From 7c7a0d4f24f90b33297715dbb0aadeacf0c883fb Mon Sep 17 00:00:00 2001
From: patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>
Date: Sun, 23 Dec 2012 17:32:41 +0000
Subject: [PATCH] Mostly costmetic updates

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5452 42af7a65-404d-4744-a932-0658087f49c3
---
 Documentation/NuttX.html          | 15 +++++------
 README.txt                        | 24 +++++++++++-------
 arch/arm/src/arm/up_doirq.c       |  8 +++---
 arch/arm/src/armv7-m/up_doirq.c   |  8 +++---
 arch/avr/src/avr/up_doirq.c       |  8 +++---
 arch/avr/src/avr32/up_doirq.c     |  8 +++---
 arch/hc/src/common/up_doirq.c     |  8 +++---
 arch/mips/src/mips32/up_doirq.c   |  8 +++---
 arch/sh/src/common/up_doirq.c     |  9 +++++++
 arch/z16/src/common/up_doirq.c    |  9 +++++++
 arch/z80/include/z80/chip.h       |  6 ++---
 arch/z80/src/common/up_internal.h | 41 ++++++++++++++-----------------
 arch/z80/src/ez80/switch.h        | 26 +++++++++++---------
 arch/z80/src/z180/switch.h        | 25 +++++++++----------
 arch/z80/src/z8/switch.h          | 28 ++++++++++++---------
 arch/z80/src/z80/switch.h         | 26 +++++++++++---------
 16 files changed, 149 insertions(+), 108 deletions(-)

diff --git a/Documentation/NuttX.html b/Documentation/NuttX.html
index f48994babdf..84f298d3acf 100644
--- a/Documentation/NuttX.html
+++ b/Documentation/NuttX.html
@@ -1078,7 +1078,6 @@ svn checkout -r5447 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code
 svn checkout -r5447 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code
 </pre></ul>
 
-
 <p>
   <b>Additional new features and extended functionality</b>
 </p>
@@ -1244,7 +1243,7 @@ svn checkout -r5447 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code
           This build: (1) Uses all Windows style paths, (2) Uses primarily Windows batch commands from <code>CMD.exe</code>, with (3) a few extensions from <i>GNUWin32</i>.
         </p>
         <p>
-          This capability should still be considered a work in progress because: (1) it has not been verfied on all targets and tools, and (2) still lacks some of the creature-comforts of the more mature environments (like a function <code>configure.sh</code> script and <code>make menuconfig</code> support).
+          This capability should still be considered a work in progress because: (1) It has not been verfied on all targets and tools, and (2) it still lacks some of the creature-comforts of the more mature environments (like a functional <code>configure.sh</code> script and <code>make menuconfig</code> support).
       </li>
       <li>
         Example Windows native builds for STM32F4Discovery, eZ80, z16f, z8, Z80, and Z180.
@@ -1890,8 +1889,7 @@ svn checkout -r5447 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code
       </li>
     </ol>
     <p>
-      These ports uses a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin (with native Windows GNU
-      tools or Cygwin-based GNU tools).
+      These ports uses a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin (with native Windows GNU tools or Cygwin-based GNU tools).
     </p>
     <ul>
       <p>
@@ -1999,8 +1997,7 @@ svn checkout -r5447 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code
       <b>Atmel AT91SAM3U</b>.
       This port uses the <a href="http://www.atmel.com/">Atmel</a> SAM3U-EK
       development board that features the AT91SAM3U4E MCU.
-      This port uses a GNU arm-nuttx-elf or arm-eabi toolchain* under either Linux or Cygwin (with native Windows GNU
-      tools or Cygwin-based GNU tools).
+      This port uses a GNU arm-nuttx-elf or arm-eabi toolchain* under either Linux or Cygwin (with native Windows GNU tools or Cygwin-based GNU tools).
     </p>
     <ul>
       <p>
@@ -2884,7 +2881,7 @@ BFD_ASSERT (*plt_offset != (bfd_vma) -1);
       <b>Zilog z16f Microncontroller</b>.
       This port use the Zilog z16f2800100zcog development kit and the Zilog
       ZDS-II Windows command line tools.
-      The development environment is Cygwin under WinXP.
+      The development environment is either Windows native or Cygwin under Windows.
     </p>
     <ul>
       <p>
@@ -2914,7 +2911,7 @@ BFD_ASSERT (*plt_offset != (bfd_vma) -1);
     <p>
       Both boards are based on the eZ80F091 part and both use the Zilog ZDS-II
       Windows command line tools.
-      The development environment is Cygwin under WinXP.
+      The development environment is either Windows native or Cygwin under Windows.
     </p>
     <ul>
       <p>
@@ -2946,7 +2943,7 @@ BFD_ASSERT (*plt_offset != (bfd_vma) -1);
     </ul>
     <p>
       and the Zilog ZDS-II Windows command line tools.
-      The development environment is Cygwin under WinXP.
+      The development environment is either Windows native or Cygwin under Windows.
     </p>
     <ul>
        <p>
diff --git a/README.txt b/README.txt
index b71012cd8b5..dc3c9fb673c 100644
--- a/README.txt
+++ b/README.txt
@@ -10,7 +10,7 @@ README
   o Configuring NuttX
     - Instantiating "Canned" Configurations
     - NuttX Configuration Tool
-    - NuttX Configuration Tool from DOS
+    - NuttX Configuration Tool under DOS
   o Toolchains
     - Cross-Development Toolchains
     - NuttX Buildroot Toolchain
@@ -292,16 +292,16 @@ NuttX Configuration Tool
      install 'mconf', make certain that your PATH variable includes
      a path to that installation directory.
 
