Incorporate patch 1899525

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@720 42af7a65-404d-4744-a932-0658087f49c3

arch/z80/src/Makefile

@@ -38,6 +38,7 @@
 
 -include $(TOPDIR)/Make.defs
 -include chip/Make.defs
+-include board/Make.defs
 
 ############################################################################
 # Compiler-Dependent Make

arch/z80/src/Makefile.sdcc

@@ -71,7 +71,7 @@ DEPSRCS		= $(CSRCS)
 ARCH_SRCDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src
 BOARDDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src/board
 
-VPATH		= chip:common
+VPATH		= chip:common:board
 
 # Libraries
 

arch/z80/src/z80/Make.defs

@@ -33,11 +33,13 @@
 #
 ############################################################################
 
+ifeq ($(CONFIG_ARCH_HAVEHEAD),)
 ifeq ($(CONFIG_LINKER_ROM_AT_0000),y)
 HEAD_ASRC	= z80_rom.asm
 else
 HEAD_ASRC	= z80_head.asm
 endif
+endif
 
 CMN_ASRCS	= 
 CMN_CSRCS	= up_initialize.c up_allocateheap.c up_createstack.c \

arch/z80/src/z80/README.txt

@@ -0,0 +1,49 @@
+arch/z80/src/z80
+^^^^^^^^^^^^^^^^
+
+The arch/z80 directories contain files to support a variety of 8-bit architectures
+from ZiLOG (and spin-architectures such as the Rabbit2000).  The arch/z80/src/z80
+sub-directory contains logic unique to the classic Z80 chip.
+
+Files in this directory include:
+
+z80_head.asm
+	This is the main entry point into the Z80 program.  This includes the
+	handler for the RESET, power-up interrupt vector and address zero and all
+	RST interrupts.
+
+z80_rom.asm
+	Some architectures may hae ROM located at address zero.  In this case, a
+	special version of the "head" logic must be used.  This specail "head"
+	file is probably board-specific and, hence, belongs in the board-specific
+	configs/<board-name>/src directory.  This file may, however, be used as
+	a model for such a board-specific file.
+
+	z80_rom.S is enabled by specifying CONFIG_LINKER_ROM_AT_0000 in the
+	configuration file.
+
+	A board specific version in the configs/<board-name>/src directory can be
+	used by:
+	
+	1. Define CONFIG_ARCH_HAVEHEAD
+	2. Add the board-specific head file, say <filename>.asm, to
+	   configs/<board-name>/src
+	3. Add a file called Make.defs in the configs/<board-name>/src directory
+	   containing the line:  HEAD_ASRC = <file-name>.asm
+
+Make.defs
+	This is the standard makefile fragment that must be provided in all
+	chip directories.  This fragment identifies the chip-specific file to
+	be used in building libarch.
+
+chip.h
+	This is the standard header file that must be provided in all chip
+	directories.
+
+z80_initialstate.c, z80_copystate.c,  z80_restoreusercontext.asm, and
+z80_saveusercontext.asm, switch
+ 	These files implement the Z80 context switching logic
+
+z80_schedulesigaction.c and  z80_sigdeliver.c
+	These files implement Z80 signal handling.
+