Add support for OpenBSD

It just rejects the generic System V ABI and has other syscall numbers.

1 files changed, 0 insertions, 733 deletions

diff --git a/bfc-amd64-linux.c b/bfc-amd64-linux.c
deleted file mode 100644
index 1579681..0000000
--- a/bfc-amd64-linux.c
+++ /dev/null
@@ -1,733 +0,0 @@
-// This is an exercise in futility more than anything else
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <assert.h>
-#include <errno.h>
-
-#ifdef __unix__
-#include <fcntl.h>
-#endif
-
-#define exit_fatal(...)                                                        \
-	do {                                                                       \
-		fprintf (stderr, "fatal: " __VA_ARGS__);                               \
-		exit (EXIT_FAILURE);                                                   \
-	} while (0)
-
-// --- Safe memory management --------------------------------------------------
-
-static void *
-xcalloc (size_t m, size_t n)
-{
-	void *p = calloc (m, n);
-	if (!p)
-		exit_fatal ("calloc: %s\n", strerror (errno));
-	return p;
-}
-
-static void *
-xrealloc (void *o, size_t n)
-{
-	void *p = realloc (o, n);
-	if (!p && n)
-		exit_fatal ("realloc: %s\n", strerror (errno));
-	return p;
-}
-
-// --- Dynamically allocated strings -------------------------------------------
-
-struct str
-{
-	char *str;                          ///< String data, null terminated
-	size_t alloc;                       ///< How many bytes are allocated
-	size_t len;                         ///< How long the string actually is
-};
-
-static void
-str_init (struct str *self)
-{
-	self->len = 0;
-	self->str = xcalloc (1, (self->alloc = 16));
-}
-
-static void
-str_ensure_space (struct str *self, size_t n)
-{
-	// We allocate at least one more byte for the terminating null character
-	size_t new_alloc = self->alloc;
-	while (new_alloc <= self->len + n)
-		new_alloc <<= 1;
-	if (new_alloc != self->alloc)
-		self->str = xrealloc (self->str, (self->alloc = new_alloc));
-}
-
-static void
-str_append_data (struct str *self, const void *data, size_t n)
-{
-	str_ensure_space (self, n);
-	memcpy (self->str + self->len, data, n);
-	self->str[self->len += n] = '\0';
-}
-
-static void
-str_append_c (struct str *self, char c)
-{
-	str_append_data (self, &c, 1);
-}
-
-// --- Application -------------------------------------------------------------
-
-enum command
-{
-	RIGHT, LEFT, INC, DEC, IN, OUT, BEGIN, END,
-	SET, EAT, INCACC, DECACC
-};
-
-bool grouped[] = { 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 };
-struct instruction { enum command cmd; int offset; size_t arg; };
-#define INSTRUCTION(c, o, a) (struct instruction) { (c), (o), (a) }
-
-// - - Debugging - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-#ifdef DEBUG
-static void
-debug_dump_instruction (FILE *fp, const struct instruction *in)
-{
-	const char *name;
-	switch (in->cmd)
-	{
-	case RIGHT:  name = "RIGHT "; break;
-	case LEFT:   name = "LEFT  "; break;
-	case INC:    name = "INC   "; break;
-	case DEC:    name = "DEC   "; break;
-	case OUT:    name = "OUT   "; break;
-	case IN:     name = "IN    "; break;
-	case BEGIN:  name = "BEGIN "; break;
-	case END:    name = "END   "; break;
-	case SET:    name = "SET   "; break;
-	case EAT:    name = "EAT   "; break;
-	case INCACC: name = "INCACC"; break;
-	case DECACC: name = "DECACC"; break;
-	}
-	fprintf (fp, "%s %zu", name, in->arg);
-	if (in->offset != 0)
-		fprintf (fp, " [%d]", in->offset);
-	fprintf (fp, "\n");
-}
-
-static void
-debug_dump (const char *filename, struct instruction *in, size_t len)
-{
-	FILE *fp = fopen (filename, "w");
-	long indent = 0;
-	for (size_t i = 0; i < len; i++)
-	{
-		if (in[i].cmd == END)
-			indent--;
-		for (long k = 0; k < indent; k++)
-			fputs ("  ", fp);
-		debug_dump_instruction (fp, &in[i]);
-		if (in[i].cmd == BEGIN)
-			indent++;
-	}
-	fclose (fp);
-}
-#else
-#define debug_dump(...)
