Add basic Z80 CPU support

Supported ISAs:
- Z80 (all undocumented instructions)
- Z180
- eZ80 (Z80 mode only)

Datasheets:
Z80: https://www.zilog.com/manage_directlink.php?filepath=docs/z80/um0080&extn=.pdf
Z180: https://www.zilog.com/manage_directlink.php?filepath=docs/z180/ps0140&extn=.pdf
eZ80: http://www.zilog.com/force_download.php?filepath=YUhSMGNEb3ZMM2QzZHk1NmFXeHZaeTVqYjIwdlpHOWpjeTlWVFRBd056Y3VjR1Jt

To debug Z80 programs using GDB you must configure and embed
z80-stub.c to your program (SDCC compiler is required). Or
you may use some simulator with GDB support.

gdb/ChangeLog:

	* Makefile.in (ALL_TARGET_OBS): Add z80-tdep.c.
	* NEWS: Mention z80 support.
	* configure.tgt: Handle z80*.
	* features/Makefile (XMLTOC): Add z80.xml.
	* features/z80-cpu.xml: New.
	* features/z80.c: Generate.
	* features/z80.xml: New.
	* z80-tdep.c: New file.
	* z80-tdep.h: New file.

gdb/stubs/ChangeLog:

	* z80-stub.c: New file.

Change-Id: Id0b7a6e210c3f93c6853c5e3031b7bcee47d0db9

gdb/Makefile.in

@@ -853,7 +853,8 @@ ALL_TARGET_OBS = \
 	xstormy16-tdep.o \
 	xtensa-config.o \
 	xtensa-linux-tdep.o \
-	xtensa-tdep.o
+	xtensa-tdep.o \
+	z80-tdep.o
 
 # The following native-target dependent variables are defined on
 # configure.nat.

gdb/NEWS

@@ -429,6 +429,7 @@ alias [-a] [--] ALIAS = COMMAND [DEFAULT-ARGS...]
 
 GNU/Linux/RISC-V (gdbserver)	riscv*-*-linux*
 BPF				bpf-unknown-none
+Z80				z80-unknown-*
 
 * Python API
 

gdb/configure.tgt

@@ -761,6 +761,10 @@ xtensa*-*-*linux*)
 	# Target: GNU/Linux Xtensa
 	gdb_target_obs="xtensa-linux-tdep.o symfile-mem.o linux-tdep.o"
 	;;
+z80*)
+	# Target: Z80
+	gdb_target_obs="z80-tdep.o"
+	;;
 
 esac
 

gdb/features/Makefile

@@ -170,7 +170,8 @@ XMLTOC = \
 	s390x-tevx-linux64.xml \
 	s390x-vx-linux64.xml \
 	s390-gs-linux64.xml \
-	s390x-gs-linux64.xml
+	s390x-gs-linux64.xml \
+	z80.xml
 
 TDESC_CFILES = $(patsubst %.xml,%.c,$(XMLTOC))
 GDB = false

gdb/features/z80-cpu.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2020 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.z80.cpu">
+  <flags id="af_flags" size="2">
+    <field name="C" start="0" end="0"/>
+    <field name="N" start="1" end="1"/>
+    <field name="P/V" start="2" end="2"/>
+    <field name="F3" start="3" end="3"/>
+    <field name="H" start="4" end="4"/>
+    <field name="F5" start="5" end="5"/>
+    <field name="Z" start="6" end="6"/>
+    <field name="S" start="7" end="7"/>
+  </flags>
+  <reg name="af" bitsize="16" type="af_flags"/>
+  <reg name="bc" bitsize="16" type="uint16"/>
+  <reg name="de" bitsize="16" type="data_ptr"/>
+  <reg name="hl" bitsize="16" type="data_ptr"/>
+  <reg name="sp" bitsize="16" type="data_ptr" />
+  <reg name="pc" bitsize="32" type="code_ptr" />
+  <reg name="ix" bitsize="16" type="data_ptr"/>
+  <reg name="iy" bitsize="16" type="data_ptr"/>
+  <reg name="af'" bitsize="16" type="af_flags"/>
+  <reg name="bc'" bitsize="16" type="uint16"/>
+  <reg name="de'" bitsize="16" type="data_ptr"/>
+  <reg name="hl'" bitsize="16" type="data_ptr"/>
+  <reg name="ir" bitsize="16" type="uint16"/>
+</feature>

