8051 integration

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@59 42af7a65-404d-4744-a932-0658087f49c3

19 files changed, 722 insertions, 156 deletions

diff --git a/nuttx/arch/pjrc-8051/defconfig b/nuttx/arch/pjrc-8051/defconfig
index 28044f43f..54bab70ea 100644
--- a/nuttx/arch/pjrc-8051/defconfig
+++ b/nuttx/arch/pjrc-8051/defconfig
@@ -42,7 +42,7 @@
 CONFIG_ARCH=pjrc-8051
 CONFIG_ARCH_8052=y
 CONFIG_ARCH_PJRC=y
-CONFIG_8051_LEDS=n
+CONFIG_8051_LEDS=y
 
 #
 # General OS setup
diff --git a/nuttx/arch/pjrc-8051/include/irq.h b/nuttx/arch/pjrc-8051/include/irq.h
index 819a73df7..45891986a 100644
--- a/nuttx/arch/pjrc-8051/include/irq.h
+++ b/nuttx/arch/pjrc-8051/include/irq.h
@@ -90,28 +90,52 @@
 #define FRAME_RETLS 0
 #define FRAME_RETMS 1
 
-/* Then a full context save area which can be indexed with
- * the following definitions (relative to the beginning of
- * the initial frame.
+/* Then a partial context context save area that can be
+ * indexed with the following definitions (relative to the
+ * beginning of the initial frame.
  */
 
 #define FRAME_ACC   2
 #define FRAME_IE    3
 #define FRAME_DPL   4
 #define FRAME_DPH   5
-#define FRAME_B     6
-#define FRAME_R2    7
-#define FRAME_R3    8
-#define FRAME_R4    9
-#define FRAME_R5    10
-#define FRAME_R6    11
-#define FRAME_R7    12
-#define FRAME_R0    13
-#define FRAME_R1    14
-#define FRAME_PSW   15
-#define FRAME_BP    16
-
-#define FRAME_SIZE  17
+
+#define FRAME_SIZE  6
+
+/* The remaining registers are not saved on the stack (due
+ * to the limited stack size of the 8051/2) but in an array
+ * in the TCB:
+ */
+
+#define REGS_B      0
+#define REGS_R2     1
+#define REGS_R3     2
+#define REGS_R4     3
+#define REGS_R5     4
+#define REGS_R6     5
+#define REGS_R7     6
+#define REGS_R0     7
+#define REGS_R1     8
+#define REGS_PSW    9
+#define REGS_BP     10
+
+#define REGS_SIZE   11
+
+/* Note that the stack pointer is not saved.  Rather, the
+ * size of the saved stack frame is saved in the 'nbytes'
+ * field.  Since that stack begins at a fixed location, the
+ * top-of-stack pointer can be derived from the saved size.
+ */
+
+/* These are offsets into struct xcptcontext that can be
+ * used from assembly language to access the structure.
+ */
+
+#define XCPT_NBYTES 0
+#define XCPT_STACK  1
+#define XCPT_REGS   (STACK_SIZE+1)
+
+#define XCPT_SIZE   (STACK_SIZE+REGS_SIZE+1)
 
 /************************************************************
  * Public Types
@@ -122,8 +146,26 @@
 #ifndef __ASSEMBLY__
 struct xcptcontext
 {
+   /* This is the number of valid bytes currently saved in
+    * stack[].  Since that stack begins at a fixed location,
+    * the top-of-stack pointer can be derived from this size.
+    */
+
    ubyte nbytes;
+
+   /* This is the saved stack.  Space is allocated for the 
+    * entire 256 byte IRAM (minus register and bit usage at
+    * the beginning).
+    */
+
    ubyte stack[STACK_SIZE];
+
+   /* These are save 8051/2 registers.  These are saved
+    * separately from the stack to increase the effective
+    * stack size.
+    */
+
+   ubyte regs[REGS_SIZE];
 };
 #endif /* __ASSEMBLY */
 
diff --git a/nuttx/arch/pjrc-8051/src/pjrc.h b/nuttx/arch/pjrc-8051/src/pjrc.h
index 41f5a7e21..fd875d388 100644
--- a/nuttx/arch/pjrc-8051/src/pjrc.h
+++ b/nuttx/arch/pjrc-8051/src/pjrc.h
@@ -150,7 +150,7 @@ xdata at 0xF903 ubyte p82c55_def_config;
 #define LED_STARTED                 0
 #define LED_HEAPALLOCATE            1
 #define LED_IRQSENABLED             2
-#define LED_UNUSED1                 3
+#define LED_IDLE                    3
 #define LED_UNUSED2                 4
 #define LED_INIRQ                   5
 #define LED_ASSERTION               6
diff --git a/nuttx/arch/pjrc-8051/src/up_blocktask.c b/nuttx/arch/pjrc-8051/src/up_blocktask.c
index e8ea55523..9d9094a77 100644
--- a/nuttx/arch/pjrc-8051/src/up_blocktask.c
+++ b/nuttx/arch/pjrc-8051/src/up_blocktask.c
@@ -131,7 +131,7 @@ void up_block_task(FAR _TCB *tcb, tstate_t task_state)
                * Just copy the current registers into the OLD rtcb.
                */
 
-               up_savestack(&tcb->xcp, g_irqtos);
+               up_saveirqcontext(&tcb->xcp);
 
               /* Restore the exception context of the rtcb at the (new) head 
                * of the g_readytorun task list.
diff --git a/nuttx/arch/pjrc-8051/src/up_debug.c b/nuttx/arch/pjrc-8051/src/up_debug.c
index 6f1485aaa..3ca2acae7 100644
--- a/nuttx/arch/pjrc-8051/src/up_debug.c
+++ b/nuttx/arch/pjrc-8051/src/up_debug.c
@@ -80,7 +80,7 @@ static void _up_putcolon(void) __naked
 {
   _asm
         mov     a, #0x3a
-        lcall	PM2_ENTRY_COUT
+        ljmp	PM2_ENTRY_COUT
   _endasm;
 }
 
