rp2040

commit f9584892ede82f88c87a567f79f8e11fed42cdfa
parent e7760c1a36c1865d4df268b65cd8d53a126a7d3d
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Wed, 27 Mar 2024 07:43:12 +0900

change sp from msp to psp. something weird

Diffstat:
M
ex3/main.c
 | 
3
+++
M
ex3/proc.s
 | 
12
++++++++++++

2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/ex3/main.c b/ex3/main.c
@@ -9,6 +9,7 @@ void wfi(void);
 void print_sp(void);
 void *memcpy(void *s1, void *s2, long n);
 void restore_context(unsigned int [17]);
+void set_psp(void);
 
 // A proc represents a process in execution.
 typedef struct proc {
@@ -64,6 +65,8 @@ main(void) {
 	p1.r[16] = 0;
 	p1.next = NULL;
 
+	set_psp();
+
 	proc0();
 
 	return 0;
diff --git a/ex3/proc.s b/ex3/proc.s
@@ -163,3 +163,14 @@ restore_context:
 	msr xpsr, r1
 	ldm r0, {r0-r7}
 	bx r8
+
+	// void set_psp(void);
+	// Set_psp changes the stack to use to psp and set it to 0x20000100
+	// TODO: ISB barrier?
+	.global set_psp
+set_psp:
+	mov r0, #2
+	msr control, r0
+	ldr r0, =0x20000100
+	mov sp, r0
+	bx lr
+\ No newline at end of file