-#endif
-
-// - - Optimization passes - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-static size_t
-optimize_assignment (struct instruction *irb, size_t irb_len)
-{
-	size_t in = 0, out = 0;
-	for (; in < irb_len; in++, out++)
-	{
-		if (in + 2 < irb_len
-		 && irb[in    ].cmd == BEGIN
-		 && irb[in + 1].cmd == DEC && irb[in + 1].arg == 1
-		 && irb[in + 2].cmd == END)
-		{
-			irb[out] = INSTRUCTION (SET, 0, 0);
-			in += 2;
-		}
-		else if (out && irb[out - 1].cmd == SET && irb[in].cmd == INC)
-			irb[--out].arg += irb[in].arg;
-		else if (out != in)
-			irb[out] = irb[in];
-	}
-	return out;
-}
-
-// Add the offset of the LEFT/RIGHT instruction to the accumulator
-static bool
-add_direction_offset (struct instruction *irb, intptr_t *acc)
-{
-	if (irb->cmd == RIGHT)
-		*acc += irb->arg;
-	else if (irb->cmd == LEFT)
-		*acc -= (intptr_t) irb->arg;
-	else
-		return false;
-	return true;
-}
-
-// Add offsets to INC/DEC/SET stuck between LEFT/RIGHT
-// and compress the LEFT/RIGHT sequences
-static size_t
-optimize_offseted_inc_dec (struct instruction *irb, size_t irb_len)
-{
-	size_t in = 0, out = 0;
-	for (in = 0, out = 0; in < irb_len; in++, out++)
-	{
-		intptr_t dir = 0;
-		if (!add_direction_offset (&irb[in], &dir))
-		{
-			irb[out] = irb[in];
-			continue;
-		}
-
-		while (in + 2 < irb_len)
-		{
-			// An immediate offset has its limits on x86-64
-			if (dir < INT8_MIN || dir > INT8_MAX)
-				break;
-			intptr_t diff = 0;
-			if (!add_direction_offset (&irb[in + 2], &diff))
-				break;
-			int cmd = irb[in + 1].cmd;
-			if (cmd != INC && cmd != DEC && cmd != SET)
-				break;
-
-			irb[out] = irb[in + 1];
-			irb[out].offset = dir;
-
-			dir += diff;
-			out += 1;
-			in += 2;
-		}
-
-		for (; in + 1 < irb_len; in++)
-			if (!add_direction_offset (&irb[in + 1], &dir))
-				break;
-
-		if (!dir)
-			out--;
-		else if (dir > 0)
-			irb[out] = INSTRUCTION (RIGHT, 0, dir);
-		else
-			irb[out] = INSTRUCTION (LEFT, 0, -dir);
-	}
-	return out;
-}
-
-// Try to eliminate loops that eat a cell and add/subtract its value
-// to/from some other cell
-static size_t
-optimize_inc_dec_loops (struct instruction *irb, size_t irb_len)
-{
-	size_t in = 0, out = 0;
-	for (in = 0, out = 0; in < irb_len; in++, out++)
-	{
-		irb[out] = irb[in];
-		if (irb[in].cmd != BEGIN)
-			continue;
-
-		bool ok = false;
-		size_t count = 0;
-		for (size_t k = in + 1; k < irb_len; k++)
-		{
-			if (irb[k].cmd == END)
-			{
-				ok = true;
-				break;
-			}
-			if (irb[k].cmd != INC
-			 && irb[k].cmd != DEC)
-				break;
-			count++;
-		}
-		if (!ok)
-			continue;
-
-		// Stable sort operations by their offsets, put [0] first
-		bool sorted;
-		do
-		{
-			sorted = true;
-			for (size_t k = 1; k < count; k++)
-			{
-				if (irb[in + k].offset == 0)
-					continue;
-				if (irb[in + k + 1].offset != 0
-				 && irb[in + k].offset <= irb[in + k + 1].offset)
-					continue;
-
-				struct instruction tmp = irb[in + k + 1];
-				irb[in + k + 1] = irb[in + k];
-				irb[in + k] = tmp;