-NuttX Configuration Tool from DOS
----------------------------------
+NuttX Configuration Tool under DOS
+----------------------------------
 
-Recent versions of NuttX support building NuttX from a native Windows
-CMD.exe shell (see "Native Windows Build" below).  But kconfig-frontends
-is a Linux tool.  There have been some successes building a Windows
-native version of the kconfig-frontends tool, but that is not ready
-for prime time.
+  Recent versions of NuttX support building NuttX from a native Windows
+  CMD.exe shell (see "Native Windows Build" below).  But kconfig-frontends
+  is a Linux tool.  There have been some successes building a Windows
+  native version of the kconfig-frontends tool, but that is not ready
+  for prime time.
 
-At this point, there are only a few options for the Windows user:
+  At this point, there are only a few options for the Windows user:
 
   1. You can run the configuration tool using Cygwin.  However, the
      Cygwin Makefile.win will complain so to do this will, you have
@@ -566,6 +566,12 @@ Native Windows Build
   http://www.mingw.org/.  If you are using GNUWin32, then it is recommended
   the you not install the optional MSYS components as there may be conflicts.
 
+  This capability should still be considered a work in progress because:
+  (1) It has not been verfied on all targets and tools, and
+  (2) itstill lacks some of the creature-comforts of the more mature environments
+  (like a functional configure.sh script and 'make menuconfig' support.
+  See the section "NuttX Configuration Tool under DOS" above).
+
 Installing GNUWin32
 -------------------
 
diff --git a/arch/arm/src/arm/up_doirq.c b/arch/arm/src/arm/up_doirq.c
index c82587fff09..7cd1a6a1be7 100644
--- a/arch/arm/src/arm/up_doirq.c
+++ b/arch/arm/src/arm/up_doirq.c
@@ -79,9 +79,11 @@ void up_doirq(int irq, uint32_t *regs)
   uint32_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/arm/src/armv7-m/up_doirq.c b/arch/arm/src/armv7-m/up_doirq.c
index 375054fba62..6063f9ca1cb 100644
--- a/arch/arm/src/armv7-m/up_doirq.c
+++ b/arch/arm/src/armv7-m/up_doirq.c
@@ -79,9 +79,11 @@ uint32_t *up_doirq(int irq, uint32_t *regs)
   uint32_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/avr/src/avr/up_doirq.c b/arch/avr/src/avr/up_doirq.c
index e38bf7fa845..7533d215921 100644
--- a/arch/avr/src/avr/up_doirq.c
+++ b/arch/avr/src/avr/up_doirq.c
@@ -79,9 +79,11 @@ uint8_t *up_doirq(uint8_t irq, uint8_t *regs)
   uint8_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/avr/src/avr32/up_doirq.c b/arch/avr/src/avr32/up_doirq.c
index 7ade35fadcd..2d4a5e14a91 100644
--- a/arch/avr/src/avr32/up_doirq.c
+++ b/arch/avr/src/avr32/up_doirq.c
@@ -79,9 +79,11 @@ uint32_t *up_doirq(int irq, uint32_t *regs)
   uint32_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/hc/src/common/up_doirq.c b/arch/hc/src/common/up_doirq.c
index d03b007df1c..4a56dedbdc9 100644
--- a/arch/hc/src/common/up_doirq.c
+++ b/arch/hc/src/common/up_doirq.c
@@ -79,9 +79,11 @@ uint8_t *up_doirq(int irq, uint8_t *regs)
   uint8_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/mips/src/mips32/up_doirq.c b/arch/mips/src/mips32/up_doirq.c
index 29cdf9c60a0..b963881e305 100644
--- a/arch/mips/src/mips32/up_doirq.c
+++ b/arch/mips/src/mips32/up_doirq.c
@@ -79,9 +79,11 @@ uint32_t *up_doirq(int irq, uint32_t *regs)
   uint32_t *savestate;
 
