2009-07-28 Joel Sherrill <joel.sherrill@oarcorp.com>

	* cpu.c, cpu_asm.S, rtems/score/cpu.h: Context switch now works well
	enough to run ticker to completion with the simulator clock idle
	task. But if you comment out the printk's in _CPU_Context_Initialize,
	it hangs. This remains to be investigated.

4 files changed, 103 insertions, 96 deletions

diff --git a/cpukit/score/cpu/avr/ChangeLog b/cpukit/score/cpu/avr/ChangeLog
index 2a36794e38..7a7d9a543a 100644
--- a/cpukit/score/cpu/avr/ChangeLog
+++ b/cpukit/score/cpu/avr/ChangeLog
@@ -1,3 +1,10 @@
+2009-07-28	Joel Sherrill <joel.sherrill@oarcorp.com>
+
+	* cpu.c, cpu_asm.S, rtems/score/cpu.h: Context switch now works well
+	enough to run ticker to completion with the simulator clock idle
+	task. But if you comment out the printk's in _CPU_Context_Initialize,
+	it hangs. This remains to be investigated.
+
 2009-07-23	Joel Sherrill <joel.sherrill@oarcorp.com>
 
 	* cpu.c, cpu_asm.S: Unsuccessful attempt to fix.
diff --git a/cpukit/score/cpu/avr/cpu.c b/cpukit/score/cpu/avr/cpu.c
index 8fe4c0e421..c4ec993eb3 100644
--- a/cpukit/score/cpu/avr/cpu.c
+++ b/cpukit/score/cpu/avr/cpu.c
@@ -71,36 +71,53 @@ void _CPU_Context_Initialize(
 {
   uint16_t stack;
   uint16_t start;
-  uint16_t *tmpsp;
+  uint8_t  *tmp_sp;
+  uint8_t   start_low;
+  uint8_t   start_high;
 
   /* calc stack high end */
   stack = (uint16_t) (stack_base) + (uint16_t) (size);
-
   /* calc stack pointer initial value */
-  stack -= 2;
-
-  the_context->stack_pointer = stack;
-  tmpsp = (uint16_t *) stack;
+  the_context->stack_pointer = (stack - 18);
+  /* put the entry point on the stack */
   start = (uint16_t) entry_point;
-  *tmpsp = start;
-#if 0
-  tmpsp[0] = start & 0xff;
-  tmpsp[1] = (start >> 8) & 0xff;
-#endif
+  start_low = start & 0xff;
+  start_high = start >> 8;
+  tmp_sp = (uint8_t *) (stack+1);
+  tmp_sp[0] = start_high;
+  tmp_sp[1] = start_low;
 
-  /* FIXME on level */
-  if (new_level) the_context->status = 0;
-  else           the_context->status = 0;
+  if (new_level) the_context->status = 0x00; //interrupts are enabled
+  else           the_context->status = 0x80; //interrupts are disabled
 
+  /*
+   * JOEL: Why if I comment out these three lines does ticker not run?
+   */
 #if 1
-  printk("");
+  printk( "tmp_sp=0x%04x ", ((uint16_t)tmp_sp) );
   printk("the_context = 0x%x\n", the_context);
   printk("entry = 0x%x\n", entry_point);
+#endif
+#if 0
   printk("sp = 0x%x\n\n",stack);
+
+ { int i; uint8_t *p;
+   p = (uint8_t *)(stack - 18);
+   for( i=0 ; i<=20 ; i+=8 ) {
+     printk( "0x%04x ", ((uint16_t)&p[i]) );
+     printk(
+      "0x%02x 0x%02x 0x%02x 0x%02x   ",
+      p[i + 0], p[i + 1], p[i + 2], p[i + 3]
+     );
+     printk(
+      "0x%02x 0x%02x 0x%02x 0x%02x\n",
+      p[i + 4], p[i + 5], p[i + 6], p[i + 7]
+     );
+   }
+ }
 #endif
 }
 
-
 /*PAGE
  *
  *  _CPU_ISR_Get_level
diff --git a/cpukit/score/cpu/avr/cpu_asm.S b/cpukit/score/cpu/avr/cpu_asm.S
index 9e29d7157e..39c0d3ddd3 100644
--- a/cpukit/score/cpu/avr/cpu_asm.S
+++ b/cpukit/score/cpu/avr/cpu_asm.S
@@ -208,78 +208,79 @@ SYM(_CPU_Context_restore_fp):
 