@@ -126,7 +126,7 @@ static void _up_dump8(__code char *ptr, ubyte b)
 #ifdef CONFIG_FRAME_DUMP
 void up_dumpstack(void)
 {
-  NEAR ubyte *start = (NEAR ubyte *)(UP_STACK_BASE & 0xf0);
+  NEAR ubyte *start = (NEAR ubyte *)(STACK_BASE & 0xf0);
   NEAR ubyte *end   = (NEAR ubyte *)SP;
   ubyte i;
 
@@ -138,7 +138,16 @@ void up_dumpstack(void)
       for (i = 0; i < 8; i++)
         {
           _up_putspace();
-          _up_puthex(*start);
+          if (start < (NEAR ubyte *)(STACK_BASE) ||
+              start > end)
+            {
+              _up_putspace();
+              _up_putspace();
+            }
+          else
+            {
+              _up_puthex(*start);
+            }
           start++;
         }
       _up_putnl();
@@ -153,11 +162,52 @@ void up_dumpstack(void)
 #ifdef CONFIG_FRAME_DUMP
 void up_dumpframe(FAR struct xcptcontext *context)
 {
-  FAR ubyte *start = &context->stack[context->nbytes - FRAME_SIZE];
-  _up_dump16(" RET  ", start[FRAME_RETMS], start[FRAME_RETLS]);
-  _up_dump8(" IE   ", start[FRAME_IE]);
-  _up_dump16(" DPTR ", start[FRAME_DPH], start[FRAME_DPL]);
-  _up_dump8(" PSW  ", start[FRAME_PSW]);
+#ifdef CONFIG_FRAME_DUMP_SHORT
+  FAR ubyte *stack = &context->stack[context->nbytes - FRAME_SIZE];
+  FAR ubyte *regs  = context->regs;
+
+  _up_dump16(" RET  ", stack[FRAME_RETMS], stack[FRAME_RETLS]);
+  _up_dump8 (" IE   ", stack[FRAME_IE]);
+  _up_dump16(" DPTR ", stack[FRAME_DPH], stack[FRAME_DPL]);
+  _up_dump8 (" PSW  ", regs[REGS_PSW]);
+  _up_dump8 (" SP   ", context->nbytes + (STACK_BASE-1));
+#else
+  FAR ubyte *stack = &context->stack[context->nbytes - FRAME_SIZE];
+  FAR ubyte *regs  = context->regs;
+  ubyte i, j, k;
+
+  _up_dump8 ("  NBYTES ", context->nbytes);
+
+  for (i = 0; i < context->nbytes; i += 8)
+    {
+      _up_puthex(i);
+      _up_putcolon();
+
+      for (j = 0; j < 8; j++)
+        {
+          k = i + j;
+          _up_putspace();
+          if (k >= context->nbytes)
+            {
+              _up_putspace();
+              _up_putspace();
+            }
+          else
+            {
+              _up_puthex(context->stack[k]);
+            }
+        }
+      _up_putnl();
+    }
+
+  _up_puts("  REGS:");
+  for (i = 0; i < REGS_SIZE; i++)
+    {
+      _up_putspace();
+      _up_puthex(context->regs[i]);
+    }
+   _up_putnl();
+#endif
 }
 #endif
 
diff --git a/nuttx/arch/pjrc-8051/src/up_delay.c b/nuttx/arch/pjrc-8051/src/up_delay.c
index 7b682033f..111d2c0df 100644
--- a/nuttx/arch/pjrc-8051/src/up_delay.c
+++ b/nuttx/arch/pjrc-8051/src/up_delay.c
@@ -38,6 +38,7 @@
  ************************************************************/
 
 #include <nuttx/config.h>
+#include <sys/types.h>
 #include "up_internal.h"
 
 /************************************************************
diff --git a/nuttx/arch/pjrc-8051/src/up_head.S b/nuttx/arch/pjrc-8051/src/up_head.S
index 33d9db3dd..1981e5dd8 100644
--- a/nuttx/arch/pjrc-8051/src/up_head.S
+++ b/nuttx/arch/pjrc-8051/src/up_head.S
@@ -57,12 +57,14 @@
 
 	.globl	_g_irqtos
 	.globl	_g_irqcontext
+	.globl	_g_irqregs
 
 /************************************************************
  * Public Functions
  ************************************************************/
 
 	.globl	_irq_dispatch
+	.globl	_up_restoreregisters
 
 /************************************************************
  * Program entry points
@@ -157,33 +159,31 @@ _up_interrupt:
 	push	ie
 	clr	ea
 
-	/* Now push the remaining registers with interrupt disabled */
+	/* Save the remaining registers with interrupts disabled 
+	 *
+	 * a, ie, and dptr go on the stack.
+	 */
 
 	push	dpl
 	push	dph
-	push	b
-	push	ar2
-	push	ar3
-	push	ar4
-	push	ar5
-	push	ar6
-	push	ar7
-	push	ar0
-	push	ar1
-	push	psw
-	clr	psw
-	push	_bp
-
-	/* Save the IRQ number in r3 */
 
-#ifdef CONFIG_8051_LEDS
+	/* Other registers go into the IRQ register save area */
+
 	push	acc
+	mov	dptr, #_g_irqregs
+	lcall	_up_saveregisters
+
+	/* Show interrupt status on the LEDs */
+
+#ifdef CONFIG_8051_LEDS
 	mov	dpl, #LED_INIRQ
 	lcall	_up_ledon
-	pop	ar2
-#else
-	mov	r2, a
 #endif
+
+	/* Save the IRQ number in r2 */
+
+	pop	ar2
+
 	/* Mark that we are in an interrupt and provide the top
 	 * of stack pointer to the context switching logic.
 	 */
@@ -197,7 +197,7 @@ _up_interrupt:
 	 * structure.
 	 */
 
