int);
 void proc0(void);
 void halt(void);
+void *get_sp(void);
+void wfi(void);
 
 extern void proc0_start, proc0_size;
+extern void proc1_start, proc1_size;
 extern char msg0;
+extern char msg1;
 
 // A proc represents a process in execution.
 typedef struct proc {
@@ -14,14 +18,14 @@ typedef struct proc {
 	unsigned int id;
 	// R is the registers of the process with r[13] be sp, r[14] lr, r[15] pc.
 	void *r[16];
+	// Next is the next process to execute.
+	struct proc *next;
 } proc;
 
 // A proc_tab is the queue of waiting processes.
 typedef struct proc_tab {
 	// Head is the head of the queue.
 	proc *head;
-	// Next is the next process to execute.
-	proc *next;
 	// Tail is the tail of the queue.
 	proc *tail;
 } proc_tab;
@@ -31,24 +35,48 @@ proc_tab *ptab;
 int
 main(void) {
 	init();
-	puts("reset");
-	proc *p0 = (proc *) 0x20041000, *p1 = (proc *) 0x20041100; // sram5
+	proc p0, p1;
 
 	memcpy((void *)0x20000000, (void *)&proc0_start, (long) &proc0_size);
-	puts(&msg0);
-	p0->r[13] = (void *) 0x20000100; // sp
-	p0->r[14] = (void *) 0xdeadbeef; // lr
-	p0->r[15] = (void *) 0x20000000; // pc
+	memcpy((void *)0x20000100, (void *)&proc1_start, (long) &proc1_size);
+
+	p0.r[13] = (void *) 0x20000100; // sp
+	p0.r[14] = (void *) 0xdeadbeef; // lr
+	p0.r[15] = (void *) 0x20000000; // pc
 
-	p1->r[13] = (void *) 0x20000200; // sp
-	p1->r[14] = (void *) 0xdeadbeef; // lr
-	p1->r[15] = (void *) 0x20000100; // pc
+	p1.r[13] = (void *) 0x20000200; // sp
+	p1.r[14] = (void *) 0xdeadbeef; // lr
+	p1.r[15] = (void *) 0x20000100; // pc
+
+	for (;;) {
+		wfi();
+ 		setreg();
+	}
 
 	return 0;
 }
 
 void
+save_context(proc *p)
+{}
+
+void
+restore_context(proc *p)
+{
+
+}
+
+void
 scheduler(void) {
+	int *sp1, *sp0;
+	sp1 = (int *)get_sp();
+	sp0 = sp1 + 16;
+	for (; sp1 <= sp0; sp1++) {
+		printh(sp1);
+		printh(*sp1);
+		puts("");
+	}
+	puts("");
 	puts("scheduler called");
 }
 
diff --git a/ex3/memmap.ld b/ex3/memmap.ld
@@ -34,4 +34,7 @@ SECTIONS
 	.proc1 0x20000100 : {
 		*(.proc1)
 	} > SRAM AT > FLASH
+	proc1_start = LOADADDR(.proc1);
+	proc1_size = SIZEOF(.proc1);
+
 }
diff --git a/ex3/proc.s b/ex3/proc.s
@@ -19,5 +19,33 @@ proc1:
 	bl puts
 	b proc1
 	.align 2
+	.global msg1
 msg1:
 	.asciz "proc1"
+
+	.align 1
+	.section .text
+	// void *get_sp(void);
+	// Get_sp returns the current stack pointer.
+	.global get_sp
+get_sp:
+	mov r0, sp
+	bx lr
+
+	.align 1
+	// Set_reg sets registers for debugging.
+	// Modified registers are:
+	// 	ReturnAddress(), LR, R12, R3, R2, R1 and R0.
+	.global setreg
+setreg:
+	push {lr}
+	mov r0, #0x12
+	mov r12, r0
+	mov r0, #0x14
+	mov lr, r0
+	mov r0, #0
+	mov r1, #1
+	mov r2, #2
+	mov r3, #3
+	bl printh // BUG: some alignment fault?
+	pop {pc}
diff --git a/ex3/start.s b/ex3/start.s
@@ -284,6 +284,11 @@ halt:
 	wfe
 	b halt
 
+	.global wfi
+wfi:
+	wfi
+	bx lr
+
 // The following functions make no side effects and
 // can be used anywhare without pushing and popping
 // registers.