use ldm instruction instead of libkernel for entering user mode; get rid of libkernel (no longer needed)

1 files changed, 15 insertions, 0 deletions

diff --git a/psr.h b/psr.h
index 9809fc4..b2adafb 100644
--- a/psr.h
+++ b/psr.h
@@ -64,4 +64,19 @@ inline static PSR_t read_CPSR(void)
   return CPSR;
 }
 
+inline static PSR_t read_SPSR(void)
+{
+  PSR_t SPSR;
+  // get content of saved program status register
+  asm("mrs %0, spsr" : "=r" (SPSR.raw) :: "memory");
+  
+  return SPSR;
+}
+
+inline static void write_SPSR(PSR_t SPSR)
+{
+  // set content of saved program status register
+  asm("msr spsr, %0" :: "r" (SPSR.raw));
+}
+
 #endif // PSR_H