-	mov	dptr,#_g_irqcontext
+	mov	dptr, #_g_irqcontext
 	clr	a
 	movx	@dptr,a
 	inc	dptr
@@ -238,8 +238,17 @@ _up_interrupt:
 	movx	a, @dptr
 	mov	r3, a
 
-        orl     a, r2
-        jz      00003$
+	orl	a, r2
+	jnz	00001$
+
+	/* No context switch is pending.  Restore registers
+	 * from the interrupt register save area.
+	 */
+
+	mov	dptr, #_g_irqregs
+	sjmp	00004$
+
+00001$: /****************************************************/
 
 	/* A context switch is pending, clear g_irqcontext */
 
@@ -285,6 +294,8 @@ _up_interrupt:
 	/* Save r2-3 = &context->stack */
 
 	inc	dptr
+	push	dpl
+	push	dph
 	mov	r2, dpl
 	mov	r3, dph
 
@@ -293,9 +304,10 @@ _up_interrupt:
 	mov	r0, #STACK_BASE
 
 	/* Top of the copy loop */
-00001$:
-	dec	r4
-	jz	00002$
+00002$:
+	mov	a, r4	/* a = bytes left to transfer */
+	dec	r4	/* (for next time through the loop) */
+	jz	00003$	/* Jump if a = 0 (done) */
 
 	/* Fetch the next byte from context->stack */
 
@@ -316,38 +328,69 @@ _up_interrupt:
 	/* Increment the IRAM pointer */
 
 	inc	r0
-	sjmp	00001$
+	sjmp	00002$
 
-	/* Set the new stack pointer */
+	/* The entire stack has been copied from XRAM into
+	 * IRAM.  Set the new stack pointer
+	 */
 
-00002$:
+00003$:
+	pop	dph
+	pop	dpl
 	mov	sp, r5
 
 #ifdef CONFIG_INTERRUPT_FRAME_DUMP
+	push	dpl
+	push	dph
 	lcall	_up_dumpstack
+	pop	dpl
+	pop	dph
 #endif
-	/* Then restore the context from the stack and return
-	 * from the interrupt
+	/* Get the pointer to the register save area */
+
+	mov	a, #FRAME_SIZE
+	add	a, dpl
+	mov	dpl, a
+	clr	a
+	addc	a, dph
+	mov	dph, a
+	
+00004$: /****************************************************/
+
+	/* Restore the context from the register save area
+	 * and return from the interrupt.  At this point, dptr
+	 * holds the pointer to the memory region that holds
+	 * the register save area. This could be either
+	 * g_irqregs (no context switch) or &g_irqcontext->regs
+	 * (context switch).
 	 */
 
-00003$:
 #ifdef CONFIG_8051_LEDS
+	push	dpl
+	push	dph
 	mov	dpl, #LED_INIRQ
 	lcall	_up_ledoff
+	pop	dpl
+	pop	dph
 #endif
-	pop	_bp 
-	pop	psw
-	pop	ar1 
-	pop	ar0 
-	pop	ar7 
-	pop	ar6 
-	pop	ar5 
-	pop	ar4 
-	pop	ar3 
-	pop	ar2 
-	pop	b
+	/* Restore registers from the register save area */
+
+	lcall	_up_restoreregisters
+
+	/* Restore registers from the stack and return */
+
 	pop	dph
 	pop	dpl
-	pop	ie
+
+	/* Restore the interrupt state per the stored IE value */
+
+	pop	acc
+	jb	acc.7,00005$
+	clr	ie.7
+	sjmp	00006$
+00005$:
+	setb	ie.7
+
+00006$:
 	pop	acc
 	reti
diff --git a/nuttx/arch/pjrc-8051/src/up_idle.c b/nuttx/arch/pjrc-8051/src/up_idle.c
index fcc89ed9b..c413c3f41 100644
--- a/nuttx/arch/pjrc-8051/src/up_idle.c
+++ b/nuttx/arch/pjrc-8051/src/up_idle.c
@@ -50,6 +50,10 @@
  * Private Data
  ************************************************************/
 
+#if defined(CONFIG_8051_LEDS) && defined(CONFIG_8051_BRINGUP)
+static ubyte g_ledtoggle = 0;
+#endif
+
 /************************************************************
  * Private Functions
  ************************************************************/
@@ -75,5 +79,16 @@
 
 void up_idle(void)
 {
+#if defined(CONFIG_8051_LEDS) && defined(CONFIG_8051_BRINGUP)
+  g_ledtoggle++;
+  if (g_ledtoggle == 0x80)
+    {
+      up_ledon(LED_IDLE);
+    }
+  else if (g_ledtoggle == 0x00)
+    {
+      up_ledoff(LED_IDLE);
+    }
+#endif
 }
 
diff --git a/nuttx/arch/pjrc-8051/src/up_initialize.c b/nuttx/arch/pjrc-8051/src/up_initialize.c
index d0680b6cf..4d988501b 100644
--- a/nuttx/arch/pjrc-8051/src/up_initialize.c
+++ b/nuttx/arch/pjrc-8051/src/up_initialize.c
@@ -60,6 +60,16 @@
 
 ubyte g_irqtos;
 
+/* Registers are saved in the following global array during
+ * interrupt processing.  If a context switch is performed
+ * during the interrupt handling, these registers will be
+ * copied into the TCB again (NOTE:  We could save a copy
+ * if the interrupt handling logic saved the registers
+ * directly into (_TCB*)g_readytorun.head->xcp.regs).
+ */
+
+ubyte g_irqregs[REGS_SIZE];
+
 /* If during execution of an interrup handler, a context
  * switch must be performed, the follwing will be set to
  * to that address of the relevant context structure.  The
@@ -69,6 +79,13 @@ ubyte g_irqtos;
 
 FAR struct xcptcontext *g_irqcontext;
 