gdb/features/z80.c

@@ -0,0 +1,44 @@
+/* THIS FILE IS GENERATED.  -*- buffer-read-only: t -*- vi:set ro:
+  Original: z80.xml */
+
+#include "defs.h"
+#include "osabi.h"
+#include "target-descriptions.h"
+
+struct target_desc *tdesc_z80;
+static void
+initialize_tdesc_z80 (void)
+{
+  target_desc_up result = allocate_target_description ();
+  set_tdesc_architecture (result.get (), bfd_scan_arch ("z80"));
+
+  struct tdesc_feature *feature;
+
+  feature = tdesc_create_feature (result.get (), "org.gnu.gdb.z80.cpu");
+  tdesc_type_with_fields *type_with_fields;
+  type_with_fields = tdesc_create_flags (feature, "af_flags", 2);
+  tdesc_add_flag (type_with_fields, 0, "C");
+  tdesc_add_flag (type_with_fields, 1, "N");
+  tdesc_add_flag (type_with_fields, 2, "P/V");
+  tdesc_add_flag (type_with_fields, 3, "F3");
+  tdesc_add_flag (type_with_fields, 4, "H");
+  tdesc_add_flag (type_with_fields, 5, "F5");
+  tdesc_add_flag (type_with_fields, 6, "Z");
+  tdesc_add_flag (type_with_fields, 7, "S");
+
+  tdesc_create_reg (feature, "af", 0, 1, NULL, 16, "af_flags");
+  tdesc_create_reg (feature, "bc", 1, 1, NULL, 16, "uint16");
+  tdesc_create_reg (feature, "de", 2, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "hl", 3, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "sp", 4, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "pc", 5, 1, NULL, 32, "code_ptr");
+  tdesc_create_reg (feature, "ix", 6, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "iy", 7, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "af'", 8, 1, NULL, 16, "af_flags");
+  tdesc_create_reg (feature, "bc'", 9, 1, NULL, 16, "uint16");
+  tdesc_create_reg (feature, "de'", 10, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "hl'", 11, 1, NULL, 16, "data_ptr");
+  tdesc_create_reg (feature, "ir", 12, 1, NULL, 16, "uint16");
+
+  tdesc_z80 = result.release ();
+}

gdb/features/z80.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2020 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>z80</architecture>
+  <xi:include href="z80-cpu.xml"/>
+</target>

gdb/z80-tdep.h

@@ -0,0 +1,52 @@
+/* Target-dependent code for the Z80.
+
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef Z80_TDEP_H
+#define Z80_TDEP_H
+
+/* Register pair constants
+   Order optimized for gdb-stub implementation
+   Most of register pairs are 16 bit length on Z80 and
+   24 bit on eZ80 in ADL or MADL modes */
+enum z80_regnum
+{
+  Z80_AF_REGNUM,
+  Z80_BC_REGNUM,
+  Z80_DE_REGNUM,
+  Z80_HL_REGNUM,
+  Z80_SP_REGNUM,	/* SPL on eZ80 CPU */
+  Z80_PC_REGNUM,
+  Z80_IX_REGNUM,
+  Z80_IY_REGNUM,
+  Z80_AFA_REGNUM,
+  Z80_BCA_REGNUM,
+  Z80_DEA_REGNUM,
+  Z80_HLA_REGNUM,
+  Z80_IR_REGNUM,
+/* eZ80 only registers */
+  Z80_SPS_REGNUM	/* SPS register of eZ80 CPU */
+};
+
+#define Z80_NUM_REGS	13
+#define Z80_REG_BYTES	(Z80_NUM_REGS*2)
+
+#define EZ80_NUM_REGS	(Z80_NUM_REGS + 1)
+#define EZ80_REG_BYTES	(EZ80_NUM_REGS*3)
+
+#endif /* z80-tdep.h */