porting: Add x86_64 scaffold: exit and write in assembly.

* lib/x86_64-mes-gcc/exit-42.S: New file.
* lib/x86_64-mes-gcc/hello-mes.S: New file.
* lib/x86_64-mes/elf64-0exit-42.hex2: New file.
* lib/x86_64-mes/elf64-0hello-mes.hex2: New file.
* lib/x86_64-mes/elf64-body-exit-42.hex2: Rewrite..
* lib/x86_64-mes/elf64-body-hello-mes.hex2:
* lib/x86_64-mes/elf64-0header.hex2: Fix copyright header.
* lib/x86_64-mes/elf64-header.hex2: Likewise.
* lib/x86_64-mes/elf-0footer.hex2: Remove.

lib/x86_64-mes-gcc/exit-42.S

@@ -0,0 +1,46 @@
+/*
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes 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.
+ *
+ * GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** Commentary: */
+
+/* Using gdb, esp. GUD in GNU Emacs is recommended
+M-x gdb-display-disassembly-buffer
+M-x gdb-display-io-buffer
+set disassemble-next-line on
+break _start
+run
+info registers
+si
+p/x $rax
+RET
+...
+*/
+
+/** Code: */
+
+SYS_exit = 0x3c			/* Linux syscall: exit.  */
+	.globl _start		/* Magic linker symbol: --entry-address.  */
+
+	.text			/* Program text. */
+_start:
+	movabs	$SYS_exit,%rax	/* System call function: exit, in %rax.  */
+	movabs	$42,%rdi	/* First parameter: exit status, in %rdi. */
+	syscall			/* Call system.  */
+	hlt 			/* Should not be reached.  */

lib/x86_64-mes-gcc/hello-mes.S

@@ -0,0 +1,58 @@
+/*
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes 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.
+ *
+ * GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** Commentary: */
+
+/* Using gdb, esp. GUD in GNU Emacs is recommended
+M-x gdb-display-disassembly-buffer
+M-x gdb-display-io-buffer
+set disassemble-next-line on
+break _start
+run
+info registers
+si
+p/x $rax
+RET
+...
+*/
+
+/** Code: */
+
+SYS_exit 	= 0x3c		/* Linux syscalls.  */
+SYS_write 	= 0x01
+stdout		= 1		/* File discriptor */
+	.globl _start		/* Magic linker symbol: --entry-address.  */
+
+	.text			/* Program text. */
+_start:
+	movabs	$SYS_write,%rax	/* System call function: write, in %rax.  */
+	movabs	$stdout,%rdi	/* 1st parameter: file descriptor, in %rdi. */
+	movabs	$hello,%rsi	/* 2nd parameter: address, in %rsi. */
+	movabs	$(bye-hello),%rdx	/* 3rd parameter: byte count %rdx. */
+	syscall			/* Call system.  */
+
+	movabs	$SYS_exit,%rax	/* System call function: exit, in %rax.  */
+	movabs	$0,%rdi		/* 1st parameter: exit status, in %rdi. */
+	syscall			/* Call system.  */
+	hlt 			/* Should not be reached.  */
+
+	.data
+hello:	.ascii	"Hello, GNU Mes!\n"
+bye:	.byte	0

lib/x86_64-mes/elf-0footer.hex2

@@ -1,26 +0,0 @@
-### Copyright (C) 2017 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
-### This file is part of stage0.
-###
-### stage0 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.
-###
-### stage0 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 stage0.  If not, see <http://www.gnu.org/licenses/>.
-
-### stage0's hex2 format for x86_64
-###    !<label>          1 byte relative
-###    $<label>          2 byte address
-###    @<label>          2 byte relative
-###    &<label>          4 byte address
-###    %<label>          4 byte relative
-###    local_<label>     function-local
-###    string_<index>    string #<index>
-
-:ELF_end

lib/x86_64-mes/elf64-0exit-42.hex2

@@ -0,0 +1,36 @@
+### GNU Mes --- Maxwell Equations of Software
+### Copyright © 2017,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+###
+### This file is part of GNU Mes.
+###
+### GNU Mes 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.
+###
+### GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+
+### Commentary:
+
+# elf64-exit-42.hex2: `exit 42' for x86_64-linux written in hex2
+# assembly, for usage with elf64-0header.hex2.  This produces a 160-byte
+# binary (a0 hex).  Inspiration was taken from GNU Gcc output of
+# exit-42.S.
+
+### Code:
+
+# @80
+:ELF_text
+48 b8 3c 00 00 00 00 00 00 00  # movabs $0x3c,%rax
+48 bf 2a 00 00 00 00 00 00 00  # movabs $42,%rdi
+0f 05                          # syscall
+f4                             # hlt
+
+00 00 00 00 00 00 00 00 00     # align to @a0
+:ELF_end