+/* It is faster to look up 8-bit shifts in this table than
+ * to comput them.
+ */
+
+const ubyte g_ntobit[8] = 
+  { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
+
 /************************************************************
  * Private Functions
  ************************************************************/
diff --git a/nuttx/arch/pjrc-8051/src/up_initialstate.c b/nuttx/arch/pjrc-8051/src/up_initialstate.c
index 1eae39fa9..7fc0ddc39 100644
--- a/nuttx/arch/pjrc-8051/src/up_initialstate.c
+++ b/nuttx/arch/pjrc-8051/src/up_initialstate.c
@@ -75,6 +75,7 @@
 void up_initial_state(FAR _TCB *tcb)
 {
   FAR ubyte *frame = tcb->xcp.stack;
+  FAR ubyte *regs  = tcb->xcp.regs;
 
   /* This is the form of initial stack frame
    *
@@ -96,10 +97,21 @@ void up_initial_state(FAR _TCB *tcb)
    frame[FRAME_RETLS] = (((uint16)tcb->start) & 0xff);
    frame[FRAME_RETMS] = (((uint16)tcb->start) >> 8);
 
-  /* The context save area follows the return address. */
+  /* The context save area for registers a, ie, and dpstr
+   * follows the return address in the stack frame.
+   */
+
+  frame[FRAME_IE] = 0x80;
+
+  /* Save the number of bytes in the frame (which will be used
+   * to intialize the stack pointer when the task is started).
+   */
+
+  tcb->xcp.nbytes = FRAME_SIZE;
 
-  frame[FRAME_IE]     = 0x80;
-  frame[FRAME_PSW]    = 0;
+  /* Initialize the remaining register save area which is
+   * outside of the stack save area.
+   */
 
-  tcb->xcp.nbytes     = FRAME_SIZE;
+  tcb->xcp.regs[REGS_PSW] = 0;
 }
diff --git a/nuttx/arch/pjrc-8051/src/up_internal.h b/nuttx/arch/pjrc-8051/src/up_internal.h
index 19c628f5c..634803054 100644
--- a/nuttx/arch/pjrc-8051/src/up_internal.h
+++ b/nuttx/arch/pjrc-8051/src/up_internal.h
@@ -41,6 +41,7 @@
  **************************************************************************/
 
 #include <nuttx/config.h>
+#include <arch/irq.h>
 #ifdef CONFIG_ARCH_PJRC
 # include "pjrc.h"
 #endif
@@ -51,10 +52,13 @@
 
 /* Bring-up debug configurations */
 
-#define CONFIG_FRAME_DUMP 1             /* Enabled stack/frame dumping logic */
-#define CONFIG_SUPPRESS_INTERRUPTS 1    /* Do not enable interrupts */
-#define CONFIG_SWITCH_FRAME_DUMP 1      /* Dump frames from normal switches */
+#define CONFIG_8051_BRINGUP         1   /* Enables some bringup features */
+#define CONFIG_FRAME_DUMP           1   /* Enable stack/frame dumping logic */
+#undef  CONFIG_FRAME_DUMP_SHORT         /* Terse frame dump output */
+#define CONFIG_SUPPRESS_INTERRUPTS  1   /* Do not enable interrupts */
+#define CONFIG_SWITCH_FRAME_DUMP    1   /* Dump frames from normal switches */
 #undef  CONFIG_INTERRUPT_FRAME_DUMP     /* Dump frames from interrupt switches */
+#define CONFIG_LED_DEBUG            1   /* Enabled debug output from LED logic */
 
 /**************************************************************************
  * Public Types
@@ -75,6 +79,16 @@
 
 extern ubyte g_irqtos;
 
+/* Registers are saved in the following global array during
+ * interrupt processing.  If a context switch is performed
+ * during the interrupt handling, these registers will be
+ * copied into the TCB again (NOTE:  We could save a copy
+ * if the interrupt handling logic saved the registers
+ * directly into (_TCB*)g_readytorun.head->xcp.regs).
+ */
+
+extern ubyte g_irqregs[REGS_SIZE];
+
 /* If during execution of an interrup handler, a context
  * switch must be performed, the follwing will be set to
  * to that address of the relevant context structure.  The
@@ -84,6 +98,12 @@ extern ubyte g_irqtos;
 
 extern FAR struct xcptcontext *g_irqcontext;
 
+/* It is faster to look up 8-bit shifts in this table than
+ * to comput them.
+ */
+
+extern const ubyte g_ntobit[8];
+
 #endif /* __ASSEMBLY */
 
 /**************************************************************************
@@ -95,11 +115,13 @@ extern FAR struct xcptcontext *g_irqcontext;
 #if CONFIG_MM_REGIONS > 1
 extern void  up_addregion(void);
 #endif
-extern void up_delay(ubyte milliseconds) __naked;
+extern void  up_delay(ubyte milliseconds) __naked;
 extern void  up_irqinitialize(void);
 extern void  up_restorecontext(FAR struct xcptcontext *context) _naked;
+extern void  up_restoreregisters(FAR ubyte *regs) _naked;
 extern ubyte up_savecontext(FAR struct xcptcontext *context) __naked;
-extern void  up_savestack(FAR struct xcptcontext *context, ubyte tos);
+extern void  up_saveregisters(FAR ubyte *regs) _naked;
+extern void  up_saveirqcontext(FAR struct xcptcontext *context);
 extern void  up_timerinit(void);
 
 /* Defined in up_assert.c */
@@ -116,8 +138,8 @@ extern void up_dumpframe(FAR struct xcptcontext *context);
 
 #ifdef CONFIG_8051_LEDS
 extern void up_ledinit(void);
-extern void up_ledon(int led);
-extern void up_ledoff(int led);
+extern void up_ledon(ubyte led);
+extern void up_ledoff(ubyte led);
 #else
 # define up_ledinit()
 # define up_ledon(led)
diff --git a/nuttx/arch/pjrc-8051/src/up_irq.c b/nuttx/arch/pjrc-8051/src/up_irq.c
index 8d024ca3a..bf76b25a8 100644
--- a/nuttx/arch/pjrc-8051/src/up_irq.c
+++ b/nuttx/arch/pjrc-8051/src/up_irq.c
@@ -43,6 +43,8 @@
 #include <8052.h>
 #include "up_internal.h"
 