-				sorted = false;
-			}
-		}
-		while (!sorted);
-
-		// Abort the optimization on duplicate offsets (complication with [0])
-		for (size_t k = 1; k < count; k++)
-			if (irb[in + k].offset == irb[in + k + 1].offset)
-				ok = false;
-		// XXX: can't make the code longer either
-		for (size_t k = 1; k <= count; k++)
-			if (irb[in + k].arg != 1)
-				ok = false;
-		if (!ok
-		 || irb[in + 1].cmd != DEC
-		 || irb[in + 1].offset != 0)
-			continue;
-
-		int min_safe_left_offset = 0;
-		if (in > 1 && irb[in - 1].cmd == RIGHT)
-			min_safe_left_offset = -irb[in - 1].arg;
-
-		bool cond_needed_for_safety = false;
-		for (size_t k = 0; k < count; k++)
-			if (irb[in + k + 1].offset < min_safe_left_offset)
-			{
-				cond_needed_for_safety = true;
-				break;
-			}
-
-		in++;
-		if (cond_needed_for_safety)
-			out++;
-
-		irb[out] = INSTRUCTION (EAT, 0, 0);
-		for (size_t k = 1; k < count; k++)
-			irb[out + k] = INSTRUCTION (irb[in + k].cmd == INC
-				? INCACC : DECACC, irb[in + k].offset, 0);
-
-		in += count;
-		out += count;
-
-		if (cond_needed_for_safety)
-			irb[out] = INSTRUCTION (END, 0, 0);
-		else
-			out--;
-	}
-	return out;
-}
-
-// - - Loop pairing  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-static void
-pair_loops (struct instruction *irb, size_t irb_len)
-{
-	size_t nesting = 0;
-	size_t *stack = xcalloc (sizeof *stack, irb_len);
-	for (size_t i = 0; i < irb_len; i++)
-	{
-		switch (irb[i].cmd)
-		{
-		case BEGIN:
-			stack[nesting++] = i;
-			break;
-		case END:
-			if (nesting <= 0)
-				exit_fatal ("unbalanced loops\n");
-
-			--nesting;
-			irb[stack[nesting]].arg = i + 1;
-
-			// Looping can be disabled by optimizations
-			if (irb[i].arg)
-				irb[i].arg = stack[nesting] + 1;
-		default:
-			break;
-		}
-	}
-	free (stack);
-
-	if (nesting != 0)
-		exit_fatal ("unbalanced loops\n");
-}
-
-// - - Main  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-int
-main (int argc, char *argv[])
-{
-	if (argc > 3)
-		exit_fatal ("usage: %s [INPUT-FILE] [OUTPUT-FILE]\n", argv[0]);
-
-	FILE *input_file = stdin;
-	if (argc > 1 && !(input_file = fopen (argv[1], "r")))
-		exit_fatal ("fopen: %s: %s\n", argv[1], strerror (errno));
-
-	const char *output_path = "a.out";
-	if (argc > 2)
-		output_path = argv[2];
-
-	struct str buffer;
-	str_init (&buffer);
-
-	int c;
-	while ((c = fgetc (input_file)) != EOF)
-		str_append_c (&buffer, c);
-	if (ferror (input_file))
-		exit_fatal ("can't read program\n");
-	fclose (input_file);
-
-// - - Decode, group and optimize  - - - - - - - - - - - - - - - - - - - - - - -
-
-	// This is our Intermediate Representation Buffer
-	struct instruction *irb = xcalloc (sizeof *irb, buffer.len);
-	size_t irb_len = 0;
-
-	for (size_t i = 0; i < buffer.len; i++)
-	{
-		enum command cmd;
-		switch (buffer.str[i])
-		{
-		case '>': cmd = RIGHT; break;
-		case '<': cmd = LEFT;  break;
-		case '+': cmd = INC;   break;
-		case '-': cmd = DEC;   break;
-		case '.': cmd = OUT;   break;
-		case ',': cmd = IN;    break;