lib/x86_64-mes/elf64-0header.hex2

@@ -1,28 +1,36 @@
 ### Copyright (C) 2016 Jeremiah Orians
-### Copyright (C) 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+### Copyright (C) 2017,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
-### This file is part of stage0.
 ###
-### stage0 is free software: you can redistribute it and/or modify
+### This file is part of GNU Mes.
-### 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.
 ###
-### stage0 is distributed in the hope that it will be useful,
+### GNU Mes is free software; you can redistribute it and/or modify it
-### but WITHOUT ANY WARRANTY; without even the implied warranty of
+### 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.
+###
+### GNU Mes 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 stage0.  If not, see <http://www.gnu.org/licenses/>.
+### along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-### stage0's hex2 format for x86_64
+### Commentary:
-###    !<label>          1 byte relative
+
-###    $<label>          2 byte address
+# elf64-0header.hex2: Simplest 64 bit elf header in hex2.  Only a text
-###    @<label>          2 byte relative
+# segment, no data segment, no symbol tables.
-###    &<label>          4 byte address
+
-###    %<label>          4 byte relative
+# stage0's hex2 format for x86_64
-###    local_<label>     function-local
+#    !<label>          1 byte relative
-###    string_<index>    string #<index>
+#    $<label>          2 byte address
+#    @<label>          2 byte relative
+#    &<label>          4 byte address
+#    %<label>          4 byte relative
+#    local_<label>     function-local
+#    string_<index>    string #<index>
+
+### Code:
 
 :ELF_base
 7F 45 4C 46                    # e_ident[EI_MAG0-3] ELF's magic number
@@ -58,11 +66,6 @@
 
 00 00                          # e_shstrndx index of the section names
 
-# @34
-00 00 00 00
-00 00 00 00
-00 00 00 00
-
 # @40
 :ELF_program_headers
 :ELF_program_header__text
@@ -75,4 +78,6 @@
 %ELF_end>ELF_base 00 00 00 00  # ph_memsz
 01 00 00 00 00 00 00 00        # ph_align
 
+00 00 00 00 00 00 00 00        # align to @80
+# @80
 :ELF_text

lib/x86_64-mes/elf64-0hello-mes.hex2

@@ -0,0 +1,52 @@
+### GNU Mes --- Maxwell Equations of Software
+### Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+###
+### This file is part of GNU Mes.
+###
+### GNU Mes 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.
+###
+### GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+
+### Commentary:
+
+# elf64-hello-mes.hex2: `Hello, GNU Mes!' for x86_64-linux written in
+# hex2 assembly, for usage with elf64-0header.hex2.  This produces a
+# 224-byte binary (e0 hex).  Inspiration was taken from GNU Gcc output
+# of hello-mes.S.
+
+### Code:
+
+# @80
+:ELF_text
+                               # print <hello>
+48 b8 01 00 00 00 00 00 00 00  # movabs $1,%rax
+48 bf 01 00 00 00 00 00 00 00  # movabs $1,%rdi
+48 be &hello 00 00 00 00       # movabs $<hello>,%rsi
+48 ba %bye>hello 00 00 00 00   # mov    $(bye-hello),%rdx
+0f 05                          # syscall
+
+                               # exit 0
+48 b8 3c 00 00 00 00 00 00 00  # movabs $0x3c,%rax
+48 bf 00 00 00 00 00 00 00 00  # movabs $0,%rdi
+0f 05                          # syscall
+f4                             # hlt
+
+00 00 00 00 00 00 00 00 00     # align to @d0
+00 00 00 00 00 00
+
+# @d0
+:ELF_data
+:hello
+48 65 6c 6c 6f 2c 20 47        # Hello, G
+4e 55 20 4d 65 73 21 0a        # NU Mes!\n
+:bye
+:ELF_end

lib/x86_64-mes/elf64-body-exit-42.hex2

@@ -1,47 +1,51 @@
-### Copyright (C) 2017, 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+### GNU Mes --- Maxwell Equations of Software
-### This file is part of stage0.
+### Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ###
-### stage0 is free software: you can redistribute it and/or modify
+### This file is part of GNU Mes.
-### 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.
 ###
-### stage0 is distributed in the hope that it will be useful,
+### GNU Mes is free software; you can redistribute it and/or modify it
-### but WITHOUT ANY WARRANTY; without even the implied warranty of
+### 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.
+###
+### GNU Mes 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 stage0.  If not, see <http://www.gnu.org/licenses/>.
+### along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-### stage0's hex2 format for x86_64
+### Commentary:
-###    !<label>          1 byte relative
-###    $<label>          2 byte address
-###    @<label>          2 byte relative
-###    &<label>          4 byte address
-###    %<label>          4 byte relative
-###    local_<label>     function-local
-###    string_<index>    string #<index>
 
-### elf64-body-exit-42.hex2: 64 bit elf body in hex2 for `exit 42'
+# elf64-body-exit-42.hex2: `exit 42' for x86_64-linux written in hex2
+# assembly, for usage with generic elf64-header.hex2 and
+# elf64-footer-single-main.hex.
 