+#include <debug.h>
+extern int g_nints;
 /************************************************************
  * Definitions
  ************************************************************/
@@ -69,7 +71,7 @@
 
 void up_irqinitialize(void)
 {
-#ifndef CONFIG_SUPPRESS_INTERRUPTS
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
   /* Disable all interrupts */
 
   IE = 0;
@@ -122,7 +124,7 @@ void up_disable_irq(int irq)
 {
   if ((unsigned)irq < NR_IRQS)
     {
-       IE |= (1 << irq);
+      IE &= ~(g_ntobit[irq]);
     }
 }
 
@@ -138,6 +140,6 @@ void up_enable_irq(int irq)
 {
   if ((unsigned)irq < NR_IRQS)
     {
-      IE &= ~(1 << irq);
+      IE |= g_ntobit[irq];
     }
 }
diff --git a/nuttx/arch/pjrc-8051/src/up_leds.c b/nuttx/arch/pjrc-8051/src/up_leds.c
index 2c1243601..41d8ac8fa 100644
--- a/nuttx/arch/pjrc-8051/src/up_leds.c
+++ b/nuttx/arch/pjrc-8051/src/up_leds.c
@@ -45,16 +45,75 @@
  * Definitions
  ************************************************************/
 
+#define RESET_KLUDGE_NEEDED 1
+
 /************************************************************
  * Private Data
  ************************************************************/
 
-static uint32 g_ledstate;
+static ubyte g_ledstate;
 
 /************************************************************
  * Private Functions
  ************************************************************/
 
+#if defined(CONFIG_LED_DEBUG) && defined(CONFIG_8051_LEDS)
+static void _up_puthex(ubyte hex) __naked
+{
+  hex; /* To avoid unreferenced argument warning */
+  _asm
+        mov     a, dpl
+        ljmp    PM2_ENTRY_PHEX
+  _endasm;
+}
+
+static void _up_putch(ubyte ch) __naked
+{
+  _asm
+        mov     a, dpl
+        ljmp	PM2_ENTRY_COUT
+  _endasm;
+}
+
+static void _up_putnl(void) __naked
+{
+  _asm
+	ljmp	PM2_ENTRY_NEWLINE
+  _endasm;
+}
+
+# define _up_showledinit() \
+  _up_putch('I'); \
+  _up_puthex(g_ledstate); _up_putch(':'); \
+  _up_puthex(p82c55_port_e); _up_putnl();
+
+# define _up_showledreset() \
+  _up_putch('R'); \
+  _up_puthex(led); _up_putch(':'); \
+  _up_puthex(g_ledstate); _up_putch(':'); \
+  _up_puthex(p82c55_port_e); _up_putnl();
+
+# define _up_showledon() \
+  _up_putch('+'); \
+  _up_puthex(led); _up_putch(':'); \
+  _up_puthex(g_ledstate); _up_putch(':'); \
+  _up_puthex(p82c55_port_e); _up_putnl();
+
+# define _up_showledoff() \
+  _up_putch('-'); \
+  _up_puthex(led); _up_putch(':'); \
+  _up_puthex(g_ledstate); _up_putch(':'); \
+  _up_puthex(p82c55_port_e); _up_putnl();
+
+#else
+
+# define _up_showledinit()
+# define _up_showledreset()
+# define _up_showledon()
+# define _up_showledoff()
+
+#endif
+
 /************************************************************
  * Public Funtions
  ************************************************************/
@@ -68,38 +127,71 @@ void up_ledinit(void)
 {
   /* Set all ports as outputs */
 
-  p82c55_abc_config = 128;
   p82c55_def_config = 128;
 
   /* Turn LED 1-7 off; turn LED 0 on */
 
-  g_ledstate    = 0x000000fe;
+  g_ledstate    = 0xfe;
   p82c55_port_e = g_ledstate;
+
+  _up_showledinit();
 }
 
 /************************************************************
  * Name: up_ledon
  ************************************************************/
 
-void up_ledon(int led)
+void up_ledon(ubyte led)
 {
+#ifdef RESET_KLUDGE_NEEDED
+  /* I don't understand why this happens yet, but sometimes
+   * it is necessary to reconfigure port E.
+   */
+
+  if (g_ledstate != p82c55_port_e)
+    {
+      _up_showledreset();
+      p82c55_def_config = 128;
+    }
+#endif
+
+  /* Clear the bit in port E corresponding to LED to turn it on */
+
   if (led < 8)
     {
-      g_ledstate   &= ~(1 << led);
+      g_ledstate   &= ~(g_ntobit[led]);
       p82c55_port_e = g_ledstate;
     }
+
+  _up_showledon();
 }
 
 /************************************************************
  * Name: up_ledoff
  ************************************************************/
 
-void up_ledoff(int led)
+void up_ledoff(ubyte led)
 {
+#ifdef RESET_KLUDGE_NEEDED
+  /* I don't understand why this happens yet, but sometimes
+   * it is necessary to reconfigure port E.
+   */
+
+  if (g_ledstate != p82c55_port_e)
+    {
+      _up_showledreset();
+      p82c55_def_config = 128;
+    }
+#endif
+
+  /* Set the bit in port E corresponding to LED to turn it off */
+
   if (led < 8)
     {
-      g_ledstate   |= (1 << led);
+      g_ledstate   |= g_ntobit[led];
       p82c55_port_e = g_ledstate;
     }
+
+  _up_showledoff();
 }
 #endif /* CONFIG_8051_LEDS */
diff --git a/nuttx/arch/pjrc-8051/src/up_releasepending.c b/nuttx/arch/pjrc-8051/src/up_releasepending.c
index dfab2ecb5..8a58da9e6 100644
--- a/nuttx/arch/pjrc-8051/src/up_releasepending.c
+++ b/nuttx/arch/pjrc-8051/src/up_releasepending.c
@@ -94,7 +94,7 @@ void up_release_pending(void)
            * Just copy the current registers into the OLD rtcb.
            */
 