 	PUBLIC(_CPU_Context_switch)
 SYM(_CPU_Context_switch):
-	mov	r26, r24
+	mov	r26, r24 	/* r26,r27 is X or current context */
 	mov	r27, r25
-	mov	r24, r22
+	mov	r24, r22        /* r24,r25 is heir context */
  	mov	r25, r23
-	st	X+, r2
-	st	X+, r3
-	st	X+, r4
-	st	X+, r5
-	st	X+, r6
-	st	X+, r7
-	st 	X+, r8
-	st	X+, r9
-	st	X+, r10
-	st	X+, r11
-	st	X+, r12
-	st	X+, r13
-	st	X+, r14
-	st	X+, r15
-	st	X+, r16
-	st	X+, r17
-	st	X+, r28
-	st	X+, r29
-	st	X+, r29
-	lds 	r23,0x5f  /*load sreg*/
-	st 	X+, r23
-	lds	r23,0x5d /*spl*/
-	st	X+, r23
-	lds 	r23,0x5e /*sph*/
-	
+	/*save registers*/
+	push	r2
+	push	r3
+	push	r4
+	push	r5
+	push	r6
+	push	r7
+	push	r8
+	push	r9
+	push	r10
+	push	r11
+	push	r12
+	push	r13
+	push	r14
+	push	r15
+	push	r16
+	push	r17
+	push	r28
+	push	r29
+	/*load sreg*/
+	lds 	r23,0x5F  /*load sreg*/
+	/*disable interrupts*/
+	cli
+	/*load stack pointer*/
+	lds	r22,0x5D /*spl*/
+	lds 	r21,0x5E /*sph*/
+	/*save sp to context struct*/
+	/*save low then high byte --- verify this delete when verified*/
+	st	X+, r22
+	st	X+, r21
+	/*save sreg and sp to context struct*/
+	st 	X, r23
+
+
 	PUBLIC(_CPU_Context_restore)
 
 SYM(_CPU_Context_restore):
 	mov	r26,r24         /* R26/27 are X */
 	mov	r27,r25
-	ld	r2, X+
-	ld	r3, X+
-	ld	r4, X+
-	ld	r5, X+
-	ld	r6, X+
-	ld	r7, X+
-	ld	r8, X+
-	ld	r9, X+
-	ld	r10, X+
-	ld	r11, X+
-	ld	r12, X+
-	ld	r13, X+
-	ld	r14, X+
-	ld	r15, X+
-	ld	r16, X+
-	ld	r17, X+
-	ld	r28, X+	
-	ld	r29, X+
+	/*restore stack pointer*/
 	ld	r25, X+
-	sts	0x5f,r25 /*sreg*/
-	ld	r25, X+
-	sts	0x5d,r25  /*spl*/
-	ld	r25, X+
-	sts 	0x5e ,r25 /*sph*/
+	ld	r24, X+	
+	sts	0x5E, r24 /*sph*/
+	sts 	0x5D, r25 /*spl*/
+	/*restore registers from stack*/
+	pop	r29
+	pop	r28
+	pop	r17
+	pop	r16
+	pop	r15
+	pop	r14
+	pop	r13
+	pop	r12
+	pop	r11
+	pop	r10
+	pop	r9
+	pop	r8
+	pop	r7
+	pop	r6
+	pop	r5
+	pop	r4
+	pop	r3
+	pop	r2
+	/*restore status register*/
+	ld	r23, X
+	sts	0x5f,r23 /*sreg*/	
 	ret
 
 
-	PUBLIC(_CPU_Push)
-SYM(_CPU_Push):
-	lds	r20, 0x5d /*spl*/
-	lds	r21, 0x5e /*sph*/
-	sts	0x5d, r24  /*spl*/
-	sts	0x5e, r25  /*sph*/	
-	push	r22
-	push	r23
-	sts	0x5d, r20  /*spl*/
-	sts 	0x5e, r21  /*sph*/
-	ret
 
 /*
  *  _CPU_Context_restore
diff --git a/cpukit/score/cpu/avr/rtems/score/cpu.h b/cpukit/score/cpu/avr/rtems/score/cpu.h
index 28d575ccf9..d23d3b3555 100644
--- a/cpukit/score/cpu/avr/rtems/score/cpu.h
+++ b/cpukit/score/cpu/avr/rtems/score/cpu.h
@@ -424,26 +424,8 @@ extern "C" {
  */
 
 typedef struct {
-	uint8_t		reg2;
-	uint8_t		reg3;
-	uint8_t		reg4;
-	uint8_t		reg5;
-	uint8_t		reg6;
-	uint8_t		reg7;
-	uint8_t		reg8;
-	uint8_t		reg9;
-	uint8_t		reg10;
-	uint8_t		reg11;
-	uint8_t		reg12;
-	uint8_t		reg13;
-	uint8_t		reg14;
-	uint8_t		reg15;
-	uint8_t		reg16;
-	uint8_t		reg17;
-	uint8_t		reg28;
-	uint8_t		reg29;
-   	uint8_t		status; //SREG 
     	uint16_t 	stack_pointer;
+   	uint8_t		status; //SREG 
 } Context_Control;
 
 #define _CPU_Context_Get_SP( _context ) \