-# @200
+# This ELF binary contains a symbol table, which means that objdump and
+# gdb can be used to inspect and debug.
+
+### Code:
+
+# @300
 :ELF_text
 :_start
 # exit(42)
-e8 %main                       # callq  +11 <main>
+e8 %main                       # call  +11 <main>
 00 00 00
 00 00 00 00
 00 00 00 00
 
-# @210
+# @310
 :main
-48 c7 c7 2a 00 00 00           # mov    $42,%rdi
+48 b8 3c 00 00 00 00 00 00 00  # movabs $0x3c,%rax
-48 c7 c0 3c 00 00 00           # mov    $0x3c,%rax
+48 bf 2a 00 00 00 00 00 00 00  # movabs $42,%rdi
 0f 05                          # syscall
+f4                             # hlt
 
-00 00 00 00
+00 00 00 00 00 00 00 00 00     # align to 330
 
-# @220
+# @330
 :ELF_data
 65 78 69 74 34 32 20 64 61 74 61 20 68 65 72 65 # exit42 data here"
+00

lib/x86_64-mes/elf64-body-hello-mes.hex2

@@ -0,0 +1,63 @@
+### GNU Mes --- Maxwell Equations of Software
+### Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+###
+### This file is part of GNU Mes.
+###
+### GNU Mes 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.
+###
+### GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+
+### Commentary:
+
+# elf64-body-hello-mes.hex2: `Hello, GNU Mes!' for x86_64-linux written
+# in hex2 assembly, for usage with generic elf64-header.hex2 and
+# elf64-footer-single-main.hex.
+
+# This ELF binary contains a symbol table which means that objdump and
+# gdb can be used to inspect and debug.
+
+### Code:
+
+# @300
+:ELF_text
+:_start
+# exit(42)
+e8 %main                       # call  +11 <main>
+00 00 00
+00 00 00 00
+00 00 00 00
+
+# @310
+:main
+                               # print <hello>
+48 b8 01 00 00 00 00 00 00 00  # movabs $1,%rax
+48 bf 01 00 00 00 00 00 00 00  # movabs $1,%rdi
+48 be &hello 00 00 00 00       # movabs $<hello>,%rsi
+48 ba %bye>hello 00 00 00 00   # mov    $(bye-hello),%rdx
+0f 05                          # syscall
+
+                               # exit 0
+48 b8 3c 00 00 00 00 00 00 00  # movabs $0x3c,%rax
+48 bf 00 00 00 00 00 00 00 00  # movabs $0,%rdi
+0f 05                          # syscall
+f4                             # hlt
+
+00 00 00 00 00 00 00 00 00     # align to @360
+00 00 00 00 00 00
+
+# @360
+:ELF_data
+:hello
+48 65 6c 6c 6f 2c 20 47        # Hello, G
+4e 55 20 4d 65 73 21 0a        # NU Mes!\n
+:bye
+:ELF_end

lib/x86_64-mes/elf64-header.hex2

@@ -1,28 +1,36 @@
 ### Copyright (C) 2016 Jeremiah Orians
-### Copyright (C) 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+### Copyright (C) 2017,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
-### This file is part of stage0.
 ###
-### stage0 is free software: you can redistribute it and/or modify
+### This file is part of GNU Mes.
-### 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.
 ###
-### stage0 is distributed in the hope that it will be useful,
+### GNU Mes is free software; you can redistribute it and/or modify it
-### but WITHOUT ANY WARRANTY; without even the implied warranty of
+### 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.
+###
+### GNU Mes 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 stage0.  If not, see <http://www.gnu.org/licenses/>.
+### along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-### stage0's hex2 format for x86_64
+### Commentary:
-###    !<label>          1 byte relative
+
-###    $<label>          2 byte address
+# elf64-header.hex2: 64 bit elf header in hex2, with text segment, data
-###    @<label>          2 byte relative
+# segment and symbol tables.
-###    &<label>          4 byte address
+
-###    %<label>          4 byte relative
+# stage0's hex2 format for x86_64
-###    local_<label>     function-local
+#    !<label>          1 byte relative
-###    string_<index>    string #<index>
+#    $<label>          2 byte address
+#    @<label>          2 byte relative
+#    &<label>          4 byte address
+#    %<label>          4 byte relative
+#    local_<label>     function-local
+#    string_<index>    string #<index>
+
+### Code:
 
 :ELF_base
 7F 45 4c 46                    # e_ident[EI_MAG0-3] ELF's magic number