   /* Nested interrupts are not supported in this implementation.  If you want
-   * implemented nested interrupts, you would have to (1) change the way that
-   * current regs is handled and (2) the design associated with
-   * CONFIG_ARCH_INTERRUPTSTACK.
+   * to implement nested interrupts, you would have to (1) change the way that
+   * current_regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not work for
+   * that purpose as implemented here because only the outermost nested
+   * interrupt can result in a context switch (it can probably be deleted).
    */
 
   /* Current regs non-zero indicates that we are processing an interrupt;
diff --git a/arch/sh/src/common/up_doirq.c b/arch/sh/src/common/up_doirq.c
index 717196682b7..185fa968456 100644
--- a/arch/sh/src/common/up_doirq.c
+++ b/arch/sh/src/common/up_doirq.c
@@ -79,6 +79,15 @@ uint32_t *up_doirq(int irq, uint32_t* regs)
     {
        uint32_t *savestate;
 
+       /* Nested interrupts are not supported in this implementation.  If
+        * you want to implement nested interrupts, you would have to (1)
+        * change the way that current_regs is handled and (2) the design
+        * associated with CONFIG_ARCH_INTERRUPTSTACK.  The savestate
+        * variable will not work for that purpose as implemented here
+        * because only the outermost nested interrupt can result in a
+        * context switch (it can probably be deleted).
+        */
+
        /* Current regs non-zero indicates that we are processing
         * an interrupt; current_regs is also used to manage
         * interrupt level context switches.
diff --git a/arch/z16/src/common/up_doirq.c b/arch/z16/src/common/up_doirq.c
index 670e6985d44..9964f44325b 100644
--- a/arch/z16/src/common/up_doirq.c
+++ b/arch/z16/src/common/up_doirq.c
@@ -90,6 +90,15 @@ FAR chipreg_t *up_doirq(int irq, FAR chipreg_t *regs)
     {
       FAR chipreg_t *savestate;
 
+      /* Nested interrupts are not supported in this implementation.  If
+       * you want to implement nested interrupts, you would have to (1) change
+       * the way that current_regs is handled and (2) the design associated
+       * with CONFIG_ARCH_INTERRUPTSTACK.  The savestate variable will not
+       * work for that purpose as implemented here because only the outermost
+       * nested interrupt can result in a context switch (it can probably be
+       * deleted).
+       */
+
       /* Current regs non-zero indicates that we are processing
        * an interrupt; current_regs is also used to manage
        * interrupt level context switches.
diff --git a/arch/z80/include/z80/chip.h b/arch/z80/include/z80/chip.h
index 5c0c61166a0..c355eb78877 100644
--- a/arch/z80/include/z80/chip.h
+++ b/arch/z80/include/z80/chip.h
@@ -34,8 +34,8 @@
  *
  ************************************************************************************/
 
-#ifndef __ARCH_Z80_SRC_Z80_CHIP_H
-#define __ARCH_Z80_SRC_Z80_CHIP_H
+#ifndef __ARCH_Z80_INCLUDE_Z80_CHIP_H
+#define __ARCH_Z80_INCLUDE_Z80_CHIP_H
 
 /************************************************************************************
  * Included Files
@@ -76,4 +76,4 @@ extern "C" {
 #endif
 #endif
 