-		case '[': cmd = BEGIN; break;
-		case ']': cmd = END;   break;
-		default:  continue;
-		}
-
-		// The most basic optimization is to group identical commands together
-		if (!irb_len || !grouped[cmd] || irb[irb_len - 1].cmd != cmd)
-			irb_len++;
-
-		irb[irb_len - 1].cmd = cmd;
-		irb[irb_len - 1].arg++;
-	}
-
-	debug_dump ("bf-no-opt.txt",            irb, irb_len);
-	irb_len = optimize_assignment          (irb, irb_len);
-	debug_dump ("bf-pre-offsets.txt",       irb, irb_len);
-	irb_len = optimize_offseted_inc_dec    (irb, irb_len);
-	debug_dump ("bf-pre-incdec-unloop.txt", irb, irb_len);
-	irb_len = optimize_inc_dec_loops       (irb, irb_len);
-	debug_dump ("bf-optimized.txt",         irb, irb_len);
-	pair_loops                             (irb, irb_len);
-	debug_dump ("bf-final.txt",             irb, irb_len);
-
-// - - Code generation - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-	str_init (&buffer);
-	size_t *offsets    = xcalloc (sizeof *offsets,    irb_len + 1);
-	bool   *sets_flags = xcalloc (sizeof *sets_flags, irb_len);
-
-#define CODE(x) { char t[] = x; str_append_data (&buffer, t, sizeof t - 1); }
-#define LE(v) (uint8_t[]) { v, v>>8, v>>16, v>>24, v>>32, v>>40, v>>48, v>>56 }
-#define DB(x) { uint64_t v = (x); str_append_data (&buffer, LE (v), 1); }
-#define DW(x) { uint64_t v = (x); str_append_data (&buffer, LE (v), 2); }
-#define DD(x) { uint64_t v = (x); str_append_data (&buffer, LE (v), 4); }
-#define DQ(x) { uint64_t v = (x); str_append_data (&buffer, LE (v), 8); }
-
-	enum
-	{
-		ELF_LOAD_CODE = 0x400000,             // where code is loaded (usual)
-		ELF_LOAD_DATA = 0x800000              // where the tape is placed
-	};
-
-	CODE ("\xB8") DD (ELF_LOAD_DATA)          // mov rax, "ELF_LOAD_DATA"
-	CODE ("\x30\xDB")                         // xor bl, bl
-
-	for (size_t i = 0; i < irb_len; i++)
-	{
-		offsets[i] = buffer.len;
-
-		size_t arg = irb[i].arg;
-		assert (arg <= UINT32_MAX);
-
-		int offset = irb[i].offset;
-		assert (offset <= INT8_MAX && offset >= INT8_MIN);
-
-		// Don't save what we've just loaded
-		if (irb[i].cmd == LEFT || irb[i].cmd == RIGHT)
-			if (i < 2 || i + 1 >= irb_len
-			 || (irb[i - 2].cmd != LEFT && irb[i - 2].cmd != RIGHT)
-			 || irb[i - 1].cmd != BEGIN
-			 || irb[i + 1].cmd != END)
-				CODE ("\x88\x18")             // mov [rax], bl
-
-		switch (irb[i].cmd)
-		{
-		case RIGHT:
-			// add rax, "arg" -- optimistic, no boundary checking
-			if (arg > INT8_MAX) { CODE ("\x48\x05")     DD (arg) }
-			else                { CODE ("\x48\x83\xC0") DB (arg) }
-			break;
-		case LEFT:
-			// sub rax, "arg" -- optimistic, no boundary checking
-			if (arg > INT8_MAX) { CODE ("\x48\x2D")     DD (arg) }
-			else                { CODE ("\x48\x83\xE8") DB (arg) }
-			break;
-
-		case EAT:
-			// NOTE: the kernel destroys rcx and r11 on syscalls,
-			//   there must be no OUT or IN between EAT and INCACC/DECACC
-			CODE ("\x88\xD9" "\x30\xDB")      // mov cl, bl; xor bl, bl
-			sets_flags[i] = true;
-			break;
-		case INCACC:
-			if (offset)
-			{
-				CODE ("\x00\x48") DB (offset) // add [rax+"offset"], cl
-			}
-			else
-			{
-				CODE ("\x00\xCB")             // add bl, cl
-				sets_flags[i] = true;
-			}
-			break;
-		case DECACC:
-			if (offset)
-			{
-				CODE ("\x28\x48") DB (offset) // sub [rax+"offset"], cl
-			}
-			else
-			{
-				CODE ("\x28\xCB")             // sub bl, cl
-				sets_flags[i] = true;
-			}
-			break;
-
-		case INC:
-			if (offset)
-			{
-				CODE ("\x80\x40") DB (offset) // add byte [rax+"offset"], "arg"
-			}
-			else
-			{
-				CODE ("\x80\xC3")             // add bl, "arg"
-				sets_flags[i] = true;
-			}
-			DB (arg)
-			break;
-		case DEC:
-			if (offset)
-			{
-				CODE ("\x80\x68") DB (offset) // sub byte [rax+"offset"], "arg"
-			}
-			else
-			{
-				CODE ("\x80\xEB")             // sub bl, "arg"
-				sets_flags[i] = true;
-			}
-			DB (arg)
-			break;
-		case SET:
-			if (offset)
-			{
-				CODE ("\xC6\x40") DB (offset) // mov byte [rax+"offset"], "arg"
-			}
-			else
-				CODE ("\xB3")                 // mov bl, "arg"
-			DB (arg)
-			break;
-
-		case OUT:
-			CODE ("\xE8") DD (0)              // call "write"
-			break;
-		case IN:
-			CODE ("\xE8") DD (0)              // call "read"
-			break;
-
-		case BEGIN:
-			// Don't test the register when the flag has been set already;
-			// this doesn't have much of an effect in practice
-			if (!i || !sets_flags[i - 1])
-				CODE ("\x84\xDB")             // test bl, bl
-			CODE ("\x0F\x84\x00\x00\x00\x00") // jz "offsets[arg]"
-			break;
-		case END:
-			// We know that the cell is zero, make this an "if", not a "loop";
-			// this doesn't have much of an effect in practice
-			if (!arg)
-				break;
-
-			if (!i || !sets_flags[i - 1])
-				CODE ("\x84\xDB")             // test bl, bl
-			CODE ("\x0F\x85\x00\x00\x00\x00") // jnz "offsets[arg]"
-			break;
-		}
-
-		// No sense in reading it out when we overwrite it immediately;
-		// this doesn't have much of an effect in practice
-		if (irb[i].cmd == LEFT || irb[i].cmd == RIGHT)
-			if (i + 1 >= irb_len
-			 || irb[i + 1].cmd != SET
-			 || irb[i + 1].offset != 0)
-				CODE ("\x8A\x18")             // mov bl, [rax]
-	}
-	// When there is a loop at the end we need to be able to jump past it
-	offsets[irb_len] = buffer.len;
-
-	// Write an epilog which handles all the OS interfacing
-	//
-	// System V x86-64 ABI:
-	//   rax <-> both syscall number and return value
-	//   args -> rdi, rsi, rdx, r10, r8, r9
-	//   trashed <- rcx, r11
-
-	enum { SYS_READ = 0, SYS_WRITE = 1, SYS_EXIT = 60 };
-
-	CODE ("\xB8") DD (SYS_EXIT)  // mov eax, 0x3c
-	CODE ("\x48\x31\xFF")        // xor rdi, rdi
-	CODE ("\x0F\x05")            // syscall
-
-	size_t fatal_offset = buffer.len;
-	CODE ("\x48\x89\xF7")        // mov rdi, rsi -- use the string in rsi
-	CODE ("\x30\xC0")            // xor al, al -- look for the nil byte
-	CODE ("\x48\x31\xC9")        // xor rcx, rcx
-	CODE ("\x48\xF7\xD1")        // not rcx -- start from -1
-	CODE ("\xFC" "\xF2\xAE")     // cld; repne scasb -- decrement until found