-           up_savestack(&rtcb->xcp, g_irqtos);
+           up_saveirqcontext(&rtcb->xcp);
 
           /* Restore the exception context of the rtcb at the (new) head 
            * of the g_readytorun task list.
diff --git a/nuttx/arch/pjrc-8051/src/up_reprioritizertr.c b/nuttx/arch/pjrc-8051/src/up_reprioritizertr.c
index 6aa1da68a..1b8a3adbf 100644
--- a/nuttx/arch/pjrc-8051/src/up_reprioritizertr.c
+++ b/nuttx/arch/pjrc-8051/src/up_reprioritizertr.c
@@ -142,7 +142,7 @@ void up_reprioritize_rtr(FAR _TCB *tcb, ubyte priority)
                * Just copy the current registers into the OLD rtcb.
                */
 
-               up_savestack(&tcb->xcp, g_irqtos);
+               up_saveirqcontext(&tcb->xcp);
 
               /* Restore the exception context of the rtcb at the (new) head 
                * of the g_readytorun task list.
diff --git a/nuttx/arch/pjrc-8051/src/up_restorecontext.c b/nuttx/arch/pjrc-8051/src/up_restorecontext.c
index ce5735db9..bdb2fea24 100644
--- a/nuttx/arch/pjrc-8051/src/up_restorecontext.c
+++ b/nuttx/arch/pjrc-8051/src/up_restorecontext.c
@@ -69,6 +69,66 @@
  **************************************************************************/
 
 /**************************************************************************
+ * Name: up_restoreregisters
+ *
+ * Description:
+ *   Restore the saved registers from the context save area.  This function
+ *   is called from up_restorecontext (below) and also from interrupt
+ *   handling logic.
+ *
+ *   Note that this function does not restore:
+ *   a, dptr, ie - these are saved in the stack area
+ *   sp - this can be inferred from g_irqtos or struct xcptontext.nbytes.
+ *
+ * Inputs:
+ *   context - the context register array from which to restore the
+ *   register values
+ *
+ * Return:
+ *   None
+ *
+ **************************************************************************/
+
+void up_restoreregisters(FAR ubyte *regs) _naked
+{
+ _asm
+	movx	a, @dptr
+	mov	b, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r2, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r3, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r4, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r5, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r6, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r7, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r0, a
+	inc	dptr
+	movx	a, @dptr
+	mov	r1, a
+	inc	dptr
+	movx	a, @dptr
+	mov	psw, a
+	inc	dptr
+	movx	a, @dptr
+	mov	_bp, a
+	ret
+  _endasm;
+}
+
+/**************************************************************************
  * Name: up_restorecontext
  *
  * Description:
@@ -95,6 +155,10 @@ void up_restorecontext(FAR struct xcptcontext *context) __naked
 	ar0 = 0x00
 	ar1 = 0x01
 
+	/* Dump the contents of the saved frame before it is copied back
+	 * to memory/registers.
+	 */
+
 #ifdef CONFIG_SWITCH_FRAME_DUMP
 	push	dpl
 	push	dph
@@ -109,14 +173,17 @@ void up_restorecontext(FAR struct xcptcontext *context) __naked
 
 	clr	ea
 
-	/* Register usage in the following:
+	/* The following logic will copy the stack from the
+	 * context save structure into IRAM.  We cannot use
+	 * the stack in anyway during this copy.  Instead,
+	 * we will use registers as follows:
 	 *
-	 * R0   - Holds working the 8-bit IRAM pointer
+	 * R0   - Holds the working 8-bit IRAM pointer
 	 * R1   - Not used
 	 * R2-3 - Holds the working 16-bit XRAM pointer
 	 * R4   - Holds the working byte count
 	 * R5   - Holds the new stack pointer
-	 * R6-7 - Not used
+	 * R6-7 - Saved context pointer
 	 */
 
 	/* Fetch r4 = context->nbytes */
@@ -129,26 +196,32 @@ void up_restorecontext(FAR struct xcptcontext *context) __naked
 	add	a, #(STACK_BASE-1)
 	mov	r5, a
 
-	/* Save r2-3 = &context->stack */
+	/* Save r2-3 and r6-r7 = &context->stack */
 
 	inc	dptr
 	mov	r2, dpl
 	mov	r3, dph
+	mov	r6, dpl
+	mov	r7, dph
 
 	/* Set r0 = stack base address */
 
 	mov	r0, #STACK_BASE
 
-	/* Top of the copy loop */
+	/* Top of the copy loop -- we cannot use the stack
+	 * again until we finish the copy and set the new
+	 * stack pointer (saved in r5)
+	 */
 00001$:
-	dec	r4
-	jz	00002$
+	mov	a, r4	/* a = bytes left to transfer */
+	dec	r4	/* (for next time through the loop) */
+	jz	00002$	/* Jump if a = 0 (done) */
 
 	/* Fetch the next byte from context->stack */
 
 	mov	dpl, r2
 	mov	dph, r3
-	movx	a,@dptr
+	movx	a, @dptr
 
 	/* Increment the XRAM pointer */
 
@@ -166,26 +239,40 @@ void up_restorecontext(FAR struct xcptcontext *context) __naked
 	sjmp	00001$
 00002$:
 
-	/* Set the new stack pointer */
+	/* Set the new stack pointer and recover the
+	 * context->stack pointer.
+	 */
 
 	mov	sp, r5
+	mov	dpl, r6
+	mov	dph, r7
+
+	/* Dump the stack contents after they have
+	 * been restored to IRAM
+	 */
 