-#endif  /* __ARCH_Z80_SRC_Z80_CHIP_H */
+#endif  /* __ARCH_Z80_INCLUDE_Z80_CHIP_H */
diff --git a/arch/z80/src/common/up_internal.h b/arch/z80/src/common/up_internal.h
index def13b54621..5f1750b644e 100644
--- a/arch/z80/src/common/up_internal.h
+++ b/arch/z80/src/common/up_internal.h
@@ -94,28 +94,26 @@
 
 #ifndef __ASSEMBLY__
 #ifdef __cplusplus
-#define EXTERN extern "C"
-extern "C" {
-#else
-#define EXTERN extern
+extern "C"
+{
 #endif
 
 /* Supplied by chip- or board-specific logic */
 
-EXTERN void up_irqinitialize(void);
-EXTERN int  up_timerisr(int irq, FAR chipreg_t *regs);
+void up_irqinitialize(void);
+int  up_timerisr(int irq, FAR chipreg_t *regs);
 
 #ifdef USE_LOWSERIALINIT
-EXTERN void up_lowserialinit(void);
+void up_lowserialinit(void);
 #endif
 
 /* Defined in up_doirq.c */
 
-EXTERN FAR chipreg_t *up_doirq(uint8_t irq, FAR chipreg_t *regs);
+FAR chipreg_t *up_doirq(uint8_t irq, FAR chipreg_t *regs);
 
 /* Define in up_sigdeliver */
 
-EXTERN void up_sigdeliver(void);
+void up_sigdeliver(void);
 
 /* Defined in CPU-specific logic (only for Z180) */
 
@@ -132,7 +130,7 @@ void up_addregion(void);
 /* Defined in up_serial.c */
 
 #ifdef USE_SERIALDRIVER
-EXTERN void up_serialinit(void);
+void up_serialinit(void);
 #else
 # define up_serialinit()
 #endif
@@ -140,7 +138,7 @@ EXTERN void up_serialinit(void);
 /* Defined in drivers/lowconsole.c */
 
 #ifdef CONFIG_DEV_LOWCONSOLE
-EXTERN void lowconsole_init(void);
+void lowconsole_init(void);
 #else
 # define lowconsole_init()
 #endif
@@ -159,14 +157,14 @@ extern void up_puts(const char *str);
 
 /* Defined in up_timerisr.c */
 
-EXTERN void up_timerinit(void);
+void up_timerinit(void);
 
 /* Defined in board/up_leds.c */
 
 #ifdef CONFIG_ARCH_LEDS
-EXTERN void up_ledinit(void);
-EXTERN void up_ledon(int led);
-EXTERN void up_ledoff(int led);
+void up_ledinit(void);
+void up_ledon(int led);
+void up_ledoff(int led);
 #else
 # define up_ledinit()
 # define up_ledon(led)
@@ -176,16 +174,16 @@ EXTERN void up_ledoff(int led);
 /* Architecture specific hook into the timer interrupt handler */
 
 #ifdef CONFIG_ARCH_TIMERHOOK
-EXTERN void up_timerhook(void);
+void up_timerhook(void);
 #endif
 
 /* Defined in board/up_network.c */
 
 #ifdef CONFIG_NET
-EXTERN int  up_netinitialize(void);
-EXTERN void up_netuninitialize(void);
+int  up_netinitialize(void);
+void up_netuninitialize(void);
 # ifdef CONFIG_ARCH_MCFILTER
-EXTERN int up_multicastfilter(FAR struct uip_driver_s *dev, FAR uint8_t *mac, bool enable);
+int up_multicastfilter(FAR struct uip_driver_s *dev, FAR uint8_t *mac, bool enable);
 # else
 #   define up_multicastfilter(dev, mac, enable)
 # endif
@@ -197,19 +195,18 @@ EXTERN int up_multicastfilter(FAR struct uip_driver_s *dev, FAR uint8_t *mac, bo
 
 /* Return the current value of the stack pointer (used in stack dump logic) */
 
-EXTERN uint16_t up_getsp(void);
+uint16_t up_getsp(void);
 
 /* Dump stack and registers */
 
 #ifdef CONFIG_ARCH_STACKDUMP
-EXTERN void up_stackdump(void);
+void up_stackdump(void);
 # define REGISTER_DUMP() _REGISTER_DUMP()
 #else
 # define up_stackdump()
 # define REGISTER_DUMP()
 #endif
 