-	CODE ("\x48\xF7\xD1")        // not rcx
-	CODE ("\x48\x8D\x51\xFF")    // lea rdx, [rcx-1] -- save length in rdx
-	CODE ("\xB8") DD (SYS_WRITE) // mov eax, "SYS_WRITE"
-	CODE ("\xBF") DD (2)         // mov edi, "STDERR_FILENO"
-	CODE ("\x0F\x05")            // syscall
-
-	CODE ("\xB8") DD (SYS_EXIT)  // mov eax, "SYS_EXIT"
-	CODE ("\xBF") DD (1)         // mov edi, "EXIT_FAILURE"
-	CODE ("\x0F\x05")            // syscall
-
-	size_t read_offset = buffer.len;
-	CODE ("\x50")                // push rax -- save tape position
-	CODE ("\xB8") DD (SYS_READ)  // mov eax, "SYS_READ"
-	CODE ("\x48\x89\xC7")        // mov rdi, rax -- STDIN_FILENO
-	CODE ("\x66\x6A\x00")        // push word 0 -- the default value for EOF
-	CODE ("\x48\x89\xE6")        // mov rsi, rsp -- the char starts at rsp
-	CODE ("\xBA") DD (1)         // mov edx, 1 -- count
-	CODE ("\x0F\x05")            // syscall
-	CODE ("\x66\x5B")            // pop bx
-
-	CODE ("\x48\x83\xF8\x00")    // cmp rax, 0
-	CODE ("\x48\x8D\x35") DD (4) // lea rsi, [rel read_message]
-	CODE ("\x7C")                // jl "fatal_offset" -- write failure message
-	DB ((intptr_t) fatal_offset - (intptr_t) (buffer.len + 1))
-	CODE ("\x58")                // pop rax -- restore tape position
-	CODE ("\xC3")                // ret
-	CODE ("fatal: read failed\n\0")
-
-	size_t write_offset = buffer.len;
-	CODE ("\x50")                // push rax -- save tape position
-	CODE ("\xB8") DD (SYS_WRITE) // mov eax, "SYS_WRITE"
-	CODE ("\x48\x89\xC7")        // mov rdi, rax -- STDOUT_FILENO
-	CODE ("\x66\x53")            // push bx
-	CODE ("\x48\x89\xE6")        // mov rsi, rsp -- the char starts at rsp
-	CODE ("\xBA") DD (1)         // mov edx, 1 -- count
-	CODE ("\x0F\x05")            // syscall
-	CODE ("\x66\x5B")            // pop bx
-
-	CODE ("\x48\x83\xF8\x00")    // cmp rax, 0
-	CODE ("\x48\x8D\x35") DD (4) // lea rsi, [rel write_message]
-	CODE ("\x7C")                // jl "fatal_offset" -- write failure message
-	DB ((intptr_t) fatal_offset - (intptr_t) (buffer.len + 1))
-	CODE ("\x58")                // pop rax -- restore tape position
-	CODE ("\xC3")                // ret
-	CODE ("fatal: write failed\n\0")
-
-	// Now that we know where each instruction is, fill in relative jumps
-	for (size_t i = 0; i < irb_len; i++)
-	{
-		if (!irb[i].arg)
-			continue;
-
-		// This must accurately reflect the code generators
-		intptr_t target, fixup = offsets[i];
-		if (irb[i].cmd == BEGIN || irb[i].cmd == END)
-		{
-			fixup += (i && sets_flags[i - 1]) ? 2 : 4;
-			target = offsets[irb[i].arg];
-		}
-		else if (irb[i].cmd == IN)  { fixup++; target = read_offset;  }
-		else if (irb[i].cmd == OUT) { fixup++; target = write_offset; }
-		else continue;
-
-		uint64_t v = target - (fixup + 4);
-		memcpy (buffer.str + fixup, LE (v), 4);
-	}
-	free (offsets);
-	free (sets_flags);
-
-// - - Output  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-	// Now that we know how long the machine code is, we can write the header.
