First milestone

Today the pdp10-elf project reached its first milestone: linking and executing a simple but not entirely trivial program:

> cat test-pdp10/crt0.s 
	.text
	.globl	_start
	.type	_start,@function
_start:
	# AC1 = argc
	# AC2 = argv
	# AC3 = envp
	# c.f. sim_core:run/6
	pushj	017,main
	pushj	017,_exit		# _exit(main())
	.size	_start,.-_start
> cat test-pdp10/exit.s 
	.text
	.globl	_exit
	.type	_exit,@function
_exit:			# AC1 = exit status
	jsys	0136	# __NR_exit_group
	halt	0
	.size	_exit,.-_exit
> cat test-pdp10/main.s 
	.text
	.globl	main
	.type	main,@function
main:
	movei	1,42		# return 42
	popj	017,
	.size	main,.-main
> _build/default/bin/as -o crt0.o test-pdp10/crt0.s
> _build/default/bin/as -o exit.o test-pdp10/exit.s
> _build/default/bin/ar ruv libc.a crt0.o exit.o 
a - crt0.o
a - exit.o
> _build/default/bin/as -o main.o test-pdp10/main.s
> _build/default/bin/ld main.o libc.a
> _build/default/bin/readelf -a --disassemble a.out
ELF Header:
  Magic:				7f 45 4c 46 24 02 01 00 00 00 00 00 00 00 00 00
  Class:				36 (ELF36)
  Data:					2 (2's complement, big endian)
  Version:				1 (current)
  OS/ABI:				0 (Generic)
  ABI Version:				0
  Type:					2 (Executable file)
  Machine:				64 (Digital Equipment Corp. PDP-10)
  Version:				1 (current)
  Entry point address:			0x201008
  Start of program headers:		52
  Start of section headers:		0
  Flags:				0x0
  Size of this header:			52
  Size of program headers:		32
  Number of program headers:		1
  Size of section headers:		40
  Number of section headers:		0
  Section header string table index:	0

Section Headers:
  [Nr] Name Type Addr Off Size ES Flg Lk Inf Al
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), Z (compressed)
  I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
  O (extra OS processing required), o (OS specific), p (processor specific)

Program Headers:
  Type   Offset      VirtAddr    PhysAddr    FileSiz     MemSiz      Flg Align
  LOAD   0x000001000 0x000201000 0x000000000 0x000000018 0x000000018 R E 0x1000

Disassembly of segment nr 0:
 0x201000:	0201040000052	movei 1,42
 0x201004:	0263740000000	popj 15,0
 0x201008:	0260740002000	pushj 15,1024
 0x20100c:	0260740002004	pushj 15,1028
 0x201010:	0104000000136	jsys 0,94
 0x201014:	0254200000000	halt 0

> _build/default/bin/sim a.out && echo $?
42

(The addresses are actually correct, they only look strange due to the mix of hex and octal. I'll have to stick with octal I think.)

Now on to adapting XKL's GCC port for these "binutils".