-#undef EXTERN
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/z80/src/ez80/switch.h b/arch/z80/src/ez80/switch.h
index 0bac6aed1ae..0970b25ce78 100644
--- a/arch/z80/src/ez80/switch.h
+++ b/arch/z80/src/ez80/switch.h
@@ -67,7 +67,14 @@
 
 #define IN_INTERRUPT()           (current_regs != NULL)
 
-/* The following macro is used when the system enters interrupt handling logic */
+/* The following macro is used when the system enters interrupt handling logic
+ *
+ * NOTE: Nested interrupts are not supported in this implementation.  If you want
+ * to implement nested interrupts, you would have to change the way that
+ * current_regs is handled.  The savestate variable would not work for
+ * that purpose as implemented here because only the outermost nested
+ * interrupt can result in a context switch (it can probably be deleted).
+ */
 
 #define DECL_SAVESTATE() \
   FAR chipreg_t *savestate
@@ -132,33 +139,30 @@ extern volatile chipreg_t *current_regs;
 
 #ifndef __ASSEMBLY__
 #ifdef __cplusplus
-#define EXTERN extern "C"
-extern "C" {
-#else
-#define EXTERN extern
+extern "C"
+{
 #endif
 
 /* Defined in ez80_copystate.c */
 
-EXTERN void ez80_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
+void ez80_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
 
 /* Defined in ez80_saveusercontext.asm */
 
-EXTERN int ez80_saveusercontext(FAR chipreg_t *regs);
+int ez80_saveusercontext(FAR chipreg_t *regs);
 
 /* Defined in ez80_restorecontext.asm */
 
-EXTERN void ez80_restorecontext(FAR chipreg_t *regs);
+void ez80_restorecontext(FAR chipreg_t *regs);
 
 /* Defined in ez80_sigsetup.c */
 
-EXTERN void ez80_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, chipreg_t *regs);
+void ez80_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, chipreg_t *regs);
 
 /* Defined in ez80_registerdump.c */
 
-EXTERN void ez80_registerdump(void);
+void ez80_registerdump(void);
 
-#undef EXTERN
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/z80/src/z180/switch.h b/arch/z80/src/z180/switch.h
index ae80f4f76dc..7bf851a7cef 100644
--- a/arch/z80/src/z180/switch.h
+++ b/arch/z80/src/z180/switch.h
@@ -77,9 +77,11 @@
  * - savestate holds the previous value of current_state.
  * - savecpr holds the previous value of current_cpr.
  *
- * TODO:  I think this logic is bad... I do not thing that this will really
- * handle nested interrupts correctly.  What if we are nested and then a
- * context switch occurs?  current_regs will not be updated correctly!
+ * NOTE: Nested interrupts are not supported in this implementation.  If you want
+ * to implement nested interrupts, you would have to change the way that
+ * current_regs/cbr is handled.  The savestate/savecbr variables would not work
+ * for that purpose as implemented here because only the outermost nested
+ * interrupt can result in a context switch (they can probabaly be deleted).
  */
 
 #define DECL_SAVESTATE() \
@@ -203,33 +205,30 @@ extern uint8_t current_cbr;
 
 #ifndef __ASSEMBLY__
 #ifdef __cplusplus
-#define EXTERN extern "C"
-extern "C" {
-#else
-#define EXTERN extern
+extern "C"
+{
 #endif
 
 /* Defined in z180_copystate.c */
 
-EXTERN void z180_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
+void z180_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
 
 /* Defined in z180_saveusercontext.asm */
 
-EXTERN int z180_saveusercontext(FAR chipreg_t *regs);
+int z180_saveusercontext(FAR chipreg_t *regs);
 
 /* Defined in z180_restoreusercontext.asm */
 
-EXTERN void z180_restoreusercontext(FAR chipreg_t *regs);
+void z180_restoreusercontext(FAR chipreg_t *regs);
 
 /* Defined in z180_sigsetup.c */
 
-EXTERN void z180_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
+void z180_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
 
 /* Defined in z180_registerdump.c */
 
-EXTERN void z180_registerdump(void);
+void z180_registerdump(void);
 