 #ifdef CONFIG_SWITCH_FRAME_DUMP
+	push	dpl
+	push	dph
 	lcall	_up_dumpstack
+	pop	dph
+	pop	dpl
 #endif
-	/* Then restore the context from the stack */
-
-	pop	_bp 
-	pop	psw
-	pop	ar1 
-	pop	ar0 
-	pop	ar7 
-	pop	ar6 
-	pop	ar5 
-	pop	ar4 
-	pop	ar3 
-	pop	ar2 
-	pop	b 
+	/* Get the pointer to the register save area */
+
+	mov	a, #FRAME_SIZE
+	add	a, dpl
+	mov	dpl, a
+	clr	a
+	addc	a, dph
+	mov	dph, a
+
+	/* Restore registers from the register save area */
+
+	lcall	_up_restoreregisters
+
+	/* Restore registers from the new stack */
+
 	pop	dph
 	pop	dpl 
 
@@ -197,8 +284,8 @@ void up_restorecontext(FAR struct xcptcontext *context) __naked
 	sjmp	00004$
   00003$:
 	setb	ie.7
-  00004$:
 
+  00004$:
 	pop acc
 	ret
   _endasm;
diff --git a/nuttx/arch/pjrc-8051/src/up_savecontext.c b/nuttx/arch/pjrc-8051/src/up_savecontext.c
index 9631c2a11..346f9271d 100644
--- a/nuttx/arch/pjrc-8051/src/up_savecontext.c
+++ b/nuttx/arch/pjrc-8051/src/up_savecontext.c
@@ -66,10 +66,134 @@
  **************************************************************************/
 
 /**************************************************************************
+ * Name: up_savestack
+ *
+ * Description:
+ *   Save the entire interrupt stack contents in the provided context
+ *   structure.
+ *
+ * Inputs:
+ *   context - the context structure in which to save the stack info
+ *
+ * Return:
+ *   None
+ *
+ * Assumptions:
+ *   - Interrupts are disabled
+ *
+ **************************************************************************/
+
+static void up_savestack(FAR struct xcptcontext *context, ubyte tos)
+{
+  /* Copy the current stack frame from internal RAM to XRAM. */
+
+  ubyte nbytes     = tos - (STACK_BASE-1);
+  NEAR ubyte *src  = (NEAR ubyte*)STACK_BASE;
+  FAR  ubyte *dest = context->stack;
+
+  context->nbytes = nbytes;
+  while (nbytes--)
+    {
+      *dest++ = *src++;
+    }
+}
+
+/**************************************************************************
+ * Name: up_saveregs
+ *
+ * Description:
+ *   Save the interrupt registers into the TCB.
+ *
+ * Inputs:
+ *   context - the context structure in which to save the register info
+ *
+ * Return:
+ *   None
+ *
+ * Assumptions:
+ *   - Interrupts are disabled
+ *
+ **************************************************************************/
+
+static void up_saveregs(FAR struct xcptcontext *context, ubyte tos)
+{
+  /* Copy the irq register save area into the TCB */
+
+  FAR ubyte *src  = g_irqregs;
+  FAR ubyte *dest = context->regs;
+  ubyte nbytes    = REGS_SIZE;
+
+  while (nbytes--)
+    {
+      *dest++ = *src++;
+    }
+}
+
+/**************************************************************************
  * Public Functions
  **************************************************************************/
 
 /**************************************************************************
+ * Name: up_saveregisters
+ *
+ * Description:
+ *   Save the current registers in the context save area.  This function
+ *   is called from up_savecontext (below) and also from interrupt
+ *   handling logic.
+ *
+ *   Note that this function does not save:
+ *   a, dptr, ie - these are saved in the stack area
+ *   sp - this can be inferred from g_irqtos or struct xcptontext.nbytes.
+ *
+ * Inputs:
+ *   regs - the context register array in which to save the register info
+ *
+ * Return:
+ *   None
+ *
+ **************************************************************************/
+
+void up_saveregisters(FAR ubyte *regs) _naked
+{
+ _asm
+	mov	a, b
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r2
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r3
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r4
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r5
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r6
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r7
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r0
+	movx	@dptr, a
+	inc	dptr
+	mov	a, r1
+	movx	@dptr, a
+	inc	dptr
+	mov	a, psw
+	movx	@dptr, a
+	clr	psw
+	inc	dptr
+	mov	a, _bp
+	movx	@dptr, a
+	ret
+  _endasm;
+}
+
+/**************************************************************************
  * Name: up_savecontext
  *
  * Description:
@@ -89,8 +213,14 @@ ubyte up_savecontext(FAR struct xcptcontext *context) _naked
 {
  _asm
 	/* Create the stack frame that we want when it is time to restore
-	 * this* context.  The return address will be the return address
+	 * this context.  The return address will be the return address
 	 * of this function, the return value will be zero.
+         *
+         * ...
+         * return address (2 bytes, already on the stack)
+         * register a=0   (1 byte)
+         * register ie    (1 byte)
+         * register dptr  (2 bytes)
 	 */
 
 	clr	a
@@ -100,42 +230,95 @@ ubyte up_savecontext(FAR struct xcptcontext *context) _naked
 	push	acc	/* DPL = 1 */
 	clr	a
 	push	acc	/* DPH = 0 */
-	push	b
-	push	ar2
-	push	ar3
-	push	ar4
-	push	ar5
-	push	ar6
-	push	ar7
-	push	ar0
-	push	ar1
-	push	psw
-	clr	psw
-	push	_bp
 