-	// Note that for PIE we would need to depend on the dynamic linker, so no.
-	//
-	// Recommended reading:
-	//   http://www.muppetlabs.com/~breadbox/software/tiny/teensy.html
-	//   man 5 elf
-
-	struct str code = buffer;
-	str_init (&buffer);
-
-	enum
-	{
-		ELF_HEADER_SIZE = 64,           // size of the ELF header
-		ELF_PROGRAM_ENTRY_SIZE = 56,    // size of a program header
-		ELF_SECTION_ENTRY_SIZE = 64,    // size of a section header
-		ELF_META_SIZE = ELF_HEADER_SIZE + 2 * ELF_PROGRAM_ENTRY_SIZE
-	};
-
-	// ELF header
-	CODE ("\x7F" "ELF\x02\x01\x01")     // ELF, 64-bit, little endian, v1
-	CODE ("\x00\x00" "\0\0\0\0\0\0\0")  // Unix System V ABI, v0, padding
-	DW (2) DW (62) DD (1)               // executable, x86-64, v1
-	DQ (ELF_LOAD_CODE + ELF_META_SIZE)  // entry point address
-	DQ (ELF_HEADER_SIZE) DQ (0)         // program, section header offset
-	DD (0)                              // no processor-specific flags
-	DW (ELF_HEADER_SIZE)                // ELF header size
-	DW (ELF_PROGRAM_ENTRY_SIZE) DW (2)  // program hdr tbl entry size, count
-	DW (ELF_SECTION_ENTRY_SIZE) DW (0)  // section hdr tbl entry size, count
-	DW (0)                              // no section index for strings
-
-	// Program header for code
-	// The entry point address seems to require alignment, so map start of file
-	DD (1) DD (5)                       // PT_LOAD, PF_R | PF_X
-	DQ (0)                              // offset within the file
-	DQ (ELF_LOAD_CODE)                  // address in virtual memory
-	DQ (ELF_LOAD_CODE)                  // address in physical memory
-	DQ (ELF_META_SIZE + code.len)       // length within the file
-	DQ (ELF_META_SIZE + code.len)       // length within memory
-	DQ (4096)                           // segment alignment
-
-	// Program header for the tape
-	DD (1) DD (6)                       // PT_LOAD, PF_R | PF_W
-	DQ (0)                              // offset within the file
-	DQ (ELF_LOAD_DATA)                  // address in virtual memory
-	DQ (ELF_LOAD_DATA)                  // address in physical memory
-	DQ (0)                              // length within the file
-	DQ (1 << 20)                        // one megabyte of memory
-	DQ (4096)                           // segment alignment
-
-	// The section header table is optional and we don't need it for anything
-
-	FILE *output_file;
-#ifdef __unix__
-	int output_fd;
-	if ((output_fd = open (output_path, O_CREAT | O_WRONLY, 0777)) < 0)
-		exit_fatal ("open: %s: %s\n", output_path, strerror (errno));
-	if (!(output_file = fdopen (output_fd, "w")))
-		exit_fatal ("fdopen: %s\n", strerror (errno));
-#else
-	if (!(output_file = fopen (output_path, "w")))
-		exit_fatal ("fopen: %s: %s\n", output_path, strerror (errno));
-#endif
-
-	fwrite (buffer.str, buffer.len, 1, output_file);
-	fwrite (code.str, code.len, 1, output_file);
-	fclose (output_file);
-	return 0;
-}