-#undef EXTERN
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/z80/src/z8/switch.h b/arch/z80/src/z8/switch.h
index 45089947ca9..17f15b6daf2 100644
--- a/arch/z80/src/z8/switch.h
+++ b/arch/z80/src/z8/switch.h
@@ -112,7 +112,14 @@
 #define IN_INTERRUPT() \
   (g_z8irqstate.state != Z8_IRQSTATE_NONE)
 
-/* The following macro is used when the system enters interrupt handling logic */
+/* The following macro is used when the system enters interrupt handling logic
+ *
+ * NOTE: Nested interrupts are not supported in this implementation.  If you want
+ * to implement nested interrupts, you would have to change the way that
+ * current_regs is handled.  The savestate variable would not work for
+ * that purpose as implemented here because only the outermost nested
+ * interrupt can result in a context switch (it can probably be deleted).
+ */
 
 #define DECL_SAVESTATE() \
   struct z8_irqstate_s savestate
@@ -216,37 +223,34 @@ extern struct z8_irqstate_s g_z8irqstate;
 
 #ifndef __ASSEMBLY__
 #ifdef __cplusplus
-#define EXTERN extern "C"
-extern "C" {
-#else
-#define EXTERN extern
+extern "C"
+{
 #endif
 
 /* Defined in z8_irq.c */
 
-EXTERN void up_maskack_irq(int irq);
+void up_maskack_irq(int irq);
 
 /* Defined in z8_saveusercontext.asm */
 
-EXTERN int z8_saveusercontext(FAR chipreg_t *regs);
+int z8_saveusercontext(FAR chipreg_t *regs);
 
 /* Defined in z8_saveirqcontext.c */
 
-EXTERN void z8_saveirqcontext(FAR chipreg_t *regs);
+void z8_saveirqcontext(FAR chipreg_t *regs);
 
 /* Defined in z8_restorecontext.asm */
 
-EXTERN void z8_restorecontext(FAR chipreg_t *regs);
+void z8_restorecontext(FAR chipreg_t *regs);
 
 /* Defined in z8_sigsetup.c */
 
-EXTERN void z8_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
+void z8_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
 
 /* Defined in z8_registerdump.c */
 
-EXTERN void z8_registerdump(void);
+void z8_registerdump(void);
 
-#undef EXTERN
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/z80/src/z80/switch.h b/arch/z80/src/z80/switch.h
index 3732a32a397..4a49c70eff5 100644
--- a/arch/z80/src/z80/switch.h
+++ b/arch/z80/src/z80/switch.h
@@ -66,7 +66,14 @@
 
 #define IN_INTERRUPT()           (current_regs != NULL)
 
-/* The following macro is used when the system enters interrupt handling logic */
+/* The following macro is used when the system enters interrupt handling logic
+ *
+ * NOTE: Nested interrupts are not supported in this implementation.  If you want
+ * to implement nested interrupts, you would have to change the way that
+ * current_regs is handled.  The savestate variable would not work for
+ * that purpose as implemented here because only the outermost nested
+ * interrupt can result in a context switch (it can probably be deleted).
+ */
 
 #define DECL_SAVESTATE() \
   FAR chipreg_t *savestate
@@ -131,33 +138,30 @@ extern volatile chipreg_t *current_regs;
 
 #ifndef __ASSEMBLY__
 #ifdef __cplusplus
-#define EXTERN extern "C"
-extern "C" {
-#else
-#define EXTERN extern
+extern "C"
+{
 #endif
 
 /* Defined in z80_copystate.c */
 
-EXTERN void z80_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
+void z80_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
 
 /* Defined in z80_saveusercontext.asm */
 
-EXTERN int z80_saveusercontext(FAR chipreg_t *regs);
+int z80_saveusercontext(FAR chipreg_t *regs);
 
 /* Defined in z80_restoreusercontext.asm */
 
-EXTERN void z80_restoreusercontext(FAR chipreg_t *regs);
+void z80_restoreusercontext(FAR chipreg_t *regs);
 
 /* Defined in z80_sigsetup.c */
 
-EXTERN void z80_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
+void z80_sigsetup(FAR _TCB *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
 
 /* Defined in z80_registerdump.c */
 
-EXTERN void z80_registerdump(void);
+void z80_registerdump(void);
 
-#undef EXTERN
 #ifdef __cplusplus
 }
 #endif