-	/* Disable interrupts while we create a snapshot of the stack */
+	/* Dump the stack contents before they are occupied into XRAM */
+
+#ifdef CONFIG_SWITCH_FRAME_DUMP
+	push	dpl
+	push	dph
+	lcall	_up_dumpstack
+	pop	dph
+	pop	dpl
+#endif
+	/* Disable interrupts while we create a snapshot of the stack
+         * and registers.  At this point, we have 5 bytes on the stack
+	 * to account for.
+         */
 
 	push	ie
 	mov	ea, 0
 
-	/* Now copy the current stack frame (including the saved execution
-	 * context) from internal RAM to XRAM.
+	/* Save the registers in the context save area */
+
+	push	dpl
+	push	dph
+	mov	a, #XCPT_REGS
+	add	a, dpl
+	mov	dpl, a
+	clr	a
+	addc	a, dph
+	mov	dph, a
+	lcall	_up_saveregisters
+	pop	dph
+	pop	dpl
+
+#ifdef CONFIG_SWITCH_FRAME_DUMP
+	/* Save the address of the context structure.  We will
+	 * need this later to dump the saved frame.  Now we have
+	 * 7 bytes on the stack to account for.
+	 */
+
+	push	dpl
+	push	dph
+
+	/* Push the top of frame stack pointer.  We need to
+	 * decrement the current SP value by three to account
+	 * for dpst+IE on the stack above the end of the frame.
 	 */
 
-	push	sp
+	mov	a, sp
+	subb	a, #3
+#else
+	/* Push the top of frame stack pointer.  We need to
+	 * decrement the current stack pointer by one to account
+	 * for IE that we saved on the stack.
+	 */
+
+	mov	a, sp
+	dec	a
+#endif
+	push	acc
+
+	/* Copy the current stack frame from internal RAM to XRAM. */
+
 	lcall	_up_savestack
 	pop	acc
 
+	/* Dump the contents of the saved frame after it has been
+	 * copied from  memory/registers.
+	 */
+
+#ifdef CONFIG_SWITCH_FRAME_DUMP
+	pop	dph
+	pop	dpl
+	push	dpl
+	push	dph
+	lcall	_up_dumpframe
+	pop	dph
+	pop	dpl
+	lcall	_up_dumpstack
+#endif
+
 	/* Restore the interrupt state */
 
 	pop	ie
 
 	/* Now that we have a snapshot of the desired stack frame saved,
-	 * restore the correct stackpointer.
+	 * we can release the stack frame (all but the return address)
 	 */
 
 	mov	a, sp
-	subb	a, #15
+	subb	a, #4
 	mov	sp, a
 	mov	dpl,#0
 	ret
@@ -143,14 +326,16 @@ ubyte up_savecontext(FAR struct xcptcontext *context) _naked
 }
 
 /**************************************************************************
- * Name: up_savestack
+ * Name: up_saveirqcontext
  *
  * Description:
- *   Save the entire interrupt stack contents in the provided context
- *   structure.
+ *   The interrupt context was saved in g_irqtos and g_irqregs when the
+ *   interrupt was taken.  If a context switch from the interrupted task
+ *   will be made at the interrupt level, then these saved values must be
+ *   copied into the TCB.
  *
  * Inputs:
- *   context - the context structure in which to save the stack info
+ *   context - the structure in which to save the context info
  *
  * Return:
  *   None
@@ -160,19 +345,17 @@ ubyte up_savecontext(FAR struct xcptcontext *context) _naked
  *
  **************************************************************************/
 
-void up_savestack(FAR struct xcptcontext *context, ubyte tos)
+void up_saveirqcontext(FAR struct xcptcontext *context)
 {
-  /* Now copy the current stack frame (including the saved execution
-   * context) from internal RAM to XRAM.
-   */
+  /* Save the number of bytes in the stack */
 
-  ubyte nbytes     = tos - (STACK_BASE-1);
-  NEAR ubyte *src  = (NEAR ubyte*)STACK_BASE;
-  FAR  ubyte *dest = context->stack;
+   context->nbytes = g_irqtos - (STACK_BASE-1);
 
-  context->nbytes = nbytes;
-  while (nbytes--)
-    {
-      *dest++ = *src++;
-    }
+  /* Copy the current stack frame from internal RAM to XRAM. */
+
+  up_savestack(context, g_irqtos);
+
+  /* Copy the saved registers into the TCB */
+
+  up_saveregisters(context->regs);
 }
diff --git a/nuttx/arch/pjrc-8051/src/up_unblocktask.c b/nuttx/arch/pjrc-8051/src/up_unblocktask.c
index 3f09d7ce5..005e74e54 100644
--- a/nuttx/arch/pjrc-8051/src/up_unblocktask.c
+++ b/nuttx/arch/pjrc-8051/src/up_unblocktask.c
@@ -122,7 +122,7 @@ void up_unblock_task(FAR _TCB *tcb)
                * Just copy the current stack into the OLD rtcb.
                */
 
-               up_savestack(&rtcb->xcp, g_irqtos);
+               up_saveirqcontext(&rtcb->xcp);
 
               /* Restore the exception context of the rtcb at the (new) head 
                * of the g_readytorun task list.
diff --git a/nuttx/sched/task_setup.c b/nuttx/sched/task_setup.c
index 3573e72d9..744f5fbf4 100644
--- a/nuttx/sched/task_setup.c
+++ b/nuttx/sched/task_setup.c
@@ -64,7 +64,7 @@
 
 /* This is the name for un-named tasks */
 
-static FAR char g_noname[] = "no name";
+static const char g_noname[] = "no name";
 
 /************************************************************
  * Private Function Prototypes
@@ -247,7 +247,7 @@ STATUS task_argsetup(FAR _TCB *tcb, const char *name,
 
   if (!name)
     {
-      name = g_noname;
+      name = (char *)g_noname;
     }
 
   /* copy the name into the TCB */
@@ -260,7 +260,7 @@ STATUS task_argsetup(FAR _TCB *tcb, const char *name,
 #if CONFIG_TASK_NAME_SIZE > 0
   tcb->argv[0] = tcb->name;
 #else
-  tcb->argv[0] = g_noname;
+  tcb->argv[0] = (char *)g_noname;
 #endif
 
   /* For pthreads, args are strictly pass-by-value; the char*
@@ -294,7 +294,7 @@ STATUS task_argsetup(FAR _TCB *tcb, const char *name,
 
       /* And just copy the argument. For pthreads, there
        * is really only a single argument, argv[0].  It is
-       * copy as a value -- NOT duplicated.
+       * copied as a value -- NOT duplicated.
        */
 
       i = 2;